-- primitives for editing drawings
Drawing = {}
require 'drawing_tests'
-- All drawings span 100% of some conceptual 'page width' and divide it up
-- into 256 parts.
function Drawing.draw(State, line_index, y)
  local line = State.lines[line_index]
  local line_cache = State.line_cache[line_index]
  line_cache.starty = y
  local pmx,pmy = App.mouse_x(), App.mouse_y()
  if pmx < State.right and pmy > line_cache.starty and pmy < line_cache.starty+Drawing.pixels(line.h, State.width) then
    App.color(Icon_color)
    love.graphics.rectangle('line', State.left,line_cache.starty, State.width,Drawing.pixels(line.h, State.width))
    if icon[State.current_drawing_mode] then
      icon[State.current_drawing_mode](State.right-22, line_cache.starty+4)
    else
      icon[State.previous_drawing_mode](State.right-22, line_cache.starty+4)
    end
    if App.mouse_down(1) and love.keyboard.isDown('h') then
      draw_help_with_mouse_pressed(State, line_index)
      return
    end
  end
  if line.show_help then
    draw_help_without_mouse_pressed(State, line_index)
    return
  end
  local mx = Drawing.coord(pmx-State.left, State.width)
  local my = Drawing.coord(pmy-line_cache.starty, State.width)
  for _,shape in ipairs(line.shapes) do
    assert(shape)
    if geom.on_shape(mx,my, line, shape) then
      App.color(Focus_stroke_color)
    else
      App.color(Stroke_color)
    end
    Drawing.draw_shape(line, shape, line_cache.starty, State.left,State.right)
  end
  local function px(x) return Drawing.pixels(x, State.width)+State.left end
  local function py(y) return Drawing.pixels(y, State.width)+line_cache.starty end
  for i,p in ipairs(line.points) do
    if p.deleted == nil then
      if Drawing.near(p, mx,my, State.width) then
        App.color(Focus_stroke_color)
        love.graphics.circle('line', px(p.x),py(p.y), Same_point_distance)
      else
        App.color(Stroke_color)
        love.graphics.circle('fill', px(p.x),py(p.y), 2)
      end
      if p.name then
        -- TODO: clip
        local x,y = px(p.x)+5, py(p.y)+5
        love.graphics.print(p.name, x,y)
        if State.current_drawing_mode == 'name' and i == line.pending.target_point then
          -- create a faint red box for the name
          App.color(Current_name_background_color)
          local name_text
          -- TODO: avoid computing name width on every repaint
          if p.name == '' then
            name_text = State.em
          else
            name_text = App.newText(love.graphics.getFont(), p.name)
          end
          love.graphics.rectangle('fill', x,y, App.width(name_text), State.line_height)
        end
      end
    end
  end
  App.color(Current_stroke_color)
  Drawing.draw_pending_shape(line, line_cache.starty, State.left,State.right)
end
function Drawing.draw_shape(drawing, shape, top, left,right)
  local width = right-left
  local function px(x) return Drawing.pixels(x, width)+left end
  local function py(y) return Drawing.pixels(y, width)+top end
  if shape.mode == 'freehand' then
    local prev = nil
    for _,point in ipairs(shape.points) do
      if prev then
        love.graphics.line(px(prev.x),py(prev.y), px(point.x),py(point.y))
      end
      prev = point
    end
  elseif shape.mode == 'line' or shape.mode == 'manhattan' then
    local p1 = drawing.points[shape.p1]
    local p2 = drawing.points[shape.p2]
    love.graphics.line(px(p1.x),py(p1.y), px(p2.x),py(p2.y))
  elseif shape.mode == 'polygon' or shape.mode == 'rectangle' or shape.mode == 'square' then
    local prev = nil
    for _,point in ipairs(shape.vertices) do
      local curr = drawing.points[point]
      if prev then
        love.graphics.line(px(prev.x),py(prev.y), px(curr.x),py(curr.y))
      end
      prev = curr
    end
    -- close the loop
    local curr = drawing.points[shape.vertices[1]]
    love.graphics.line(px(prev.x),py(prev.y), px(curr.x),py(curr.y))
  elseif shape.mode == 'circle' then
    -- TODO: clip
    local center = drawing.points[shape.center]
    love.graphics.circle('line', px(center.x),py(center.y), Drawing.pixels(shape.radius, width))
  elseif shape.mode == 'arc' then
    local center = drawing.points[shape.center]
    love.graphics.arc('line', 'open', px(center.x),py(center.y), Drawing.pixels(shape.radius, width), shape.start_angle, shape.end_angle, 360)
  elseif shape.mode == 'deleted' then
    -- ignore
  else
    print(shape.mode)
    assert(false)
  end
end
function Drawing.draw_pending_shape(drawing, top, left,right)
  local width = right-left
  local pmx,pmy = App.mouse_x(), App.mouse_y()
  local function px(x) return Drawing.pixels(x, width)+left end
  local function py(y) return Drawing.pixels(y, width)+top end
  local mx = Drawing.coord(pmx-left, width)
  local my = Drawing.coord(pmy-top, width)
  -- recreate pixels from coords to precisely mimic how the drawing will look
  -- after mouse_released
  pmx,pmy = px(mx), py(my)
  local shape = drawing.pending
  if shape.mode == nil then
    -- nothing pending
  elseif shape.mode == 'freehand' then
    local shape_copy = deepcopy(shape)
    Drawing.smoothen(shape_copy)
    Drawing.draw_shape(drawing, shape_copy, top, left,right)
  elseif shape.mode == 'line' then
    if mx < 0 or mx >= 256 or my < 0 or my >= drawing.h then
      return
    end
    local p1 = drawing.points[shape.p1]
    love.graphics.line(px(p1.x),py(p1.y), pmx,pmy)
  elseif shape.mode == 'manhattan' then
    if mx < 0 or mx >= 256 or my < 0 or my >= drawing.h then
      return
    end
    local p1 = drawing.points[shape.p1]
    if math.abs(mx-p1.x) > math.abs(my-p1.y) then
      love.graphics.line(px(p1.x),py(p1.y), pmx,     py(p1.y))
    else
      love.graphics.line(px(p1.x),py(p1.y), px(p1.x),pmy)
    end
  elseif shape.mode == 'polygon' then
    -- don't close the loop on a pending polygon
    local prev = nil
    for _,point in ipairs(shape.vertices) do
      local curr = drawing.points[point]
      if prev then
        love.graphics.line(px(prev.x),py(prev.y), px(curr.x),py(curr.y))
      end
      prev = curr
    end
    love.graphics.line(px(prev.x),py(prev.y), pmx,pmy)
  elseif shape.mode == 'rectangle' then
    local first = drawing.points[shape.vertices[1]]
    if #shape.vertices == 1 then
      love.graphics.line(px(first.x),py(first.y), pmx,pmy)
      return
    end
    local second = drawing.points[shape.vertices[2]]
    local thirdx,thirdy, fourthx,fourthy = Drawing.complete_rectangle(first.x,first.y, second.x,second.y, mx,my)
    love.graphics.line(px(first.x),py(first.y), px(second.x),py(second.y))
    love.graphics.line(px(second.x),py(second.y), px(thirdx),py(thirdy))
    love.graphics.line(px(thirdx),py(thirdy), px(fourthx),py(fourthy))
    love.graphics.line(px(fourthx),py(fourthy), px(first.x),py(first.y))
  elseif shape.mode == 'square' then
    local first = drawing.points[shape.vertices[1]]
    if #shape.vertices == 1 then
      love.graphics.line(px(first.x),py(first.y), pmx,pmy)
      return
    end
    local second = drawing.points[shape.vertices[2]]
    local thirdx,thirdy, fourthx,fourthy = Drawing.complete_square(first.x,first.y, second.x,second.y, mx,my)
    love.graphics.line(px(first.x),py(first.y), px(second.x),py(second.y))
    love.graphics.line(px(second.x),py(second.y), px(thirdx),py(thirdy))
    love.graphics.line(px(thirdx),py(thirdy), px(fourthx),py(fourthy))
    love.graphics.line(px(fourthx),py(fourthy), px(first.x),py(first.y))
  elseif shape.mode == 'circle' then
    local center = drawing.points[shape.center]
    if mx < 0 or mx >= 256 or my < 0 or my >= drawing.h then
      return
    end
    local cx,cy = px(center.x), py(center.y)
    love.graphics.circle('line', cx,cy, geom.dist(cx,cy, App.mouse_x(),App.mouse_y()))
  elseif shape.mode == 'arc' then
    local center = drawing.points[shape.center]
    if mx < 0 or mx >= 256 or my < 0 or my >= drawing.h then
      return
    end
    shape.end_angle = geom.angle_with_hint(center.x,center.y, mx,my, shape.end_angle)
    local cx,cy = px(center.x), py(center.y)
    love.graphics.arc('line', 'open', cx,cy, Drawing.pixels(shape.radius, width), shape.start_angle, shape.end_angle, 360)
  elseif shape.mode == 'move' then
    -- nothing pending; changes are immediately committed
  elseif shape.mode == 'name' then
    -- nothing pending; changes are immediately committed
  else
    print(shape.mode)
    assert(false)
  end
end
function Drawing.in_drawing(drawing, line_cache, x,y, left,right)
  if line_cache.starty == nil then return false end  -- outside current page
  local width = right-left
  return y >= line_cache.starty and y < line_cache.starty + Drawing.pixels(drawing.h, width) and x >= left and x < right
end
function Drawing.mouse_pressed(State, drawing_index, x,y, mouse_button)
  local drawing = State.lines[drawing_index]
  local line_cache = State.line_cache[drawing_index]
  local cx = Drawing.coord(x-State.left, State.width)
  local cy = Drawing.coord(y-line_cache.starty, State.width)
  if State.current_drawing_mode == 'freehand' then
    drawing.pending = {mode=State.current_drawing_mode, points={{x=cx, y=cy}}}
  elseif State.current_drawing_mode == 'line' or State.current_drawing_mode == 'manhattan' then
    local j = Drawing.find_or_insert_point(drawing.points, cx, cy, State.width)
    drawing.pending = {mode=State.current_drawing_mode, p1=j}
  elseif State.current_drawing_mode == 'polygon' or State.current_drawing_mode == 'rectangle' or State.current_drawing_mode == 'square' then
    local j = Drawing.find_or_insert_point(drawing.points, cx, cy, State.width)
    drawing.pending = {mode=State.current_drawing_mode, vertices={j}}
  elseif State.current_drawing_mode == 'circle' then
    local j = Drawing.find_or_insert_point(drawing.points, cx, cy, State.width)
    drawing.pending = {mode=State.current_drawing_mode, center=j}
  elseif State.current_drawing_mode == 'move' then
    -- all the action is in mouse_released
  elseif State.current_drawing_mode == 'name' then
    -- nothing
  else
    print(State.current_drawing_mode)
    assert(false)
  end
end
-- a couple of operations on drawings need to constantly check the state of the mouse
function Drawing.update(State)
  if State.lines.current_drawing == nil then return end
  local drawing = State.lines.current_drawing
  local line_cache = State.line_cache[State.lines.current_drawing_index]
  assert(drawing.mode == 'drawing')
  local pmx, pmy = App.mouse_x(), App.mouse_y()
  local mx = Drawing.coord(pmx-State.left, State.width)
  local my = Drawing.coord(pmy-line_cache.starty, State.width)
  if App.mouse_down(1) then
    if Drawing.in_drawing(drawing, line_cache, pmx,pmy, State.left,State.right) then
      if drawing.pending.mode == 'freehand' then
        table.insert(drawing.pending.points, {x=mx, y=my})
      elseif drawing.pending.mode == 'move' then
        drawing.pending.target_point.x = mx
        drawing.pending.target_point.y = my
        Drawing.relax_constraints(drawing, drawing.pending.target_point_index)
      end
    end
  elseif State.current_drawing_mode == 'move' then
    if Drawing.in_drawing(drawing, line_cache, pmx, pmy, State.left,State.right) then
      drawing.pending.target_point.x = mx
      drawing.pending.target_point.y = my
      Drawing.relax_constraints(drawing, drawing.pending.target_point_index)
    end
  else
    -- do nothing
  end
end
function Drawing.relax_constraints(drawing, p)
  for _,shape in ipairs(drawing.shapes) do
    if shape.mode == 'manhattan' then
      if shape.p1 == p then
        shape.mode = 'line'
      elseif shape.p2 == p then
        shape.mode = 'line'
      end
    elseif shape.mode == 'rectangle' or shape.mode == 'square' then
      for _,v in ipairs(shape.vertices) do
        if v == p then
          shape.mode = 'polygon'
        end
      end
    end
  end
end
function Drawing.mouse_released(State, x,y, mouse_button)
  if State.current_drawing_mode == 'move' then
    State.current_drawing_mode = State.previous_drawing_mode
    State.previous_drawing_mode = nil
    if State.lines.current_drawing then
      State.lines.current_drawing.pending = {}
      State.lines.current_drawing = nil
    end
  elseif State.lines.current_drawing then
    local drawing = State.lines.current_drawing
    local line_cache = State.line_cache[State.lines.current_drawing_index]
    if drawing.pending then
      if drawing.pending.mode == nil then
        -- nothing pending
      elseif drawing.pending.mode == 'freehand' then
        -- the last point added during update is good enough
        Drawing.smoothen(drawing.pending)
        table.insert(drawing.shapes, drawing.pending)
      elseif drawing.pending.mode == 'line' then
        local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
        if mx >= 0 and mx < 256 and my >= 0 and my < drawing.h then
          drawing.pending.p2 = Drawing.find_or_insert_point(drawing.points, mx,my, State.width)
          table.insert(drawing.shapes, drawing.pending)
        end
      elseif drawing.pending.mode == 'manhattan' then
        local p1 = drawing.points[drawing.pending.p1]
        local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
        if mx >= 0 and mx < 256 and my >= 0 and my < drawing.h then
          if math.abs(mx-p1.x) > math.abs(my-p1.y) then
            drawing.pending.p2 = Drawing.find_or_insert_point(drawing.points, mx, p1.y, State.width)
          else
            drawing.pending.p2 = Drawing.find_or_insert_point(drawing.points, p1.x, my, State.width)
          end
          local p2 = drawing.points[drawing.pending.p2]
          App.mouse_move(State.left+Drawing.pixels(p2.x, State.width), line_cache.starty+Drawing.pixels(p2.y, State.width))
          table.insert(drawing.shapes, drawing.pending)
        end
      elseif drawing.pending.mode == 'polygon' then
        local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
        if mx >= 0 and mx < 256 and my >= 0 and my < drawing.h then
          table.insert(drawing.pending.vertices, Drawing.find_or_insert_point(drawing.points, mx,my, State.width))
          table.insert(drawing.shapes, drawing.pending)
        end
      elseif drawing.pending.mode == 'rectangle' then
        assert(#drawing.pending.vertices <= 2)
        if #drawing.pending.vertices == 2 then
          local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
          if mx >= 0 and mx < 256 and my >= 0 and my < drawing.h then
            local first = drawing.points[drawing.pending.vertices[1]]
            local second = drawing.points[drawing.pending.vertices[2]]
            local thirdx,thirdy, fourthx,fourthy = Drawing.complete_rectangle(first.x,first.y, second.x,second.y, mx,my)
            table.insert(drawing.pending.vertices, Drawing.find_or_insert_point(drawing.points, thirdx,thirdy, State.width))
            table.insert(drawing.pending.vertices, Drawing.find_or_insert_point(drawing.points, fourthx,fourthy, State.width))
            table.insert(drawing.shapes, drawing.pending)
          end
        else
          -- too few points; draw nothing
        end
      elseif drawing.pending.mode == 'square' then
        assert(#drawing.pending.vertices <= 2)
        if #drawing.pending.vertices == 2 then
          local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
          if mx >= 0 and mx < 256 and my >= 0 and my < drawing.h then
            local first = drawing.points[drawing.pending.vertices[1]]
            local second = drawing.points[drawing.pending.vertices[2]]
            local thirdx,thirdy, fourthx,fourthy = Drawing.complete_square(first.x,first.y, second.x,second.y, mx,my)
            table.insert(drawing.pending.vertices, Drawing.find_or_insert_point(drawing.points, thirdx,thirdy, State.width))
            table.insert(drawing.pending.vertices, Drawing.find_or_insert_point(drawing.points, fourthx,fourthy, State.width))
            table.insert(drawing.shapes, drawing.pending)
          end
        end
      elseif drawing.pending.mode == 'circle' then
        local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
        if mx >= 0 and mx < 256 and my >= 0 and my < drawing.h then
          local center = drawing.points[drawing.pending.center]
          drawing.pending.radius = round(geom.dist(center.x,center.y, mx,my))
          table.insert(drawing.shapes, drawing.pending)
        end
      elseif drawing.pending.mode == 'arc' then
        local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
        if mx >= 0 and mx < 256 and my >= 0 and my < drawing.h then
          local center = drawing.points[drawing.pending.center]
          drawing.pending.end_angle = geom.angle_with_hint(center.x,center.y, mx,my, drawing.pending.end_angle)
          table.insert(drawing.shapes, drawing.pending)
        end
      elseif drawing.pending.mode == 'name' then
        -- drop it
      else
        print(drawing.pending.mode)
        assert(false)
      end
      State.lines.current_drawing.pending = {}
      State.lines.current_drawing = nil
    end
  end
end
function Drawing.keychord_pressed(State, chord)
  if chord == 'C-p' and not App.mouse_down(1) then
    State.current_drawing_mode = 'freehand'
  elseif App.mouse_down(1) and chord == 'l' then
    State.current_drawing_mode = 'line'
    local _,drawing = Drawing.current_drawing(State)
    if drawing.pending.mode == 'freehand' then
      drawing.pending.p1 = Drawing.find_or_insert_point(drawing.points, drawing.pending.points[1].x, drawing.pending.points[1].y, State.width)
    elseif drawing.pending.mode == 'polygon' or drawing.pending.mode == 'rectangle' or drawing.pending.mode == 'square' then
      drawing.pending.p1 = drawing.pending.vertices[1]
    elseif drawing.pending.mode == 'circle' or drawing.pending.mode == 'arc' then
      drawing.pending.p1 = drawing.pending.center
    end
    drawing.pending.mode = 'line'
  elseif chord == 'C-l' and not App.mouse_down(1) then
    State.current_drawing_mode = 'line'
  elseif App.mouse_down(1) and chord == 'm' then
    State.current_drawing_mode = 'manhattan'
    local drawing = Drawing.select_drawing_at_mouse(State)
    if drawing.pending.mode == 'freehand' then
      drawing.pending.p1 = Drawing.find_or_insert_point(drawing.points, drawing.pending.points[1].x, drawing.pending.points[1].y, State.width)
    elseif drawing.pending.mode == 'line' then
      -- do nothing
    elseif drawing.pending.mode == 'polygon' or drawing.pending.mode == 'rectangle' or drawing.pending.mode == 'square' then
      drawing.pending.p1 = drawing.pending.vertices[1]
    elseif drawing.pending.mode == 'circle' or drawing.pending.mode == 'arc' then
      drawing.pending.p1 = drawing.pending.center
    end
    drawing.pending.mode = 'manhattan'
  elseif chord == 'C-m' and not App.mouse_down(1) then
    State.current_drawing_mode = 'manhattan'
  elseif chord == 'C-g' and not App.mouse_down(1) then
    State.current_drawing_mode = 'polygon'
  elseif App.mouse_down(1) and chord == 'g' then
    State.current_drawing_mode = 'polygon'
    local _,drawing = Drawing.current_drawing(State)
    if drawing.pending.mode == 'freehand' then
      drawing.pending.vertices = {Drawing.find_or_insert_point(drawing.points, drawing.pending.points[1].x, drawing.pending.points[1].y, State.width)}
    elseif drawing.pending.mode == 'line' or drawing.pending.mode == 'manhattan' then
      if drawing.pending.vertices == nil then
        drawing.pending.vertices = {drawing.pending.p1}
      end
    elseif drawing.pending.mode == 'rectangle' or drawing.pending.mode == 'square' then
      -- reuse existing vertices
    elseif drawing.pending.mode == 'circle' or drawing.pending.mode == 'arc' then
      drawing.pending.vertices = {drawing.pending.center}
    end
    drawing.pending.mode = 'polygon'
  elseif chord == 'C-r' and not App.mouse_down(1) then
    State.current_drawing_mode = 'rectangle'
  elseif App.mouse_down(1) and chord == 'r' then
    State.current_drawing_mode = 'rectangle'
    local _,drawing = Drawing.current_drawing(State)
    if drawing.pending.mode == 'freehand' then
      drawing.pending.vertices = {Drawing.find_or_insert_point(drawing.points, drawing.pending.points[1].x, drawing.pending.points[1].y, State.width)}
    elseif drawing.pending.mode == 'line' or drawing.pending.mode == 'manhattan' then
      if drawing.pending.vertices == nil then
        drawing.pending.vertices = {drawing.pending.p1}
      end
    elseif drawing.pending.mode == 'polygon' or drawing.pending.mode == 'square' then
      -- reuse existing (1-2) vertices
    elseif drawing.pending.mode == 'circle' or drawing.pending.mode == 'arc' then
      drawing.pending.vertices = {drawing.pending.center}
    end
    drawing.pending.mode = 'rectangle'
  elseif chord == 'C-s' and not App.mouse_down(1) then
    State.current_drawing_mode = 'square'
  elseif App.mouse_down(1) and chord == 's' then
    State.current_drawing_mode = 'square'
    local _,drawing = Drawing.current_drawing(State)
    if drawing.pending.mode == 'freehand' then
      drawing.pending.vertices = {Drawing.find_or_insert_point(drawing.points, drawing.pending.points[1].x, drawing.pending.points[1].y, State.width)}
    elseif drawing.pending.mode == 'line' or drawing.pending.mode == 'manhattan' then
      if drawing.pending.vertices == nil then
        drawing.pending.vertices = {drawing.pending.p1}
      end
    elseif drawing.pending.mode == 'polygon' then
      while #drawing.pending.vertices > 2 do
        table.remove(drawing.pending.vertices)
      end
    elseif drawing.pending.mode == 'rectangle' then
      -- reuse existing (1-2) vertices
    elseif drawing.pending.mode == 'circle' or drawing.pending.mode == 'arc' then
      drawing.pending.vertices = {drawing.pending.center}
    end
    drawing.pending.mode = 'square'
  elseif App.mouse_down(1) and chord == 'p' and State.current_drawing_mode == 'polygon' then
    local _,drawing,line_cache = Drawing.current_drawing(State)
    local mx,my = Drawing.coord(App.mouse_x()-State.left, State.width), Drawing.coord(App.mouse_y()-line_cache.starty, State.width)
    local j = Drawing.find_or_insert_point(drawing.points, mx,my, State.width)
    table.insert(drawing.pending.vertices, j)
  elseif App.mouse_down(1) and chord == 'p' and (State.current_drawing_mode == 'rectangle' or State.current_drawing_mode == 'square') then
    local _,drawing,line_cache = Drawing.current_drawing(State)
    local mx,my = Drawing.coord(App.mouse_x()-State.left, State.width), Drawing.coord(App.mouse_y()-line_cache.starty, State.width)
    local j = Drawing.find_or_insert_point(drawing.points, mx,my, State.width)
    while #drawing.pending.vertices >= 2 do
      table.remove(drawing.pending.vertices)
    end
    table.insert(drawing.pending.vertices, j)
  elseif chord == 'C-o' and not App.mouse_down(1) then
    State.current_drawing_mode = 'circle'
  elseif App.mouse_down(1) and chord == 'a' and State.current_drawing_mode == 'circle' then
    local _,drawing,line_cache = Drawing.current_drawing(State)
    drawing.pending.mode = 'arc'
    local mx,my = Drawing.coord(App.mouse_x()-State.left, State.width), Drawing.coord(App.mouse_y()-line_cache.starty, State.width)
    local center = drawing.points[drawing.pending.center]
    drawing.pending.radius = round(geom.dist(center.x,center.y, mx,my))
    drawing.pending.start_angle = geom.angle(center.x,center.y, mx,my)
  elseif App.mouse_down(1) and chord == 'o' then
    State.current_drawing_mode = 'circle'
    local _,drawing = Drawing.current_drawing(State)
    if drawing.pending.mode == 'freehand' then
      drawing.pending.center = Drawing.find_or_insert_point(drawing.points, drawing.pending.points[1].x, drawing.pending.points[1].y, State.width)
    elseif drawing.pending.mode == 'line' or drawing.pending.mode == 'manhattan' then
      drawing.pending.center = drawing.pending.p1
    elseif drawing.pending.mode == 'polygon' or drawing.pending.mode == 'rectangle' or drawing.pending.mode == 'square' then
      drawing.pending.center = drawing.pending.vertices[1]
    end
    drawing.pending.mode = 'circle'
  elseif chord == 'C-u' and not App.mouse_down(1) then
    local drawing_index,drawing,line_cache,i,p = Drawing.select_point_at_mouse(State)
    if drawing then
      if State.previous_drawing_mode == nil then
        State.previous_drawing_mode = State.current_drawing_mode
      end
      State.current_drawing_mode = 'move'
      drawing.pending = {mode=State.current_drawing_mode, target_point=p, target_point_index=i}
      State.lines.current_drawing_index = drawing_index
      State.lines.current_drawing = drawing
    end
  elseif chord == 'C-n' and not App.mouse_down(1) then
    local drawing_index,drawing,line_cache,point_index,p = Drawing.select_point_at_mouse(State)
    if drawing then
      if State.previous_drawing_mode == nil then
        -- don't clobber
        State.previous_drawing_mode = State.current_drawing_mode
      end
      State.current_drawing_mode = 'name'
      p.name = ''
      drawing.pending = {mode=State.current_drawing_mode, target_point=point_index}
      State.lines.current_drawing_index = drawing_index
      State.lines.current_drawing = drawing
    end
  elseif chord == 'C-d' and not App.mouse_down(1) then
    local _,drawing,_,i,p = Drawing.select_point_at_mouse(State)
    if drawing then
      for _,shape in ipairs(drawing.shapes) do
        if Drawing.contains_point(shape, i) then
          if shape.mode == 'polygon' then
            local idx = table.find(shape.vertices, i)
            assert(idx)
            table.remove(shape.vertices, idx)
            if #shape.vertices < 3 then
              shape.mode = 'deleted'
            end
          else
            shape.mode = 'deleted'
          end
        end
      end
      drawing.points[i].deleted = true
    end
    local drawing,_,_,shape = Drawing.select_shape_at_mouse(State)
    if drawing then
      shape.mode = 'deleted'
    end
  elseif chord == 'C-h' and not App.mouse_down(1) then
    local drawing = Drawing.select_drawing_at_mouse(State)
    if drawing then
      drawing.show_help = true
    end
  elseif chord == 'escape' and App.mouse_down(1) then
    local _,drawing = Drawing.current_drawing(State)
    drawing.pending = {}
  end
end
function Drawing.complete_rectangle(firstx,firsty, secondx,secondy, x,y)
  if firstx == secondx then
    return x,secondy, x,firsty
  end
  if firsty == secondy then
    return secondx,y, firstx,y
  end
  local first_slope = (secondy-firsty)/(secondx-firstx)
  -- slope of second edge:
  --    -1/first_slope
  -- equation of line containing the second edge:
  --    y-secondy = -1/first_slope*(x-secondx)
  -- => 1/first_slope*x + y + (- secondy - secondx/first_slope) = 0
  -- now we want to find the point on this line that's closest to the mouse pointer.
  -- https://en.wikipedia.org/wiki/Distance_from_a_point_to_a_line#Line_defined_by_an_equation
  local a = 1/first_slope
  local c = -secondy - secondx/first_slope
  local thirdx = round(((x-a*y) - a*c) / (a*a + 1))
  local thirdy = round((a*(-x + a*y) - c) / (a*a + 1))
  -- slope of third edge = first_slope
  -- equation of line containing third edge:
  --     y - thirdy = first_slope*(x-thirdx)
  --  => -first_slope*x + y + (-thirdy + thirdx*first_slope) = 0
  -- now we want to find the point on this line that's closest to the first point
  local a = -first_slope
  local c = -thirdy + thirdx*first_slope
  local fourthx = round(((firstx-a*firsty) - a*c) / (a*a + 1))
  local fourthy = round((a*(-firstx + a*firsty) - c) / (a*a + 1))
  return thirdx,thirdy, fourthx,fourthy
end
function Drawing.complete_square(firstx,firsty, secondx,secondy, x,y)
  -- use x,y only to decide which side of the first edge to complete the square on
  local deltax = secondx-firstx
  local deltay = secondy-firsty
  local thirdx = secondx+deltay
  local thirdy = secondy-deltax
  if not geom.same_side(firstx,firsty, secondx,secondy, thirdx,thirdy, x,y) then
    deltax = -deltax
    deltay = -deltay
    thirdx = secondx+deltay
    thirdy = secondy-deltax
  end
  local fourthx = firstx+deltay
  local fourthy = firsty-deltax
  return thirdx,thirdy, fourthx,fourthy
end
function Drawing.current_drawing(State)
  local x, y = App.mouse_x(), App.mouse_y()
  for drawing_index,drawing in ipairs(State.lines) do
    if drawing.mode == 'drawing' then
      local line_cache = State.line_cache[drawing_index]
      if Drawing.in_drawing(drawing, line_cache, x,y, State.left,State.right) then
        return drawing_index,drawing,line_cache
      end
    end
  end
  return nil
end
function Drawing.select_shape_at_mouse(State)
  for drawing_index,drawing in ipairs(State.lines) do
    if drawing.mode == 'drawing' then
      local x, y = App.mouse_x(), App.mouse_y()
      local line_cache = State.line_cache[drawing_index]
      if Drawing.in_drawing(drawing, line_cache, x,y, State.left,State.right) then
        local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
        for i,shape in ipairs(drawing.shapes) do
          assert(shape)
          if geom.on_shape(mx,my, drawing, shape) then
            return drawing,line_cache,i,shape
          end
        end
      end
    end
  end
end
function Drawing.select_point_at_mouse(State)
  for drawing_index,drawing in ipairs(State.lines) do
    if drawing.mode == 'drawing' then
      local x, y = App.mouse_x(), App.mouse_y()
      local line_cache = State.line_cache[drawing_index]
      if Drawing.in_drawing(drawing, line_cache, x,y, State.left,State.right) then
        local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
        for i,point in ipairs(drawing.points) do
          assert(point)
          if Drawing.near(point, mx,my, State.width) then
            return drawing_index,drawing,line_cache,i,point
          end
        end
      end
    end
  end
end
function Drawing.select_drawing_at_mouse(State)
  for drawing_index,drawing in ipairs(State.lines) do
    if drawing.mode == 'drawing' then
      local x, y = App.mouse_x(), App.mouse_y()
      local line_cache = State.line_cache[drawing_index]
      if Drawing.in_drawing(drawing, line_cache, x,y, State.left,State.right) then
        return drawing
      end
    end
  end
end
function Drawing.contains_point(shape, p)
  if shape.mode == 'freehand' then
    -- not supported
  elseif shape.mode == 'line' or shape.mode == 'manhattan' then
    return shape.p1 == p or shape.p2 == p
  elseif shape.mode == 'polygon' or shape.mode == 'rectangle' or shape.mode == 'square' then
    return table.find(shape.vertices, p)
  elseif shape.mode == 'circle' then
    return shape.center == p
  elseif shape.mode == 'arc' then
    return shape.center == p
    -- ugh, how to support angles
  elseif shape.mode == 'deleted' then
    -- already done
  else
    print(shape.mode)
    assert(false)
  end
end
function Drawing.smoothen(shape)
  assert(shape.mode == 'freehand')
  for _=1,7 do
    for i=2,#shape.points-1 do
      local a = shape.points[i-1]
      local b = shape.points[i]
      local c = shape.points[i+1]
      b.x = round((a.x + b.x + c.x)/3)
      b.y = round((a.y + b.y + c.y)/3)
    end
  end
end
function round(num)
  return math.floor(num+.5)
end
function Drawing.find_or_insert_point(points, x,y, width)
  -- check if UI would snap the two points together
  for i,point in ipairs(points) do
    if Drawing.near(point, x,y, width) then
      return i
    end
  end
  table.insert(points, {x=x, y=y})
  return #points
end
function Drawing.near(point, x,y, width)
  local px,py = Drawing.pixels(x, width),Drawing.pixels(y, width)
  local cx,cy = Drawing.pixels(point.x, width), Drawing.pixels(point.y, width)
  return (cx-px)*(cx-px) + (cy-py)*(cy-py) < Same_point_distance*Same_point_distance
end
function Drawing.pixels(n, width)  -- parts to pixels
  return math.floor(n*width/256)
end
function Drawing.coord(n, width)  -- pixels to parts
  return math.floor(n*256/width)
end
function table.find(h, x)
  for k,v in pairs(h) do
    if v == x then
      return k
    end
  end
end

