module ParasitemiaUI.GUI

open System
open System.IO
open System.Linq
open System.Windows
open System.Windows.Media
open System.Windows.Markup
open System.Windows.Shapes
open System.Windows.Controls
open System.Diagnostics
open Microsoft.Win32 // For the common dialogs.

open Emgu.CV.WPF

open Logger

open ParasitemiaCore.Config
open ParasitemiaCore.Utils
open Types

let run (defaultConfig: Config) (fileToOpen: string option) =
    let app = new Application()
    let win = Views.MainWindow()

    let state = State.State(defaultConfig)
    let mutable currentScale = 1.
    let mutable displayHealthy = false
    let warningBelowNumberOfRBC = 1000

    // Initializations.
    let canvasCurrentImageColor = win.canvasCurrentImage.Background
    win.menuHightlightRBC.IsChecked <- displayHealthy

    // Utils.
    let extractRBCPreview (img: Emgu.CV.Image<Emgu.CV.Structure.Bgr, byte>) (rbc: RBC) : Emgu.CV.Image<Emgu.CV.Structure.Bgr, byte> =
        let rbcWidth = rbc.size.Width
        let rbcHeight = rbc.size.Height
        let x = rbc.center.X - rbcWidth / 2. |> roundInt
        let y = rbc.center.Y - rbcHeight / 2. |> roundInt
        let w = roundInt rbcWidth
        let h = roundInt rbcHeight
        img.GetSubRect(System.Drawing.Rectangle(System.Drawing.Point((if x < 0 then 0 else x), (if y < 0 then 0 else y)),
                                                System.Drawing.Size((if x + w >= img.Width then img.Width - x else w),
                                                                    (if y + h >= img.Height then img.Height - y else h))))

    let setRBCFrameStyle (srcImg: SourceImage) (rbc: RBC) (frame: Views.RBCFrame) =
        frame.Opacity <- if displayHealthy || rbc.setManually || rbc.infected then 1. else 0.
        let color = if rbc.infected then srcImg.InfectedRBCColor else srcImg.HealthyRBCColor
        frame.manuallyAdded.Visibility <- if rbc.setManually then Visibility.Visible else Visibility.Hidden
        frame.manuallyAdded.Fill <- color
        frame.border.Stroke <- color

    let RBCFrameFromExisting (srcImg: SourceImage) (rbc: RBC) (frame: Views.RBCFrame) : Views.RBCFrame =
        frame.Visibility <- Visibility.Visible
        frame.Height <- rbc.size.Height
        frame.Width <- rbc.size.Width
        frame.Tag <- rbc
        setRBCFrameStyle srcImg rbc frame
        frame.border.StrokeThickness <- 1.
        frame.txtRBCNumber.Text <- rbc.num.ToString()
        frame

    let updateDocumentStatus () =
        win.txtDocumentStatus.Text <- if state.FilePath = "" then "<New document>" else state.FilePath

    let statusMessageTimer = Threading.DispatcherTimer()
    statusMessageTimer.Tick.AddHandler(fun obj args -> statusMessageTimer.Stop(); win.txtMessageStatus.Text <- "")
    statusMessageTimer.Interval <- TimeSpan(0, 0, 2)
    let displayStatusMessage (message: string) =
        win.txtMessageStatus.Text <- message
        statusMessageTimer.Stop()
        statusMessageTimer.Start()

    let highlightRBCFrame (frame: Views.RBCFrame) (highlight: bool) =
        let rbc = frame.Tag :?> RBC
        if highlight
        then
            frame.border.StrokeThickness <- 3.
            if not rbc.infected && not rbc.setManually && not displayHealthy then frame.Opacity <- 1.
        else
            frame.border.StrokeThickness <- 1.
            if not rbc.infected && not rbc.setManually && not displayHealthy then frame.Opacity <- 0.

