using System.Collections;
using System.ComponentModel;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Media;
using ytLive.Helpers;
using ytLive.Models;
using ytLive.ViewModels;

namespace ytLive;

public partial class MainWindow : Window
{
    private readonly MainViewModel _viewModel;

    public MainWindow()
    {
        AppLog.Write("MainWindow ctor: before InitializeComponent");
        InitializeComponent();
        AppLog.Write("MainWindow ctor: after InitializeComponent");
        _viewModel = (MainViewModel)DataContext;
        _viewModel.PropertyChanged += OnViewModelPropertyChanged;
        // When a focused scene is deleted, never land focus on a hidden scene.
        SceneList.IsSelectable = item => item is Scene { IsHidden: false };
        UpdateTaskbarOverlay();
        UpdateSelectionOverlay();
        AppLog.Write("MainWindow ctor: end");
    }

    private void MainWindow_Loaded(object sender, RoutedEventArgs e)
    {
        AppLog.Write("MainWindow loaded");
    }

    private void OnViewModelPropertyChanged(object? sender, PropertyChangedEventArgs e)
    {
        if (e.PropertyName == nameof(MainViewModel.IsLive))
            UpdateTaskbarOverlay();
        else if (e.PropertyName == nameof(MainViewModel.SelectedSource))
            UpdateSelectionOverlay();
    }

    private void MainWindow_Closing(object? sender, CancelEventArgs e)
    {
        _viewModel.Shutdown();
    }

    private void UpdateTaskbarOverlay()
    {
        TaskbarInfo.Overlay = _viewModel.IsLive
            ? (ImageSource)FindResource("LiveOverlay")
            : null;
    }

    private void SceneNameBox_IsVisibleChanged(object sender, DependencyPropertyChangedEventArgs e)
    {
        if (sender is TextBox { IsVisible: true } box)
        {
            box.Focus();
            box.SelectAll();
        }
    }

    private void SceneList_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        if (e.AddedItems.Count > 0 && e.AddedItems[0] is Scene { IsHidden: true } hidden)
        {
            var list = (ListBox)sender;
            list.SelectedItem = _viewModel.ActiveScene;
        }
    }

    private void GearButton_Click(object sender, RoutedEventArgs e)
    {
        if (sender is Button { ContextMenu: { } menu } button)
        {
            menu.PlacementTarget = button;
            menu.Placement = System.Windows.Controls.Primitives.PlacementMode.Bottom;
            menu.IsOpen = true;
        }
    }

    private void AddSourceButton_Click(object sender, RoutedEventArgs e)
    {
        if (sender is Button { ContextMenu: { } menu } button)
        {
            menu.PlacementTarget = button;
            menu.Placement = System.Windows.Controls.Primitives.PlacementMode.Bottom;
            menu.IsOpen = true;
        }
    }

    // ─── Preview image selection / move / resize ───
    private bool _isDraggingOverlay;
    private bool _isResizing;
    private Point _grabOffset;
    private double _resizeAspect;

    private void Window_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    {
        if (e.OriginalSource is not DependencyObject original) return;
        if (IsDescendantOf(original, PreviewGrid)) return;
        if (IsDescendantOf(original, SourceList)) return;
        if (IsDescendantOf(original, OpacityChip)) return;
        _viewModel.SelectedSource = null;
    }

    private static bool IsDescendantOf(DependencyObject? child, DependencyObject ancestor)
    {
        while (child != null && !ReferenceEquals(child, ancestor))
            child = VisualTreeHelper.GetParent(child);
        return child != null;
    }

    private void UpdateSelectionOverlay()
    {
        var selected = _viewModel.SelectedSource is { } s && IsDraggableSource(s);
        SelectionOverlay.Visibility = selected ? Visibility.Visible : Visibility.Collapsed;
        OpacityChip.Visibility = selected ? Visibility.Visible : Visibility.Collapsed;
        if (selected)
            OpacityValueText.Text = $"{Math.Round(_viewModel.SelectedSource!.Opacity * 100)}%";
    }

