using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Shapes;
using TeamAAS_VP.ViewModels;

namespace TeamAAS_VP.Views
{
    public partial class ImageView : UserControl
    {
        private Point _start;
        private Shape _previewShape;
        private bool _isDown;

        private UIElement _dragTarget;
        private Point _dragOffset;

        // 新增：记录当前选中的批注元素
        private UIElement _selectedAnnotation;

        public ImageView()
        {
            InitializeComponent();
            Loaded += ImageView_Loaded;
        }

        private void ImageView_Loaded(object sender, RoutedEventArgs e)
        {
            var vm = DataContext as ImageViewModel;
            vm?.AttachRenderTarget(RootPixelRender, AnnoCanvas);
            vm?.LoadLast();

            // 让 KeyDown 可用
            AnnoCanvas.Focus();
        }

        private ImageViewModel Vm => DataContext as ImageViewModel;

        private Point GetPixelPoint(MouseEventArgs e)
        {
            var p = e.GetPosition(AnnoCanvas);

            var vm = Vm;
            if (vm == null || vm.PixelWidth <= 0 || vm.PixelHeight <= 0)
            {
                return p;
            }

            var actualW = AnnoCanvas.ActualWidth;
            var actualH = AnnoCanvas.ActualHeight;
            if (actualW <= 0 || actualH <= 0) return p;

            var scaleX = actualW / vm.PixelWidth;
            var scaleY = actualH / vm.PixelHeight;

            if (scaleX <= 0) scaleX = 1;
            if (scaleY <= 0) scaleY = 1;

            return new Point(p.X / scaleX, p.Y / scaleY);
        }

        private UIElement GetAnnotationElementFromOriginalSource(object originalSource)
        {
            // 右键/左键命中的可能是：Rectangle/TextBlock/Grid/Line/Polygon 等子元素
            var element = originalSource as DependencyObject;
            while (element != null)
            {
                if (element is Rectangle) return (UIElement)element;
                if (element is TextBlock) return (UIElement)element;
                if (element is Grid) return (UIElement)element;

                // 命中箭头内部：Line/Polygon -> 往上找 Grid
                element = System.Windows.Media.VisualTreeHelper.GetParent(element);
            }

            return null;
        }

        private void SelectAnnotation(UIElement element)
        {
            _selectedAnnotation = element;

            // 简单选中效果（可选）：给选中项加虚线描边
            // 只处理 Rectangle / Grid(箭头) 的视觉效果；TextBlock 不做边框避免影响显示
            foreach (var child in AnnoCanvas.Children)
            {
                if (child is Rectangle rr)
                {
                    rr.StrokeDashArray = null;
                }
            }

            if (_selectedAnnotation is Rectangle r)
            {
                r.StrokeDashArray = new System.Windows.Media.DoubleCollection() { 2, 2 };
            }
        }

        private void DeleteSelectedAnnotation()
        {
            if (Vm == null) return;
            if (_selectedAnnotation == null) return;

            Vm.RemoveAnnotation(_selectedAnnotation);
            _selectedAnnotation = null;
        }

        private void AnnoCanvas_MouseRightButtonDown(object sender, MouseButtonEventArgs e)
        {
            if (Vm == null) return;

            var hit = GetAnnotationElementFromOriginalSource(e.OriginalSource);
            if (hit == null || hit == AnnoCanvas)
            {
                _selectedAnnotation = null;
                return;
            }

            SelectAnnotation(hit);
            AnnoCanvas.Focus();

            var menu = new ContextMenu();
            var deleteItem = new MenuItem() { Header = "删除" };
            deleteItem.Click += (s, ev) => DeleteSelectedAnnotation();
            menu.Items.Add(deleteItem);

            // 打开菜单
            menu.PlacementTarget = AnnoCanvas;
            menu.IsOpen = true;

            e.Handled = true;
        }

        private void AnnoCanvas_KeyDown(object sender, KeyEventArgs e)
        {
            if (e.Key == Key.Delete)
            {
                DeleteSelectedAnnotation();
                e.Handled = true;
            }
        }

        private void AnnoCanvas_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
        {
            if (Vm == null) return;

            _isDown = true;
            _start = GetPixelPoint(e);
            AnnoCanvas.CaptureMouse();

            // Select 模式：左键点中即选中
            if (Vm.Tool == "Select")
            {
                var hit = GetAnnotationElementFromOriginalSource(e.OriginalSource);
                if (hit != null && hit != AnnoCanvas)
                {
                    SelectAnnotation(hit);
                    _dragTarget = hit;

                    var p = _start;
                    var left = Canvas.GetLeft(_dragTarget);
                    var top = Canvas.GetTop(_dragTarget);
                    if (double.IsNaN(left)) left = 0;
                    if (double.IsNaN(top)) top = 0;

                    _dragOffset = new Point(p.X - left, p.Y - top);
                }
                else
                {
                    _selectedAnnotation = null;
                    _dragTarget = null;
                }
                return;
            }

            if (Vm.Tool == "Rect")
            {
                var rect = Vm.CreateRect();
                Canvas.SetLeft(rect, _start.X);
                Canvas.SetTop(rect, _start.Y);
                rect.Width = 1;
                rect.Height = 1;

                _previewShape = rect;
                AnnoCanvas.Children.Add(rect);
                return;
            }

            if (Vm.Tool == "Arrow")
            {
                var g = Vm.CreateArrowGroup(_start, _start);
                AnnoCanvas.Children.Add(g);
                _previewShape = g.Tag as Shape;
                return;
            }

            if (Vm.Tool == "Text")
            {
                Vm.CreateTextAt(AnnoCanvas, _start);
                _isDown = false;
                AnnoCanvas.ReleaseMouseCapture();
            }
        }

        private void AnnoCanvas_MouseMove(object sender, MouseEventArgs e)
        {
            if (!_isDown || Vm == null) return;

            var p = GetPixelPoint(e);

            if (Vm.Tool == "Select")
            {
                if (_dragTarget != null && _dragTarget != AnnoCanvas && e.LeftButton == MouseButtonState.Pressed)
                {
                    Canvas.SetLeft(_dragTarget, p.X - _dragOffset.X);
                    Canvas.SetTop(_dragTarget, p.Y - _dragOffset.Y);
                }
                return;
            }

            if (Vm.Tool == "Rect" && _previewShape is Rectangle r)
            {
                var x = Math.Min(p.X, _start.X);
                var y = Math.Min(p.Y, _start.Y);
                var w = Math.Abs(p.X - _start.X);
                var h = Math.Abs(p.Y - _start.Y);

                Canvas.SetLeft(r, x);
                Canvas.SetTop(r, y);
                r.Width = Math.Max(1, w);
                r.Height = Math.Max(1, h);
                return;
            }

            if (Vm.Tool == "Arrow")
            {
                Vm.UpdateLastArrow(AnnoCanvas, p);
            }
        }

        private void AnnoCanvas_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
        {
            if (Vm == null) return;

            _isDown = false;
            AnnoCanvas.ReleaseMouseCapture();

            var p = GetPixelPoint(e);

            if (Vm.Tool == "Arrow")
            {
                Vm.CommitLastArrow(AnnoCanvas, p);
            }

            _previewShape = null;
            _dragTarget = null;
        }
    }
}