using System;
using System.ComponentModel;
using System.Runtime.InteropServices;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Forms;
using System.Windows.Input;
using System.Windows.Interop;

namespace CustomControls
{
    [DesignTimeVisible(false)]
    public partial class ChromeWindow : Window, IForm
    {
        private IntPtr handle;

        public System.Windows.Controls.ContentControl ContentControl => this.AppArea;

        private bool extendedAppArea;
        public bool ExtendedAppArea
        {
            get => extendedAppArea;
            set
            {
                extendedAppArea = value;
                Grid.SetRow(this.AppArea, value ? 0 : 1);
                Grid.SetRowSpan(this.AppArea, value ? 2 : 1);
            }
        }

        private double extendedAppAreaSize;
        public double ExtendedAppAreaSize
        {
            get => extendedAppAreaSize;
            set
            {
                extendedAppAreaSize = value;
                this.TitleArea.Margin = new Thickness(value, 0, 0, 0);
                this.TitleDock.Margin = new Thickness(-value, 0, 0, 0);
                this.TitleText.Margin = new Thickness(value + 8, 0, 140, 0);
            }
        }

        public System.Drawing.Size ClientSizeDelta
        {
            get
            {
                double scale = Helper.GetDpiScale(this);
                return new System.Drawing.Size(0, (int)(scale * (ExtendedAppArea ? 0 : TitleArea.Height)));
            }
        }

        private FormBorderStyle formBorderStyle;
        public FormBorderStyle FormBorderStyle
        {
            get => formBorderStyle;
            set
            {
                formBorderStyle = value;
                MinimizeBox = MaximizeBox = value == FormBorderStyle.Sizable || value == FormBorderStyle.SizableToolWindow;
                ShowIcon = value == FormBorderStyle.Sizable;
            }
        }

        private bool maximizeBox;
        public bool MaximizeBox
        {
            get => maximizeBox;
            set
            {
                maximizeBox = value;
                UpdateMaximizeRestoreState();
            }
        }

        private bool minimizeBox;
        public bool MinimizeBox
        {
            get => minimizeBox;
            set
            {
                minimizeBox = value;
                MinimizeButton.Visibility = value ? Visibility.Visible : Visibility.Collapsed;
            }
        }

        public bool ShowIcon
        {
            get => TitleIcon.Visibility == Visibility.Visible;
            set => TitleIcon.Visibility = value ? Visibility.Visible : Visibility.Collapsed;
        }

        public ChromeWindow()
        {
            InitializeComponent();
            StateChanged += (s, e) => UpdateMaximizeRestoreState();
            SourceInitialized += (s, e) =>
            {
                handle = new WindowInteropHelper(this).Handle;
                HwndSource.FromHwnd(handle).AddHook(WindowProc);
                UpdateMaximizeRestoreState();
            };
        }

        private IntPtr WindowProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
        {
            const int WM_GETMINMAXINFO = 0x24;
            const int WM_NCCALCSIZE = 0x83;
            const int WM_NCHITTEST = 0x84;
            const int HT_CLIENT = 1;

            // 1. in order to use snap features, we have to set the ResizeMode to CanResize
            // 2. setting WindowStyle to SingleBorderWindow is required to get maximize/restore animations
            // 3. use WM_NCCALCSIZE (handle and return 0) to remove non-client area
            // 4. the maximized window's client area is off now. Don't try to reduce it using wpf margins: on a multi-monitor system this will degrade rendering performance
            // 5. update WM_NCCALCSIZE to return smaller client area when maximized
            // 6. now we have popping effect when maximized window is shown first time (due to changed nc size)
            // 7. handle WM_GETMINMAXINFO to return smaller maximized bounds to cheat Windows
            // 8. the only side effect we have is a single pixel gap at the bottom of maximized window

            switch (msg)
            {
                case WM_GETMINMAXINFO:
                    WmGetMinMaxInfo(hwnd, lParam);
                    handled = true;
                    break;

