using Godot;
using System;
using System.Collections.Generic;
using System.Text.Json;

public partial class ChunkManager : Node2D
{
	[Export] public NodePath PlayerPath;
	[Export] public NodePath PackManagerPath;
	[Export] public int LoadRadius = 1; // 1 -> 3x3

	private CharacterBody2D? _player;
	private PackManager? _packs;

	private WorldIndex? _world;
	private Dictionary<(int x, int y), string> _chunkMap = new();
	private readonly Dictionary<(int x, int y), Node2D> _loaded = new();

	public override void _Ready()
	{
		_player = GetNodeOrNull<CharacterBody2D>(PlayerPath);
		if (_player == null)
		{
			GD.PrintErr("ChunkManager: PlayerPath not set or invalid.");
			return;
		}

		_packs = GetNodeOrNull<PackManager>(PackManagerPath);
		if (_packs == null)
		{
			// fallback: search up the tree for PackManager
			_packs = GetParent()?.GetNodeOrNull<PackManager>("PackManager");
		}

		if (_packs == null)
		{
			GD.PrintErr("ChunkManager: PackManager not found. Add it to your Main scene.");
			return;
		}

		LoadWorldIndex();
	}

	private void LoadWorldIndex()
	{
		var worldPath = _packs.Resolve("data/world/world_main.json");
		if (worldPath == null)
		{
			GD.PrintErr("ChunkManager: Could not resolve data/world/world_main.json from packs.");
			return;
		}

		var json = FileAccess.GetFileAsString(worldPath);
		_world = JsonSerializer.Deserialize<WorldIndex>(json);
		if (_world == null)
		{
			GD.PrintErr("ChunkManager: Failed to parse world index.");
			return;
		}

		_chunkMap = _world.BuildChunkMap();
		GD.Print($"World loaded: {_world.world_id}, chunks: {_chunkMap.Count}, chunk_size_px={_world.chunk_size_px}");
	}

	public override void _Process(double delta)
	{
		if (_player == null || _world == null) return;

		var (cx, cy) = WorldPosToChunk(_player.GlobalPosition, _world.chunk_size_px);

		for (int dy = -LoadRadius; dy <= LoadRadius; dy++)
		for (int dx = -LoadRadius; dx <= LoadRadius; dx++)
		{
			var key = (cx + dx, cy + dy);
			EnsureLoaded(key.x, key.y);
		}

		// Unload chunks that are too far
		var keysToRemove = new List<(int x, int y)>();
		foreach (var kv in _loaded)
		{
			var (x, y) = kv.Key;
			if (Math.Abs(x - cx) > LoadRadius || Math.Abs(y - cy) > LoadRadius)
				keysToRemove.Add((x, y));
		}
		foreach (var k in keysToRemove)
		{
			_loaded[k].QueueFree();
			_loaded.Remove(k);
		}
	}

	private void EnsureLoaded(int x, int y)
	{
		var key = (x, y);
		if (_loaded.ContainsKey(key)) return;
		if (!_chunkMap.TryGetValue(key, out var relPath)) return;

		// Use pack resolve for the chunk file itself
		var chunkPath = _packs!.Resolve(relPath);
		if (chunkPath == null)
		{
			GD.PrintErr($"Chunk missing in packs: {relPath}");
			return;
		}

		// For now, we don't parse chunk contents yet; we just visualize existence + biome by file naming/placeholder.
		// Next step: parse biome from JSON and use it to color.
		var chunkJson = FileAccess.GetFileAsString(chunkPath);
		using var doc = JsonDocument.Parse(chunkJson);
		var biome = doc.RootElement.TryGetProperty("biome", out var b) ? b.GetString() : "biome:unknown";

		var node = CreateDebugChunkNode(x, y, _world!.chunk_size_px, biome ?? "biome:unknown");
		AddChild(node);
		_loaded[key] = node;
	}

	private static (int cx, int cy) WorldPosToChunk(Vector2 pos, int chunkSizePx)
	{
		int cx = Mathf.FloorToInt(pos.X / chunkSizePx);
		int cy = Mathf.FloorToInt(pos.Y / chunkSizePx);
		return (cx, cy);
	}

	private static Node2D CreateDebugChunkNode(int cx, int cy, int chunkSizePx, string biome)
	{
		var n = new Node2D();
		n.Name = $"Chunk_{cx}_{cy}";
		n.Position = new Vector2(cx * chunkSizePx, cy * chunkSizePx);

		var rect = new ColorRect();
		rect.Size = new Vector2(chunkSizePx, chunkSizePx);
		rect.MouseFilter = Control.MouseFilterEnum.Ignore;

		rect.Color = biome switch
		{
			"biome:forest" => new Color(0.1f, 0.35f, 0.1f, 0.25f),
			"biome:plains" => new Color(0.35f, 0.35f, 0.1f, 0.25f),
			"biome:town" => new Color(0.25f, 0.25f, 0.25f, 0.25f),
			_ => new Color(0.2f, 0.2f, 0.2f, 0.25f)
		};

		// Add an outline using a Panel (cheap) or just rely on transparency for now
		n.AddChild(rect);
		return n;
	}
}