    let zoomToRBC (rbc: RBC) =
        win.scrollViewCurrentImage.ScrollToHorizontalOffset(rbc.center.X * currentScale - win.scrollViewCurrentImage.ViewportWidth / 2. + win.borderCurrentImage.BorderThickness.Left)
        win.scrollViewCurrentImage.ScrollToVerticalOffset(rbc.center.Y * currentScale - win.scrollViewCurrentImage.ViewportHeight / 2. + win.borderCurrentImage.BorderThickness.Top)


    let txtImageName_TextChanged =
        TextChangedEventHandler(fun obj args -> state.CurrentImage |> Option.iter(fun srcImg -> state.SetName srcImg win.txtImageName.Text))

    let updateCurrentImageInformation () =
        win.txtImageName.TextChanged.RemoveHandler(txtImageName_TextChanged)
        win.txtImageInformation1.Inlines.Clear()
        win.txtImageInformation2.Inlines.Clear()
        win.txtImageName.Text <- ""

        match state.CurrentImage with
        | Some srcImg ->
            win.gridImageInformation.Visibility <- Visibility.Visible
            win.txtImageName.Text <- srcImg.name
            win.txtImageName.TextChanged.AddHandler(txtImageName_TextChanged)

            // The left part.
            let parasitemiaStr = Utils.percentText (state.ImageParasitemia srcImg)
            win.txtImageInformation1.Inlines.Add(Documents.Run("Parasitemia: ", FontWeight = FontWeights.Bold))
            win.txtImageInformation1.Inlines.Add(parasitemiaStr)
            win.txtImageInformation1.Inlines.Add(Documents.LineBreak())

            win.txtImageInformation1.Inlines.Add(Documents.Run("Last analysis: ", FontWeight = FontWeights.Bold))
            win.txtImageInformation1.Inlines.Add(Documents.Run(if srcImg.dateLastAnalysis.Ticks = 0L then "<Never>" else srcImg.dateLastAnalysis.ToLocalTime().ToString()))

            // The right part part.
            win.txtImageInformation2.Inlines.Add(Documents.Run("Added infected erythrocyte: ", FontWeight = FontWeights.Bold))
            win.txtImageInformation2.Inlines.Add(Documents.Run((state.ImageNbManuallyChangedRBCStr srcImg true) + " " + (state.ImageManuallyChangedRBCStr srcImg true)))
            win.txtImageInformation2.Inlines.Add(Documents.LineBreak())
            win.txtImageInformation2.Inlines.Add(Documents.Run("Removed infected erythrocyte: ", FontWeight = FontWeights.Bold))
            win.txtImageInformation2.Inlines.Add(Documents.Run((state.ImageNbManuallyChangedRBCStr srcImg false) + " " + (state.ImageManuallyChangedRBCStr srcImg false)))

        | _ ->
            win.gridImageInformation.Visibility <- Visibility.Hidden

    let updateGlobalParasitemia () =
        win.txtGlobalParasitemia.Inlines.Clear()
        let total, infected = state.GlobalParasitemia
        win.txtGlobalParasitemia.Inlines.Add(Documents.Run(Utils.percentText (total, infected), FontWeight = FontWeights.Bold))
        if total > 0 && total < warningBelowNumberOfRBC
        then
            win.txtGlobalParasitemia.Inlines.Add(
                Documents.Run(
                    sprintf " Warning: the number of erythrocytes should be above %d" warningBelowNumberOfRBC,
                    FontWeight = FontWeights.Bold,
                    Foreground = Brushes.Red))

    let updateViewportPreview () =
        for preview in win.stackPreviews.Children |> Seq.cast<Views.ImageSourcePreview> do
            let srcImg = preview.Tag :?> SourceImage
            if Some srcImg = state.CurrentImage then
                preview.viewport.Visibility <- Visibility.Visible

                let canvasWidth = win.canvasCurrentImage.ActualWidth * currentScale
                let canvasHeight = win.canvasCurrentImage.ActualHeight * currentScale
                let previewWidth = (preview.ActualWidth - preview.BorderThickness.Left - preview.BorderThickness.Right)
                let previewHeight = (preview.ActualHeight - preview.BorderThickness.Top - preview.BorderThickness.Bottom)

                let marginLeft = previewWidth * (win.scrollViewCurrentImage.HorizontalOffset - win.borderCurrentImage.BorderThickness.Left) / canvasWidth - 2.
                let marginRight = previewWidth * (canvasWidth - (win.scrollViewCurrentImage.HorizontalOffset - win.borderCurrentImage.BorderThickness.Right) - win.scrollViewCurrentImage.ViewportWidth) / canvasWidth - 2.
                let marginTop = previewHeight * (win.scrollViewCurrentImage.VerticalOffset - win.borderCurrentImage.BorderThickness.Top) / canvasHeight - 2.
                let marginBottom = previewHeight * (canvasHeight - (win.scrollViewCurrentImage.VerticalOffset - win.borderCurrentImage.BorderThickness.Bottom) - win.scrollViewCurrentImage.ViewportHeight) / canvasHeight - 2.