    // Static images and the webcam share the move/resize/selection behavior.
    private static bool IsDraggableSource(Source source)
        => source.Type is SourceType.Image or SourceType.Webcam;

    private void MirrorButton_Click(object sender, RoutedEventArgs e)
    {
        if (_viewModel.SelectedSource is { Type: SourceType.Webcam } source)
            source.IsMirrored = !source.IsMirrored;
    }

    private void ShapeButton_Click(object sender, RoutedEventArgs e)
    {
        if (_viewModel.SelectedSource is { Type: SourceType.Webcam } source)
            source.ClipShape = source.ClipShape == ClipShape.Traditional ? ClipShape.Round : ClipShape.Traditional;
    }

    private void OpacitySlider_ValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e)
        => OpacityValueText.Text = $"{Math.Round(e.NewValue * 100)}%";

    private void Preview_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    {
        if (OpacityChip.IsMouseOver) return;

        var grid = (Grid)sender;
        var toCanvas = CanvasGrid.TransformToVisual(grid).Inverse;
        var p = toCanvas.Transform(e.GetPosition(grid));
        var selected = _viewModel.SelectedSource;

        if (selected is { } sel && IsDraggableSource(sel) && HitHandle(e.GetPosition(grid), sel))
        {
            _isResizing = true;
            _resizeAspect = sel.Width / Math.Max(1, sel.Height);
            grid.CaptureMouse();
            e.Handled = true;
            return;
        }

        var hit = HitImage(p);
        if (hit != null)
        {
            _viewModel.SelectedSource = hit;
            _isDraggingOverlay = true;
            _grabOffset = new Point(p.X - hit.X, p.Y - hit.Y);
            grid.CaptureMouse();
            e.Handled = true;
            return;
        }

        _viewModel.SelectedSource = null;
    }

    private void Preview_MouseMove(object sender, MouseEventArgs e)
    {
        if (!_isDraggingOverlay && !_isResizing) return;

        var grid = (Grid)sender;
        var toCanvas = CanvasGrid.TransformToVisual(grid).Inverse;
        var p = toCanvas.Transform(e.GetPosition(grid));
        var selected = _viewModel.SelectedSource;
        if (selected == null)
        {
            EndPreviewDrag(grid);
            return;
        }

        if (_isDraggingOverlay)
        {
            var minX = -(selected.Width - 20);
            var maxX = 1920 - 20;
            var minY = -(selected.Height - 20);
            var maxY = 1080 - 20;
            selected.X = Math.Clamp(p.X - _grabOffset.X, Math.Min(minX, maxX), Math.Max(minX, maxX));
            selected.Y = Math.Clamp(p.Y - _grabOffset.Y, Math.Min(minY, maxY), Math.Max(minY, maxY));
        }
        else if (_isResizing)
        {
            var newW = Math.Clamp(p.X - selected.X, 32, 1920);
            var newH = newW / _resizeAspect;
            if (newH > 1080)
            {
                newH = 1080;
                newW = newH * _resizeAspect;
            }
            selected.Width = newW;
            selected.Height = newH;
        }
    }

    private void Preview_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
        => EndPreviewDrag((Grid)sender);

    private void EndPreviewDrag(Grid grid)
    {
        if (_isDraggingOverlay || _isResizing)
            grid.ReleaseMouseCapture();
        _isDraggingOverlay = false;
        _isResizing = false;
    }

    private bool HitHandle(Point mouseScreen, Source source)
    {
        var corner = CanvasGrid.TransformToVisual(PreviewGrid).Transform(new Point(source.X + source.Width, source.Y + source.Height));
        return Math.Abs(mouseScreen.X - corner.X) <= 20 && Math.Abs(mouseScreen.Y - corner.Y) <= 20;
    }