  check_eq(Editor_state.cursor1.line, 1, 'F - test_click_on_wrapping_line_takes_margins_into_account/cursor:line')
  check_eq(Editor_state.cursor1.pos, 2, 'F - test_click_on_wrapping_line_takes_margins_into_account/cursor:pos')
  check_nil(Editor_state.selection1.line, 'F - test_click_on_wrapping_line_takes_margins_into_account/selection is empty to avoid perturbing future edits')
  App.screen.check(y, 'mno', 'F - test_pagedown_followed_by_down_arrow_does_not_scroll_screen_up/screen:3')
  edit.run_after_text_input(Editor_state, 'a')
  edit.run_after_keychord(Editor_state, 'up')
  -- cursor wraps
  check_eq(Editor_state.cursor1.line, 1, 'F - test_search_wrap_upwards/1/cursor:line')
  check_eq(Editor_state.cursor1.pos, 5, 'F - test_search_wrap_upwards/1/cursor:pos')
end
  edit.run_after_text_input(Editor_state, 'a')
  edit.run_after_keychord(Editor_state, 'return')
  -- cursor wraps
  check_eq(Editor_state.cursor1.line, 1, 'F - test_search_wrap/1/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_search_wrap/1/cursor:pos')
end
function test_search_wrap_upwards()
  io.write('\ntest_search_wrap_upwards')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc abd'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  -- search upwards for a string
  edit.run_after_keychord(Editor_state, 'C-f')
  edit.run_after_text_input(Editor_state, 'a')
  -- search for previous occurrence
  edit.run_after_keychord(Editor_state, 'up')
  check_eq(Editor_state.cursor1.line, 1, 'F - test_search_upwards/2/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_search_upwards/2/cursor:pos')
end
function test_search_wrap()
  io.write('\ntest_search_wrap')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=3}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  -- search for a string
  edit.run_after_keychord(Editor_state, 'C-f')
  edit.run_after_text_input(Editor_state, 'de')
  edit.run_after_keychord(Editor_state, 'down')
  edit.run_after_keychord(Editor_state, 'return')
  check_eq(Editor_state.cursor1.line, 4, 'F - test_search/2/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_search/2/cursor:pos')
end
function test_search_upwards()
  io.write('\ntest_search_upwards')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc abd'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=2}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  -- search for a string
  edit.run_after_keychord(Editor_state, 'C-f')
  edit.run_after_text_input(Editor_state, 'd')
  edit.run_after_keychord(Editor_state, 'return')
  check_eq(Editor_state.cursor1.line, 2, 'F - test_search/1/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_search/1/cursor:pos')
  -- reset cursor
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  -- search for second occurrence
  edit.run_after_keychord(Editor_state, 'C-f')
  edit.run_after_text_input(Editor_state, 'x')
  check_eq(Editor_state.lines[1].data, 'xbc', 'F - test_undo_restores_selection/baseline')
  check_nil(Editor_state.selection1.line, 'F - test_undo_restores_selection/baseline:selection')
  -- undo
  edit.run_after_keychord(Editor_state, 'C-z')
  edit.run_after_keychord(Editor_state, 'C-z')
  -- selection is restored
  check_eq(Editor_state.selection1.line, 1, 'F - test_undo_restores_selection/line')
  check_eq(Editor_state.selection1.pos, 2, 'F - test_undo_restores_selection/pos')
end
  edit.run_after_text_input(Editor_state, 'g')
  check_eq(Editor_state.cursor1.line, 2, 'F - test_undo_insert_text/baseline/cursor:line')
  check_eq(Editor_state.cursor1.pos, 5, 'F - test_undo_insert_text/baseline/cursor:pos')
  edit.run_after_text_input(Editor_state, 's')
  edit.run_after_text_input(Editor_state, 't')
  edit.run_after_text_input(Editor_state, 'u')
  check_eq(Editor_state.cursor1.pos, 28, 'F - test_position_cursor_on_recently_edited_wrapping_line/cursor:pos')
  y = Editor_state.top
  App.screen.check(y, 'abc def ghi ', 'F - test_position_cursor_on_recently_edited_wrapping_line/baseline2/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'jkl mno pqr ', 'F - test_position_cursor_on_recently_edited_wrapping_line/baseline2/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'stu', 'F - test_position_cursor_on_recently_edited_wrapping_line/baseline2/screen:3')
  -- try to move the cursor earlier in the third screen line by clicking the mouse
  edit.run_after_text_input(Editor_state, 'j')
  edit.run_after_text_input(Editor_state, 'k')
  edit.run_after_text_input(Editor_state, 'l')
  check_eq(Editor_state.screen_top1.line, 2, 'F - test_typing_on_bottom_line_scrolls_down/screen_top')
  check_eq(Editor_state.cursor1.line, 3, 'F - test_typing_on_bottom_line_scrolls_down/cursor:line')
  check_eq(Editor_state.cursor1.pos, 7, 'F - test_typing_on_bottom_line_scrolls_down/cursor:pos')
  y = Editor_state.top
  App.screen.check(y, 'def', 'F - test_typing_on_bottom_line_scrolls_down/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghij', 'F - test_typing_on_bottom_line_scrolls_down/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'kl', 'F - test_typing_on_bottom_line_scrolls_down/screen:3')
end
function test_left_arrow_scrolls_up_in_wrapped_line()
  io.write('\ntest_left_arrow_scrolls_up_in_wrapped_line')
  -- display lines starting from second screen line of a line
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi jkl', 'mno'}
  Text.redraw_all(Editor_state)
  Editor_state.screen_top1 = {line=3, pos=5}
  Editor_state.screen_bottom1 = {}
  -- cursor is at top of screen
  Editor_state.cursor1 = {line=3, pos=5}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'jkl', 'F - test_left_arrow_scrolls_up_in_wrapped_line/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'mno', 'F - test_left_arrow_scrolls_up_in_wrapped_line/baseline/screen:2')
  -- after hitting the left arrow the screen scrolls up to first screen line
  edit.run_after_keychord(Editor_state, 'left')
  y = Editor_state.top
  App.screen.check(y, 'ghi ', 'F - test_left_arrow_scrolls_up_in_wrapped_line/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'jkl', 'F - test_left_arrow_scrolls_up_in_wrapped_line/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'mno', 'F - test_left_arrow_scrolls_up_in_wrapped_line/screen:3')
  check_eq(Editor_state.screen_top1.line, 3, 'F - test_left_arrow_scrolls_up_in_wrapped_line/screen_top')
  check_eq(Editor_state.screen_top1.pos, 1, 'F - test_left_arrow_scrolls_up_in_wrapped_line/screen_top')
  check_eq(Editor_state.cursor1.line, 3, 'F - test_left_arrow_scrolls_up_in_wrapped_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 4, 'F - test_left_arrow_scrolls_up_in_wrapped_line/cursor:pos')
end
function test_right_arrow_scrolls_down_in_wrapped_line()
  io.write('\ntest_right_arrow_scrolls_down_in_wrapped_line')
  -- display the first three lines with the cursor on the bottom line
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi jkl', 'mno'}
  Text.redraw_all(Editor_state)
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  -- cursor is at bottom right of screen
  Editor_state.cursor1 = {line=3, pos=5}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_right_arrow_scrolls_down_in_wrapped_line/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_right_arrow_scrolls_down_in_wrapped_line/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi ', 'F - test_right_arrow_scrolls_down_in_wrapped_line/baseline/screen:3')  -- line wrapping includes trailing whitespace
  -- after hitting the right arrow the screen scrolls down by one line
  edit.run_after_keychord(Editor_state, 'right')
  check_eq(Editor_state.screen_top1.line, 2, 'F - test_right_arrow_scrolls_down_in_wrapped_line/screen_top')
  check_eq(Editor_state.cursor1.line, 3, 'F - test_right_arrow_scrolls_down_in_wrapped_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 6, 'F - test_right_arrow_scrolls_down_in_wrapped_line/cursor:pos')
  y = Editor_state.top
  App.screen.check(y, 'def', 'F - test_right_arrow_scrolls_down_in_wrapped_line/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi ', 'F - test_right_arrow_scrolls_down_in_wrapped_line/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'jkl', 'F - test_right_arrow_scrolls_down_in_wrapped_line/screen:3')
end
function test_home_scrolls_up_in_wrapped_line()
  io.write('\ntest_home_scrolls_up_in_wrapped_line')
  -- display lines starting from second screen line of a line
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi jkl', 'mno'}
  Text.redraw_all(Editor_state)
  Editor_state.screen_top1 = {line=3, pos=5}
  Editor_state.screen_bottom1 = {}
  -- cursor is at top of screen
  Editor_state.cursor1 = {line=3, pos=5}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'jkl', 'F - test_home_scrolls_up_in_wrapped_line/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'mno', 'F - test_home_scrolls_up_in_wrapped_line/baseline/screen:2')
  -- after hitting home the screen scrolls up to first screen line
  edit.run_after_keychord(Editor_state, 'home')
  y = Editor_state.top
  App.screen.check(y, 'ghi ', 'F - test_home_scrolls_up_in_wrapped_line/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'jkl', 'F - test_home_scrolls_up_in_wrapped_line/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'mno', 'F - test_home_scrolls_up_in_wrapped_line/screen:3')
  check_eq(Editor_state.screen_top1.line, 3, 'F - test_home_scrolls_up_in_wrapped_line/screen_top')
  check_eq(Editor_state.screen_top1.pos, 1, 'F - test_home_scrolls_up_in_wrapped_line/screen_top')
  check_eq(Editor_state.cursor1.line, 3, 'F - test_home_scrolls_up_in_wrapped_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_home_scrolls_up_in_wrapped_line/cursor:pos')
end
function test_end_scrolls_down_in_wrapped_line()
  io.write('\ntest_end_scrolls_down_in_wrapped_line')
  -- display the first three lines with the cursor on the bottom line
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi jkl', 'mno'}
  Text.redraw_all(Editor_state)
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  -- cursor is at bottom right of screen
  Editor_state.cursor1 = {line=3, pos=5}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_end_scrolls_down_in_wrapped_line/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_end_scrolls_down_in_wrapped_line/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi ', 'F - test_end_scrolls_down_in_wrapped_line/baseline/screen:3')  -- line wrapping includes trailing whitespace
  -- after hitting end the screen scrolls down by one line
  edit.run_after_keychord(Editor_state, 'end')
  check_eq(Editor_state.screen_top1.line, 2, 'F - test_end_scrolls_down_in_wrapped_line/screen_top')
  check_eq(Editor_state.cursor1.line, 3, 'F - test_end_scrolls_down_in_wrapped_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 8, 'F - test_end_scrolls_down_in_wrapped_line/cursor:pos')
  y = Editor_state.top
  App.screen.check(y, 'def', 'F - test_end_scrolls_down_in_wrapped_line/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi ', 'F - test_end_scrolls_down_in_wrapped_line/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'jkl', 'F - test_end_scrolls_down_in_wrapped_line/screen:3')
end
function test_position_cursor_on_recently_edited_wrapping_line()
  -- draw a line wrapping over 2 screen lines
  io.write('\ntest_position_cursor_on_recently_edited_wrapping_line')
  App.screen.init{width=100, height=200}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc def ghi jkl mno pqr ', 'xyz'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=25}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc def ghi ', 'F - test_position_cursor_on_recently_edited_wrapping_line/baseline1/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'jkl mno pqr ', 'F - test_position_cursor_on_recently_edited_wrapping_line/baseline1/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'xyz', 'F - test_position_cursor_on_recently_edited_wrapping_line/baseline1/screen:3')
  -- add to the line until it's wrapping over 3 screen lines
  edit.run_after_text_input(Editor_state, 'a')
  check_eq(Editor_state.screen_top1.line, 2, 'F - test_inserting_text_on_final_line_avoids_scrolling_down_when_not_at_bottom/screen_top')
  check_eq(Editor_state.cursor1.line, 2, 'F - test_inserting_text_on_final_line_avoids_scrolling_down_when_not_at_bottom/cursor:line')
  check_eq(Editor_state.cursor1.pos, 2, 'F - test_inserting_text_on_final_line_avoids_scrolling_down_when_not_at_bottom/cursor:pos')
  local y = Editor_state.top
  App.screen.check(y, 'a', 'F - test_inserting_text_on_final_line_avoids_scrolling_down_when_not_at_bottom/screen:1')
end
function test_typing_on_bottom_line_scrolls_down()
  io.write('\ntest_typing_on_bottom_line_scrolls_down')
  -- display a few lines with cursor on bottom line
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi', 'jkl'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=3, pos=4}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_typing_on_bottom_line_scrolls_down/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_typing_on_bottom_line_scrolls_down/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_typing_on_bottom_line_scrolls_down/baseline/screen:3')
  -- after typing something the line wraps and the screen scrolls down
end
function test_up_arrow_moves_cursor()
  io.write('\ntest_up_arrow_moves_cursor')
  -- display the first 3 lines with the cursor on the bottom line
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi', 'jkl'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=3, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_up_arrow_moves_cursor/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_up_arrow_moves_cursor/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_up_arrow_moves_cursor/baseline/screen:3')
  -- after hitting the up arrow the cursor moves up by 1 line
  edit.run_after_keychord(Editor_state, 'up')
  check_eq(Editor_state.screen_top1.line, 1, 'F - test_up_arrow_moves_cursor/screen_top')
  check_eq(Editor_state.cursor1.line, 2, 'F - test_up_arrow_moves_cursor/cursor')
  -- the screen is unchanged
  y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_up_arrow_moves_cursor/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_up_arrow_moves_cursor/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_up_arrow_moves_cursor/screen:3')
end
function test_up_arrow_scrolls_up_by_one_line()
  io.write('\ntest_up_arrow_scrolls_up_by_one_line')
  -- display the lines 2/3/4 with the cursor on line 2
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi', 'jkl'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=2, pos=1}
  Editor_state.screen_top1 = {line=2, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'def', 'F - test_up_arrow_scrolls_up_by_one_line/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_up_arrow_scrolls_up_by_one_line/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'jkl', 'F - test_up_arrow_scrolls_up_by_one_line/baseline/screen:3')
  -- after hitting the up arrow the screen scrolls up by one line
  edit.run_after_keychord(Editor_state, 'up')
  check_eq(Editor_state.screen_top1.line, 1, 'F - test_up_arrow_scrolls_up_by_one_line/screen_top')
  check_eq(Editor_state.cursor1.line, 1, 'F - test_up_arrow_scrolls_up_by_one_line/cursor')
  y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_up_arrow_scrolls_up_by_one_line/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_up_arrow_scrolls_up_by_one_line/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_up_arrow_scrolls_up_by_one_line/screen:3')
end
function test_up_arrow_scrolls_up_by_one_screen_line()
  io.write('\ntest_up_arrow_scrolls_up_by_one_screen_line')
  -- display lines starting from second screen line of a line
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi jkl', 'mno'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=3, pos=6}
  Editor_state.screen_top1 = {line=3, pos=5}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'jkl', 'F - test_up_arrow_scrolls_up_by_one_screen_line/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'mno', 'F - test_up_arrow_scrolls_up_by_one_screen_line/baseline/screen:2')
  -- after hitting the up arrow the screen scrolls up to first screen line
  edit.run_after_keychord(Editor_state, 'up')
  y = Editor_state.top
  App.screen.check(y, 'ghi ', 'F - test_up_arrow_scrolls_up_by_one_screen_line/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'jkl', 'F - test_up_arrow_scrolls_up_by_one_screen_line/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'mno', 'F - test_up_arrow_scrolls_up_by_one_screen_line/screen:3')
  check_eq(Editor_state.screen_top1.line, 3, 'F - test_up_arrow_scrolls_up_by_one_screen_line/screen_top')
  check_eq(Editor_state.screen_top1.pos, 1, 'F - test_up_arrow_scrolls_up_by_one_screen_line/screen_top')
  check_eq(Editor_state.cursor1.line, 3, 'F - test_up_arrow_scrolls_up_by_one_screen_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_up_arrow_scrolls_up_by_one_screen_line/cursor:pos')
end
function test_up_arrow_scrolls_up_to_final_screen_line()
  io.write('\ntest_up_arrow_scrolls_up_to_final_screen_line')
  -- display lines starting just after a long line
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc def', 'ghi', 'jkl', 'mno'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=2, pos=1}
  Editor_state.screen_top1 = {line=2, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'ghi', 'F - test_up_arrow_scrolls_up_to_final_screen_line/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'jkl', 'F - test_up_arrow_scrolls_up_to_final_screen_line/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'mno', 'F - test_up_arrow_scrolls_up_to_final_screen_line/baseline/screen:3')
  -- after hitting the up arrow the screen scrolls up to final screen line of previous line
  edit.run_after_keychord(Editor_state, 'up')
  y = Editor_state.top
  App.screen.check(y, 'def', 'F - test_up_arrow_scrolls_up_to_final_screen_line/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_up_arrow_scrolls_up_to_final_screen_line/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'jkl', 'F - test_up_arrow_scrolls_up_to_final_screen_line/screen:3')
  check_eq(Editor_state.screen_top1.line, 1, 'F - test_up_arrow_scrolls_up_to_final_screen_line/screen_top')
  check_eq(Editor_state.screen_top1.pos, 5, 'F - test_up_arrow_scrolls_up_to_final_screen_line/screen_top')
  check_eq(Editor_state.cursor1.line, 1, 'F - test_up_arrow_scrolls_up_to_final_screen_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 5, 'F - test_up_arrow_scrolls_up_to_final_screen_line/cursor:pos')
end
function test_up_arrow_scrolls_up_to_empty_line()
  io.write('\ntest_up_arrow_scrolls_up_to_empty_line')
  -- display a screenful of text with an empty line just above it outside the screen
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'', 'abc', 'def', 'ghi', 'jkl'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=2, pos=1}
  Editor_state.screen_top1 = {line=2, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_up_arrow_scrolls_up_to_empty_line/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_up_arrow_scrolls_up_to_empty_line/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_up_arrow_scrolls_up_to_empty_line/baseline/screen:3')
  -- after hitting the up arrow the screen scrolls up by one line
  edit.run_after_keychord(Editor_state, 'up')
  check_eq(Editor_state.screen_top1.line, 1, 'F - test_up_arrow_scrolls_up_to_empty_line/screen_top')
  check_eq(Editor_state.cursor1.line, 1, 'F - test_up_arrow_scrolls_up_to_empty_line/cursor')
  y = Editor_state.top
  -- empty first line
  y = y + Editor_state.line_height
  App.screen.check(y, 'abc', 'F - test_up_arrow_scrolls_up_to_empty_line/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_up_arrow_scrolls_up_to_empty_line/screen:3')
end
function test_pageup()
  io.write('\ntest_pageup')
  App.screen.init{width=120, height=45}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=2, pos=1}
  Editor_state.screen_top1 = {line=2, pos=1}
  Editor_state.screen_bottom1 = {}
  -- initially the last two lines are displayed
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'def', 'F - test_pageup/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_pageup/baseline/screen:2')
  -- after pageup the cursor goes to first line
  edit.run_after_keychord(Editor_state, 'pageup')
  check_eq(Editor_state.screen_top1.line, 1, 'F - test_pageup/screen_top')
  check_eq(Editor_state.cursor1.line, 1, 'F - test_pageup/cursor')
  y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_pageup/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_pageup/screen:2')
end
function test_pageup_scrolls_up_by_screen_line()
  io.write('\ntest_pageup_scrolls_up_by_screen_line')
  -- display the first three lines with the cursor on the bottom line
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc def', 'ghi', 'jkl', 'mno'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=2, pos=1}
  Editor_state.screen_top1 = {line=2, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'ghi', 'F - test_pageup_scrolls_up_by_screen_line/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'jkl', 'F - test_pageup_scrolls_up_by_screen_line/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'mno', 'F - test_pageup_scrolls_up_by_screen_line/baseline/screen:3')  -- line wrapping includes trailing whitespace
  -- after hitting the page-up key the screen scrolls up to top
  edit.run_after_keychord(Editor_state, 'pageup')
  check_eq(Editor_state.screen_top1.line, 1, 'F - test_pageup_scrolls_up_by_screen_line/screen_top')
  check_eq(Editor_state.cursor1.line, 1, 'F - test_pageup_scrolls_up_by_screen_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_pageup_scrolls_up_by_screen_line/cursor:pos')
  y = Editor_state.top
  App.screen.check(y, 'abc ', 'F - test_pageup_scrolls_up_by_screen_line/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_pageup_scrolls_up_by_screen_line/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_pageup_scrolls_up_by_screen_line/screen:3')
end
function test_pageup_scrolls_up_from_middle_screen_line()
  io.write('\ntest_pageup_scrolls_up_from_middle_screen_line')
  -- display a few lines starting from the middle of a line (Editor_state.cursor1.pos > 1)
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc def', 'ghi jkl', 'mno'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=2, pos=5}
  Editor_state.screen_top1 = {line=2, pos=5}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'jkl', 'F - test_pageup_scrolls_up_from_middle_screen_line/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'mno', 'F - test_pageup_scrolls_up_from_middle_screen_line/baseline/screen:3')  -- line wrapping includes trailing whitespace
  -- after hitting the page-up key the screen scrolls up to top
  edit.run_after_keychord(Editor_state, 'pageup')
  check_eq(Editor_state.screen_top1.line, 1, 'F - test_pageup_scrolls_up_from_middle_screen_line/screen_top')
  check_eq(Editor_state.cursor1.line, 1, 'F - test_pageup_scrolls_up_from_middle_screen_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_pageup_scrolls_up_from_middle_screen_line/cursor:pos')
  y = Editor_state.top
  App.screen.check(y, 'abc ', 'F - test_pageup_scrolls_up_from_middle_screen_line/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_pageup_scrolls_up_from_middle_screen_line/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi ', 'F - test_pageup_scrolls_up_from_middle_screen_line/screen:3')
end
function test_enter_on_bottom_line_scrolls_down()
  io.write('\ntest_enter_on_bottom_line_scrolls_down')
  -- display a few lines with cursor on bottom line
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi', 'jkl'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=3, pos=2}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_enter_on_bottom_line_scrolls_down/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_enter_on_bottom_line_scrolls_down/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_enter_on_bottom_line_scrolls_down/baseline/screen:3')
  -- after hitting the enter key the screen scrolls down
  edit.run_after_keychord(Editor_state, 'return')
  check_eq(Editor_state.screen_top1.line, 2, 'F - test_enter_on_bottom_line_scrolls_down/screen_top')
  check_eq(Editor_state.cursor1.line, 4, 'F - test_enter_on_bottom_line_scrolls_down/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_enter_on_bottom_line_scrolls_down/cursor:pos')
  y = Editor_state.top
  App.screen.check(y, 'def', 'F - test_enter_on_bottom_line_scrolls_down/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'g', 'F - test_enter_on_bottom_line_scrolls_down/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'hi', 'F - test_enter_on_bottom_line_scrolls_down/screen:3')
end
function test_enter_on_final_line_avoids_scrolling_down_when_not_at_bottom()
  io.write('\ntest_enter_on_final_line_avoids_scrolling_down_when_not_at_bottom')
  -- display just the bottom line on screen
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi', 'jkl'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=4, pos=2}
  Editor_state.screen_top1 = {line=4, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'jkl', 'F - test_enter_on_final_line_avoids_scrolling_down_when_not_at_bottom/baseline/screen:1')
  -- after hitting the enter key the screen does not scroll down
  edit.run_after_keychord(Editor_state, 'return')
  check_eq(Editor_state.screen_top1.line, 4, 'F - test_enter_on_final_line_avoids_scrolling_down_when_not_at_bottom/screen_top')
  check_eq(Editor_state.cursor1.line, 5, 'F - test_enter_on_final_line_avoids_scrolling_down_when_not_at_bottom/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_enter_on_final_line_avoids_scrolling_down_when_not_at_bottom/cursor:pos')
  y = Editor_state.top
  App.screen.check(y, 'j', 'F - test_enter_on_final_line_avoids_scrolling_down_when_not_at_bottom/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'kl', 'F - test_enter_on_final_line_avoids_scrolling_down_when_not_at_bottom/screen:2')
end
function test_inserting_text_on_final_line_avoids_scrolling_down_when_not_at_bottom()
  io.write('\ntest_inserting_text_on_final_line_avoids_scrolling_down_when_not_at_bottom')
  -- display just an empty bottom line on screen
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', ''}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=2, pos=1}
  Editor_state.screen_top1 = {line=2, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  -- after hitting the inserting_text key the screen does not scroll down
  App.screen.check(y, 'kl', 'F - test_pagedown_followed_by_down_arrow_does_not_scroll_screen_up/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghij', 'F - test_pagedown_followed_by_down_arrow_does_not_scroll_screen_up/screen:1')
  y = y + Editor_state.line_height
  check_eq(Editor_state.screen_top1.line, 3, 'F - test_pagedown_followed_by_down_arrow_does_not_scroll_screen_up/screen_top')
  check_eq(Editor_state.cursor1.line, 3, 'F - test_pagedown_followed_by_down_arrow_does_not_scroll_screen_up/cursor:line')
  check_eq(Editor_state.cursor1.pos, 5, 'F - test_pagedown_followed_by_down_arrow_does_not_scroll_screen_up/cursor:pos')
  y = Editor_state.top
  check_eq(Editor_state.screen_top1.line, 3, 'F - test_pagedown_followed_by_down_arrow_does_not_scroll_screen_up/baseline2/screen_top')
  check_eq(Editor_state.cursor1.line, 3, 'F - test_pagedown_followed_by_down_arrow_does_not_scroll_screen_up/baseline2/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_pagedown_followed_by_down_arrow_does_not_scroll_screen_up/baseline2/cursor:pos')
  -- after hitting down arrow the screen doesn't scroll down further, and certainly doesn't scroll up
  edit.run_after_keychord(Editor_state, 'down')
  App.screen.check(y, 'ghij', 'F - test_pagedown_followed_by_down_arrow_does_not_scroll_screen_up/baseline/screen:3')
  -- after hitting pagedown the screen scrolls down to start of a long line
  edit.run_after_keychord(Editor_state, 'pagedown')
  App.screen.check(y, 'def', 'F - test_pagedown_followed_by_down_arrow_does_not_scroll_screen_up/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'abc', 'F - test_pagedown_followed_by_down_arrow_does_not_scroll_screen_up/baseline/screen:1')
  y = y + Editor_state.line_height
function test_pagedown_followed_by_down_arrow_does_not_scroll_screen_up()
  io.write('\ntest_pagedown_followed_by_down_arrow_does_not_scroll_screen_up')
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghijkl', 'mno'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=3, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  edit.run_after_text_input(Editor_state, 'g')
  local y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_edit_wrapping_text/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'de', 'F - test_edit_wrapping_text/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'fg', 'F - test_edit_wrapping_text/screen:3')
end
function test_insert_newline()
  io.write('\ntest_insert_newline')
  -- display a few lines
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi', 'jkl'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=2}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_insert_newline/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_insert_newline/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_insert_newline/baseline/screen:3')
  -- hitting the enter key splits the line
  edit.run_after_keychord(Editor_state, 'return')
  check_eq(Editor_state.screen_top1.line, 1, 'F - test_insert_newline/screen_top')
  check_eq(Editor_state.cursor1.line, 2, 'F - test_insert_newline/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_insert_newline/cursor:pos')
  y = Editor_state.top
  App.screen.check(y, 'a', 'F - test_insert_newline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'bc', 'F - test_insert_newline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_insert_newline/screen:3')
end
function test_insert_newline_at_start_of_line()
  io.write('\ntest_insert_newline_at_start_of_line')
  -- display a line
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  -- hitting the enter key splits the line
  edit.run_after_keychord(Editor_state, 'return')
  check_eq(Editor_state.cursor1.line, 2, 'F - test_insert_newline_at_start_of_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_insert_newline_at_start_of_line/cursor:pos')
  check_eq(Editor_state.lines[1].data, '', 'F - test_insert_newline_at_start_of_line/data:1')
  check_eq(Editor_state.lines[2].data, 'abc', 'F - test_insert_newline_at_start_of_line/data:2')
end
function test_insert_from_clipboard()
  io.write('\ntest_insert_from_clipboard')
  -- display a few lines
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi', 'jkl'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=2}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_insert_from_clipboard/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_insert_from_clipboard/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_insert_from_clipboard/baseline/screen:3')
  -- paste some text including a newline, check that new line is created
  App.clipboard = 'xy\nz'
  edit.run_after_keychord(Editor_state, 'C-v')
  check_eq(Editor_state.screen_top1.line, 1, 'F - test_insert_from_clipboard/screen_top')
  check_eq(Editor_state.cursor1.line, 2, 'F - test_insert_from_clipboard/cursor:line')
  check_eq(Editor_state.cursor1.pos, 2, 'F - test_insert_from_clipboard/cursor:pos')
  y = Editor_state.top
  App.screen.check(y, 'axy', 'F - test_insert_from_clipboard/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'zbc', 'F - test_insert_from_clipboard/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_insert_from_clipboard/screen:3')
  edit.keychord_press(Editor_state, 'd', 'd')
  edit.text_input(Editor_state, 'D')
  edit.key_release(Editor_state, 'd')
  App.fake_key_release('lshift')
  -- selected text is deleted and replaced with the key
  check_nil(Editor_state.selection1.line, 'F - test_edit_with_shift_key_deletes_selection')
  check_eq(Editor_state.lines[1].data, 'Dbc', 'F - test_edit_with_shift_key_deletes_selection/data')
end
function test_copy_does_not_reset_selection()
  io.write('\ntest_copy_does_not_reset_selection')
  -- display a line of text with a selection
  App.screen.init{width=75, height=80}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.selection1 = {line=1, pos=2}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  -- copy selection
  edit.run_after_keychord(Editor_state, 'C-c')
  check_eq(App.clipboard, 'a', 'F - test_copy_does_not_reset_selection/clipboard')
  -- selection is reset since shift key is not pressed
  check(Editor_state.selection1.line, 'F - test_copy_does_not_reset_selection')
end
function test_cut()
  io.write('\ntest_cut')
  -- display a line of text with some part selected
  App.screen.init{width=75, height=80}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.selection1 = {line=1, pos=2}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  -- press a key
  edit.run_after_keychord(Editor_state, 'C-x')
  check_eq(App.clipboard, 'a', 'F - test_cut/clipboard')
  -- selected text is deleted
  check_eq(Editor_state.lines[1].data, 'bc', 'F - test_cut/data')
end
function test_paste_replaces_selection()
  io.write('\ntest_paste_replaces_selection')
  -- display a line of text with a selection
  App.screen.init{width=75, height=80}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=2, pos=1}
  Editor_state.selection1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  -- set clipboard
  App.clipboard = 'xyz'
  -- paste selection
  edit.run_after_keychord(Editor_state, 'C-v')
  -- selection is reset since shift key is not pressed
  -- selection includes the newline, so it's also deleted
  check_eq(Editor_state.lines[1].data, 'xyzdef', 'F - test_paste_replaces_selection')
end
function test_deleting_selection_may_scroll()
  io.write('\ntest_deleting_selection_may_scroll')
  -- display lines 2/3/4
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi', 'jkl'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=3, pos=2}
  Editor_state.screen_top1 = {line=2, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'def', 'F - test_deleting_selection_may_scroll/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_deleting_selection_may_scroll/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'jkl', 'F - test_deleting_selection_may_scroll/baseline/screen:3')
  -- set up a selection starting above the currently displayed page
  Editor_state.selection1 = {line=1, pos=2}
  -- delete selection
  edit.run_after_keychord(Editor_state, 'backspace')
  -- page scrolls up
  check_eq(Editor_state.screen_top1.line, 1, 'F - test_deleting_selection_may_scroll')
  check_eq(Editor_state.lines[1].data, 'ahi', 'F - test_deleting_selection_may_scroll/data')
end
  edit.run_after_text_input(Editor_state, 'x')
  -- selected text is deleted and replaced with the key
  check_eq(Editor_state.lines[1].data, 'xbc', 'F - test_edit_deletes_selection')
end
function test_edit_with_shift_key_deletes_selection()
  io.write('\ntest_edit_with_shift_key_deletes_selection')
  -- display a line of text with some part selected
  App.screen.init{width=75, height=80}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.selection1 = {line=1, pos=2}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  -- mimic precise keypresses for a capital letter
  App.fake_key_press('lshift')
  edit.key_release(Editor_state, 'lshift')
  -- selection persists even after shift is release
  check_eq(Editor_state.selection1.line, 1, 'F - test_select_text/selection:line')
  check_eq(Editor_state.selection1.pos, 1, 'F - test_select_text/selection:pos')
  check_eq(Editor_state.cursor1.line, 1, 'F - test_select_text/cursor:line')
  check_eq(Editor_state.cursor1.pos, 2, 'F - test_select_text/cursor:pos')
end
function test_cursor_movement_without_shift_resets_selection()
  io.write('\ntest_cursor_movement_without_shift_resets_selection')
  -- display a line of text with some part selected
  App.screen.init{width=75, height=80}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.selection1 = {line=1, pos=2}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  -- press an arrow key without shift
  edit.run_after_keychord(Editor_state, 'right')
  -- no change to data, selection is reset
  check_nil(Editor_state.selection1.line, 'F - test_cursor_movement_without_shift_resets_selection')
  check_eq(Editor_state.lines[1].data, 'abc', 'F - test_cursor_movement_without_shift_resets_selection/data')
end
function test_draw_text_wrapping_within_word()
  -- arrange a screen line that needs to be split within a word
  io.write('\ntest_draw_text_wrapping_within_word')
  App.screen.init{width=60, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abcd e fghijk', 'xyz'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abcd ', 'F - test_draw_text_wrapping_within_word/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'e fgh', 'F - test_draw_text_wrapping_within_word/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ijk', 'F - test_draw_text_wrapping_within_word/screen:3')
end
function test_draw_wrapping_text_containing_non_ascii()
  -- draw a long line containing non-ASCII
  io.write('\ntest_draw_wrapping_text_containing_non_ascii')
  App.screen.init{width=60, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'madam I’m adam', 'xyz'}  -- notice the non-ASCII apostrophe
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'mad', 'F - test_draw_wrapping_text_containing_non_ascii/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'am I', 'F - test_draw_wrapping_text_containing_non_ascii/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, '’m a', 'F - test_draw_wrapping_text_containing_non_ascii/screen:3')
end
function test_click_on_wrapping_line()
  io.write('\ntest_click_on_wrapping_line')
  -- display a wrapping line
  App.screen.init{width=75, height=80}
  Editor_state = edit.initialize_test_state()
                               --  12345678901234
  Editor_state.lines = load_array{"madam I'm adam"}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'madam ', 'F - test_click_on_wrapping_line/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, "I'm ad", 'F - test_click_on_wrapping_line/baseline/screen:2')
  y = y + Editor_state.line_height
  -- click past end of second screen line
  edit.run_after_mouse_click(Editor_state, App.screen.width-2,y-2, 1)
  -- cursor moves to end of screen line
  check_eq(Editor_state.cursor1.line, 1, 'F - test_click_on_wrapping_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 12, 'F - test_click_on_wrapping_line/cursor:pos')
end
function test_click_on_wrapping_line_rendered_from_partway_at_top_of_screen()
  io.write('\ntest_click_on_wrapping_line_rendered_from_partway_at_top_of_screen')
  -- display a wrapping line from its second screen line
  App.screen.init{width=75, height=80}
  Editor_state = edit.initialize_test_state()
                               --  12345678901234
  Editor_state.lines = load_array{"madam I'm adam"}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=8}
  Editor_state.screen_top1 = {line=1, pos=7}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, "I'm ad", 'F - test_click_on_wrapping_line_rendered_from_partway_at_top_of_screen/baseline/screen:2')
  y = y + Editor_state.line_height
  -- click past end of second screen line
  edit.run_after_mouse_click(Editor_state, App.screen.width-2,y-2, 1)
  -- cursor moves to end of screen line
  check_eq(Editor_state.cursor1.line, 1, 'F - test_click_on_wrapping_line_rendered_from_partway_at_top_of_screen/cursor:line')
  check_eq(Editor_state.cursor1.pos, 12, 'F - test_click_on_wrapping_line_rendered_from_partway_at_top_of_screen/cursor:pos')
end
function test_click_past_end_of_wrapping_line()
  io.write('\ntest_click_past_end_of_wrapping_line')
  -- display a wrapping line
  App.screen.init{width=75, height=80}
  Editor_state = edit.initialize_test_state()
                               --  12345678901234
  Editor_state.lines = load_array{"madam I'm adam"}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'madam ', 'F - test_click_past_end_of_wrapping_line/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, "I'm ad", 'F - test_click_past_end_of_wrapping_line/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'am', 'F - test_click_past_end_of_wrapping_line/baseline/screen:3')
  y = y + Editor_state.line_height
  -- click past the end of it
  edit.run_after_mouse_click(Editor_state, App.screen.width-2,y-2, 1)
  -- cursor moves to end of line
  check_eq(Editor_state.cursor1.pos, 15, 'F - test_click_past_end_of_wrapping_line/cursor')  -- one more than the number of UTF-8 code-points
end
function test_click_past_end_of_wrapping_line_containing_non_ascii()
  io.write('\ntest_click_past_end_of_wrapping_line_containing_non_ascii')
  -- display a wrapping line containing non-ASCII
  App.screen.init{width=75, height=80}
  Editor_state = edit.initialize_test_state()
                               --  12345678901234
  Editor_state.lines = load_array{'madam I’m adam'}  -- notice the non-ASCII apostrophe
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'madam ', 'F - test_click_past_end_of_wrapping_line_containing_non_ascii/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'I’m ad', 'F - test_click_past_end_of_wrapping_line_containing_non_ascii/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'am', 'F - test_click_past_end_of_wrapping_line_containing_non_ascii/baseline/screen:3')
  y = y + Editor_state.line_height
  -- click past the end of it
  edit.run_after_mouse_click(Editor_state, App.screen.width-2,y-2, 1)
  -- cursor moves to end of line
  check_eq(Editor_state.cursor1.pos, 15, 'F - test_click_past_end_of_wrapping_line_containing_non_ascii/cursor')  -- one more than the number of UTF-8 code-points
end
function test_click_past_end_of_word_wrapping_line()
  io.write('\ntest_click_past_end_of_word_wrapping_line')
  -- display a long line wrapping at a word boundary on a screen of more realistic length
  App.screen.init{width=160, height=80}
  Editor_state = edit.initialize_test_state()
                                -- 0        1         2
                                -- 123456789012345678901
  Editor_state.lines = load_array{'the quick brown fox jumped over the lazy dog'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'the quick brown fox ', 'F - test_click_past_end_of_word_wrapping_line/baseline/screen:1')
  y = y + Editor_state.line_height
  -- click past the end of the screen line
  edit.run_after_mouse_click(Editor_state, App.screen.width-2,y-2, 1)
  -- cursor moves to end of screen line
  check_eq(Editor_state.cursor1.pos, 20, 'F - test_click_past_end_of_word_wrapping_line/cursor')
function test_click_on_wrapping_line_takes_margins_into_account()
  io.write('\ntest_click_on_wrapping_line_takes_margins_into_account')
  -- display two lines with cursor on one of them
  App.screen.init{width=100, height=80}
  Editor_state = edit.initialize_test_state()
  Editor_state.left = 50  -- occupy only right side of screen
  Editor_state.lines = load_array{'abc def ghi jkl mno pqr stu'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=20}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  -- click on the other line
  edit.draw(Editor_state)
  edit.run_after_mouse_click(Editor_state, Editor_state.left+8,Editor_state.top+5, 1)
  -- cursor moves
  check_eq(Editor_state.cursor1.line, 1, 'F - test_click_on_wrapping_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 2, 'F - test_click_on_wrapping_line/cursor:pos')
  check_nil(Editor_state.selection1.line, 'F - test_click_on_wrapping_line/selection is empty to avoid perturbing future edits')
end
function test_click_on_wrapping_line()
  io.write('\ntest_click_on_wrapping_line')
  -- display two lines with cursor on one of them
  App.screen.init{width=50, height=80}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc def ghi jkl mno pqr stu'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=20}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  -- click on the other line
  edit.draw(Editor_state)
  edit.run_after_mouse_click(Editor_state, Editor_state.left+8,Editor_state.top+5, 1)
  -- cursor moves
  check_eq(Editor_state.cursor1.line, 1, 'F - test_click_on_empty_line/cursor')
end
function test_draw_text()
  io.write('\ntest_draw_text')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_draw_text/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_draw_text/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_draw_text/screen:3')
end
function test_draw_wrapping_text()
  io.write('\ntest_draw_wrapping_text')
  App.screen.init{width=50, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'defgh', 'xyz'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_draw_wrapping_text/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'de', 'F - test_draw_wrapping_text/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'fgh', 'F - test_draw_wrapping_text/screen:3')
end
function test_draw_word_wrapping_text()
  io.write('\ntest_draw_word_wrapping_text')
  App.screen.init{width=60, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc def ghi', 'jkl'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc ', 'F - test_draw_word_wrapping_text/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def ', 'F - test_draw_word_wrapping_text/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_draw_word_wrapping_text/screen:3')
end
function test_click_on_empty_line()
  io.write('\ntest_click_on_empty_line')
  -- display two lines with the first one empty
  App.screen.init{width=50, height=80}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'', 'def'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=2, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  -- click on the empty line
  edit.draw(Editor_state)
  edit.run_after_mouse_click(Editor_state, Editor_state.left+8,Editor_state.top+5, 1)
  -- cursor moves
  check_eq(Editor_state.cursor1.line, 1, 'F - test_click_takes_margins_into_account/cursor:line')
  check_eq(Editor_state.cursor1.pos, 2, 'F - test_click_takes_margins_into_account/cursor:pos')
  check_nil(Editor_state.selection1.line, 'F - test_click_takes_margins_into_account/selection is empty to avoid perturbing future edits')
end
function test_click_takes_margins_into_account()
  io.write('\ntest_click_takes_margins_into_account')
  -- display two lines with cursor on one of them
  App.screen.init{width=100, height=80}
  Editor_state = edit.initialize_test_state()
  Editor_state.left = 50  -- occupy only right side of screen
  Editor_state.lines = load_array{'abc', 'def'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=2, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  -- click on the other line
  edit.draw(Editor_state)
  edit.run_after_mouse_click(Editor_state, Editor_state.left+8,Editor_state.top+5, 1)
  -- cursor moves
  edit.run_after_text_input(Editor_state, 'a')
  local y = Editor_state.top
  App.screen.check(y, 'a', 'F - test_insert_first_character/screen:1')
end
function test_press_ctrl()
  io.write('\ntest_press_ctrl')
  -- press ctrl while the cursor is on text
  App.screen.init{width=50, height=80}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{''}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.run_after_keychord(Editor_state, 'C-m')
end
function test_move_left()
  io.write('\ntest_move_left')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'a'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=2}
  edit.draw(Editor_state)
  edit.run_after_keychord(Editor_state, 'left')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_move_left')
end
function test_move_right()
  io.write('\ntest_move_right')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'a'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  edit.draw(Editor_state)
  edit.run_after_keychord(Editor_state, 'right')
  check_eq(Editor_state.cursor1.pos, 2, 'F - test_move_right')
end
function test_move_left_to_previous_line()
  io.write('\ntest_move_left_to_previous_line')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=2, pos=1}
  edit.draw(Editor_state)
  edit.run_after_keychord(Editor_state, 'left')
  check_eq(Editor_state.cursor1.line, 1, 'F - test_move_left_to_previous_line/line')
  check_eq(Editor_state.cursor1.pos, 4, 'F - test_move_left_to_previous_line/pos')  -- past end of line
end
function test_move_right_to_next_line()
  io.write('\ntest_move_right_to_next_line')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=4}  -- past end of line
  edit.draw(Editor_state)
  edit.run_after_keychord(Editor_state, 'right')
  check_eq(Editor_state.cursor1.line, 2, 'F - test_move_right_to_next_line/line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_move_right_to_next_line/pos')
end
function test_move_to_start_of_word()
  io.write('\ntest_move_to_start_of_word')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=3}
  edit.draw(Editor_state)
  edit.run_after_keychord(Editor_state, 'M-left')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_move_to_start_of_word')
end
function test_move_to_start_of_previous_word()
  io.write('\ntest_move_to_start_of_previous_word')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc def'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=4}  -- at the space between words
  edit.draw(Editor_state)
  edit.run_after_keychord(Editor_state, 'M-left')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_move_to_start_of_previous_word')
end
function test_skip_to_previous_word()
  io.write('\ntest_skip_to_previous_word')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc def'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=5}  -- at the start of second word
  edit.draw(Editor_state)
  edit.run_after_keychord(Editor_state, 'M-left')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_skip_to_previous_word')
end
function test_skip_past_tab_to_previous_word()
  io.write('\ntest_skip_past_tab_to_previous_word')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc def\tghi'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=10}  -- within third word
  edit.draw(Editor_state)
  edit.run_after_keychord(Editor_state, 'M-left')
  check_eq(Editor_state.cursor1.pos, 9, 'F - test_skip_past_tab_to_previous_word')
end
function test_skip_multiple_spaces_to_previous_word()
  io.write('\ntest_skip_multiple_spaces_to_previous_word')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc  def'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=6}  -- at the start of second word
  edit.draw(Editor_state)
  edit.run_after_keychord(Editor_state, 'M-left')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_skip_multiple_spaces_to_previous_word')
end
function test_move_to_start_of_word_on_previous_line()
  io.write('\ntest_move_to_start_of_word_on_previous_line')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc def', 'ghi'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=2, pos=1}
  edit.draw(Editor_state)
  edit.run_after_keychord(Editor_state, 'M-left')
  check_eq(Editor_state.cursor1.line, 1, 'F - test_move_to_start_of_word_on_previous_line/line')
  check_eq(Editor_state.cursor1.pos, 5, 'F - test_move_to_start_of_word_on_previous_line/pos')
end
function test_move_past_end_of_word()
  io.write('\ntest_move_past_end_of_word')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc def'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  edit.draw(Editor_state)
  edit.run_after_keychord(Editor_state, 'M-right')
  check_eq(Editor_state.cursor1.pos, 4, 'F - test_move_past_end_of_word')
end
function test_skip_to_next_word()
  io.write('\ntest_skip_to_next_word')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc def'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=4}  -- at the space between words
  edit.draw(Editor_state)
  edit.run_after_keychord(Editor_state, 'M-right')
  check_eq(Editor_state.cursor1.pos, 8, 'F - test_skip_to_next_word')
end
function test_skip_past_tab_to_next_word()
  io.write('\ntest_skip_past_tab_to_next_word')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc\tdef'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}  -- at the space between words
  edit.draw(Editor_state)
  edit.run_after_keychord(Editor_state, 'M-right')
  check_eq(Editor_state.cursor1.pos, 4, 'F - test_skip_past_tab_to_next_word')
end
function test_skip_multiple_spaces_to_next_word()
  io.write('\ntest_skip_multiple_spaces_to_next_word')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc  def'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=4}  -- at the start of second word
  edit.draw(Editor_state)
  edit.run_after_keychord(Editor_state, 'M-right')
  check_eq(Editor_state.cursor1.pos, 9, 'F - test_skip_multiple_spaces_to_next_word')
end
function test_move_past_end_of_word_on_next_line()
  io.write('\ntest_move_past_end_of_word_on_next_line')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc def', 'ghi'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=8}
  edit.draw(Editor_state)
  edit.run_after_keychord(Editor_state, 'M-right')
  check_eq(Editor_state.cursor1.line, 2, 'F - test_move_past_end_of_word_on_next_line/line')
  check_eq(Editor_state.cursor1.pos, 4, 'F - test_move_past_end_of_word_on_next_line/pos')
end
  check_eq(Editor_state.cursor1.line, 1, 'F - test_click_to_left_of_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_click_to_left_of_line/cursor:pos')
  check_nil(Editor_state.selection1.line, 'F - test_click_to_left_of_line/selection is empty to avoid perturbing future edits')
end
function test_click_to_left_of_line()
  io.write('\ntest_click_to_left_of_line')
  -- display a line with the cursor in the middle
  App.screen.init{width=50, height=80}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=3}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  -- click to the left of the line
  edit.draw(Editor_state)
  edit.run_after_mouse_click(Editor_state, Editor_state.left-4,Editor_state.top+5, 1)
  -- cursor moves to start of line
  Editor_state.selection1 = {}
  edit.draw(Editor_state)  -- populate line_cache.starty for each line Editor_state.line_cache
  edit.run_after_mouse_release(Editor_state, Editor_state.left+8,Editor_state.top+5, 1)
  check_eq(Editor_state.cursor1.line, 1, 'F - test_click_moves_cursor/cursor:line')
  check_eq(Editor_state.cursor1.pos, 2, 'F - test_click_moves_cursor/cursor:pos')
  -- selection is empty to avoid perturbing future edits
  check_nil(Editor_state.selection1.line, 'F - test_click_moves_cursor/selection:line')
  check_nil(Editor_state.selection1.pos, 'F - test_click_moves_cursor/selection:pos')
end
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  Editor_state.lines = load_array{'abc', 'def', 'xyz'}
  Text.redraw_all(Editor_state)
function test_click_moves_cursor()
  io.write('\ntest_click_moves_cursor')
  App.screen.init{width=50, height=60}
  Editor_state = edit.initialize_test_state()

