using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using Unity.Collections;
using Unity.Jobs;
using Unity.VisualScripting;
using UnityEngine;
using UnityEngine.Tilemaps;

public class GenerateTileMap : MonoBehaviour
{
    public int? seed;
    public static int maxWidth = 255;
    public static int maxDepth = 384;
    public static int groundDepth = 255;
    private float scale;
    private float offsetX;
    private float offsetY; 
    private NativeArray<float> perlinNoiseCache;
    Tilemap tilemap;
    public CustomRuleTile forestRuleTile;
    public TileBase borderTile;
    private List<Generateable> generateables;

    public const int CHUNK_SIZE = 16; // Size of each chunk
    public int LOAD_DISTANCE = 2; // Number of chunks to load around player
    private const int CACHE_CLEAR_DISTANCE = 8; // Distance in chunks before clearing cache (should be > LOAD_DISTANCE)
    private Vector2Int lastCacheClearPosition; // Track position where cache was last cleared

    [NonSerialized]
    public List<Vector3Int> destroyedTiles = new List<Vector3Int>();
    private Dictionary<Vector2Int, bool> loadedChunks = new Dictionary<Vector2Int, bool>();
    private Dictionary<Vector2Int, TileBase[]> chunkCache = new Dictionary<Vector2Int, TileBase[]>();
    private Transform playerTransform; // Reference to player/camera
    private Vector2Int lastLoadedChunk;
    private GameManager gameManager;

    private void Awake()
    {
        gameManager = FindObjectOfType<GameManager>();
        tilemap = GetComponent<Tilemap>();
        playerTransform = GameObject.FindGameObjectWithTag("Player").transform; // Make sure your player has the "Player" tag
#if DEBUG
        seed = 0123456789;
#endif
        if (seed == null)
        {
            seed = GenerateSeed(9);
        }

        SetSettingsFromSeed(seed.Value);

        // Position adjusted to center horizontally, but align top at y=0
        transform.position = new Vector3((maxWidth / 2) * -1, -1, transform.position.z);

        LoadGenerateablesFromResources();
    }
    private void Update()
    {
        if (playerTransform == null) return;
        //Debug.Log($"Player Position: {playerTransform.position}");
        Vector2Int currentChunk = GetChunkPosition(playerTransform.position);
        //Debug.Log($"Current Chunk: {currentChunk}");
        if (currentChunk != lastLoadedChunk)
        {
            StartCoroutine(UpdateLoadedChunks(currentChunk, destroyedTiles));
            lastLoadedChunk = currentChunk;
            // Check if we need to clear the cache
            ClearDistantChunks(currentChunk);
        }
    }

    public (int seed, Dictionary<Vector2Int, TileBase[]> chunkCache, List<Vector3Int> destroyedTiles) GetSaveValues()
    {
        return (seed.Value, chunkCache, destroyedTiles);
    }
    public void LoadChunkDataFromSave(List<SerializedChunkData> serializedChunks)
    {
        chunkCache.Clear();
        foreach (var chunk in serializedChunks)
        {
            TileBase[] tiles = chunk.tileNames.Select(name =>
                name == "null" ? null :
                name == forestRuleTile.name ? forestRuleTile :
                forestRuleTile.siblings.FirstOrDefault(s => s.name == name)
            ).ToArray();

            chunkCache[chunk.position] = tiles;
        }
    }
    private IEnumerator UpdateLoadedChunks(Vector2Int currentChunk, List<Vector3Int> destroyedTiles)
    {
        // Unload distant chunks
        List<Vector2Int> chunksToUnload = new List<Vector2Int>();
        foreach (var chunk in loadedChunks.Keys)
        {
            if (Mathf.Abs(chunk.x - currentChunk.x) > LOAD_DISTANCE ||
                Mathf.Abs(chunk.y - currentChunk.y) > LOAD_DISTANCE)
            {
                chunksToUnload.Add(chunk);
                UnloadChunk(chunk);
            }
        }
        foreach (var chunk in chunksToUnload)
        {
            loadedChunks.Remove(chunk);
        }

