Lattice/Lattice.UI.DragDrop.WinUI/Integration/WinUIDragDropIntegrationService.cs

using Lattice.Core.DragDrop.Abstractions;
using Lattice.Core.DragDrop.Models;
using Lattice.Core.DragDrop.Services;
using Lattice.Core.Geometry;
using Lattice.UI.DragDrop.Abstractions;
using Lattice.UI.DragDrop.WinUI.Behaviors;
using Microsoft.UI.Xaml;
using Microsoft.UI.Xaml.Input;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Threading.Tasks;

namespace Lattice.UI.DragDrop.WinUI.Integration;

/// <summary>
/// Сервис интеграции Drag & Drop с WinUI приложением.
/// </summary>
public sealed class WinUIDragDropIntegrationService : IDisposable
{
    #region Вложенные типы

    private sealed class DragSourceAdapter : IDragSource
    {
        private readonly FrameworkElement _element;
        private readonly Func<DragInfo> _dragInfoFactory;
        private readonly IDragDropService _dragDropService;
        private Point _dragStartPosition;
        private bool _isDragging;
        private bool _disposed;

        public DragSourceAdapter(
            FrameworkElement element,
            Func<DragInfo> dragInfoFactory,
            IDragDropService dragDropService)
        {
            _element = element ?? throw new ArgumentNullException(nameof(element));
            _dragInfoFactory = dragInfoFactory ?? throw new ArgumentNullException(nameof(dragInfoFactory));
            _dragDropService = dragDropService ?? throw new ArgumentNullException(nameof(dragDropService));

            SubscribeToEvents();
        }

        private void SubscribeToEvents()
        {
            _element.PointerPressed += OnPointerPressed;
            _element.PointerMoved += OnPointerMoved;
            _element.PointerReleased += OnPointerReleased;
            _element.PointerCanceled += OnPointerCanceled;
            _element.PointerCaptureLost += OnPointerCaptureLost;
        }

        private void UnsubscribeFromEvents()
        {
            _element.PointerPressed -= OnPointerPressed;
            _element.PointerMoved -= OnPointerMoved;
            _element.PointerReleased -= OnPointerReleased;
            _element.PointerCanceled -= OnPointerCanceled;
            _element.PointerCaptureLost -= OnPointerCaptureLost;
        }

        private void OnPointerPressed(object sender, PointerRoutedEventArgs e)
        {
            if (_isDragging || _disposed) return;

            var point = e.GetCurrentPoint(_element);
            _dragStartPosition = new Point(point.Position.X, point.Position.Y);
        }

        private void OnPointerMoved(object sender, PointerRoutedEventArgs e)
        {
            if (_isDragging || _disposed) return;

            var currentPoint = e.GetCurrentPoint(_element);
            var currentPosition = new Point(currentPoint.Position.X, currentPoint.Position.Y);

            var distance = CalculateDistance(_dragStartPosition, currentPosition);
            if (distance > _dragDropService.DragStartThreshold)
            {
                StartDragOperation(currentPosition);
            }
        }

        private async Task StartDragOperation(Point position)
        {
            try
            {
                var dragInfo = _dragInfoFactory();

                // Обновляем позицию в dragInfo
                var screenPosition = GetScreenPosition(position);
                dragInfo = new DragInfo(
                    dragInfo.Data,
                    dragInfo.AllowedEffects,
                    screenPosition,
                    dragInfo.Source
                );

                _isDragging = await _dragDropService.StartDragAsync(this, screenPosition);
            }
            catch (Exception ex)
            {
                Debug.WriteLine($"Error starting drag: {ex.Message}");
                _isDragging = false;
            }
        }

        private Point GetScreenPosition(Point relativePosition)
        {
            var transform = _element.TransformToVisual(null);
            var point = transform.TransformPoint(new Windows.Foundation.Point(relativePosition.X, relativePosition.Y));
            return new Point(point.X, point.Y);
        }

        private double CalculateDistance(Point p1, Point p2)
        {
            var dx = p2.X - p1.X;
            var dy = p2.Y - p1.Y;
            return Math.Sqrt(dx * dx + dy * dy);
        }

        private async void OnPointerReleased(object sender, PointerRoutedEventArgs e)
        {
            if (!_isDragging || _disposed) return;

            await _dragDropService.EndDragAsync();
            _isDragging = false;
        }

        private void OnPointerCanceled(object sender, PointerRoutedEventArgs e)
        {
            if (!_isDragging || _disposed) return;