                case WM_NCCALCSIZE:
                    if (NativeMethods.IsWindowMaximized(hwnd))
                    {
                        var rc = Marshal.PtrToStructure<NativeMethods.RECT>(lParam);
                        var screen = Screen.FromHandle(hwnd);
                        rc.left = screen.WorkingArea.Left;
                        rc.top = screen.WorkingArea.Top;
                        rc.right = screen.WorkingArea.Right;
                        rc.bottom = screen.WorkingArea.Bottom - 1; // -1 to allow auto-hide taskbar (at the bottom)
                        Marshal.StructureToPtr(rc, lParam, true);
                    }
                    else if (wParam.ToInt32() != 0)
                    {
                        var rc = Marshal.PtrToStructure<NativeMethods.RECT>(lParam);
                        // cheat Windows to force a flicker free resize
                        rc.bottom += 1;
                        Marshal.StructureToPtr(rc, lParam, true);
                    }

                    var retVal = IntPtr.Zero;
                    if (wParam.ToInt32() != 0)
                    {
                        // returning VALIDRECTS | REDRAW gives the smoothest resize behavior
                        retVal = new IntPtr(0x0400 | 0x0100 | 0x0200);
                    }

                    handled = true;
                    return retVal;

                case WM_NCHITTEST:
                    // required for Win7 (caption buttons issue)
                    handled = true;
                    return new IntPtr(HT_CLIENT);
            }
            return (IntPtr)0;
        }

        private void WmGetMinMaxInfo(IntPtr hwnd, IntPtr lParam)
        {
            var mmi = Marshal.PtrToStructure<NativeMethods.MINMAXINFO>(lParam);

            var screen = Screen.FromHandle(hwnd);
            mmi.ptMaxPosition.X = screen.WorkingArea.Left - screen.Bounds.Left;
            mmi.ptMaxPosition.Y = screen.WorkingArea.Top - screen.Bounds.Top;
            mmi.ptMaxSize.X = screen.WorkingArea.Width;
            mmi.ptMaxSize.Y = screen.WorkingArea.Height - 1; // -1 is a cheat to remove popping effect when maximize window on startup
            mmi.ptMinTrackSize.X = 50;
            mmi.ptMinTrackSize.Y = 50;

            Marshal.StructureToPtr(mmi, lParam, true);
        }

        private void CommandBinding_CanExecute(object sender, CanExecuteRoutedEventArgs e)
        {
            e.CanExecute = true;
        }

        private void CommandBinding_Executed_Minimize(object sender, ExecutedRoutedEventArgs e)
        {
            SystemCommands.MinimizeWindow(this);
        }

        private void CommandBinding_Executed_Maximize(object sender, ExecutedRoutedEventArgs e)
        {
            WindowState = WindowState.Maximized;// SystemCommands.MaximizeWindow(this); // issue with dragging maximized window
        }

        private void CommandBinding_Executed_Restore(object sender, ExecutedRoutedEventArgs e)
        {
            SystemCommands.RestoreWindow(this);
        }

        private void CommandBinding_Executed_Close(object sender, ExecutedRoutedEventArgs e)
        {
            SystemCommands.CloseWindow(this);
        }

        private void UpdateMaximizeRestoreState()
        {
            if (WindowState == WindowState.Maximized)
            {
                RestoreButton.Visibility = MaximizeBox ? Visibility.Visible : Visibility.Collapsed;
                MaximizeButton.Visibility = Visibility.Collapsed;
                WindowBorder.Visibility = Visibility.Collapsed;
                ResizingBorder.Visibility = Visibility.Collapsed;
                NativeMethods.DropShadow(handle, false);
            }
            else
            {
                RestoreButton.Visibility = Visibility.Collapsed;
                MaximizeButton.Visibility = MaximizeBox ? Visibility.Visible : Visibility.Collapsed;
                WindowBorder.Visibility = Visibility.Visible;
                ResizingBorder.Visibility = Visibility.Visible;
                NativeMethods.DropShadow(handle, WindowState == WindowState.Normal);
            }
        }

        private SizingAction sizingAction;

        private void UpdateCursor(FrameworkElement c, SizingAction mode)
        {
            var cursor = System.Windows.Input.Cursors.Arrow;
            switch (mode)
            {
                case SizingAction.North:
                case SizingAction.South:
                    cursor = System.Windows.Input.Cursors.SizeNS;
                    break;
                case SizingAction.West:
                case SizingAction.East:
                    cursor = System.Windows.Input.Cursors.SizeWE;
                    break;
                case SizingAction.NorthWest:
                case SizingAction.SouthEast:
                    cursor = System.Windows.Input.Cursors.SizeNWSE;
                    break;
                case SizingAction.NorthEast:
                case SizingAction.SouthWest:
                    cursor = System.Windows.Input.Cursors.SizeNESW;
                    break;
            }