                preview.viewport.Margin <-
                    Thickness(
                        marginLeft,
                        marginTop,
                        marginRight,
                        marginBottom)
            else
                preview.viewport.Visibility <- Visibility.Hidden

    let rec setAsInfected (srcImg: SourceImage) (rbc: RBC) (infected: bool) =
        state.SetAsInfected rbc infected
        win.canvasCurrentImage.Children
        |> Seq.cast<Views.RBCFrame>
        |> Seq.iter
            (fun frame ->
                if (frame.Tag :?> RBC) = rbc
                then
                    setRBCFrameStyle srcImg rbc frame)
        updateRBCFramesPreview ()
        updateCurrentImageInformation ()
        updateGlobalParasitemia ()

    and RBCFrame (srcImg: SourceImage) (rbc: RBC) : Views.RBCFrame =
        let frame = RBCFrameFromExisting srcImg rbc (Views.RBCFrame())
        frame.SetValue(Panel.ZIndexProperty, Int32.MaxValue - rbc.num) // To be sure the
        frame.menuRBCSetAsHealthy.Click.AddHandler(fun obj args -> setAsInfected srcImg (frame.Tag :?> RBC) false)
        frame.menuRBCSetAsInfected.Click.AddHandler(fun obj args -> setAsInfected srcImg (frame.Tag :?> RBC) true)
        frame.ContextMenuOpening.AddHandler(
            fun obj args ->
                if (frame.Tag :?> RBC).infected
                then
                    frame.menuRBCSetAsHealthy.Visibility <- Visibility.Visible
                    frame.menuRBCSetAsInfected.Visibility <- Visibility.Collapsed
                else
                    frame.menuRBCSetAsHealthy.Visibility <- Visibility.Collapsed
                    frame.menuRBCSetAsInfected.Visibility <- Visibility.Visible)

        frame.ContextMenuClosing.AddHandler(fun obj args -> if not frame.IsMouseOver then highlightRBCFrame frame false )
        frame.MouseEnter.AddHandler(fun obj args -> highlightRBCFrame frame true)
        frame.MouseLeave.AddHandler(fun obj args -> if not frame.grid.ContextMenu.IsOpen then highlightRBCFrame frame false)
        frame

    and updateRBCFramesPreview () =
        match state.CurrentImage with
        | Some srcImg ->
            let mutable currentPreview = 0
            for rbc in srcImg.rbcs |> List.filter (fun rbc -> displayHealthy || rbc.infected) do
                let previewInfected =
                    if currentPreview < win.stackRBC.Children.Count
                    then
                        RBCFrameFromExisting srcImg rbc (win.stackRBC.Children.[currentPreview] :?> Views.RBCFrame)
                    else
                        let f = RBCFrame srcImg rbc
                        f.MouseLeftButtonUp.AddHandler(fun obj args -> zoomToRBC (f.Tag :?> RBC))
                        win.stackRBC.Children.Add(f) |> ignore
                        f

                currentPreview <- currentPreview + 1

                previewInfected.Height <- win.stackRBC.ActualHeight
                previewInfected.Width <- win.stackRBC.ActualHeight * rbc.size.Width / rbc.size.Height
                previewInfected.border.Fill <- ImageBrush(BitmapSourceConvert.ToBitmapSource(extractRBCPreview srcImg.img rbc))

            win.stackRBC.Children.RemoveRange(currentPreview, win.stackRBC.Children.Count - currentPreview)
        | _ -> ()

        updateViewportPreview ()

    let updateRBCFramesCurrent () =
        match state.CurrentImage with
        | Some srcImg ->
            let mutable currentCanvas = 0
            for rbc in srcImg.rbcs do
                let frame =
                    if currentCanvas < win.canvasCurrentImage.Children.Count
                    then
                        RBCFrameFromExisting srcImg rbc (win.canvasCurrentImage.Children.[currentCanvas] :?> Views.RBCFrame)
                    else
                        let f = RBCFrame srcImg rbc
                        f.Root.Opacity <- 0.7
                        win.canvasCurrentImage.Children.Add(f) |> ignore
                        f

                currentCanvas <- currentCanvas + 1

                Canvas.SetLeft(frame, rbc.center.X - rbc.size.Width / 2.)
                Canvas.SetTop(frame, rbc.center.Y - rbc.size.Height / 2.)

