using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Events;
using UnityEngine.Serialization;
using Pooling;

namespace Minigames.DivingForPictures
{
    /// <summary>
    /// Spawns and manages trench wall tiles for the endless descender minigame.
    /// </summary>
    public class TrenchTileSpawner : MonoBehaviour
    {
        [Header("Tile Prefabs")]
        [Tooltip("List of possible trench tile prefabs.")]
        [SerializeField] private List<GameObject> tilePrefabs;

        [Header("Tile Settings")] 
        [SerializeField] private int initialTileCount = 3;
        [SerializeField] private float tileSpawnBuffer = 1f;

        [Header("Movement Settings")]
        [SerializeField] private float moveSpeed = 3f;
        [SerializeField] private float speedUpFactor = 0.2f;
        [SerializeField] private float speedUpInterval = 10f;
        [SerializeField] private float maxMoveSpeed = 12f;

        [Header("Object Pooling")]
        [SerializeField] private bool useObjectPooling = true;
        [SerializeField] private int maxPerPrefabPoolSize = 2;
        [SerializeField] private int totalMaxPoolSize = 10;

        [Header("Events")]
        [FormerlySerializedAs("OnTileSpawned")] 
        public UnityEvent<GameObject> onTileSpawned;
        
        [FormerlySerializedAs("OnTileDestroyed")] 
        public UnityEvent<GameObject> onTileDestroyed;

        // Private fields
        private readonly Dictionary<GameObject, float> _tileHeights = new Dictionary<GameObject, float>();
        private readonly List<GameObject> _activeTiles = new List<GameObject>();
        private readonly Dictionary<int, int> _tileLastUsed = new Dictionary<int, int>();
        
        private int _spawnCounter;
        private float _speedUpTimer;
        private Camera _mainCamera;
        private float _screenBottom;
        private float _screenTop;
        private TrenchTilePool _tilePool;

        private const float TileSpawnZ = -1f;
        private const float DefaultTileHeight = 5f;

        private void Awake()
        {
            _mainCamera = Camera.main;
            
            // Calculate tile heights for each prefab
            CalculateTileHeights();
            
            // Ensure all prefabs have Tile components
            ValidateTilePrefabs();
            
            if (useObjectPooling)
            {
                InitializeObjectPool();
            }
        }

        // Validate that all prefabs have Tile components
        private void ValidateTilePrefabs()
        {
            for (int i = 0; i < tilePrefabs.Count; i++)
            {
                if (tilePrefabs[i] == null) continue;
                
                // Check if the prefab has a Tile component
                if (tilePrefabs[i].GetComponent<Tile>() == null)
                {
                    Debug.LogWarning($"Prefab {tilePrefabs[i].name} does not have a Tile component. Adding one automatically.");
                    // Add the Tile component if it doesn't exist
                    tilePrefabs[i].AddComponent<Tile>();
                }
            }
        }

        private void Start()
        {
            CalculateScreenBounds();
            SpawnInitialTiles();
        }

        private void Update()
        {
            MoveTiles();
            HandleTileDestruction();
            HandleTileSpawning();
            HandleSpeedRamping();
        }

        /// <summary>
        /// Calculate height values for all tile prefabs
        /// </summary>
        private void CalculateTileHeights()
        {
            foreach (var prefab in tilePrefabs)
            {
                if (prefab == null)
                {
                    Debug.LogError("Null prefab found in tilePrefabs list!");
                    continue;
                }

                Renderer renderer = prefab.GetComponentInChildren<Renderer>();
                if (renderer != null)
                {
                    _tileHeights[prefab] = renderer.bounds.size.y;
                }
                else
                {
                    // Fallback in case no renderer is found
                    _tileHeights[prefab] = DefaultTileHeight;
                    Debug.LogWarning($"No renderer found in prefab {prefab.name}. Using default height of {DefaultTileHeight}.");
                }
            }
        }

        /// <summary>
        /// Initialize the object pool system
        /// </summary>
        private void InitializeObjectPool()
        {
            // Create the tile pool
            GameObject poolGO = new GameObject("TrenchTilePool");
            poolGO.transform.SetParent(transform);
            _tilePool = poolGO.AddComponent<TrenchTilePool>();
            
            // Set up the pool configuration
            _tilePool.maxPerPrefabPoolSize = maxPerPrefabPoolSize;
            _tilePool.totalMaxPoolSize = totalMaxPoolSize;
            
            // Convert the GameObject list to a Tile list
            List<Tile> prefabTiles = new List<Tile>(tilePrefabs.Count);
            foreach (var prefab in tilePrefabs)
            {
                if (prefab != null)
                {
                    Tile tileComponent = prefab.GetComponent<Tile>();
                    if (tileComponent != null)
                    {
                        prefabTiles.Add(tileComponent);
                    }
                    else
                    {
                        Debug.LogError($"Prefab {prefab.name} is missing a Tile component!");
                    }
                }
            }
            