-- Don't handle any keys here that would trigger text_input above.
function Text.keychord_press(State, chord)
--?   print('chord', chord, State.selection1.line, State.selection1.pos)
function Text.text_input(State, t)
  if App.mouse_down(1) then return end
  if App.ctrl_down() or App.alt_down() or App.cmd_down() then return end
  local before = snapshot(State, State.cursor1.line)
--?   print(State.screen_top1.line, State.screen_top1.pos, State.cursor1.line, State.cursor1.pos, State.screen_bottom1.line, State.screen_bottom1.pos)
  Text.insert_at_cursor(State, t)
  if State.cursor_y > App.screen.height - State.line_height then
    Text.populate_screen_line_starting_pos(State, State.cursor1.line)
    Text.snap_cursor_to_bottom_of_screen(State, State.left, State.right)
  end
  record_undo_event(State, {before=before, after=snapshot(State, State.cursor1.line)})
end
function Text.insert_at_cursor(State, t)
  if State.cursor1.pos then
    local byte_offset = Text.offset(State.lines[State.cursor1.line].data, State.cursor1.pos)
    State.lines[State.cursor1.line].data = string.sub(State.lines[State.cursor1.line].data, 1, byte_offset-1)..t..string.sub(State.lines[State.cursor1.line].data, byte_offset)
    Text.clear_screen_line_cache(State, State.cursor1.line)
    State.cursor1.pos = State.cursor1.pos+1
  else
    assert(State.cursor1.posB)
    local byte_offset = Text.offset(State.lines[State.cursor1.line].dataB, State.cursor1.posB)
    State.lines[State.cursor1.line].dataB = string.sub(State.lines[State.cursor1.line].dataB, 1, byte_offset-1)..t..string.sub(State.lines[State.cursor1.line].dataB, byte_offset)
    Text.clear_screen_line_cache(State, State.cursor1.line)
    State.cursor1.posB = State.cursor1.posB+1
  end
end

