using System.Drawing;

namespace System.Windows.Forms
{
    public class Form : ContainerControl, IWin32Window
    {
        private bool isDisposed;
        private bool isClosing;
        private bool isModal;

        public System.Windows.Window window { get; }

        public static bool UseCustomWindowChrome = false;

        public bool IsCustomWindowChrome => window is CustomControls.ChromeWindow;

        private DialogResult dialogResult;
        public DialogResult DialogResult
        {
            get => dialogResult;
            set
            {
                dialogResult = value;
                if (value == DialogResult.None)
                    return;
                if (!isClosing)
                    window.Close();
            }
        }

        public override string Text
        {
            get => window.Title;
            set => window.Title = value;
        }

        public override int Left 
        { 
            get => (int)(window.Left * DpiScale); 
            set => window.Left = value / DpiScale; 
        }

        public override int Top 
        { 
            get => (int)(window.Top * DpiScale); 
            set => window.Top = value / DpiScale; 
        }

        public override System.Drawing.Size ClientSize
        {
            get
            {
                var delta = ((IForm)window).ClientSizeDelta;
                return new Drawing.Size(Width - delta.Width, Height - delta.Height);
            }
            set
            {
                var delta = ((IForm)window).ClientSizeDelta;
                Width = value.Width + delta.Width;
                Height = value.Height + delta.Height;
            }
        }

        public FormBorderStyle FormBorderStyle
        {
            get => ((IForm)window).FormBorderStyle;
            set => ((IForm)window).FormBorderStyle = value;
        }

        public bool MaximizeBox
        {
            get => ((IForm)window).MaximizeBox;
            set => ((IForm)window).MaximizeBox = value;
        }

        public bool MinimizeBox
        {
            get => ((IForm)window).MinimizeBox;
            set => ((IForm)window).MinimizeBox = value;
        }

        public bool KeyPreview { get; set; } // TODO

        public bool ShowIcon
        {
            get => ((IForm)window).ShowIcon; 
            set => ((IForm)window).ShowIcon = value;
        }

        public Form MdiParent { get; set; } // TODO?

        private Icon icon;
        public Icon Icon
        {
            get => icon;
            set
            {
                icon = value;
                window.Icon = Helper.GetIcon(icon);
            }
        }

        public bool TopMost
        {
            get => window.Topmost;
            set => window.Topmost = value;
        }

        public bool ShowInTaskbar 
        { 
            get => window.ShowInTaskbar;
            set => window.ShowInTaskbar = value;
        }

        public FormStartPosition StartPosition { get; set; }

        private Button acceptButton;
        public Button AcceptButton
        {
            get => acceptButton;
            set
            {
                if (value != acceptButton)
                {
                    if (acceptButton != null)
                        (acceptButton.control as System.Windows.Controls.Button).IsDefault = false;
                    if (value != null)
                        (value.control as System.Windows.Controls.Button).IsDefault = true;
                    acceptButton = value;
                }
            }
        }

        private Button cancelButton;
        public Button CancelButton
        {
            get => cancelButton;
            set
            {
                if (value != cancelButton)
                {
                    if (cancelButton != null)
                        (cancelButton.control as System.Windows.Controls.Button).IsCancel = true;
                    if (value != null)
                        (value.control as System.Windows.Controls.Button).IsCancel = true;
                    cancelButton = value;
                }
            }
        }

        public Form Owner
        {
            get => window.Owner?.Tag as Form;
            set => window.Owner = value?.window;
        }

        public Control ActiveControl // TODO?
        {
            get
            {
                var el = System.Windows.Input.FocusManager.GetFocusedElement(window);
                if (el is System.Windows.Controls.Control ctl && ctl.Tag is Control c)
                    return c;
                return null;
            }
            set
            {
                if (value != null)
                {
                    value.Focus();
                }
            }
        }

        public FormWindowState WindowState
        {
            get => (FormWindowState)window.WindowState;
            set => window.WindowState = (Windows.WindowState)value;
        }

        public bool IsDisposed => isDisposed;

        public override Rectangle DisplayRectangle => new Rectangle(new System.Drawing.Point(0, 0), ClientSize);

        public event EventHandler Load;
        public event EventHandler Shown;
        public event EventHandler Closed;
        public event FormClosingEventHandler FormClosing;
        public event FormClosedEventHandler FormClosed;

        private void CenterWindowOnScreen()
        {
            IntPtr mon = NativeMethods.GetCurrentMonitorFromMousePosition();
            NativeMethods.RECT rect = NativeMethods.WorkAreaBoundsForMointor(mon);
            float dpiScale = (float)NativeMethods.GetDpiForMonitor(mon) / DeviceDpi;
            int newWidth = (int)(Width * dpiScale);
            int newHeight = (int)(Height * dpiScale);
            MoveWindow(rect.left + (rect.Width - newWidth) / 2, rect.top + (rect.Height - newHeight) / 2, newWidth, newHeight);
        }

        private void CenterWindowOnParent()
        {
            if (Owner != null)
            {
                // TODO: check multimonitor dpi!
                window.Left = (Owner.Left + (Owner.Width - Width) / 2) / Owner.DpiScale;
                window.Top = (Owner.Top + (Owner.Height - Height) / 2) / Owner.DpiScale;
            }
        }

        private void SetWindowPosition()
        {
            if (StartPosition == FormStartPosition.CenterScreen)
            {
                CenterWindowOnScreen();
            }
            else if (StartPosition == FormStartPosition.CenterParent)
            {
                CenterWindowOnParent();
            }
        }