            c.Cursor = cursor;
        }

        private void Border_MouseDown(object sender, MouseButtonEventArgs e)
        {
            if (e.LeftButton == MouseButtonState.Pressed && sizingAction != SizingAction.None)
            {
                NativeMethods.DragSize(handle, sizingAction);
                e.Handled = true;
            }
        }

        private void Border_MouseMove(object sender, System.Windows.Input.MouseEventArgs e)
        {
            var border = sender as Border;
            var pos = e.GetPosition(border);
            sizingAction = SizingAction.None;
            if (pos.X == 0 && pos.Y == 0)
                return;

            bool canResize = FormBorderStyle == FormBorderStyle.Sizable || FormBorderStyle == FormBorderStyle.SizableToolWindow;
            if (canResize && e.LeftButton != MouseButtonState.Pressed)
            {
                var width = border.ActualWidth;
                var height = border.ActualHeight;

                if (pos.Y <= 4) // top
                {
                    if (pos.X <= 4)
                        sizingAction = SizingAction.NorthWest;
                    else if (pos.X >= width - 4)
                        sizingAction = SizingAction.NorthEast;
                    else
                        sizingAction = SizingAction.North;
                }
                else if (pos.Y >= height - 4) // bottom
                {
                    if (pos.X <= 4)
                        sizingAction = SizingAction.SouthWest;
                    else if (pos.X >= width - 4)
                        sizingAction = SizingAction.SouthEast;
                    else
                        sizingAction = SizingAction.South;
                }
                else // middle
                {
                    if (pos.X <= 4)
                        sizingAction = SizingAction.West;
                    else if (pos.X >= width - 4)
                        sizingAction = SizingAction.East;
                }

                UpdateCursor(border, sizingAction);
            }
        }

        private void Border_MouseLeave(object sender, System.Windows.Input.MouseEventArgs e)
        {
            var border = sender as Border;
            UpdateCursor(border, SizingAction.None);
        }

        private bool restoreForDragMove;

        private void TitleArea_MouseDown(object sender, MouseButtonEventArgs e)
        {
            if (e.ClickCount > 1)
            {
                if (this.WindowState == WindowState.Maximized)
                    this.WindowState = WindowState.Normal;
                else if (this.WindowState == WindowState.Normal)
                    this.WindowState = WindowState.Maximized;
                return;
            }


            restoreForDragMove = WindowState == WindowState.Maximized;
            DragMove();
            e.Handled = true;
        }

        private void TitleArea_MouseMove(object sender, System.Windows.Input.MouseEventArgs e)
        {
            if (restoreForDragMove)
            {
                restoreForDragMove = false;

                var dpiScale = Helper.GetDpiScale(this);
                var winPoint = e.MouseDevice.GetPosition(this);
                var scrPoint = PointToScreen(winPoint);
                scrPoint.X /= dpiScale;
                scrPoint.Y /= dpiScale;
                var half = RestoreBounds.Width / 2;

                if (winPoint.X < half)
                    Left = scrPoint.X - winPoint.X;
                else if (Width - winPoint.X < half)
                    Left = scrPoint.X - RestoreBounds.Width + (Width - winPoint.X);
                else
                    Left = scrPoint.X - half;

                Top = scrPoint.Y - winPoint.Y;

                WindowState = WindowState.Normal;
                DragMove();
            }
        }

        private void TitleArea_MouseUp(object sender, MouseButtonEventArgs e)
        {
            restoreForDragMove = false;
        }

        private void TitleIcon_MouseDown(object sender, MouseButtonEventArgs e)
        {
            if (e.ClickCount > 1)
            {
                SystemCommands.CloseWindow(this);
                e.Handled = true;
            }
            else
            {
                var pt = this.PointToScreen(new Point(0, TitleArea.ActualHeight));
                var scale = Helper.GetDpiScale(this);
                SystemCommands.ShowSystemMenu(this, new Point(pt.X / scale, pt.Y / scale));
                e.Handled = true;
            }
        }
    }
}