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

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.")]
        public List<GameObject> tilePrefabs;

        [Header("Tile Settings")] 
        private const float TileHeight = 5f; // Set to match prefab height
        public int initialTileCount = 3;
        public float tileSpawnBuffer = 1f;

        [Header("Movement Settings")]
        public float moveSpeed = 3f;
        public float speedUpFactor = 0.2f;
        public float speedUpInterval = 10f;

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

        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;

        void Start()
        {
            _mainCamera = Camera.main;
            CalculateScreenBounds();
            for (int i = 0; i < initialTileCount; i++)
            {
                SpawnTileAtY(_screenBottom + i * TileHeight);
            }
        }

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

        private void CalculateScreenBounds()
        {
            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;
        }

        private void MoveTiles()
        {
            float moveDelta = moveSpeed * Time.deltaTime;
            foreach (var tile in _activeTiles)
            {
                if (tile != null)
                {
                    tile.transform.position += Vector3.up * moveDelta;
                }
            }
        }

        private void HandleTileDestruction()
        {
            if (_activeTiles.Count == 0) return;
            GameObject topTile = _activeTiles[0];
            if (topTile.transform.position.y - TileHeight / 2 > _screenTop + tileSpawnBuffer)
            {
                _activeTiles.RemoveAt(0);
                onTileDestroyed?.Invoke(topTile);
                Destroy(topTile);
            }
        }

        private void HandleTileSpawning()
        {
            if (_activeTiles.Count == 0) return;
            GameObject bottomTile = _activeTiles[^1];
            float bottomEdge = bottomTile.transform.position.y - TileHeight / 2;
            if (bottomEdge > _screenBottom - tileSpawnBuffer)
            {
                float newY = bottomTile.transform.position.y - TileHeight;
                SpawnTileAtY(newY);
            }
        }

        private void HandleSpeedRamping()
        {
            _speedUpTimer += Time.deltaTime;
            if (_speedUpTimer >= speedUpInterval)
            {
                moveSpeed += speedUpFactor;
                _speedUpTimer = 0f;
            }
        }

        private void SpawnTileAtY(float y)
        {
            int prefabIndex = GetWeightedRandomTileIndex();
            GameObject prefab = tilePrefabs[prefabIndex];
            // Use the prefab's original rotation
            GameObject tile = Instantiate(prefab, new Vector3(0f, y, 0f), prefab.transform.rotation, transform);
            _activeTiles.Add(tile);
            _tileLastUsed[prefabIndex] = _spawnCounter++;
            onTileSpawned?.Invoke(tile);
        }

        private int GetWeightedRandomTileIndex()
        {
            // Weight tiles not used recently higher
            int n = tilePrefabs.Count;
            List<float> weights = new List<float>(n);
            for (int i = 0; i < n; i++)
            {
                int lastUsed = _tileLastUsed.TryGetValue(i, out var value) ? value : -n;
                int age = _spawnCounter - lastUsed;
                float weight = Mathf.Clamp(age, 1, n * 2); // More unused = higher weight
                weights.Add(weight);
            }
            float total = 0f;
            foreach (var w in weights) total += w;
            float r = Random.value * total;
            for (int i = 0; i < n; i++)
            {
                if (r < weights[i]) return i;
                r -= weights[i];
            }
            return Random.Range(0, n); // fallback
        }

#if UNITY_EDITOR
        void OnDrawGizmosSelected()
        {
            // Draw tile bounds for debugging
            Gizmos.color = Color.cyan;
            for (int i = 0; i < initialTileCount; i++)
            {
                Vector3 center = new Vector3(0f, _screenBottom + i * TileHeight, 0f);
                Gizmos.DrawWireCube(center, new Vector3(10f, TileHeight, 1f));
            }
        }
#endif
    }
}