namespace LibraryTests

    module PropertyTests =

        open FsCheck.Xunit
        open System
        open System.Drawing
        open SmoulderingBeachBall.Domain.DomainTypes
        open System.Reflection
        open SmoulderingBeachBall.Services
        open System.IO
        open System.Threading
        open FsCheck

        (* '3000' is an arbitary value. It is used to keep the testing times sane.
        This function is used to randomly generate image sizes but you do not need to use it.
        The project can handle larger numbers than '3000' but processing takes longer.
        If you decide to change it, please keep an eye on the saving time.
        When a image is too big, the project cannot write it to disc fast enough --
        sometimes it is because of IO constraints.
        This means the tests checking for this fail/error will think the image does not exist.
        To resolved this, add a Thread.Sleep call to the affected tests.
        Just be aware, the length of sleep-time depends on the size of the image.
        Also, problems tends to arise around the 15,000 mark.
        *)
        let randomInt () = Random().Next(3000)

        let saveLocation = __SOURCE_DIRECTORY__ + "/SavingTestArea/"

        let allColours =
            let properties =
                typeof<Brushes>.GetProperties(BindingFlags.Public ||| BindingFlags.Static)
            let colours =
                seq { for prop in properties -> prop}
                |> Seq.toArray
            colours

        let randomColour () =
            let item = allColours.[Random().Next(allColours.Length)]
            item.GetValue(null, null)

        let fileSaved width height =
            saveLocation + width + "x" + height + ".png"
            |> File.Exists

        // To manually clear out the SavingTestArea folder, use this function in script.fsx.
        let resetSavingTestArea () =
            let files = Directory.GetFileSystemEntries(saveLocation)
            match files.Length with
            | 0 -> ()
            | _ ->
                files
                |> Array.iter (fun f -> File.Delete(f))

        let buildBorderOverlay () =
            Thread.Sleep 100 // Helps generate better colour variation.
            { colour = randomColour () :?> Brush
              overlayType = Border }

        let buildFullOverlay () =
            Thread.Sleep 100 // Helps generate better colour variation.
            { colour = randomColour () :?> Brush
              overlayType = Full }

        [<Property>]
        let ``Can create an image with no overlay`` () =
            resetSavingTestArea ()
            let spec =
                { // See note accompanying 'randomInt' function for constraints information.
                  width =  randomInt ()
                  height = randomInt ()
                  colour = randomColour () :?> Brush
                  filePath = saveLocation
                  overlay = None }
            makeImage spec |> Async.RunSynchronously
            fileSaved (spec.width.ToString()) (spec.height.ToString()) = true

        [<Property>]
        let ``Can create an image with border`` () =
            resetSavingTestArea ()
            let spec =
                { // See note accompanying 'randomInt' function for constraints information.
                  width =  randomInt ()
                  height = randomInt ()
                  colour = randomColour () :?> Brush
                  filePath = saveLocation
                  overlay = Some (buildBorderOverlay ()) }
            makeImage spec |> Async.RunSynchronously
            fileSaved (spec.width.ToString()) (spec.height.ToString()) = true

        [<Property>]
        let ``Can create an image with a full overlay`` () =
            resetSavingTestArea ()
            let spec =
                { // See note accompanying 'randomInt' function for constraints information.
                  width =  randomInt ()
                  height = randomInt ()
                  colour = randomColour () :?> Brush
                  filePath = saveLocation
                  overlay = Some (buildFullOverlay ()) }
            makeImage spec |> Async.RunSynchronously
            fileSaved (spec.width.ToString()) (spec.height.ToString()) = true