using Godot;
using System;
using System.Collections.Generic;
using System.Linq;

/// <summary>
/// 实验室场景主控脚本
/// </summary>
public partial class Lab : Node2D
{
    /// <summary>
    /// 地图节点类型标志位
    /// </summary>
	[Flags]
	public enum MapNodeType
	{
		Invalid = 0,    // 无效
		Walkable = 1,   // 可行走
		Wall = 2,       // 墙壁
		Blocker = 4,    // 阻挡物
		SeatUp = 8,     // 上方座位
		SeatDown = 16,  // 下方座位
	}
    
    // 墙壁矩形区域列表
	private static readonly Rect2I[] wallRectangles = {
		new(0,0,40,2),
		new(0,5,1, 15),
		new(0,20,40,1),
		new(39,2,1,18),
	};

	private readonly Dictionary<Guid, ITileDraggable> _furnitureIDs = new();
    /// <summary>
    /// 家具字典，通过ID索引
    /// </summary>
	public Dictionary<Guid, ITileDraggable> Furniture => _furnitureIDs;

	// Called when the node enters the scene tree for the first time.
    /// <summary>
    /// 场景加载完成时调用
    /// </summary>
	public override void _Ready()
	{
		var ticker = GetNode<Timer>("/root/GameManager/OneSecondTicker");
		Player.Timeline.Attach(ticker);
		Player.Timeline.Subscribe(DateOnly.Parse("2024/11/20"), Guid.NewGuid());
		Player.Timeline.OnEventTriggered += (d, e) => GD.Print($"Timeline event triggered: {d}, {e}");

		var label = GetNode<Label>("BottomBar/HBoxContainer/Date");
		label.Text = Player.Timeline.InternalDate.ToLongDateString();
		Player.Timeline.OnDayChanged += d => label.Text = d.ToLongDateString();
		var table = GetNode<Cube>("Cube");
		table.Draggable = true;
		_moneyLabel = GetNode<Label>("BottomBar/HBoxContainer/Money");

		var rect = table.TileRect;
		rect.Position += table.TilePosition;
		_furniturePlacement.Add(rect, table);
		_furnitureIDs.Add(table.Id, table);

		_tileMap = GetNode<TileMapLayer>("OutGround");
		UpdateMap();

		var student = GetNode<Student>("Student");
		student.CubeId = table.Id;

		var r = new Rect2I(0,0,1,1);
		GD.Print(H.RectHasPointInclusive(r, new Vector2I(1,0)));
	}

	private Label _moneyLabel;
	// Called every frame. 'delta' is the elapsed time since the previous frame.
    /// <summary>
    /// 每帧更新
    /// </summary>
    /// <param name="delta">帧间隔</param>
	public override void _Process(double delta)
	{
		switch(GD.RandRange(0,2)) {
			case 0:
				Player.Budget.Operational++;
				break;
			case 1:
				Player.Budget.Facility += 10;
				break;
			case 2:
				Player.Budget.Labor += 100;
				break;
		}
		_moneyLabel.Text = Player.Budget.Total.ToString("N0");
		if (_isDragging && DraggingTarget != null) {
			Vector2 mousePos = GetLocalMousePosition();
			Vector2I cell = Point2Coord(mousePos) - DraggingTarget.MouseOffset;
			var targetRect = DraggingTarget.TileRect;
			targetRect.Position += cell;
			DraggingTarget.IsCollided = wallRectangles.Any(r => r.Intersects(targetRect));
			DraggingTarget.TilePosition = cell;
		}
	}

	private bool _isDragging;
    
    /// <summary>
    /// 拾起物品
    /// </summary>
    /// <param name="target">目标物品</param>
	public void Pickup(ITileDraggable target) {
		if (target == null) return;
		_isDragging = true;
		DraggingTarget = target;
	}

    /// <summary>
    /// 放下物品
    /// </summary>
    /// <param name="target">目标物品</param>
	public void PutDown(ITileDraggable target) {
		if (target == null) return;
		_isDragging = false;
		_furniturePlacement.Remove(_furniturePlacement.First(kv => kv.Value == target).Key);
		var rect = target.TileRect;
		rect.Position += target.TilePosition;
		_furniturePlacement.Add(rect, target);
		DraggingTarget = null;
		UpdateMap();
	}
    
    /// <summary>
    /// 当前正在拖拽的目标
    /// </summary>
	public ITileDraggable DraggingTarget { get; set; }

	public const int MapWidth = 40;
	public const int MapHeight = 21;

	private readonly MapNodeType[,] _blocks = new MapNodeType[MapWidth, MapHeight];

	private Dictionary<Rect2I, ITileDraggable> _furniturePlacement = new ();

	private TileMapLayer _tileMap;

    /// <summary>
    /// 更新地图数据
    /// </summary>
	public void UpdateMap()
	{
		for (int i = 0; i < MapWidth; i++) {
			for (int j = 0; j < MapHeight; j++) {
				Vector2I vec = new (i,j);
				if (wallRectangles.Any(w => w.HasPoint(vec))) {
					_blocks[i, j] = MapNodeType.Wall;
				} else if (_furniturePlacement.Any(f => f.Key.HasPoint(vec))) {
					MapNodeType t = 0;
					foreach (var kv in _furniturePlacement.Where(f => f.Key.HasPoint(vec))) {
						t |= kv.Value.GetTileType(vec - kv.Value.TilePosition);
					}
					if ((t & MapNodeType.Walkable) != 0 && (t & MapNodeType.Blocker) != 0){
						t ^= MapNodeType.Walkable;
					}
					_blocks[i ,j] = t;
				} else {
					_blocks[i, j] = MapNodeType.Walkable;
				}
			}
		}
	}