        // Load new chunks
        yield return LoadChunksAroundPosition(currentChunk, destroyedTiles);
    }

    private void UnloadChunk(Vector2Int chunk)
    {
        var emptyTiles = new TileBase[CHUNK_SIZE * CHUNK_SIZE];
        BatchSetTiles(chunk, emptyTiles);
    }
    private void LoadGenerateablesFromResources()
    {
        // Clear existing siblings
        forestRuleTile.siblings.Clear();

        // Load all Item prefabs from the "Resources/Items" folder
        GameObject[] generateablePrefabs = Resources.LoadAll<GameObject>("Generateable");
        generateables = new List<Generateable>();
        foreach (GameObject prefab in generateablePrefabs)
        {
            Generateable generateable = prefab.GetComponent<Generateable>();
            if (generateable != null)
            {
                generateable.tile = ScriptableObject.CreateInstance<CustomRuleTile>();
                generateable.tile.m_DefaultGameObject = prefab;
                generateable.tile.m_DefaultSprite = generateable.sprite;
                generateables.Add(generateable);
                forestRuleTile.siblings.Add(generateable.tile);
            }
            else
            {
                Debug.LogWarning($"Prefab {prefab.name} does not have an Item component");
            }
        }

        GenerateableDatabase.Instance.InitializeFromGenerateables(generateables);

        if (generateables.Count == 0)
        {
            Debug.LogWarning("No items found in Resources/Items folder");
        }
    }

    public void SetSettingsFromSeed(int seed)
    {
        UnityEngine.Random.State randomState = UnityEngine.Random.state;

        UnityEngine.Random.InitState(seed);
        scale = UnityEngine.Random.Range(17f, 23f);
        offsetX = UnityEngine.Random.Range(-10000f, 10000f);
        offsetY = UnityEngine.Random.Range(-10000f, 10000f);

        UnityEngine.Random.state = randomState;

        CachePerlinNoise();
    }

    private int GenerateSeed(int size)
    {
        System.Random rand = new System.Random();
        string seedNumbers = "0123456789";
        char[] chars = new char[size];
        for (int i = 0; i < size; i++)
        {
            chars[i] = seedNumbers[rand.Next(seedNumbers.Length)];
        }
        return int.Parse(new string(chars));
    }
    private void CachePerlinNoise()
    {
        perlinNoiseCache = new NativeArray<float>(maxWidth * maxDepth, Allocator.Persistent);
        for (int x = 0; x < maxWidth; x++)
        {
            for (int y = 0; y < maxDepth; y++)
            {
                float xPerlin = ((float)x / maxWidth) * scale + offsetX;
                float yPerlin = ((float)Math.Abs(y) / groundDepth) * scale + offsetY;
                perlinNoiseCache[x * groundDepth + y] = Mathf.PerlinNoise(xPerlin, yPerlin);
            }
        }
    }

    public IEnumerator GenerateTiles(Action finishedCallback, List<Vector3Int> destroyedTiles)
    {
        // Get initial player chunk position
        Vector2Int currentChunk = GetChunkPosition(playerTransform.position);
        lastLoadedChunk = currentChunk;

        // Generate initial chunks around player
        yield return LoadChunksAroundPosition(currentChunk, destroyedTiles);

        finishedCallback();
    }
    public Vector2Int GetChunkPosition(Vector3 worldPosition)
    {
        // Adjust for tilemap offset
        float adjustedX = worldPosition.x - transform.position.x;
        float adjustedY = (worldPosition.y - transform.position.y) + CHUNK_SIZE;