  edit.mouse_release(State, x,y, mouse_button)
  App.screen.contents = {}
  edit.mouse_release(State, x,y, mouse_button)
  edit.mouse_press(State, x,y, mouse_button)
  App.screen.contents = {}
  App.screen.contents = {}
  edit.keychord_press(State, chord)
  edit.key_release(State, chord)
  edit.mouse_press(State, x,y, mouse_button)
  App.fake_mouse_release(x,y, mouse_button)
  App.screen.contents = {}
-- not all keys are text_input
function edit.run_after_keychord(State, chord)
function edit.run_after_text_input(State, t)
  edit.keychord_press(State, t)
  edit.text_input(State, t)
  edit.key_release(State, t)
  App.screen.contents = {}
-- all text_input events are also keypresses
-- TODO: handle chords of multiple keys
function edit.key_release(State, key, scancode)
end
function edit.update_font_settings(State, font_height)
  State.font_height = font_height
    Text.keychord_press(State, chord)
  end
end
function edit.eradicate_locations_after_the_fold(State)
  -- eradicate side B from any locations we track
  if State.cursor1.posB then
    State.cursor1.posB = nil
    State.cursor1.pos = utf8.len(State.lines[State.cursor1.line].data)
    State.cursor1.pos = Text.pos_at_start_of_screen_line(State, State.cursor1)
  end
  if State.screen_top1.posB then
    State.screen_top1.posB = nil
    State.screen_top1.pos = utf8.len(State.lines[State.screen_top1.line].data)
    State.screen_top1.pos = Text.pos_at_start_of_screen_line(State, State.screen_top1)
  end
end
      Drawing.keychord_press(State, chord)
      record_undo_event(State, {before=before, after=snapshot(State, drawing_index)})
      schedule_save(State)
    end
  elseif chord == 'escape' and not App.mouse_down(1) then
    for _,line in ipairs(State.lines) do
      if line.mode == 'drawing' then
        line.show_help = false
      end
    end
  elseif State.current_drawing_mode == 'name' then
    if chord == 'return' then
      State.current_drawing_mode = State.previous_drawing_mode
      State.previous_drawing_mode = nil
    else
      local before = snapshot(State, State.lines.current_drawing_index)
      local drawing = State.lines.current_drawing
      local p = drawing.points[drawing.pending.target_point]
      if chord == 'escape' then
        p.name = nil
        record_undo_event(State, {before=before, after=snapshot(State, State.lines.current_drawing_index)})
      elseif chord == 'backspace' then
        local len = utf8.len(p.name)
        local byte_offset = Text.offset(p.name, len-1)
        if len == 1 then byte_offset = 0 end
        p.name = string.sub(p.name, 1, byte_offset)
        record_undo_event(State, {before=before, after=snapshot(State, State.lines.current_drawing_index)})
      end
    end
    schedule_save(State)
function edit.keychord_press(State, chord, key)
  if State.selection1.line and
      not State.lines.current_drawing and
      -- printable character created using shift key => delete selection
      -- (we're not creating any ctrl-shift- or alt-shift- combinations using regular/printable keys)
      (not App.shift_down() or utf8.len(key) == 1) and
      Text.text_input(State, t)
    end
function edit.text_input(State, t)
  if State.search_term then
    State.search_term = State.search_term..t
    State.search_text = nil
    Text.search_next(State)
    Drawing.mouse_release(State, x,y, mouse_button)
    schedule_save(State)
    if Drawing.before then
      record_undo_event(State, {before=Drawing.before, after=snapshot(State, State.lines.current_drawing_index)})
      Drawing.before = nil
    end
function edit.mouse_release(State, x,y, mouse_button)
  if State.search_term then return end
--?   print('release')
  if State.lines.current_drawing then
        --    i.e. mouse_release should never look at shift state
        Drawing.mouse_press(State, line_index, x,y, mouse_button)
        break
      end
        State.old_cursor1 = State.cursor1
        State.old_selection1 = State.selection1
        State.mousepress_shift = App.shift_down()
function edit.mouse_press(State, x,y, mouse_button)
  if State.search_term then return end