            for i in currentCanvas .. win.canvasCurrentImage.Children.Count - 1 do
                win.canvasCurrentImage.Children.[i].Visibility <- Visibility.Hidden
        | _ -> ()

    let askDocumentPathToSave () : string option =
        let dialog = SaveFileDialog(AddExtension = true, DefaultExt = PiaZ.extension, Filter = PiaZ.filter)

        if state.FilePath <> ""
        then
            dialog.FileName <- FileInfo(state.FilePath).Name
        elif state.PatientID <> ""
        then
            dialog.FileName <- state.PatientID + PiaZ.extension

        let res = dialog.ShowDialog()
        if res.HasValue && res.Value then
            Some dialog.FileName
        else
            None

    let saveCurrentDocument () =
        try
            if state.FilePath = ""
            then
                match askDocumentPathToSave () with
                | Some filepath ->
                    state.FilePath <- filepath
                    state.Save()
                | _ -> ()
            else
                state.Save()
            updateDocumentStatus ()
            displayStatusMessage "Document saved"
        with
        | :? IOException as ex ->
            Log.Error(ex.ToString())
            MessageBox.Show(sprintf "The document cannot be save in '%s'" state.FilePath, "Error saving the document", MessageBoxButton.OK, MessageBoxImage.Error) |> ignore

    let saveCurrentDocumentAsNewFile () =
        match askDocumentPathToSave () with
        | Some filepath ->
            state.FilePath <- filepath
            saveCurrentDocument ()
        | _ -> ()

    // Ask the use to save the current document if neccessary.
    let askSaveCurrent () =
        if state.AlteredSinceLastSave
        then
            match MessageBox.Show("Would you like to save the current document?", "Saving the current document", MessageBoxButton.YesNo, MessageBoxImage.Question) with
            | MessageBoxResult.Yes -> saveCurrentDocument ()
            | _ -> ()

    let updateCurrentImage () =
        match state.CurrentImage with
        | Some srcImg ->
            win.imgLogos.Visibility <- Visibility.Collapsed

            // Highlight the preview.
            win.stackPreviews.Children
            |> Seq.cast<Views.ImageSourcePreview>
            |> Seq.iter (fun preview -> preview.border.BorderThickness <- Thickness(if preview.Tag = (srcImg :> Object) then 3. else 0.))

            win.canvasCurrentImage.Height <- float srcImg.img.Height
            win.canvasCurrentImage.Width <- float srcImg.img.Width
            win.canvasCurrentImage.Background <- ImageBrush(BitmapSourceConvert.ToBitmapSource(srcImg.img))

            updateRBCFramesCurrent ()
            updateRBCFramesPreview ()

        | None ->
            win.imgLogos.Visibility <- Visibility.Visible

            win.stackRBC.Children.Clear()
            win.canvasCurrentImage.Children.Clear()
            win.canvasCurrentImage.Background <- canvasCurrentImageColor

        updateCurrentImageInformation ()

    let setCurrentImage (srcImg: SourceImage) =
        if state.CurrentImage.IsNone || state.CurrentImage.Value <> srcImg
        then
            state.CurrentImage <- Some srcImg
            updateCurrentImage ()

    let addPreview (srcImg: SourceImage) =
        let imgCtrl = Views.ImageSourcePreview(Margin = Thickness(3.))

        imgCtrl.menuRemoveImage.Click.AddHandler(fun obj args ->
            win.stackPreviews.Children.Remove(imgCtrl)
            let srcImg = imgCtrl.Tag :?> SourceImage
            let currentRemoved = Some srcImg = state.CurrentImage
            state.RemoveSourceImage srcImg
            if currentRemoved
            then
                updateCurrentImage()

            updateGlobalParasitemia()

            // Update image numbers.
            win.stackPreviews.Children |> Seq.cast<Views.ImageSourcePreview> |> Seq.iter (fun imgPreview -> imgPreview.txtImageNumber.Text <- (imgPreview.Tag :?> SourceImage).num.ToString()))

        imgCtrl.Tag <- srcImg
        imgCtrl.txtImageNumber.Text <- srcImg.num.ToString()
        let width = 200
        let height = srcImg.img.Height * width / srcImg.img.Width
        imgCtrl.imagePreview.Source <- BitmapSourceConvert.ToBitmapSource(srcImg.img.Resize(width, height, Emgu.CV.CvEnum.Inter.Cubic))
        win.stackPreviews.Children.Add(imgCtrl) |> ignore