        return new Vector2Int(
            Mathf.FloorToInt(adjustedX / CHUNK_SIZE),
            Mathf.FloorToInt(adjustedY / CHUNK_SIZE)
        );
    }
    public void UpdateChunkCache(Vector3Int cellCoord, Vector3 cellWorldPosition)
    {
        // Update chunk cache
        Vector2Int chunkPos = GetChunkPosition(cellWorldPosition);
        if (chunkCache.TryGetValue(chunkPos, out TileBase[] cachedTiles))
        {
            int localX = cellCoord.x - (chunkPos.x * GenerateTileMap.CHUNK_SIZE);
            int localY = (chunkPos.y * GenerateTileMap.CHUNK_SIZE) - cellCoord.y - 1;
            int index = localY * GenerateTileMap.CHUNK_SIZE + localX;

            if (index >= 0 && index < cachedTiles.Length)
            {
                cachedTiles[index] = null;
                chunkCache[chunkPos] = cachedTiles;
            }
        }
    }
    private IEnumerator LoadChunksAroundPosition(Vector2Int centerChunk, List<Vector3Int> destroyedTiles)
    {
        for (int x = -LOAD_DISTANCE; x <= LOAD_DISTANCE; x++)
        {
            for (int y = -LOAD_DISTANCE; y <= LOAD_DISTANCE; y++)
            {
                Vector2Int chunkPos = new Vector2Int(centerChunk.x + x, centerChunk.y + y);
                if (!loadedChunks.ContainsKey(chunkPos))
                {
                    if (chunkCache.ContainsKey(chunkPos))
                    {
                        // Load the chunk from the cache
                        yield return LoadChunkFromCache(chunkPos);
                    }
                    else
                    {
                        // Generate the chunk
                        yield return GenerateChunk(chunkPos, destroyedTiles);
                    }
                    loadedChunks[chunkPos] = true;
                }
            }
        }
    }

    private IEnumerator LoadChunkFromCache(Vector2Int chunk)
    {
        int startX = chunk.x * CHUNK_SIZE;
        int startY = (chunk.y * CHUNK_SIZE) - 1;

        if (chunkCache.TryGetValue(chunk, out TileBase[] cachedTiles))
        {
            //for (int i = 0; i < cachedTiles.Length; i++)
            //{
            //    int x = startX + (i % CHUNK_SIZE);
            //    int y = startY - (i / CHUNK_SIZE);
            //    Vector3Int tilePos = new Vector3Int(x, y);

            //    if (!IsTileDestroyed(tilePos))
            //    {
            //        tilemap.SetTile(tilePos, cachedTiles[i]);
            //    }
            //}
            BatchSetTiles(chunk, cachedTiles, destroyedTiles);
        }
        yield return null;
    }
    private void BatchSetTiles(Vector2Int chunk, TileBase[] tiles, List<Vector3Int> destroyedTiles = null)
    {
        int startX = chunk.x * CHUNK_SIZE;
        int startY = (chunk.y * CHUNK_SIZE) - 1;

        var positions = new Vector3Int[CHUNK_SIZE * CHUNK_SIZE];
        var tileArray = new TileBase[CHUNK_SIZE * CHUNK_SIZE];

        for (int i = 0; i < tiles.Length; i++)
        {
            int x = startX + (i % CHUNK_SIZE);
            int y = startY - (i / CHUNK_SIZE);
            Vector3Int pos = new Vector3Int(x, y);

            positions[i] = pos;
            tileArray[i] = destroyedTiles != null && destroyedTiles.Contains(pos) ? null : tiles[i];
        }

        tilemap.SetTiles(positions, tileArray);
    }
    private void ClearDistantChunks(Vector2Int currentChunk)
    {
        // If this is the first time, initialize the last clear position
        if (lastCacheClearPosition == default)
        {
            lastCacheClearPosition = currentChunk;
            return;
        }

        // Calculate distance moved since last cache clear
        int distanceMoved = Mathf.Max(
            Mathf.Abs(currentChunk.x - lastCacheClearPosition.x),
            Mathf.Abs(currentChunk.y - lastCacheClearPosition.y)
        );