    private Source? HitImage(Point p)
    {
        var scene = _viewModel.ActiveScene;
        if (scene == null) return null;
        for (var i = scene.Sources.Count - 1; i >= 0; i--)
        {
            var source = scene.Sources[i];
            if (!IsDraggableSource(source) || !source.IsEnabled) continue;
            if (p.X >= source.X && p.X <= source.X + source.Width &&
                p.Y >= source.Y && p.Y <= source.Y + source.Height)
                return source;
        }
        return null;
    }

    private void SceneNameBox_KeyDown(object sender, KeyEventArgs e)
    {
        if (e.Key is Key.Enter or Key.Escape)
        {
            CommitSceneEdit(sender);
            e.Handled = true;
        }
    }

    private void SceneNameBox_LostFocus(object sender, RoutedEventArgs e)
    {
        CommitSceneEdit(sender);
    }

    private static void CommitSceneEdit(object sender)
    {
        if (sender is FrameworkElement { DataContext: Scene scene })
            scene.IsEditing = false;
    }

    // ─── List drag-to-reorder (scenes list + sources list) ───
    private Point _dragStartPoint;
    private int _dragIndex = -1;
    private bool _isDragging;
    private object? _lastHoveredItem;

    private void List_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    {
        var listBox = (ListBox)sender;
        var item = FindItemContainerAt(listBox, e.GetPosition(listBox));
        if (item == null)
        {
            if (ReferenceEquals(listBox, SourceList))
                _viewModel.SelectedSource = null;
            _dragIndex = -1;
            return;
        }
        if (listBox.ItemsSource is not IList items || items.Count == 0)
        {
            _dragIndex = -1;
            return;
        }
        _dragIndex = listBox.Items.IndexOf(item.DataContext);
        _dragStartPoint = e.GetPosition(listBox);
        _isDragging = false;
        _lastHoveredItem = null;
    }

    private void List_PreviewMouseMove(object sender, MouseEventArgs e)
    {
        if (_dragIndex < 0) return;
        var listBox = (ListBox)sender;
        if (e.LeftButton != MouseButtonState.Pressed || listBox.ItemsSource is not IList items)
        {
            EndListDrag(listBox);
            return;
        }

        var position = e.GetPosition(listBox);
        if (!_isDragging)
        {
            if (Math.Abs(position.X - _dragStartPoint.X) < SystemParameters.MinimumHorizontalDragDistance &&
                Math.Abs(position.Y - _dragStartPoint.Y) < SystemParameters.MinimumVerticalDragDistance)
                return;
            _isDragging = true;
            listBox.CaptureMouse();
        }

        var item = FindItemContainerAt(listBox, position);
        if (item == null) return;

        var targetItem = item.DataContext;
        if (ReferenceEquals(targetItem, items[_dragIndex]) || ReferenceEquals(targetItem, _lastHoveredItem))
            return;

        var targetIndex = listBox.Items.IndexOf(targetItem);
        if (targetIndex < 0) return;

        var dragged = items[_dragIndex];
        items.RemoveAt(_dragIndex);
        items.Insert(targetIndex, dragged);
        _dragIndex = targetIndex;
        _lastHoveredItem = targetItem;
    }

    private void List_PreviewMouseLeftButtonUp(object sender, MouseButtonEventArgs e)
    {
        EndListDrag((ListBox)sender);
    }

    private void EndListDrag(ListBox listBox)
    {
        if (_isDragging)
            listBox.ReleaseMouseCapture();
        _dragIndex = -1;
        _isDragging = false;
        _lastHoveredItem = null;
    }

    private static ListBoxItem? FindItemContainerAt(ListBox listBox, Point position)
    {
        var hit = listBox.InputHitTest(position) as DependencyObject;
        while (hit != null && hit != listBox)
        {
            if (hit is ListBoxItem item) return item;
            hit = VisualTreeHelper.GetParent(hit);
        }
        return null;
    }
}