        // Zoom to a mouse position into the control 'imgCtrl'.
        let zoomTo (mousePos: Point) =
            let canvasW = win.canvasCurrentImage.ActualWidth * currentScale
            let canvasH = win.canvasCurrentImage.ActualHeight * currentScale
            let centerX = (mousePos.X - imgCtrl.BorderThickness.Left) / (imgCtrl.ActualWidth - imgCtrl.BorderThickness.Left) * canvasW
            let centerY = (mousePos.Y - imgCtrl.BorderThickness.Top) / (imgCtrl.ActualHeight - imgCtrl.BorderThickness.Top) * canvasH
            win.scrollViewCurrentImage.ScrollToHorizontalOffset(centerX - win.scrollViewCurrentImage.ViewportWidth / 2. + win.borderCurrentImage.BorderThickness.Left)
            win.scrollViewCurrentImage.ScrollToVerticalOffset(centerY - win.scrollViewCurrentImage.ViewportHeight / 2. + win.borderCurrentImage.BorderThickness.Top)

        imgCtrl.MouseLeftButtonDown.AddHandler(fun obj args ->
            setCurrentImage (state.SourceImages |> Seq.find (fun srcImg -> (srcImg :> Object) = imgCtrl.Tag))
            imgCtrl.UpdateLayout()
            zoomTo (args.GetPosition(imgCtrl))
            imgCtrl.CaptureMouse() |> ignore)

        imgCtrl.MouseMove.AddHandler(fun obj args ->
            if imgCtrl.IsMouseCaptured
            then
                zoomTo (args.GetPosition(imgCtrl)))

        imgCtrl.MouseLeftButtonUp.AddHandler(fun obj args ->
            if imgCtrl.IsMouseCaptured
            then
                imgCtrl.ReleaseMouseCapture())

    let updatePreviews () =
        win.stackPreviews.Children.Clear ()
        for srcImg in state.SourceImages do
            addPreview srcImg
        updateCurrentImage ()

    let updateGUI () =
        win.txtPatient.Text <- state.PatientID
        updatePreviews ()
        updateGlobalParasitemia ()
        updateDocumentStatus ()

    let loadFile (filepath: string) =
        askSaveCurrent ()
        let previousFilePath = state.FilePath
        try
            state.FilePath <- filepath
            state.Load()
            updateGUI ()
        with
        | :? IOException as ex ->
            Log.Error(ex.ToString())
            state.FilePath <- previousFilePath
            MessageBox.Show(sprintf "The document cannot be loaded from '%s'" state.FilePath, "Error loading the document", MessageBoxButton.OK, MessageBoxImage.Error) |> ignore

    let askLoadFile () =
        let dialog = OpenFileDialog(Filter = PiaZ.filter)
        let res = dialog.ShowDialog()
        if res.HasValue && res.Value
        then loadFile dialog.FileName

    let newFile () =
        askSaveCurrent ()
        state.Reset()
        updateGUI()

    let exportResults () =
        let extension = ".txt"
        let dialog = SaveFileDialog(AddExtension = true, DefaultExt = extension)

        if state.FilePath <> ""
        then
            dialog.FileName <- Path.GetFileNameWithoutExtension(state.FilePath) + extension
        elif state.PatientID <> ""
        then
            dialog.FileName <- state.PatientID + extension

        let res = dialog.ShowDialog()
        if res.HasValue && res.Value then
            try
                Export.exportResults state dialog.FileName
            with
            | :? IOException as ex ->
                Log.Error(ex.ToString())
                MessageBox.Show(sprintf "The results cannot be exported in '%s'" state.FilePath, "Error exporting the files", MessageBoxButton.OK, MessageBoxImage.Error) |> ignore

    win.txtPatient.TextChanged.AddHandler(fun obj args -> state.PatientID <- win.txtPatient.Text)

    win.menuExit.Click.AddHandler(fun obj args -> win.Root.Close())
    win.menuSave.Click.AddHandler(fun obj args -> saveCurrentDocument ())
    win.menuSaveAs.Click.AddHandler(fun obj args -> saveCurrentDocumentAsNewFile ())
    win.menuOpen.Click.AddHandler(fun obj args -> askLoadFile ())
    win.menuNew.Click.AddHandler(fun obj args -> newFile ())
    win.menuExportResults.Click.AddHandler(fun obj args -> exportResults ())