            _dragDropService.CancelDragAsync();
            _isDragging = false;
        }

        private void OnPointerCaptureLost(object sender, PointerRoutedEventArgs e)
        {
            if (!_isDragging || _disposed) return;

            _dragDropService.CancelDragAsync();
            _isDragging = false;
        }

        #region IDragSource Implementation

        public async Task<(bool, DragInfo? dragInfo)> CancelDragAsync()
        {
            try
            {
                dragInfo = _dragInfoFactory();
                return dragInfo != null;
            }
            catch
            {
                dragInfo = null;
                return false;
            }
        }

        public async Task<bool> StartDragAsync(DragInfo dragInfo)
        {
            return true;
        }

        public async Task DragCompletedAsync(DragInfo dragInfo, Core.DragDrop.Enums.DragDropEffects effects)
        {
            _isDragging = false;
        }

        public async Task DragCancelledAsync(DragInfo dragInfo)
        {
            _isDragging = false;
        }

        #endregion

        public void Dispose()
        {
            if (_disposed) return;

            UnsubscribeFromEvents();
            _disposed = true;
            GC.SuppressFinalize(this);
        }

        public Task<(bool CanStart, DragInfo? DragInfo)> CanStartDragAsync()
        {
            throw new NotImplementedException();
        }
    }

    #endregion

    #region Поля

    private readonly IDragDropService _dragDropService;
    private readonly IDragVisualProvider _dragVisualProvider;
    private readonly IDragDropHost _dragDropHost;
    private readonly Dictionary<FrameworkElement, DragSourceAdapter> _dragSources = new();
    private readonly Dictionary<FrameworkElement, WinUIDropTargetBehavior> _dropTargets = new();
    private bool _disposed;

    #endregion

    #region Конструктор

    public WinUIDragDropIntegrationService(
        IDragDropService dragDropService,
        IDragVisualProvider dragVisualProvider,
        IDragDropHost dragDropHost)
    {
        _dragDropService = dragDropService ?? throw new ArgumentNullException(nameof(dragDropService));
        _dragVisualProvider = dragVisualProvider ?? throw new ArgumentNullException(nameof(dragVisualProvider));
        _dragDropHost = dragDropHost ?? throw new ArgumentNullException(nameof(dragDropHost));
    }

    #endregion

    #region Публичные методы

    /// <summary>
    /// Регистрирует элемент как источник перетаскивания.
    /// </summary>
    public void RegisterDragSource(FrameworkElement element, Func<DragInfo> dragInfoFactory)
    {
        if (_disposed) throw new ObjectDisposedException(nameof(WinUIDragDropIntegrationService));
        ArgumentNullException.ThrowIfNull(element);
        ArgumentNullException.ThrowIfNull(dragInfoFactory);

        if (_dragSources.ContainsKey(element)) return;

        var adapter = new DragSourceAdapter(element, dragInfoFactory, _dragDropService);
        _dragSources[element] = adapter;
    }

    /// <summary>
    /// Регистрирует элемент как источник перетаскивания с данными.
    /// </summary>
    public void RegisterDragSource(FrameworkElement element, object dragData)
    {
        RegisterDragSource(element, () =>
        {
            var position = GetScreenPosition(element, new Point(0, 0));
            return new DragInfo(
                dragData,
                Core.DragDrop.Enums.DragDropEffects.Copy | Core.DragDrop.Enums.DragDropEffects.Move,
                position,
                element
            );
        });
    }

    /// <summary>
    /// Регистрирует элемент как цель сброса.
    /// </summary>
    public void RegisterDropTarget(FrameworkElement element)
    {
        if (_disposed) throw new ObjectDisposedException(nameof(WinUIDragDropIntegrationService));
        ArgumentNullException.ThrowIfNull(element);

        if (_dropTargets.ContainsKey(element)) return;

        var behavior = new WinUIDropTargetBehavior(ServiceProviderHelper.GetServiceProvider())
        {
            AssociatedElement = element
        };

        _dropTargets[element] = behavior;