    return log_browser.keychord_press(Log_browser_state, chordkey, scancode)
  end
end
-- use this sparingly
function to_text(s)
  if Text_cache[s] == nil then
    Text_cache[s] = App.newText(love.graphics.getFont(), s)
  end
  return Text_cache[s]
end
    return edit.key_release(Editor_state, key, scancode)
  else
function source.key_release(key, scancode)
  Cursor_time = 0  -- ensure cursor is visible immediately after it moves
  if Focus == 'edit' then
    return log_browser.keychord_press(Log_browser_state, chord, key)
  end
end
    return edit.keychord_press(Editor_state, chord, key)
  else
    keychord_press_on_file_navigator(chord, key)
    return
  end
  if chord == 'C-l' then
--?     print('C-l')
    Show_log_browser_side = not Show_log_browser_side
    if Show_log_browser_side then
function source.keychord_press(chord, key)
  Cursor_time = 0  -- ensure cursor is visible immediately after it moves
--?   print('source keychord')
  if Show_file_navigator then
    return log_browser.text_input(Log_browser_state, t)
  end
end
    return edit.text_input(Editor_state, t)
  else
    text_input_on_file_navigator(t)
    return
  end
function source.text_input(t)
  Cursor_time = 0  -- ensure cursor is visible immediately after it moves
    return log_browser.mouse_release(Log_browser_state, x,y, mouse_button)
  end
end
    return edit.mouse_release(Editor_state, x,y, mouse_button)
  else
function source.mouse_release(x,y, mouse_button)
  Cursor_time = 0  -- ensure cursor is visible immediately after it moves
  if Focus == 'edit' then
-- a copy of source.file_drop when given a filename
    log_browser.mouse_press(Log_browser_state, x,y, mouse_button)
    for _,line_cache in ipairs(Editor_state.line_cache) do line_cache.starty = nil end  -- just in case we scroll
  end
end
    edit.mouse_press(Editor_state, x,y, mouse_button)
  elseif Show_log_browser_side and Log_browser_state.left <= x and x < Log_browser_state.right then
--?     print('click on log_browser side')
    if Focus ~= 'log_browser' then
      Focus = 'log_browser'
    edit.mouse_press(Editor_state, x,y, mouse_button)
    return
  end
function source.mouse_press(x,y, mouse_button)
  Cursor_time = 0  -- ensure cursor is visible immediately after it moves
--?   print('mouse click', x, y)
--?   print(Editor_state.left, Editor_state.right)
--?   print(Log_browser_state.left, Log_browser_state.right)
function source.switch_to_file(filename)
  -- first make sure to save edits on any existing file
  if Editor_state.next_save then
    save_to_disk(Editor_state)
  end
function source.file_drop(file)
  -- first make sure to save edits on any existing file
  if Editor_state.next_save then
    save_to_disk(Editor_state)
  end
  -- clear the slate for the new file
  Editor_state.filename = file:getFilename()
  file:open('r')
  Editor_state.lines = load_from_file(file)
  file:close()
  Text.redraw_all(Editor_state)
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.cursor1 = {line=1, pos=1}