            // Initialize the pool with the tile component list
            _tilePool.Initialize(prefabTiles);
            
            // Periodically trim the pool to optimize memory usage
            InvokeRepeating(nameof(TrimExcessPooledTiles), 10f, 30f);
        }

        /// <summary>
        /// Spawn the initial set of tiles
        /// </summary>
        private void SpawnInitialTiles()
        {
            for (int i = 0; i < initialTileCount; i++)
            {
                float y = _screenBottom;
                // Calculate proper Y position based on previous tiles
                if (i > 0 && _activeTiles.Count > 0)
                {
                    GameObject prevTile = _activeTiles[_activeTiles.Count - 1];
                    float prevHeight = GetTileHeight(prevTile);
                    y = prevTile.transform.position.y - prevHeight;
                }
                SpawnTileAtY(y);
            }
        }

        /// <summary>
        /// Calculate the screen bounds in world space
        /// </summary>
        private void CalculateScreenBounds()
        {
            if (_mainCamera == null)
            {
                _mainCamera = Camera.main;
                if (_mainCamera == null)
                {
                    Debug.LogError("No main camera found!");
                    return;
                }
            }

            Vector3 bottom = _mainCamera.ViewportToWorldPoint(new Vector3(0.5f, 0f, _mainCamera.nearClipPlane));
            Vector3 top = _mainCamera.ViewportToWorldPoint(new Vector3(0.5f, 1f, _mainCamera.nearClipPlane));
            _screenBottom = bottom.y;
            _screenTop = top.y;
        }

        /// <summary>
        /// Move all active tiles upward
        /// </summary>
        private void MoveTiles()
        {
            float moveDelta = moveSpeed * Time.deltaTime;
            foreach (var tile in _activeTiles)
            {
                if (tile != null)
                {
                    tile.transform.position += Vector3.up * moveDelta;
                }
            }
        }

        /// <summary>
        /// Check for tiles that have moved off screen and should be destroyed or returned to pool
        /// </summary>
        private void HandleTileDestruction()
        {
            if (_activeTiles.Count == 0) return;
            
            GameObject topTile = _activeTiles[0];
            if (topTile == null)
            {
                _activeTiles.RemoveAt(0);
                return;
            }

            float tileHeight = GetTileHeight(topTile);
            if (topTile.transform.position.y - tileHeight / 2 > _screenTop + tileSpawnBuffer)
            {
                _activeTiles.RemoveAt(0);
                onTileDestroyed?.Invoke(topTile);
                
                if (useObjectPooling && _tilePool != null)
                {
                    // Find the prefab index for this tile
                    int prefabIndex = GetPrefabIndex(topTile);
                    if (prefabIndex >= 0)
                    {
                        _tilePool.ReturnTile(topTile, prefabIndex);
                    }
                    else
                    {
                        Destroy(topTile);
                    }
                }
                else
                {
                    Destroy(topTile);
                }
            }
        }

        /// <summary>
        /// Check if new tiles need to be spawned
        /// </summary>
        private void HandleTileSpawning()
        {
            if (_activeTiles.Count == 0) return;
            
            GameObject bottomTile = _activeTiles[^1];
            if (bottomTile == null)
            {
                _activeTiles.RemoveAt(_activeTiles.Count - 1);
                return;
            }

            float tileHeight = GetTileHeight(bottomTile);
            float bottomEdge = bottomTile.transform.position.y - tileHeight / 2;
            if (bottomEdge > _screenBottom - tileSpawnBuffer)
            {
                float newY = bottomTile.transform.position.y - tileHeight;
                SpawnTileAtY(newY);
            }
        }

        /// <summary>
        /// Handle increasing the movement speed over time
        /// </summary>
        private void HandleSpeedRamping()
        {
            _speedUpTimer += Time.deltaTime;
            if (_speedUpTimer >= speedUpInterval)
            {
                moveSpeed = Mathf.Min(moveSpeed + speedUpFactor, maxMoveSpeed);
                _speedUpTimer = 0f;
            }
        }

        /// <summary>
        /// Spawn a new tile at the specified Y position
        /// </summary>
        /// <param name="y">The Y position to spawn at</param>
        private void SpawnTileAtY(float y)
        {
            if (tilePrefabs == null || tilePrefabs.Count == 0)
            {
                Debug.LogError("No tile prefabs available for spawning!");
                return;
            }

            int prefabIndex = GetWeightedRandomTileIndex();
            GameObject prefab = tilePrefabs[prefabIndex];
            if (prefab == null)
            {
                Debug.LogError($"Tile prefab at index {prefabIndex} is null!");
                return;
            }

