open Minttea
type model = {
  choices : (string * [ `selected | `unselected ]) list;
  cursor : int;
}
let initial_model =
  {
    cursor = 0;
    choices =
      [
        ("code minttea", `selected);
        ("buy minttea", `unselected);
        ("sell rest of tea", `unselected);
      ];
  }
let init _model = Command.Noop
let update event model =
  match event with
  | Event.KeyDown (Key "q" | Escape) -> (model, Command.Quit)
  | Event.KeyDown (Up | Key "k") ->
      let cursor =
        if model.cursor = 0 then List.length model.choices - 1
        else model.cursor - 1
      in
      ({ model with cursor }, Command.Noop)
  | Event.KeyDown (Down | Key "j") ->
      let cursor = 
        if model.cursor = List.length model.choices - 1 then 0
        else model.cursor + 1
      in
      ({ model with cursor }, Command.Noop)
  | Event.KeyDown (Enter | Space) ->
      let toggle status =
        match status with `selected -> `unselected | `unselected -> `selected
      in
      let choices =
        List.mapi (fun idx (name, status) ->
          let status = if idx = model.cursor then toggle status else status in
          (name, status))
        model.choices
      in
      ({ model with choices }, Command.Noop)
  | _ -> (model, Command.Noop)
let view model = 
  let options = 
    model.choices
    |> List.mapi (fun idx (name, checked) ->
        let cursor = if model.cursor = idx then ">" else " " in
        let checked = if checked = `selected then "x" else " " in
        Format.sprintf "%s [%s] %s" cursor checked name)
    |> String.concat "\n"
  in
  Format.sprintf
    {|
What should we buy at the market?
%s
Press q to quit.
  |} options
let app = Minttea.app ~init ~update ~view ()
let () = Minttea.start app ~initial_model

(lang dune 3.14)

(executable
  (name shop)
  (libraries minttea))