module DeathSocketCLI.Validation

    open DeathSocket
    open System.Drawing
    open System
    open System.IO
    open SkiaSharp

    (* This function creates a consistent line width amoung different image
    sizes. Use this when the user has no means to specify a pen width. *)
    let setPenWidth imgWidth imgHeight =
        let width = float32 imgWidth
        let height = float32 imgHeight
        if (width >= height) then
            height * (float32 0.002)
        else width * (float32 0.002)

    // System.Drawing Functions
    // ========================================================================

    let colourList =
        [ "blue", Brushes.AliceBlue
          "brown", Brushes.Brown
          "black", Brushes.Black
          "gray", Brushes.Gray
          "grey", Brushes.Gray
          "green", Brushes.Green
          "purple", Brushes.Purple
          "red", Brushes.Red
          "white", Brushes.White
          "yellow", Brushes.Yellow ]
          |> Map.ofList

    let isColourValid (colour: string) =
      colourList
      |> Map.containsKey (colour.ToLower())

    let parseColour colour =
        match (isColourValid colour) with
        | true ->
            colourList 
            |> Map.find (colour.ToLower())
        | false ->
            invalidArg "Colour"
                (String.Concat("The colour specifed is invalid.\n",
                    "Please use the 'list-colours' command to see what you can use."))

    let buildSpec (imgPath) (numRows) (numColumns) (pWidth) (colour) (newPath) : BrushSpec =
        { originalPath = imgPath
          savePath = newPath
          colour = parseColour colour
          penWidth = pWidth
          rows = numRows
          columns = numColumns }

    let buildDefaultSpec imgPath newPath =
        use stream = new FileStream (imgPath, FileMode.Open)
        use image = Image.FromStream (stream, false, false)
        let spec : BrushSpec =
            { originalPath = imgPath
              savePath = newPath
              colour = Brushes.White
              penWidth = setPenWidth (image.Width) (image.Height)
              rows = 10
              columns = 10 }
        spec

    // SkiaSharp Functions
    // ========================================================================

    let skiaColourList =
        [ "blue", SKColors.AliceBlue
          "brown", SKColors.Brown
          "black", SKColors.Black
          "gray", SKColors.Gray
          "grey", SKColors.Gray
          "green", SKColors.Green
          "purple", SKColors.Purple
          "red", SKColors.Red
          "white", SKColors.White
          "yellow", SKColors.Yellow ]
        |> Map.ofList

    let isSkiaColourValid (colour: string) =
      skiaColourList
      |> Map.containsKey (colour.ToLower())

    let parseSkiaColour colour =
        match (isSkiaColourValid colour) with
        | true ->
            skiaColourList
            |> Map.find (colour.ToLower())
        | false ->
            invalidArg "Colour"
                (String.Concat("The colour specifed is invalid.\n",
                    "Please use the 'list-skia-colours' command to see what you can use."))

    let buildSkiaSpec imgPath numRows numColumns pWidth colour newPath =
        let colour = parseSkiaColour colour
        { originalPath = imgPath
          savePath = newPath
          skColour = colour
          penWidth = pWidth
          rows = numRows
          columns = numColumns }

    let buildSkiaRGBSpec imgPath numRows numColumns pWidth r g b newPath =
        { originalPath = imgPath
          savePath = newPath
          red = (float32 r)
          green = (float32 g)
          blue = (float32 b)
          penWidth = pWidth
          rows = numRows
          columns = numColumns }