            GameObject tile;
            
            if (useObjectPooling && _tilePool != null)
            {
                tile = _tilePool.GetTile(prefabIndex);
                if (tile == null)
                {
                    Debug.LogError("Failed to get tile from pool!");
                    return;
                }

                tile.transform.position = new Vector3(0f, y, TileSpawnZ);
                tile.transform.rotation = prefab.transform.rotation;
                tile.transform.SetParent(transform);
            }
            else
            {
                // Use the prefab's original rotation
                tile = Instantiate(prefab, new Vector3(0f, y, TileSpawnZ), prefab.transform.rotation, transform);
            }
            
            _activeTiles.Add(tile);
            _tileLastUsed[prefabIndex] = _spawnCounter++;
            onTileSpawned?.Invoke(tile);
        }

        /// <summary>
        /// Gets a weighted random tile index, favoring tiles that haven't been used recently
        /// </summary>
        /// <returns>The selected prefab index</returns>
        private int GetWeightedRandomTileIndex()
        {
            int prefabCount = tilePrefabs.Count;
            List<float> weights = new List<float>(prefabCount);
            
            for (int i = 0; i < prefabCount; i++)
            {
                int lastUsed = _tileLastUsed.TryGetValue(i, out var value) ? value : -prefabCount;
                int age = _spawnCounter - lastUsed;
                float weight = Mathf.Clamp(age, 1, prefabCount * 2); // More unused = higher weight
                weights.Add(weight);
            }
            
            float totalWeight = 0f;
            foreach (var weight in weights)
            {
                totalWeight += weight;
            }
            
            float randomValue = Random.value * totalWeight;
            for (int i = 0; i < prefabCount; i++)
            {
                if (randomValue < weights[i])
                {
                    return i;
                }
                randomValue -= weights[i];
            }
            
            return Random.Range(0, prefabCount); // fallback
        }
        
        /// <summary>
        /// Gets the height of a tile based on its prefab or renderer bounds
        /// </summary>
        /// <param name="tile">The tile to measure</param>
        /// <returns>The height of the tile</returns>
        private float GetTileHeight(GameObject tile)
        {
            if (tile == null)
            {
                Debug.LogWarning("Attempted to get height of null tile!");
                return DefaultTileHeight;
            }

            // Check if this is a known prefab
            foreach (var prefab in tilePrefabs)
            {
                if (prefab == null) continue;

                // Check if this tile was created from this prefab
                if (tile.name.StartsWith(prefab.name))
                {
                    if (_tileHeights.TryGetValue(prefab, out float height))
                    {
                        return height;
                    }
                }
            }
            
            // If not found, calculate it from the renderer
            Renderer renderer = tile.GetComponentInChildren<Renderer>();
            if (renderer != null)
            {
                return renderer.bounds.size.y;
            }
            
            // Fallback
            return DefaultTileHeight;
        }
        
        /// <summary>
        /// Gets the index of the prefab that was used to create this tile
        /// </summary>
        /// <param name="tile">The tile to check</param>
        /// <returns>The index of the prefab or -1 if not found</returns>
        private int GetPrefabIndex(GameObject tile)
        {
            if (tile == null || tilePrefabs == null)
            {
                return -1;
            }

            for (int i = 0; i < tilePrefabs.Count; i++)
            {
                if (tilePrefabs[i] == null) continue;
                
                if (tile.name.StartsWith(tilePrefabs[i].name))
                {
                    return i;
                }
            }
            return -1;
        }

        /// <summary>
        /// Called periodically to trim excess pooled tiles
        /// </summary>
        private void TrimExcessPooledTiles()
        {
            if (_tilePool != null)
            {
                _tilePool.TrimExcess();
            }
        }

#if UNITY_EDITOR
        private void OnDrawGizmosSelected()
        {
            if (!Application.isPlaying)
            {
                // Only try to calculate this if _screenBottom hasn't been set by the game
                Camera editorCam = Camera.main;
                if (editorCam != null)
                {
                    Vector3 bottom = editorCam.ViewportToWorldPoint(new Vector3(0.5f, 0f, editorCam.nearClipPlane));
                    _screenBottom = bottom.y;
                }
            }

            // Draw tile bounds for debugging
            Gizmos.color = Color.cyan;
            for (int i = 0; i < initialTileCount; i++)
            {
                float height = DefaultTileHeight;
                if (tilePrefabs != null && tilePrefabs.Count > 0 && tilePrefabs[0] != null && 
                    _tileHeights.TryGetValue(tilePrefabs[0], out float h))
                {
                    height = h;
                }
                Vector3 center = new Vector3(0f, _screenBottom + i * height, 0f);
                Gizmos.DrawWireCube(center, new Vector3(10f, height, 1f));
            }
        }
#endif
    }
}