        // If we've moved far enough, clear distant chunks from cache
        if (distanceMoved >= CACHE_CLEAR_DISTANCE)
        {
            List<Vector2Int> chunksToRemove = new List<Vector2Int>();

            foreach (var chunk in chunkCache.Keys)
            {
                int distanceToPlayer = Mathf.Max(
                    Mathf.Abs(chunk.x - currentChunk.x),
                    Mathf.Abs(chunk.y - currentChunk.y)
                );

                // Remove chunks that are far from current position
                if (distanceToPlayer > LOAD_DISTANCE * 2)
                {
                    chunksToRemove.Add(chunk);
                }
            }

            // Remove the distant chunks from cache
            foreach (var chunk in chunksToRemove)
            {
                chunkCache.Remove(chunk);
            }

            lastCacheClearPosition = currentChunk;
            Debug.Log($"Cleared {chunksToRemove.Count} chunks from cache. Current cache size: {chunkCache.Count}");
        }
    }
    private IEnumerator GenerateChunk(Vector2Int chunk, List<Vector3Int> destroyedTiles)
    {
        int startX = chunk.x * CHUNK_SIZE;
        int startY = (chunk.y * CHUNK_SIZE) - 1;
        // Check if the chunk is already in the cache
        LoadChunkFromCache(chunk);

        // Create job data
        var groundJob = new GenerateGroundJob
        {
            chunkStartX = startX,
            chunkStartY = startY,
            chunkSize = CHUNK_SIZE,
            maxWidth = maxWidth,
            groundDepth = groundDepth,
            scale = scale,
            offsetX = offsetX,
            offsetY = offsetY,
            groundTiles = new NativeArray<bool>(CHUNK_SIZE * CHUNK_SIZE, Allocator.TempJob),
            perlinNoiseCache = perlinNoiseCache
        };

        // Schedule the job
        JobHandle groundJobHandle = groundJob.Schedule(CHUNK_SIZE * CHUNK_SIZE, 64);

        // Wait for the job to complete
        yield return new WaitUntil(() => groundJobHandle.IsCompleted);

        // Apply the results
        groundJobHandle.Complete();
        TileBase[] newChunkTiles = new TileBase[CHUNK_SIZE * CHUNK_SIZE];
        //for (int i = 0; i < CHUNK_SIZE * CHUNK_SIZE; i++)
        //{
        //    if (groundJob.groundTiles[i])
        //    {
        //        int x = startX + (i % CHUNK_SIZE);
        //        int y = startY - (i / CHUNK_SIZE);
        //        Vector3Int tilePos = new Vector3Int(x, y);

        //        if (!IsTileDestroyed(tilePos))
        //        {
        //            tilemap.SetTile(tilePos, forestRuleTile);
        //            newChunkTiles[i] = forestRuleTile;
        //        }
        //        else
        //        {
        //            newChunkTiles[i] = null;
        //        }
        //    }
        //    else
        //    {
        //        newChunkTiles[i] = null;
        //    }
        //}
        for (int i = 0; i < CHUNK_SIZE * CHUNK_SIZE; i++)
        {
            newChunkTiles[i] = groundJob.groundTiles[i] ? forestRuleTile : null;
        }

        // Batch update tiles
        BatchSetTiles(chunk, newChunkTiles, destroyedTiles);

        // Save the generated chunk to the cache
        chunkCache[chunk] = newChunkTiles;

        // Clean up native array
        groundJob.groundTiles.Dispose();

        // Generate ores
        if (generateables != null)
        {
            yield return GenerateOresInChunk(chunk, destroyedTiles);
        }