  return edit.key_release(Editor_state, key, scancode)
end
-- use this sparingly
function to_text(s)
  if Text_cache[s] == nil then
    Text_cache[s] = App.newText(love.graphics.getFont(), s)
  end
  return Text_cache[s]
end
function run.key_release(key, scancode)
  Cursor_time = 0  -- ensure cursor is visible immediately after it moves
  return edit.keychord_press(Editor_state, chord, key)
end
function run.keychord_press(chord, key)
  Cursor_time = 0  -- ensure cursor is visible immediately after it moves
  return edit.text_input(Editor_state, t)
end
function run.text_input(t)
  Cursor_time = 0  -- ensure cursor is visible immediately after it moves
  return edit.mouse_release(Editor_state, x,y, mouse_button)
end
function run.mouse_release(x,y, mouse_button)
  Cursor_time = 0  -- ensure cursor is visible immediately after it moves
function run.file_drop(file)
  -- first make sure to save edits on any existing file
  if Editor_state.next_save then
    save_to_disk(Editor_state)
  end
  -- clear the slate for the new file
  App.initialize_globals()
  Editor_state.filename = file:getFilename()
  file:open('r')
  Editor_state.lines = load_from_file(file)
  file:close()
  Text.redraw_all(Editor_state)
  edit.fixup_cursor(Editor_state)
  love.window.setTitle('lines.love - '..Editor_state.filename)
end
function run.draw()
  edit.draw(Editor_state)
end
function run.update(dt)
  Cursor_time = Cursor_time + dt
  edit.update(Editor_state, dt)
end
function run.quit()
  edit.quit(Editor_state)
end
function run.settings()