        protected virtual void OnLoad(EventArgs e) => Load?.Invoke(this, e);

        protected virtual void OnShown(EventArgs e) => Shown?.Invoke(this, e);

        protected virtual void OnFormClosing(FormClosingEventArgs e) => FormClosing?.Invoke(this, e);

        protected virtual void OnFormClosed(FormClosedEventArgs e)
        {
            FormClosed?.Invoke(this, e);
            OnClosed(EventArgs.Empty);
            isDisposed = true;
        }

        protected virtual void OnClosed(EventArgs e) => Closed?.Invoke(this, e);

        protected override void Dispose(bool disposing)
        {
            base.Dispose(disposing);
            if (disposing)
            {
                window.Close();
            }
        }

        public override void ResumeLayout(bool resume)
        {
            float scale = DeviceDpi / AutoScaleDimensions.Width;
            if (AutoScaleMode == AutoScaleMode.Dpi || AutoScaleMode == AutoScaleMode.Font)
            {
                if (scale != 1)
                    Scale(scale, scale);
            }
            base.ResumeLayout(resume);

            UpdateLayout();
        }

        public new void Show()
        {
            SetWindowPosition();
            OnLoad(EventArgs.Empty);
            isModal = false;
            window.Show();
        }

        public void Show(IWin32Window owner)
        {
            Owner = owner as Form;
            Show();
        }

        public DialogResult ShowDialog()
        {
            // this solves problem with dialog window & click on taskbar button
            if (Owner == null)
            {
                var ownerWindow = NativeMethods.ActiveWindow();
                if (ownerWindow != null && ownerWindow != window && ownerWindow.IsVisible)
                    window.Owner = ownerWindow;
            }

            SetWindowPosition();
            OnLoad(EventArgs.Empty);

            isModal = true;
            window.ShowDialog();
            return DialogResult;
        }

        public DialogResult ShowDialog(IWin32Window owner)
        {
            Owner = owner as Form;
            return ShowDialog();
        }

        public void Close() => window.Close();

        public new void Hide() => window.Hide();

        protected virtual void OnDpiChanged(object sender, EventArgs e)
        {
        }

        private void EnumControls(Control control, Action<Control> action)
        {
            action(control);
            foreach (Control c in control.Controls)
                EnumControls(c, action);
        }

        public void MoveWindow(Rectangle rect) => MoveWindow(rect.Left, rect.Top, rect.Width, rect.Height);

        public void MoveWindow(int left, int top, int width, int height)
        {
            NativeMethods.MoveWindow(this, new Rectangle(left, top, width, height));
            Width = (int)(window.Width * DpiScale);
            Height = (int)(window.Height * DpiScale);
        }

        // this method is called by the FR dialog form designer
        public void MoveWindow(int left, int top, System.Windows.Media.Visual target)
        {
            // do default dpi scale
            SuspendLayout();
            ResumeLayout(false);

            // Suspend/Resume pair: fix issue with FR dialog form designer when moved to another monitor (bad anchors)
            SuspendLayout();
            double rescale = Helper.GetDpiScale(target) / DpiScale;
            NativeMethods.MoveWindow(this, new Rectangle(left, top, (int)(Width * rescale), (int)(Height * rescale)));
            AutoScaleDimensions = new SizeF((int)(DeviceDpi * rescale), (int)(DeviceDpi * rescale));
            // this.ResumeLayout will rescale controls, we don't need it
            base.ResumeLayout(false); 
            // fix repaint issue
            EnumControls(this, c => { if (c != this) c.AfterDpiChange(1); });
        }

        public Form()
        {
            window = UseCustomWindowChrome ? new CustomControls.ChromeWindow() : new SystemWindow();
            var contentControl = ((IForm)window).ContentControl;
            SetContentControl(window, contentControl);
            contentControl.SizeChanged += (s, e) => UpdateLayout();
            window.UseLayoutRounding = true;

#if Demo
            var demoLabel = new Controls.TextBlock();
            demoLabel.Text = " Demo version ";
            demoLabel.HorizontalAlignment = Windows.HorizontalAlignment.Center;
            demoLabel.VerticalAlignment = VerticalAlignment.Bottom;
            demoLabel.Opacity = 0.5;
            container.Children.Add(demoLabel);
#endif

            window.Loaded += (sender, e) => OnShown(e); // this is the SWF Shown equivalent
            window.Closing += (sender, e) =>
            {
                isClosing = true;
                var args = new FormClosingEventArgs(CloseReason.UserClosing, false);
                OnFormClosing(args);
                e.Cancel = args.Cancel;
                if (args.Cancel)
                    DialogResult = DialogResult.None;
                isClosing = false;
            };
            window.Closed += (sender, e) => OnFormClosed(new FormClosedEventArgs(CloseReason.UserClosing));
            window.StateChanged += (s, e) =>
            {
                if (window.WindowState == System.Windows.WindowState.Minimized && isModal && !ShowInTaskbar)
                {
                    System.Windows.Application.Current.MainWindow.WindowState = System.Windows.WindowState.Minimized;
                }
            };

            DpiRescaler.Install(window, this, container, OnDpiChanged);

            AutoScaleDimensions = new System.Drawing.SizeF(96, 96);
            BackColor = System.Drawing.SystemColors.Control;
        }
    }

}