        // Generate borders when needed
        if (startX == 0 || startX + CHUNK_SIZE >= maxWidth ||
            startY == 0 || startY - CHUNK_SIZE <= -groundDepth)
        {
            yield return GenerateBorders();
        }
    }

    private IEnumerator GenerateOresInChunk(Vector2Int chunk, List<Vector3Int> destroyedTiles)
    {
        int startX = chunk.x * CHUNK_SIZE;
        int startY = chunk.y * CHUNK_SIZE;
        // Get the cached tiles for this chunk
        TileBase[] cachedTiles = chunkCache[chunk];

        foreach (Generateable generateable in generateables)
        {
            // Convert spawn heights to negative values if they aren't already
            int maxY = -Mathf.Abs(generateable.maxSpawnHeight);
            int minY = -Mathf.Abs(generateable.minSpawnHeight);
            // Changed condition: Check if the chunk's Y range overlaps with ore spawn range
            int chunkMaxY = startY;
            int chunkMinY = startY - CHUNK_SIZE;

            // Only process this chunk if it's within the ore's spawn height range
            if (chunkMinY <= maxY && chunkMaxY >= minY)
            {
                for (int x = startX; x < startX + CHUNK_SIZE; x++)
                {
                    if (x >= maxWidth) continue;

                    // Adjusted Y range calculation
                    int rangeStart = Mathf.Max(chunkMinY, minY);
                    int rangeEnd = Mathf.Min(chunkMaxY, maxY);

                    for (int y = rangeStart; y <= rangeEnd; y++)
                    {
                        float xPerlin = ((float)x / maxWidth) * (float)generateable.clusterWeight + offsetX;
                        float yPerlin = ((float)Mathf.Abs(y) / maxDepth) * (float)generateable.clusterWeight + offsetY;

                        float perlinNoise = Mathf.PerlinNoise(xPerlin, yPerlin);

                        if (perlinNoise <= (1f / (float)generateable.weight))
                        {
                            Vector3Int tileSpawnCoord = new Vector3Int(x, y);
                            if (!destroyedTiles.Contains(tileSpawnCoord) && tilemap.HasTile(tileSpawnCoord))
                            {
                                int clusterSize = CountPotentialClusterSize(x, y, generateable.weight, generateable.clusterWeight);
                                if (clusterSize >= generateable.minClusterSize)
                                {
                                    tilemap.SetTile(tileSpawnCoord, generateable.tile);
                                    // Update cache
                                    int localX = x - startX;
                                    int localY = startY - y - 1;
                                    int index = localY * CHUNK_SIZE + localX;
                                    if (index >= 0 && index < cachedTiles.Length)
                                    {
                                        cachedTiles[index] = generateable.tile;
                                    }
                                }
                            }
                        }
                    }
                }

                // Update every few rows to maintain performance
                if (generateables.Count > 3)
                {
                    yield return null;
                }
            }
        }
        // Update the cache with the modified tiles
        chunkCache[chunk] = cachedTiles;
    }
    private IEnumerator GenerateBorders()
    {
        // Vertical borders
        for (int x = 0; x <= maxWidth; x += maxWidth)
        {
            for (int y = -groundDepth; y <= maxDepth - groundDepth; y++)
            {
                Vector3Int borderPos = new Vector3Int(x, y);
                tilemap.SetTile(borderPos, borderTile);

                // Update cache for affected chunk
                Vector2Int chunkPos = GetChunkPosition(new Vector3(x + transform.position.x, y + transform.position.y));
                if (chunkCache.TryGetValue(chunkPos, out TileBase[] cachedTiles))
                {
                    int localX = x - (chunkPos.x * CHUNK_SIZE);
                    int localY = chunkPos.y * CHUNK_SIZE - y - 1;
                    int index = localY * CHUNK_SIZE + localX;
                    if (index >= 0 && index < cachedTiles.Length)
                    {
                        cachedTiles[index] = borderTile;
                        chunkCache[chunkPos] = cachedTiles;
                    }
                }
            }
        }
        yield return null;

