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

public partial class Lab : Node2D
{
	// Called when the node enters the scene tree for the first time.
	public override void _Ready()
	{
		var label = GetNode<Label>("TitleBar/TitleBarBodyDate/DateLabel");
		label.Text = Player.Timeline.InternalDate.ToLongDateString();
		Player.Timeline.OnDayChanged += d => label.Text = d.ToLongDateString();
		tileMap = GetNode<TileMapLayer>("TestMap");
		UpdateMap();
	}

	// Called every frame. 'delta' is the elapsed time since the previous frame.
	public override void _Process(double delta)
	{
	}


	private static readonly Vector2I tableTileCoord = new(0, 6);
	private static readonly Vector2I waterTileCoord = new(6, 9);
	private static readonly Vector2I doorTileCoord = new(9, 3);
	private static readonly Vector2I axeTileCoord = new(10, 9);
	private static readonly Vector2I blockTileCoord = new(4, 3);

	public enum MapNodeType
	{
		Table,
		Water,
		Door,
		Axe,
		Block,
		Road,
	}


	private const int MAP_WIDTH = 24;
	private const int MAP_HEIGHT = 13;

	private readonly MapNodeType[,] blocks = new MapNodeType[MAP_WIDTH, MAP_HEIGHT];


	private TileMapLayer tileMap;

	public void UpdateMap()
	{
		for (int i = 0; i < MAP_WIDTH; i++) {
			for (int j = 0; j < MAP_HEIGHT; j++) {
				var tile = tileMap.GetCellAtlasCoords(new Vector2I(i,j));
				if (tile == tableTileCoord) {
					blocks[i,j] = MapNodeType.Table;
				} else if (tile == waterTileCoord) {
					blocks[i,j] = MapNodeType.Water;
				} else if (tile == doorTileCoord) {
					blocks[i,j] = MapNodeType.Door;
				} else if (tile == axeTileCoord) {
					blocks[i,j] = MapNodeType.Axe;
				} else if (tile == blockTileCoord) {
					blocks[i,j] = MapNodeType.Block;
				} else {
					blocks[i,j] = MapNodeType.Road;
				}
			}
		}
	}


	private static bool IsValidPosition(Vector2I pos)
	{
		int x = pos.X;
		int y = pos.Y;
		if (x < 0 || x >= MAP_WIDTH || y < 0 || y >= MAP_HEIGHT) {
			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.Road) {
			neighbor.Add(new Vector2I(x-1,y));
		}
		if (IsValidPosition(new Vector2I(x+1,y)) && blocks[x+1,y] == MapNodeType.Road) {
			neighbor.Add(new Vector2I(x+1,y));
		}
		if (IsValidPosition(new Vector2I(x,y-1)) && blocks[x,y-1] == MapNodeType.Road) {
			neighbor.Add(new Vector2I(x,y-1));
		}
		if (IsValidPosition(new Vector2I(x,y+1)) && blocks[x,y+1] == MapNodeType.Road) {
			neighbor.Add(new Vector2I(x,y+1));
		}
		return neighbor;
	}

	public List<Vector2I> GetShortestPath(Vector2I start, Vector2I end)
	{
		for (int j = 0; j < MAP_HEIGHT; j++) {
			string t = "";
			for (int i = 0; i < MAP_WIDTH; i++) {
				t += $"{blocks[i,j]} ";
			}
			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);
		GD.Print(end);
        static int vec2idx(Vector2I v) => v.Y * MAP_WIDTH + v.X;
        static Vector2I idx2vec2(int i) => new(i % MAP_WIDTH, i / MAP_WIDTH);

		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[MAP_WIDTH * MAP_HEIGHT];
        int[] prev = new int[MAP_WIDTH * MAP_HEIGHT];
		bool[] visited = new bool[MAP_WIDTH * MAP_HEIGHT];

		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 min_distance = int.MaxValue;
			int u = -1;
			for (int j = 0; j < dist.Length; j++) {
				if (!visited[j] && dist[j] <= min_distance) {
					min_distance = dist[j];
					u = j;
				}
			}
			GD.Print($"u={u}");
			if (u == -1) {
				return path;
			}
			if (entriesIdx.Contains(u)){
				answer = u;
				break;
			}
			visited[u] = true;
			var neighbors = GetNeighbors(idx2vec2(u));
			int alt = dist[u] + 1;
			GD.Print($"Alt={alt}");
			foreach (var neighbor in neighbors) {
				int idx = vec2idx(neighbor);
				if (visited[idx]) continue;
				GD.Print($"Neighbor: {neighbor}, id={idx}, dist={dist[idx]}");
				if (alt < dist[idx]) {
					dist[idx] = alt;
					prev[idx] = u;
					GD.Print($"Prev({idx}) = {u}");
				}
			}
		}

		while (answer != vec2idx(start)) {
			path.Add(idx2vec2(answer));
			answer = prev[answer];
		}
		path.Reverse();
		return path;
	}

	public Vector2I GetTypedBlock(MapNodeType nType, uint idx) {
		Vector2I tileCoord;
		switch(nType) {
		case MapNodeType.Table:
			tileCoord = tableTileCoord;
			break;
		case MapNodeType.Water:
			tileCoord = waterTileCoord;
			break;
		case MapNodeType.Door:
			tileCoord = doorTileCoord;
			break;
		case MapNodeType.Axe:
			tileCoord = axeTileCoord;
			break;
		default:
			return Vector2I.Zero;
		}
		var candidates = tileMap.GetUsedCellsById(0, tileCoord, -1);
		idx %= (uint)candidates.Count;
		return candidates[(int)idx];
	}

	public Vector2I Point2Coord(Vector2 pos) {
		return tileMap.LocalToMap(tileMap.ToLocal(pos));
	}

}