function log_browser.key_release(State, key, scancode)
end
function log_browser.keychord_press(State, chord, key)
  -- move
  if chord == 'up' then
    while State.screen_top1.line > 1 do
      State.screen_top1.line = State.screen_top1.line-1
      if should_show(State.lines[State.screen_top1.line]) then
        break
      end
    end
  elseif chord == 'down' then
    while State.screen_top1.line < #State.lines do
      State.screen_top1.line = State.screen_top1.line+1
      if should_show(State.lines[State.screen_top1.line]) then
        break
      end
    end
  elseif chord == 'pageup' then
    local y = 0
    while State.screen_top1.line > 1 and y < App.screen.height - 100 do
      State.screen_top1.line = State.screen_top1.line - 1
      if should_show(State.lines[State.screen_top1.line]) then
        y = y + log_browser.height(State, State.screen_top1.line)
      end
    end
  elseif chord == 'pagedown' then
    local y = 0
    while State.screen_top1.line < #State.lines and y < App.screen.height - 100 do
      if should_show(State.lines[State.screen_top1.line]) then
        y = y + log_browser.height(State, State.screen_top1.line)
      end
      State.screen_top1.line = State.screen_top1.line + 1
    end
  end
end
function log_browser.height(State, line_index)
  local line = State.lines[line_index]
  if line.data == nil then
    -- section header
    return State.line_height
  elseif type(line.data) == 'string' then
    return State.line_height
  else
    if line.height == nil then
--?       print('nil line height! rendering off screen to calculate')
      line.height = log_render[line.data.name](line.data, State.left, App.screen.height, State.right-State.left)
    end
    return line.height
  end
end
function log_browser.text_input(State, t)
end
function log_browser.mouse_release(State, x,y, mouse_button)
end
function log_browser.mouse_press(State, x,y, mouse_button)
  local line_index = log_browser.line_index(State, x,y)
  if line_index == nil then
    -- below lower margin
    return
  end
  -- leave some space to click without focusing
  local line = State.lines[line_index]
  local xleft = log_browser.left_margin(State, line)
  local xright = log_browser.right_margin(State, line)
  if x < xleft or x > xright then
    return
  end
  -- if it's a section begin/end and the section is collapsed, expand it
  -- TODO: how to collapse?
  if line.section_begin or line.section_end then
    -- HACK: get section reference from next/previous line
    local new_section
    if line.section_begin then
      if line_index < #State.lines then
        local next_section_stack = State.lines[line_index+1].section_stack
        if next_section_stack then
          new_section = next_section_stack[#next_section_stack]
        end
      end
    elseif line.section_end then
      if line_index > 1 then
        local previous_section_stack = State.lines[line_index-1].section_stack
        if previous_section_stack then
          new_section = previous_section_stack[#previous_section_stack]
        end
      end
    end
    if new_section and new_section.expanded == nil then
      new_section.expanded = true
      return
    end
  end
  -- open appropriate file in source side
  if line.filename ~= Editor_state.filename then
    source.switch_to_file(line.filename)
  end
  -- set cursor
  Editor_state.cursor1 = {line=line.line_number, pos=1, posB=nil}
  -- make sure it's visible
  -- TODO: handle extremely long lines
  Editor_state.screen_top1.line = math.max(0, Editor_state.cursor1.line-5)
  -- show cursor
  Focus = 'edit'
  -- expand B side
  Editor_state.expanded = true
end
function log_browser.line_index(State, mx,my)
  -- duplicate some logic from log_browser.draw
  local y = State.top
  for line_index = State.screen_top1.line,#State.lines do
    local line = State.lines[line_index]
    if should_show(line) then
      y = y + log_browser.height(State, line_index)
      if my < y then
        return line_index
      end
      if y > App.screen.height then break end
    end
  end
end

function text_input_on_file_navigator(t)
  File_navigation.filter = File_navigation.filter..t
  File_navigation.candidates = source.file_navigator_candidates()
end
function keychord_press_on_file_navigator(chord, key)
  log(2, 'file navigator: '..chord)

  check_eq(Editor_state.lines[1].data, 'xbc', 'F - test_undo_restores_selection/baseline')

  edit.run_after_text_input(Editor_state, 'x')

  edit.run_after_text_input(Editor_state, 'x')

  edit.run_after_textinput(Editor_state, 'a')

  edit.run_after_text_input(Editor_state, 'a')

function test_click_with_mouse()
  io.write('\ntest_click_with_mouse')
  -- display two lines with cursor on one of them
  App.screen.init{width=50, height=80}

function test_click_moves_cursor()
  io.write('\ntest_click_moves_cursor')
  App.screen.init{width=50, height=60}

  Editor_state.lines = load_array{'abc', 'def'}

  Editor_state.lines = load_array{'abc', 'def', 'xyz'}

  Editor_state.cursor1 = {line=2, pos=1}

  Editor_state.cursor1 = {line=1, pos=1}

  -- click on the other line
  edit.draw(Editor_state)
  edit.run_after_mouse_click(Editor_state, Editor_state.left+8,Editor_state.top+5, 1)
  -- cursor moves
  check_eq(Editor_state.cursor1.line, 1, 'F - test_click_with_mouse/cursor:line')
  check_nil(Editor_state.selection1.line, 'F - test_click_with_mouse/selection is empty to avoid perturbing future edits')