	private static bool IsValidPosition(Vector2I pos)
	{
		int x = pos.X;
		int y = pos.Y;
		if (x < 0 || x >= MapWidth || y < 0 || y >= MapHeight) {
			return false;
		}
		return true;
	}
    
	private List<Vector2I> GetNeighbors(Vector2I pos) {
		int x = pos.X;
		int y = pos.Y;
		var neighbor = new List<Vector2I>();
		if (!IsValidPosition(pos)) {
			return neighbor;
		}

		if (IsValidPosition(new Vector2I(x-1,y)) && (_blocks[x-1,y] & MapNodeType.Walkable) == MapNodeType.Walkable) {
			neighbor.Add(new Vector2I(x-1,y));
		}
		if (IsValidPosition(new Vector2I(x+1,y)) && (_blocks[x+1,y] & MapNodeType.Walkable) == MapNodeType.Walkable) {
			neighbor.Add(new Vector2I(x+1,y));
		}
		if (IsValidPosition(new Vector2I(x,y-1)) && (_blocks[x,y-1] & MapNodeType.Walkable) == MapNodeType.Walkable) {
			neighbor.Add(new Vector2I(x,y-1));
		}
		if (IsValidPosition(new Vector2I(x,y+1)) && (_blocks[x,y+1] & MapNodeType.Walkable) == MapNodeType.Walkable) {
			neighbor.Add(new Vector2I(x,y+1));
		}
		return neighbor;
	}

    /// <summary>
    /// 获取最短路径
    /// </summary>
    /// <param name="start">起点</param>
    /// <param name="end">终点</param>
    /// <returns>路径点列表</returns>
	public List<Vector2I> GetShortestPath(Vector2I start, Vector2I end)
	{
		for (int j = 0; j < MapHeight; j++) {
			string t = "";
			for (int i = 0; i < MapWidth; i++) {
				if ((_blocks[i,j] & MapNodeType.SeatUp) != 0) {
					t += "U";
				} else if ((_blocks[i,j] & MapNodeType.SeatDown) != 0) {
					t += "D";
				} else {
					t += $"{_blocks[i,j].ToString()[0]}";
				}
			}
			GD.Print(t);
		}
		var path = new List<Vector2I>();
		if (_tileMap.GetCellSourceId(start) == -1 || _tileMap.GetCellSourceId(end) == -1) {
			return path;
		}
		if (start == end) {
			return path;
		}
		GD.Print($"start = {start}, end = {end}");
        static int Vec2Idx(Vector2I v) => v.Y * MapWidth + v.X;
        static Vector2I Idx2Vec2(int i) => new(i % MapWidth, i / MapWidth);

		HashSet<int> entriesIdx = new();
		foreach (var e in GetNeighbors(end)) {
			entriesIdx.Add(Vec2Idx(e));
		}
		if (entriesIdx.Count == 0) {
			return path;
		}

        // Use Dijkstra algorithm to find the shortest path
        int[] dist = new int[MapWidth * MapHeight];
        int[] prev = new int[MapWidth * MapHeight];
		bool[] visited = new bool[MapWidth * MapHeight];

		for (int i = 0; i < dist.Length; i++) {
			dist[i] = int.MaxValue;
			prev[i] = -1;
			visited[i] = false;
		}
		dist[Vec2Idx(start)] = 0;

		int answer = -1;
		for (int i = 0; i < dist.Length; i++) {
			int minDistance = int.MaxValue;
			int u = -1;
			for (int j = 0; j < dist.Length; j++) {
				if (!visited[j] && dist[j] <= minDistance) {
					minDistance = dist[j];
					u = j;
				}
			}
			if (u == -1) {
				return path;
			}
			if (entriesIdx.Contains(u)){
				answer = u;
				break;
			}
			visited[u] = true;
			var neighbors = GetNeighbors(Idx2Vec2(u));
			int alt = dist[u] + 1;
			foreach (var neighbor in neighbors) {
				int idx = Vec2Idx(neighbor);
				if (visited[idx]) continue;
				if (alt < dist[idx]) {
					dist[idx] = alt;
					prev[idx] = u;
				}
			}
		}

		while (answer != Vec2Idx(start)) {
			path.Add(Idx2Vec2(answer));
			answer = prev[answer];
		}
		path.Reverse();
		GD.Print(string.Join(',', path));
		return path;
	}

	public Vector2I GetTypedBlock(MapNodeType nType, uint idx) {
		switch(nType) {
		default:
			return Vector2I.Zero;
		}
	}

    /// <summary>
    /// 获取指定位置的地图节点类型
    /// </summary>
    /// <param name="pos">位置</param>
    /// <returns>节点类型</returns>
	public MapNodeType GetMapNodeTypeOfPosition(Vector2I pos) {
		if (!IsValidPosition(pos)) return MapNodeType.Invalid;
		return _blocks[pos.X, pos.Y];
	}

    /// <summary>
    /// 世界坐标转网格坐标
    /// </summary>
    /// <param name="pos">世界坐标</param>
    /// <returns>网格坐标</returns>
	public Vector2I Point2Coord(Vector2 pos) {
		return _tileMap.LocalToMap(_tileMap.ToLocal(pos));
	}

    /// <summary>
    /// 获取家具的特殊位置（如座位）
    /// </summary>
    /// <param name="fId">家具ID</param>
    /// <param name="idx">索引</param>
    /// <returns>特殊位置坐标</returns>
	public Vector2I GetFurSpecialPosition(Guid fId, int idx) {
		if (!_furnitureIDs.ContainsKey(fId)) return Vector2I.Zero;
		if (idx < 0 || idx > _furnitureIDs[fId].SpecialTiles.Length) return Vector2I.Zero;
		return _furnitureIDs[fId].SpecialTiles[idx].Position + _furnitureIDs[fId].TilePosition;
	}

}