structure BrowseMode =
struct
  open AppType

  open DrawMessage
  open FileMessage
  open InputMessage
  open UpdateMessage

  fun stringToVec
    (pos, str, acc, startX, startY, windowWidth, windowHeight, r, g, b) =
    if pos = String.size str then
      acc
    else
      let
        val chr = String.sub (str, pos)

        val chrFun = Vector.sub (CozetteAscii.asciiTable, Char.ord chr)
        val chrVec = chrFun
          (startX, startY, 25.0, 25.0, windowWidth, windowHeight, r, g, b)

        val acc = chrVec :: acc
      in
        stringToVec
          ( pos + 1
          , str
          , acc
          , startX + 12
          , startY
          , windowWidth
          , windowHeight
          , r
          , g
          , b
          )
      end

  fun buildFileBrowserText
    (pos, fileBrowser, acc, startY, windowWidth, windowHeight, selectedIdx) =
    if pos = Vector.length fileBrowser then
      Vector.concat acc
    else
      let
        val item = Vector.sub (fileBrowser, pos)
        val itemText =
          case item of
            IS_FILE str => str
          | IS_FOLDER str => str
        val acc =
          if pos <> selectedIdx then
            stringToVec
              ( 0
              , itemText
              , acc
              , 10
              , startY
              , windowWidth
              , windowHeight
              , 0.0
              , 0.0
              , 0.0
              )
          else
            stringToVec
              ( 0
              , itemText
              , acc
              , 10
              , startY
              , windowWidth
              , windowHeight
              , 0.35
              , 0.35
              , 0.75
              )
      in
        buildFileBrowserText
          ( pos + 1
          , fileBrowser
          , acc
          , startY + 23
          , windowWidth
          , windowHeight
          , selectedIdx
          )
      end

  fun redrawFileBrowser (model: app_type) =
    let
      val {windowWidth, windowHeight, fileBrowser, fileBrowserIdx, ...} = model
      val ww = Real32.fromInt windowWidth
      val wh = Real32.fromInt windowHeight
      val textVec = buildFileBrowserText
        (0, fileBrowser, [], 10, ww, wh, fileBrowserIdx)

      val drawMsg = DRAW_MODAL_TEXT textVec
    in
      (model, [DRAW drawMsg])
    end

  fun handleFileBrowserAndPathInBrowseMode (model, fileBrowser, path) =
    let val model = AppWith.fileBrowserAndPath (model, fileBrowser, path)
    in redrawFileBrowser model
    end

  fun browseModeArrowUp (model: app_type) =
    let
      val {fileBrowser, fileBrowserIdx, ...} = model

      val fileBrowserIdx =
        if fileBrowserIdx > 0 then fileBrowserIdx - 1
        else Int.max (0, Vector.length fileBrowser - 1)

      val model = AppWith.fileBrowserIdx (model, fileBrowserIdx)
    in
      redrawFileBrowser model
    end

  fun browseModeArrowDown (model: app_type) =
    let
      val {fileBrowser, fileBrowserIdx, ...} = model

      val fileBrowserIdx =
        if fileBrowserIdx = Vector.length fileBrowser - 1 then 0
        else fileBrowserIdx + 1

      val model = AppWith.fileBrowserIdx (model, fileBrowserIdx)
    in
      redrawFileBrowser model
    end

  fun selectCurrentFileItem model =
    let
      val {fileBrowser, fileBrowserIdx, openFilePath, ...} = model
    in
      if Vector.length fileBrowser > 0 then
        let
          val path =
            case Vector.sub (fileBrowser, fileBrowserIdx) of
              IS_FILE str => str
            | IS_FOLDER str => str
          val path = String.concat [openFilePath, "/", path]
          val fileMsg = SELECT_PATH path
        in
          (model, [FILE fileMsg])
        end
      else
        (model, [])
    end

  fun update (model: app_type, inputMsg) =
    case inputMsg of
      ARROW_UP => browseModeArrowUp model
    | ARROW_DOWN => browseModeArrowDown model
    (* todo: 
    | ARROW_LEFT =>
    *)
    | ARROW_RIGHT => selectCurrentFileItem model
    | KEY_ENTER => selectCurrentFileItem model
    | KEY_SPACE => selectCurrentFileItem model
    | FILE_BROWSER_AND_PATH {fileBrowser, path} =>
        handleFileBrowserAndPathInBrowseMode (model, fileBrowser, path)
    | SQUARES_LOAD_ERROR => CommonUpdate.squaresLoadError model
    | _ => (model, [])
end