module Validation

    open System.Drawing
    open SmoulderingBeachBall.Domain.DomainTypes
    open System

    let colourList =
        [ "blue", Brushes.AliceBlue;
          "brown", Brushes.Brown;
          "black", Brushes.Black;
          "gray", 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("[ERROR] The colour specifed is invalid.\n",
                    "Please use the 'list-colours' command to see what you can use."))

    let getDesktopPath =
        Environment.GetFolderPath(Environment.SpecialFolder.DesktopDirectory)

    let parsePath (path: string) =
        match path with
        | path when ((path.ToLower()).Equals "desktop") -> getDesktopPath
        | path when ((path.ToLower()).Equals "d") -> getDesktopPath
        | _ -> path

    let buildDefaultSpec iWidth iHeight =
        let oSpec =
            { colour = Brushes.Black
              overlayType = Full }
        let spec =
            { width = iWidth
              height = iHeight
              colour = Brushes.AntiqueWhite
              filePath = getDesktopPath
              overlay = Some oSpec
            }
        spec

    let parseOverlay (oType: string) =
        match oType.ToLower() with
        | "border" -> Border
        | "b" -> Border
        | "full" -> Full
        | "f" -> Full
        | _ -> invalidArg "Overlay Type" "The overlay type must be either 'border' or 'full'."

    let buildOverlaySpec oColour (oType: string) =
        let oSpec =
            { colour = parseColour oColour;
              overlayType = parseOverlay oType }
        oSpec

    let buildMainSpec iWidth iHeight mainColour path oSpec =
        let spec =
            { width = iWidth;
              height = iHeight;
              colour = parseColour mainColour
              filePath = parsePath path
              overlay = oSpec }
        spec

    let buildSpec iWidth iHeight mainColour oColour (oType: string) path =
        let spec =
            match oType.ToLower() with
            | "none" | "n" -> buildMainSpec iWidth iHeight mainColour path option.None
            | _ ->
                let oSpec = buildOverlaySpec oColour oType
                buildMainSpec iWidth iHeight mainColour path (Some oSpec)
        spec