        // Настраиваем события WinUI
        element.AllowDrop = true;
        element.DragEnter += OnDragEnter;
        element.DragOver += OnDragOver;
        element.DragLeave += OnDragLeave;
        element.Drop += OnDrop;
    }

    private Point GetScreenPosition(FrameworkElement element, Point relativePoint)
    {
        var transform = element.TransformToVisual(null);
        var point = transform.TransformPoint(new Windows.Foundation.Point(relativePoint.X, relativePoint.Y));
        return new Point(point.X, point.Y);
    }

    private void OnDragEnter(object sender, DragEventArgs e)
    {
        if (sender is FrameworkElement element && _dropTargets.TryGetValue(element, out var behavior))
        {
            var position = GetScreenPosition(element, e.GetPosition(element).ToCorePoint());
            var dropInfo = CreateDropInfo(e, position, element);

            if (behavior.CanAcceptDrop(dropInfo))
            {
                e.AcceptedOperation = Windows.ApplicationModel.DataTransfer.DataPackageOperation.Copy;
                behavior.DragOver(dropInfo);
            }
            else
            {
                e.AcceptedOperation = Windows.ApplicationModel.DataTransfer.DataPackageOperation.None;
            }
        }
    }

    private void OnDragOver(object sender, DragEventArgs e)
    {
        if (sender is FrameworkElement element && _dropTargets.TryGetValue(element, out var behavior))
        {
            var position = GetScreenPosition(element, e.GetPosition(element).ToCorePoint());
            var dropInfo = CreateDropInfo(e, position, element);

            if (behavior.CanAcceptDrop(dropInfo))
            {
                e.AcceptedOperation = Windows.ApplicationModel.DataTransfer.DataPackageOperation.Copy;
                behavior.DragOver(dropInfo);
            }
        }
    }

    private void OnDragLeave(object sender, DragEventArgs e)
    {
        if (sender is FrameworkElement element && _dropTargets.TryGetValue(element, out var behavior))
        {
            behavior.DragLeave();
        }
    }

    private void OnDrop(object sender, DragEventArgs e)
    {
        if (sender is FrameworkElement element && _dropTargets.TryGetValue(element, out var behavior))
        {
            var position = GetScreenPosition(element, e.GetPosition(element).ToCorePoint());
            var dropInfo = CreateDropInfo(e, position, element);
            behavior.Drop(dropInfo);
        }
    }

    private DropInfo CreateDropInfo(DragEventArgs e, Point position, FrameworkElement target)
    {
        // Извлекаем данные из DragEventArgs
        object? data = null;

        // В реальной реализации нужно извлечь данные из e.DataView
        // Это упрощенная версия
        if (e.DataView.Properties.TryGetValue("DragData", out var dragData))
        {
            data = dragData;
        }

        return new DropInfo(
            data: data,
            position: position,
            allowedEffects: Core.DragDrop.Enums.DragDropEffects.Copy | Core.DragDrop.Enums.DragDropEffects.Move,
            target: target
        );
    }

    /// <summary>
    /// Удаляет регистрацию элемента как источника.
    /// </summary>
    public void UnregisterDragSource(FrameworkElement element)
    {
        if (_disposed) throw new ObjectDisposedException(nameof(WinUIDragDropIntegrationService));

        if (_dragSources.Remove(element, out var adapter))
        {
            adapter.Dispose();
        }
    }

    /// <summary>
    /// Удаляет регистрацию элемента как цели.
    /// </summary>
    public void UnregisterDropTarget(FrameworkElement element)
    {
        if (_disposed) throw new ObjectDisposedException(nameof(WinUIDragDropIntegrationService));

        if (_dropTargets.Remove(element, out var behavior))
        {
            behavior.Detach();
            element.AllowDrop = false;
            element.DragEnter -= OnDragEnter;
            element.DragOver -= OnDragOver;
            element.DragLeave -= OnDragLeave;
            element.Drop -= OnDrop;
        }
    }

    #endregion

    #region IDisposable

    public void Dispose()
    {
        if (_disposed) return;

        foreach (var adapter in _dragSources.Values)
        {
            adapter.Dispose();
        }
        _dragSources.Clear();

        foreach (var behavior in _dropTargets.Values)
        {
            behavior.Detach();
        }
        _dropTargets.Clear();

        _disposed = true;
        GC.SuppressFinalize(this);
    }

    #endregion
}

/// <summary>
/// Методы расширения для преобразования координат.
/// </summary>
internal static class PointExtensions
{
    public static Point ToCorePoint(this Windows.Foundation.Point point)
    {
        return new Point(point.X, point.Y);
    }
}