-- TODO: app-specific stuff goes here

  love.window.setTitle('TODO')

  love.window.setTitle('Sum Grid')

draw_cell = function(n, x,y)
	local s = tostring(n)
	local w = App.width(s)
	local px = (Square_side-w)/2
	love.graphics.print(s, x+px, y+Padding)
end

Problem = {
	row_totals={0, 0},
	col_totals={0, 0},
	data={
		{0, 0},
		{0, 0},
	},
}

Draw = 'char'

solve = function()
	print('solve')
	-- copy the slots we have
	local c = Char.col_totals
	local d = Char.data
	Solution = {
		col_totals = {c[1], c[2]},
		data = {
			{d[1][1], d[1][2] },
			{ },
		}
	}
	-- fill out the remaining data
	Solution.data[2][1] = c[1] - d[1][1]
	Solution.data[2][2] = c[2] - d[1][2]
	d = Solution.data
	Solution.row_totals = {
		d[1][1] + d[1][2],
		d[2][1] + d[2][2],
	}
end

-- solution for the sum-grid problem defined by Char.
Solution = {
	row_totals={0, 0},
	col_totals={0, 0},
	data={
		{0, 0},
		{0, 0},
	},
}

-- a set of numbers that uniquely characterizes a sum-grid instance.
Char = {
	row_totals={0, 0},
	col_totals={0, 0},
	data={
		{0, 0},
		{0, 0},
	},
}

on.keychord_press = function(chord, key)
	if chord == 'C-n' then
		generate_sum_grid()
		solve()
	elseif chord == '`' then
		if Draw == 'problem' then
			Draw = 'char'
		elseif Draw == 'char' then
			Draw = 'solution'
		elseif Draw == 'solution' then
			Draw = 'problem'
		end
	end
end

generate_sum_grid = function()
	-- a sum grid is fully characterized by 4 numbers
	Char = {
		data = {
			{ math.random(1,9), math.random(1,9) },
			{ '', ''},
		},
		row_totals = { '', '' },
	}
	Char.col_totals = {
		math.random(Char.data[1][1]+1,10),
		math.random(Char.data[1][2]+1,10)
	}
end

Padding = 0

Font_size = 0

Square_side = 100

on.initialize = function()
	Font_size = Square_side*0.8
	Padding = (Square_side-Font_size)/2
	love.graphics.setFont(love.graphics.newFont(Font_size))
end

draw_sum_grid = function(g)
	-- lines
	love.graphics.setLineWidth(3)
	local x1,y1 = 250,200
	local x2,y2 = 450,400
	love.graphics.line(x1,y1, x2,y1)
	love.graphics.line(x1,y2, x2,y2)
	love.graphics.line(x1,y1, x1,y2)
	love.graphics.line(x2,y1, x2,y2)
	local xm,ym = (x1+x2)/2, (y1+y2)/2
	love.graphics.line(x1,ym, x2,ym)
	love.graphics.line(xm,y1, xm,y2)
	-- data
	draw_cell(g.col_totals[1], x1,y1-Square_side)
	draw_cell(g.col_totals[2], xm,y1-Square_side)
	draw_cell(g.row_totals[1], x1-Square_side, y1)
	draw_cell(g.row_totals[2], x1-Square_side, ym)	
	for x=1,2 do
		for y=1,2 do
			draw_cell(g.data[y][x], x1+(x-1)*Square_side, y1+(y-1)*Square_side)
		end
	end
end

on.draw = function()
	if Draw == 'problem' then
		draw_sum_grid(Problem)
	elseif Draw == 'char' then
		draw_sum_grid(Char)
	else
		draw_sum_grid(Solution)
	end
end