        // Horizontal borders
        for (int y = -groundDepth; y <= maxDepth - groundDepth; y += maxDepth)
        {
            for (int x = 1; x < maxWidth; x++)
            {
                Vector3Int borderPos = new Vector3Int(x, y);
                tilemap.SetTile(borderPos, borderTile);

                // Update cache for affected chunk
                Vector2Int chunkPos = GetChunkPosition(new Vector3(x + transform.position.x, y + transform.position.y));
                if (chunkCache.TryGetValue(chunkPos, out TileBase[] cachedTiles))
                {
                    int localX = x - (chunkPos.x * CHUNK_SIZE);
                    int localY = chunkPos.y * CHUNK_SIZE - y - 1;
                    int index = localY * CHUNK_SIZE + localX;
                    if (index >= 0 && index < cachedTiles.Length)
                    {
                        cachedTiles[index] = borderTile;
                        chunkCache[chunkPos] = cachedTiles;
                    }
                }
            }
        }
        yield return null;
    }

    private int CountPotentialClusterSize(int startX, int startY, int weight, int clusterWeight)
    {
        int size = 0;
        Queue<Vector2Int> toCheck = new Queue<Vector2Int>();
        HashSet<Vector2Int> checked_positions = new HashSet<Vector2Int>();

        toCheck.Enqueue(new Vector2Int(startX, startY));
        checked_positions.Add(new Vector2Int(startX, startY));

        while (toCheck.Count > 0)
        {
            Vector2Int current = toCheck.Dequeue();
            size++;

            // Check all 8 neighboring tiles
            for (int dx = -1; dx <= 1; dx++)
            {
                for (int dy = -1; dy <= 1; dy++)
                {
                    if (dx == 0 && dy == 0) continue;

                    Vector2Int neighbor = new Vector2Int(current.x + dx, current.y + dy);
                    if (checked_positions.Contains(neighbor)) continue;

                    float xPerlin = ((float)neighbor.x / maxWidth) * clusterWeight + offsetX;
                    float yPerlin = ((float)Mathf.Abs(neighbor.y) / maxDepth) * clusterWeight + offsetY;
                    float perlinNoise = Mathf.PerlinNoise(xPerlin, yPerlin);

                    if (perlinNoise <= (1f / (float)weight))
                    {
                        toCheck.Enqueue(neighbor);
                        checked_positions.Add(neighbor);
                    }
                }
            }
        }

        return size;
    }
    private void OnDestroy()
    {
        if (perlinNoiseCache.IsCreated)
        {
            perlinNoiseCache.Dispose();
        }
        chunkCache.Clear();
    }
#if UNITY_EDITOR
    private void OnDrawGizmos()
    {
        if (!Application.isPlaying) return;

        // Draw current chunk boundaries
        if (playerTransform != null)
        {
            Vector2Int currentChunk = GetChunkPosition(playerTransform.position);
            Gizmos.color = Color.yellow;

            for (int x = -LOAD_DISTANCE; x <= LOAD_DISTANCE; x++)
            {
                for (int y = -LOAD_DISTANCE; y <= LOAD_DISTANCE; y++)
                {
                    Vector2Int chunk = new Vector2Int(currentChunk.x + x, currentChunk.y + y);
                    Vector3 worldPos = new Vector3(
                        chunk.x * CHUNK_SIZE + transform.position.x,
                        chunk.y * CHUNK_SIZE + transform.position.y,
                        0
                    );

                    // Draw chunk boundary
                    Gizmos.DrawWireCube(
                        worldPos + new Vector3(CHUNK_SIZE / 2f, -CHUNK_SIZE / 2f, 0),
                        new Vector3(CHUNK_SIZE, CHUNK_SIZE, 0)
                    );

                    // Draw chunk coordinates
                    UnityEditor.Handles.Label(
                        worldPos + new Vector3(CHUNK_SIZE / 2f, -CHUNK_SIZE / 2f, 0),
                        $"({chunk.x}, {chunk.y})"
                    );
                }
            }
        }
    }
#endif
}