    win.menuAddSourceImage.Click.AddHandler(fun obj args ->
        let dialog = OpenFileDialog(Filter = "Image Files|*.png;*.jpg;*.tif;*.tiff", Multiselect = true)
        let res = dialog.ShowDialog()
        if res.HasValue && res.Value
        then
            let noSourceImage = state.SourceImages.Count() = 0

            for filename in dialog.FileNames do
                try
                    let srcImg = state.AddSourceImage filename defaultConfig
                    addPreview srcImg
                with
                | _ as ex ->
                    Log.Error(ex.ToString())
                    MessageBox.Show(sprintf "Unable to read the image from '%s'" filename, "Error adding an image", MessageBoxButton.OK, MessageBoxImage.Error) |> ignore

            updateGlobalParasitemia ()

            if noSourceImage
            then
                updateCurrentImage ())

    win.menuAnalysis.SubmenuOpened.AddHandler(fun obj args -> win.menuStartAnalysis.IsEnabled <- state.SourceImages.Count() > 0)

    win.menuStartAnalysis.Click.AddHandler(fun obj args ->
        if Analysis.showWindow win.Root state
        then
            updateGlobalParasitemia ()
            updateCurrentImage ())

    win.menuHightlightRBC.Click.AddHandler(fun obj args ->
        displayHealthy <- win.menuHightlightRBC.IsChecked
        updateRBCFramesPreview ()
        updateRBCFramesCurrent ())

    win.menuAbout.Click.AddHandler(fun obj args -> About.showWindow win.Root)

    win.Root.Closing.AddHandler(fun obj args -> askSaveCurrent ())

    // Zoom on the current image.
    let adjustCurrentImageBorders (deltaX: float) (deltaY: float) =
        win.borderCurrentImage.BorderThickness <-
            Thickness(
                (win.scrollViewCurrentImage.ViewportWidth + deltaX) / 2.,
                (win.scrollViewCurrentImage.ViewportHeight + deltaY) / 2.,
                (win.scrollViewCurrentImage.ViewportWidth + deltaX) / 2.,
                (win.scrollViewCurrentImage.ViewportHeight + deltaY) / 2.)

    win.canvasCurrentImage.SizeChanged.AddHandler(fun obj args ->
        let deltaX = args.NewSize.Width - args.PreviousSize.Width
        let deltaY = args.NewSize.Height - args.PreviousSize.Height
        if deltaX > 0.5 || deltaY > 0.5
        then
            adjustCurrentImageBorders 0.0 0.0
            // Center the view at the center of the image initialy.
            win.scrollViewCurrentImage.UpdateLayout()
            win.scrollViewCurrentImage.ScrollToHorizontalOffset(win.borderCurrentImage.ActualWidth / 2. - win.scrollViewCurrentImage.ViewportWidth / 2.)
            win.scrollViewCurrentImage.ScrollToVerticalOffset(win.borderCurrentImage.ActualHeight / 2. - win.scrollViewCurrentImage.ViewportHeight / 2.))

    win.scrollViewCurrentImage.SizeChanged.AddHandler(fun obj args ->
        let deltaX = args.NewSize.Width - args.PreviousSize.Width
        let deltaY = args.NewSize.Height - args.PreviousSize.Height
        adjustCurrentImageBorders deltaX deltaY
        win.scrollViewCurrentImage.ScrollToHorizontalOffset(win.scrollViewCurrentImage.HorizontalOffset + deltaX / 8.)
        win.scrollViewCurrentImage.ScrollToVerticalOffset(win.scrollViewCurrentImage.VerticalOffset + deltaY / 8.))

    let mutable maxScale = 4.
    let mutable minScale = 0.25
    let currentImageScaleTransform = ScaleTransform()
    win.canvasCurrentImage.LayoutTransform <- currentImageScaleTransform
    win.borderCurrentImage.PreviewMouseWheel.AddHandler(fun obj args ->
        let scaleFactor = if args.Delta > 0 then 2.0 else 0.5
        if scaleFactor > 1. && currentScale < maxScale || scaleFactor < 1. && currentScale > minScale
        then
            let previousScale = currentScale
            currentScale <-
                let newScale = currentScale * scaleFactor
                if newScale > maxScale then maxScale elif newScale < minScale then minScale else newScale
            let realScaleFactor = currentScale / previousScale

