using Lattice.Core.DragDrop.Services;
using Lattice.UI.DragDrop.Abstractions;
using Microsoft.UI.Xaml;
using Microsoft.UI.Xaml.Controls;
using System;

namespace Lattice.UI.DragDrop.WinUI.Services;

/// <summary>
/// Сервис интеграции Drag & Drop с WinUI приложением.
/// </summary>
public class WinUIDragDropIntegrationService : IDisposable
{
    private readonly IDragDropService _dragDropService;
    private readonly IDragVisualProvider _dragVisualProvider;
    private readonly Canvas _overlayCanvas;
    private readonly Window _window;
    private object? _currentDragVisual;
    private bool _disposed;

    /// <summary>
    /// Инициализирует новый экземпляр класса <see cref="WinUIDragDropIntegrationService"/>.
    /// </summary>
    public WinUIDragDropIntegrationService(
        Window window,
        IDragDropService dragDropService,
        IDragVisualProvider dragVisualProvider)
    {
        _window = window ?? throw new ArgumentNullException(nameof(window));
        _dragDropService = dragDropService ?? throw new ArgumentNullException(nameof(dragDropService));
        _dragVisualProvider = dragVisualProvider ?? throw new ArgumentNullException(nameof(dragVisualProvider));

        // Создаем оверлейный Canvas для визуальных элементов
        _overlayCanvas = new Canvas
        {
            IsHitTestVisible = false,
            Background = null
        };

        // Подписываемся на события перетаскивания
        SubscribeToEvents();
    }

    /// <summary>
    /// Встраивает оверлей в указанный контейнер.
    /// </summary>
    public void AttachToContainer(Panel container)
    {
        if (container == null)
            throw new ArgumentNullException(nameof(container));

        // Убеждаемся, что оверлей находится поверх всех элементов
        Canvas.SetZIndex(_overlayCanvas, int.MaxValue);
        container.Children.Add(_overlayCanvas);
    }

    private void SubscribeToEvents()
    {
        _dragDropService.DragStarted += OnDragStarted;
        _dragDropService.DragUpdated += OnDragUpdated;
        _dragDropService.DragCompleted += OnDragCompleted;
        _dragDropService.DragCancelled += OnDragCancelled;
    }

    private void UnsubscribeFromEvents()
    {
        _dragDropService.DragStarted -= OnDragStarted;
        _dragDropService.DragUpdated -= OnDragUpdated;
        _dragDropService.DragCompleted -= OnDragCompleted;
        _dragDropService.DragCancelled -= OnDragCancelled;
    }

    private void OnDragStarted(object? sender, DragStartedEventArgs e)
    {
        // Создаем визуальное представление
        _currentDragVisual = _dragVisualProvider.CreateDragVisual(
            e.DragInfo,
            e.StartPosition);

        // Добавляем на оверлей
        if (_currentDragVisual is UIElement element)
        {
            _overlayCanvas.Children.Add(element);
        }
    }

    private void OnDragUpdated(object? sender, DragUpdatedEventArgs e)
    {
        if (_currentDragVisual != null)
        {
            _dragVisualProvider.UpdateDragVisualPosition(_currentDragVisual, e.Position);
        }
    }

    private void OnDragCompleted(object? sender, DragCompletedEventArgs e)
    {
        CleanupDragVisual();
    }

    private void OnDragCancelled(object? sender, DragCancelledEventArgs e)
    {
        CleanupDragVisual();
    }

    private void CleanupDragVisual()
    {
        if (_currentDragVisual != null)
        {
            _dragVisualProvider.ReleaseDragVisual(_currentDragVisual);
            _currentDragVisual = null;
        }
    }

    /// <inheritdoc/>
    public void Dispose()
    {
        if (!_disposed)
        {
            UnsubscribeFromEvents();
            CleanupDragVisual();

            if (_overlayCanvas.Parent is Panel parent)
            {
                parent.Children.Remove(_overlayCanvas);
            }

            _disposed = true;
        }

        GC.SuppressFinalize(this);
    }
}