module internal ValidationServices

    open System.IO

    let validateFilePath path =
        match File.Exists path with
        | true -> ()
        | false -> raise (new FileNotFoundException ("No file found at " + path))

    let validateSaveFileType file =
        match Path.GetExtension file with
        | ".jpg" -> ()
        | ".JPG" -> ()
        | ".png" -> ()
        | ".PNG" -> ()
        | _ -> invalidArg "savePath" "The file type must be a .jpg or .png file."

    let validateIO iPath oPath =
        validateFilePath iPath
        validateSaveFileType oPath

    let validateDimensions dimensions =
        match dimensions with
        | (0, _) -> invalidArg "Width" "Width must be greater than 0."
        | (_, 0) -> invalidArg "Height" "Height must be greater than 0."
        | (_, _) -> ()

    let validateLineThickness thickness =
        match thickness with
        | thickness when thickness <= 0.0 -> invalidArg "LineThickness" "LineThickness must be greater than 0."
        | _ -> ()