            let centerX = win.scrollViewCurrentImage.HorizontalOffset + win.scrollViewCurrentImage.ViewportWidth / 2. - win.borderCurrentImage.BorderThickness.Left
            let centerY = win.scrollViewCurrentImage.VerticalOffset + win.scrollViewCurrentImage.ViewportHeight / 2. - win.borderCurrentImage.BorderThickness.Top

            currentImageScaleTransform.ScaleX <- currentScale
            currentImageScaleTransform.ScaleY <- currentScale

            win.scrollViewCurrentImage.ScrollToHorizontalOffset(centerX * realScaleFactor - win.scrollViewCurrentImage.ViewportWidth / 2. + win.borderCurrentImage.BorderThickness.Left)
            win.scrollViewCurrentImage.ScrollToVerticalOffset(centerY * realScaleFactor - win.scrollViewCurrentImage.ViewportHeight / 2. + win.borderCurrentImage.BorderThickness.Top)

        args.Handled <- true)

    // Pan on the current image.
    let mutable scrollStartPosition = Point(0., 0.)
    let mutable scrollStartOffsetX = 0.
    let mutable scrollStartOffsetY = 0.
    win.borderCurrentImage.PreviewMouseLeftButtonDown.AddHandler(fun obj args ->
        scrollStartPosition <- args.GetPosition(win.scrollViewCurrentImage)
        scrollStartOffsetX <- win.scrollViewCurrentImage.HorizontalOffset
        scrollStartOffsetY <- win.scrollViewCurrentImage.VerticalOffset
        win.borderCurrentImage.Cursor <- Input.Cursors.ScrollAll
        win.borderCurrentImage.CaptureMouse() |> ignore
        args.Handled <- true)

    win.borderCurrentImage.PreviewMouseMove.AddHandler(fun obj args ->
        if win.borderCurrentImage.IsMouseCaptured
        then
            let position = args.GetPosition(win.scrollViewCurrentImage)
            let deltaX = scrollStartPosition.X - position.X
            let deltaY = scrollStartPosition.Y - position.Y
            win.scrollViewCurrentImage.ScrollToHorizontalOffset(deltaX + scrollStartOffsetX)
            win.scrollViewCurrentImage.ScrollToVerticalOffset(deltaY + scrollStartOffsetY)

            args.Handled <- true)

    win.borderCurrentImage.PreviewMouseLeftButtonUp.AddHandler(fun obj args ->
        if win.borderCurrentImage.IsMouseCaptured
        then
            win.borderCurrentImage.Cursor <- Input.Cursors.Arrow
            win.borderCurrentImage.ReleaseMouseCapture()
            args.Handled <- true)

    // Shortcuts.
    // Save.
    win.Root.InputBindings.Add(
        Input.KeyBinding(
            FSharp.ViewModule.FunCommand((fun obj -> saveCurrentDocument ()), (fun obj -> true)),
            Input.KeyGesture(Input.Key.S, Input.ModifierKeys.Control))) |> ignore

    // Save as.
    win.Root.InputBindings.Add(
        Input.KeyBinding(
            FSharp.ViewModule.FunCommand((fun obj -> saveCurrentDocumentAsNewFile ()), (fun obj -> true)),
            Input.KeyGesture(Input.Key.S, Input.ModifierKeys.Control ||| Input.ModifierKeys.Shift))) |> ignore

    // Open.
    win.Root.InputBindings.Add(
        Input.KeyBinding(
            FSharp.ViewModule.FunCommand((fun obj -> askLoadFile ()), (fun obj -> true)),
            Input.KeyGesture(Input.Key.O, Input.ModifierKeys.Control))) |> ignore

    // New file.
    win.Root.InputBindings.Add(
        Input.KeyBinding(
            FSharp.ViewModule.FunCommand((fun obj -> newFile ()), (fun obj -> true)),
            Input.KeyGesture(Input.Key.N, Input.ModifierKeys.Control))) |> ignore

    // Export results.
    win.Root.InputBindings.Add(
        Input.KeyBinding(
            FSharp.ViewModule.FunCommand((fun obj -> exportResults ()), (fun obj -> true)),
            Input.KeyGesture(Input.Key.E, Input.ModifierKeys.Control))) |> ignore

    // Viewport preview.
    win.scrollViewCurrentImage.ScrollChanged.AddHandler(fun obj args -> updateViewportPreview ())

    updateDocumentStatus ()
    win.gridImageInformation.Visibility <- Visibility.Hidden

    win.Root.Show()

    match fileToOpen with
    | Some filepath -> loadFile filepath
    | None -> ()

    app.Run()