  Editor_state.selection1 = {}
  edit.draw(Editor_state)  -- populate line_cache.starty for each line Editor_state.line_cache
  edit.run_after_mouse_release(Editor_state, Editor_state.left+8,Editor_state.top+5, 1)
  check_eq(Editor_state.cursor1.line, 1, 'F - test_click_moves_cursor/cursor:line')
  check_eq(Editor_state.cursor1.pos, 2, 'F - test_click_moves_cursor/cursor:pos')
  -- selection is empty to avoid perturbing future edits
  check_nil(Editor_state.selection1.line, 'F - test_click_moves_cursor/selection:line')
  check_nil(Editor_state.selection1.pos, 'F - test_click_moves_cursor/selection:pos')

function test_click_with_mouse_to_left_of_line()
  io.write('\ntest_click_with_mouse_to_left_of_line')

function test_click_to_left_of_line()
  io.write('\ntest_click_to_left_of_line')

  check_eq(Editor_state.cursor1.line, 1, 'F - test_click_with_mouse_to_left_of_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_click_with_mouse_to_left_of_line/cursor:pos')
  check_nil(Editor_state.selection1.line, 'F - test_click_with_mouse_to_left_of_line/selection is empty to avoid perturbing future edits')

  check_eq(Editor_state.cursor1.line, 1, 'F - test_click_to_left_of_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_click_to_left_of_line/cursor:pos')
  check_nil(Editor_state.selection1.line, 'F - test_click_to_left_of_line/selection is empty to avoid perturbing future edits')

function test_click_with_mouse_takes_margins_into_account()
  io.write('\ntest_click_with_mouse_takes_margins_into_account')

function test_click_takes_margins_into_account()
  io.write('\ntest_click_takes_margins_into_account')

  check_eq(Editor_state.cursor1.line, 1, 'F - test_click_with_mouse_takes_margins_into_account/cursor:line')
  check_eq(Editor_state.cursor1.pos, 2, 'F - test_click_with_mouse_takes_margins_into_account/cursor:pos')
  check_nil(Editor_state.selection1.line, 'F - test_click_with_mouse_takes_margins_into_account/selection is empty to avoid perturbing future edits')

  check_eq(Editor_state.cursor1.line, 1, 'F - test_click_takes_margins_into_account/cursor:line')
  check_eq(Editor_state.cursor1.pos, 2, 'F - test_click_takes_margins_into_account/cursor:pos')
  check_nil(Editor_state.selection1.line, 'F - test_click_takes_margins_into_account/selection is empty to avoid perturbing future edits')

function test_click_with_mouse_on_empty_line()
  io.write('\ntest_click_with_mouse_on_empty_line')

function test_click_on_empty_line()
  io.write('\ntest_click_on_empty_line')

  check_eq(Editor_state.cursor1.line, 1, 'F - test_click_with_mouse_on_empty_line/cursor')

  check_eq(Editor_state.cursor1.line, 1, 'F - test_click_on_empty_line/cursor')

function test_click_with_mouse_on_wrapping_line()
  io.write('\ntest_click_with_mouse_on_wrapping_line')

function test_click_on_wrapping_line()
  io.write('\ntest_click_on_wrapping_line')

  check_eq(Editor_state.cursor1.line, 1, 'F - test_click_with_mouse_on_wrapping_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 2, 'F - test_click_with_mouse_on_wrapping_line/cursor:pos')
  check_nil(Editor_state.selection1.line, 'F - test_click_with_mouse_on_wrapping_line/selection is empty to avoid perturbing future edits')

  check_eq(Editor_state.cursor1.line, 1, 'F - test_click_on_wrapping_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 2, 'F - test_click_on_wrapping_line/cursor:pos')
  check_nil(Editor_state.selection1.line, 'F - test_click_on_wrapping_line/selection is empty to avoid perturbing future edits')

function test_click_with_mouse_on_wrapping_line_takes_margins_into_account()
  io.write('\ntest_click_with_mouse_on_wrapping_line_takes_margins_into_account')

function test_click_on_wrapping_line_takes_margins_into_account()
  io.write('\ntest_click_on_wrapping_line_takes_margins_into_account')

  check_eq(Editor_state.cursor1.line, 1, 'F - test_click_with_mouse_on_wrapping_line_takes_margins_into_account/cursor:line')
  check_eq(Editor_state.cursor1.pos, 2, 'F - test_click_with_mouse_on_wrapping_line_takes_margins_into_account/cursor:pos')
  check_nil(Editor_state.selection1.line, 'F - test_click_with_mouse_on_wrapping_line_takes_margins_into_account/selection is empty to avoid perturbing future edits')

  check_eq(Editor_state.cursor1.line, 1, 'F - test_click_on_wrapping_line_takes_margins_into_account/cursor:line')
  check_eq(Editor_state.cursor1.pos, 2, 'F - test_click_on_wrapping_line_takes_margins_into_account/cursor:pos')
  check_nil(Editor_state.selection1.line, 'F - test_click_on_wrapping_line_takes_margins_into_account/selection is empty to avoid perturbing future edits')

  edit.key_released(Editor_state, 'lshift')
  -- selection persists even after shift is released

  edit.key_release(Editor_state, 'lshift')
  -- selection persists even after shift is release

  edit.run_after_textinput(Editor_state, 'x')

  edit.run_after_text_input(Editor_state, 'x')

  edit.keychord_pressed(Editor_state, 'd', 'd')
  edit.textinput(Editor_state, 'D')
  edit.key_released(Editor_state, 'd')

  edit.keychord_press(Editor_state, 'd', 'd')
  edit.text_input(Editor_state, 'D')
  edit.key_release(Editor_state, 'd')

  edit.run_after_textinput(Editor_state, 'g')

  edit.run_after_text_input(Editor_state, 'g')

end
function test_move_cursor_using_mouse()
  io.write('\ntest_move_cursor_using_mouse')
  App.screen.init{width=50, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'xyz'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  Editor_state.selection1 = {}
  edit.draw(Editor_state)  -- populate line_cache.starty for each line Editor_state.line_cache
  edit.run_after_mouse_release(Editor_state, Editor_state.left+8,Editor_state.top+5, 1)
  check_eq(Editor_state.cursor1.line, 1, 'F - test_move_cursor_using_mouse/cursor:line')
  check_eq(Editor_state.cursor1.pos, 2, 'F - test_move_cursor_using_mouse/cursor:pos')
  check_nil(Editor_state.selection1.line, 'F - test_move_cursor_using_mouse/selection:line')
  check_nil(Editor_state.selection1.pos, 'F - test_move_cursor_using_mouse/selection:pos')

function test_page_down_followed_by_down_arrow_does_not_scroll_screen_up()
  io.write('\ntest_page_down_followed_by_down_arrow_does_not_scroll_screen_up')

function test_pagedown_followed_by_down_arrow_does_not_scroll_screen_up()
  io.write('\ntest_pagedown_followed_by_down_arrow_does_not_scroll_screen_up')

  App.screen.check(y, 'abc', 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/baseline/screen:1')

  App.screen.check(y, 'abc', 'F - test_pagedown_followed_by_down_arrow_does_not_scroll_screen_up/baseline/screen:1')

  App.screen.check(y, 'def', 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/baseline/screen:2')

  App.screen.check(y, 'def', 'F - test_pagedown_followed_by_down_arrow_does_not_scroll_screen_up/baseline/screen:2')

  App.screen.check(y, 'ghij', 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/baseline/screen:3')

  App.screen.check(y, 'ghij', 'F - test_pagedown_followed_by_down_arrow_does_not_scroll_screen_up/baseline/screen:3')

  check_eq(Editor_state.screen_top1.line, 3, 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/baseline2/screen_top')
  check_eq(Editor_state.cursor1.line, 3, 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/baseline2/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/baseline2/cursor:pos')

  check_eq(Editor_state.screen_top1.line, 3, 'F - test_pagedown_followed_by_down_arrow_does_not_scroll_screen_up/baseline2/screen_top')
  check_eq(Editor_state.cursor1.line, 3, 'F - test_pagedown_followed_by_down_arrow_does_not_scroll_screen_up/baseline2/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_pagedown_followed_by_down_arrow_does_not_scroll_screen_up/baseline2/cursor:pos')

  check_eq(Editor_state.screen_top1.line, 3, 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/screen_top')
  check_eq(Editor_state.cursor1.line, 3, 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/cursor:line')
  check_eq(Editor_state.cursor1.pos, 5, 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/cursor:pos')

  check_eq(Editor_state.screen_top1.line, 3, 'F - test_pagedown_followed_by_down_arrow_does_not_scroll_screen_up/screen_top')
  check_eq(Editor_state.cursor1.line, 3, 'F - test_pagedown_followed_by_down_arrow_does_not_scroll_screen_up/cursor:line')
  check_eq(Editor_state.cursor1.pos, 5, 'F - test_pagedown_followed_by_down_arrow_does_not_scroll_screen_up/cursor:pos')

  App.screen.check(y, 'ghij', 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/screen:1')

  App.screen.check(y, 'ghij', 'F - test_pagedown_followed_by_down_arrow_does_not_scroll_screen_up/screen:1')

  App.screen.check(y, 'kl', 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/screen:2')

  App.screen.check(y, 'kl', 'F - test_pagedown_followed_by_down_arrow_does_not_scroll_screen_up/screen:2')

  App.screen.check(y, 'mno', 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/screen:3')

  App.screen.check(y, 'mno', 'F - test_pagedown_followed_by_down_arrow_does_not_scroll_screen_up/screen:3')

  edit.run_after_textinput(Editor_state, 'a')

  edit.run_after_text_input(Editor_state, 'a')

  edit.run_after_textinput(Editor_state, 'j')
  edit.run_after_textinput(Editor_state, 'k')
  edit.run_after_textinput(Editor_state, 'l')

  edit.run_after_text_input(Editor_state, 'j')
  edit.run_after_text_input(Editor_state, 'k')
  edit.run_after_text_input(Editor_state, 'l')

  edit.run_after_textinput(Editor_state, 's')
  edit.run_after_textinput(Editor_state, 't')
  edit.run_after_textinput(Editor_state, 'u')

  edit.run_after_text_input(Editor_state, 's')
  edit.run_after_text_input(Editor_state, 't')
  edit.run_after_text_input(Editor_state, 'u')

  edit.run_after_textinput(Editor_state, 'g')

  edit.run_after_text_input(Editor_state, 'g')

  edit.run_after_textinput(Editor_state, 'x')

  edit.run_after_text_input(Editor_state, 'x')

  edit.run_after_textinput(Editor_state, 'd')

  edit.run_after_text_input(Editor_state, 'd')

  edit.run_after_textinput(Editor_state, 'de')

  edit.run_after_text_input(Editor_state, 'de')

  edit.run_after_textinput(Editor_state, 'a')

  edit.run_after_text_input(Editor_state, 'a')

  edit.run_after_textinput(Editor_state, 'a')

  edit.run_after_text_input(Editor_state, 'a')

  edit.run_after_textinput(Editor_state, 'a')

  edit.run_after_text_input(Editor_state, 'a')

function Text.textinput(State, t)

function Text.text_input(State, t)

-- Don't handle any keys here that would trigger love.textinput above.
function Text.keychord_pressed(State, chord)

-- Don't handle any keys here that would trigger text_input above.
function Text.keychord_press(State, chord)

function edit.mouse_pressed(State, x,y, mouse_button)

function edit.mouse_press(State, x,y, mouse_button)

        --    i.e. mouse_released should never look at shift state

        --    i.e. mouse_release should never look at shift state

        Drawing.mouse_pressed(State, line_index, x,y, mouse_button)

        Drawing.mouse_press(State, line_index, x,y, mouse_button)

function edit.mouse_released(State, x,y, mouse_button)

function edit.mouse_release(State, x,y, mouse_button)

    Drawing.mouse_released(State, x,y, mouse_button)

    Drawing.mouse_release(State, x,y, mouse_button)

function edit.textinput(State, t)

function edit.text_input(State, t)

      Text.textinput(State, t)

      Text.text_input(State, t)

function edit.keychord_pressed(State, chord, key)

function edit.keychord_press(State, chord, key)

      Drawing.keychord_pressed(State, chord)

      Drawing.keychord_press(State, chord)

    Text.keychord_pressed(State, chord)

    Text.keychord_press(State, chord)

function edit.key_released(State, key, scancode)

function edit.key_release(State, key, scancode)

-- all textinput events are also keypresses

-- all text_input events are also keypresses

function edit.run_after_textinput(State, t)
  edit.keychord_pressed(State, t)
  edit.textinput(State, t)
  edit.key_released(State, t)

function edit.run_after_text_input(State, t)
  edit.keychord_press(State, t)
  edit.text_input(State, t)
  edit.key_release(State, t)

-- not all keys are textinput

-- not all keys are text_input

  edit.keychord_pressed(State, chord)
  edit.key_released(State, chord)

  edit.keychord_press(State, chord)
  edit.key_release(State, chord)

  edit.mouse_pressed(State, x,y, mouse_button)

  edit.mouse_press(State, x,y, mouse_button)

  edit.mouse_released(State, x,y, mouse_button)

  edit.mouse_release(State, x,y, mouse_button)

  edit.mouse_pressed(State, x,y, mouse_button)

  edit.mouse_press(State, x,y, mouse_button)

  edit.mouse_released(State, x,y, mouse_button)

  edit.mouse_release(State, x,y, mouse_button)

function source.filedropped(file)

function source.file_drop(file)

-- a copy of source.filedropped when given a filename

-- a copy of source.file_drop when given a filename

function source.mouse_pressed(x,y, mouse_button)

function source.mouse_press(x,y, mouse_button)

    edit.mouse_pressed(Editor_state, x,y, mouse_button)

    edit.mouse_press(Editor_state, x,y, mouse_button)

    edit.mouse_pressed(Editor_state, x,y, mouse_button)

    edit.mouse_press(Editor_state, x,y, mouse_button)

    log_browser.mouse_pressed(Log_browser_state, x,y, mouse_button)

    log_browser.mouse_press(Log_browser_state, x,y, mouse_button)

function source.mouse_released(x,y, mouse_button)

function source.mouse_release(x,y, mouse_button)

    return edit.mouse_released(Editor_state, x,y, mouse_button)

    return edit.mouse_release(Editor_state, x,y, mouse_button)

    return log_browser.mouse_released(Log_browser_state, x,y, mouse_button)

    return log_browser.mouse_release(Log_browser_state, x,y, mouse_button)

function source.textinput(t)

function source.text_input(t)

    textinput_on_file_navigator(t)

    text_input_on_file_navigator(t)

    return edit.textinput(Editor_state, t)

    return edit.text_input(Editor_state, t)

    return log_browser.textinput(Log_browser_state, t)

    return log_browser.text_input(Log_browser_state, t)

function source.keychord_pressed(chord, key)

function source.keychord_press(chord, key)

    keychord_pressed_on_file_navigator(chord, key)

    keychord_press_on_file_navigator(chord, key)

    return edit.keychord_pressed(Editor_state, chord, key)

    return edit.keychord_press(Editor_state, chord, key)

    return log_browser.keychord_pressed(Log_browser_state, chord, key)

    return log_browser.keychord_press(Log_browser_state, chord, key)

function source.key_released(key, scancode)

function source.key_release(key, scancode)

    return edit.key_released(Editor_state, key, scancode)

    return edit.key_release(Editor_state, key, scancode)

    return log_browser.keychord_pressed(Log_browser_state, chordkey, scancode)

    return log_browser.keychord_press(Log_browser_state, chordkey, scancode)

function run.filedropped(file)

function run.file_drop(file)

function run.mouse_released(x,y, mouse_button)

function run.mouse_release(x,y, mouse_button)

  return edit.mouse_released(Editor_state, x,y, mouse_button)

  return edit.mouse_release(Editor_state, x,y, mouse_button)

function run.textinput(t)

function run.text_input(t)

  return edit.textinput(Editor_state, t)

  return edit.text_input(Editor_state, t)

function run.keychord_pressed(chord, key)

function run.keychord_press(chord, key)

  return edit.keychord_pressed(Editor_state, chord, key)