using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using UnityEngine;
using UnityEngine.SceneManagement;
using Unity.Netcode;
using Colosseum.Player;
using Colosseum.Enemy;

namespace Colosseum
{
    /// <summary>
    /// 게임 상태 열거형
    /// </summary>
    public enum GameState
    {
        Waiting,    // 대기 중
        Playing,    // 게임 진행 중
        GameOver,   // 게임 오버
        Victory     // 승리
    }

    /// <summary>
    /// 게임 전체를 관리하는 매니저.
    /// 게임 상태, 플레이어 사망 체크, 승리/패배 조건을 처리합니다.
    /// </summary>
    public class GameManager : NetworkBehaviour
    {
        [Header("UI Prefabs")]
        [Tooltip("게임 오버 UI 프리팹")]
        [SerializeField] private GameObject gameOverUIPrefab;

        [Tooltip("승리 UI 프리팹")]
        [SerializeField] private GameObject victoryUIPrefab;

        [Tooltip("승리 연출 이펙트 프리팹")]
        [SerializeField] private GameObject victoryEffectPrefab;

        [Header("Settings")]
        [Tooltip("게임 오버 후 재시작까지 대기 시간")]
        [SerializeField] private float gameOverRestartDelay = 5f;

        [Tooltip("승리 후 로비로 이동까지 대기 시간")]
        [SerializeField] private float victoryToLobbyDelay = 5f;

        [Header("Debug")]
        [SerializeField] private bool debugMode = true;

        // 싱글톤
        public static GameManager Instance { get; private set; }

        // 게임 상태
        private NetworkVariable<GameState> currentState = new NetworkVariable<GameState>(GameState.Waiting);

        // 인스턴스화된 UI
        private GameObject gameOverUIInstance;
        private GameObject victoryUIInstance;
        private GameObject victoryEffectInstance;

        // 이벤트
        public event Action<GameState> OnGameStateChanged;
        public event Action OnGameOver;
        public event Action OnVictory;

        // Properties
        public GameState CurrentState => currentState.Value;
        public bool IsGameOver => currentState.Value == GameState.GameOver;
        public bool IsVictory => currentState.Value == GameState.Victory;

        private void Awake()
        {
            // 싱글톤 설정
            if (Instance != null && Instance != this)
            {
                Destroy(gameObject);
                return;
            }
            Instance = this;
        }

        public override void OnNetworkSpawn()
        {
            currentState.OnValueChanged += HandleGameStateChanged;

            // 네트워크 씬 로드 이벤트 구독
            if (NetworkManager.Singleton.SceneManager != null)
            {
                NetworkManager.Singleton.SceneManager.OnLoadEventCompleted += OnSceneLoadCompleted;
            }

            // UI 인스턴스화 (모든 클라이언트에서)
            SpawnUI();

            if (IsServer)
            {
                // 플레이어 사망 이벤트 구독
                StartCoroutine(WaitForPlayersAndSubscribe());

                // 보스 사망 이벤트 구독
                SubscribeToBossEvents();
            }
        }

        private void OnSceneLoadCompleted(string sceneName, LoadSceneMode loadSceneMode, List<ulong> clientsCompleted, List<ulong> clientsTimedOut)
        {
            if (loadSceneMode == LoadSceneMode.Single)
            {
                if (debugMode)
                {
                    Debug.Log($"[GameManager] Scene loaded: {sceneName}");
                }

                // 씬 로드 완료 시 플레이어 리스폰
                if (IsServer)
                {
                    RespawnAllPlayersClientRpc();
                }
            }
        }

        [Rpc(SendTo.ClientsAndHost)]
        private void RespawnAllPlayersClientRpc()
        {
            // 모든 플레이어 리스폰
            var players = FindObjectsByType<PlayerNetworkController>(FindObjectsSortMode.None);
            foreach (var player in players)
            {
                player.Respawn();
            }

            // 카메라 재설정
            var playerMovement = FindObjectsByType<PlayerMovement>(FindObjectsSortMode.None);
            foreach (var movement in playerMovement)
            {
                movement.RefreshCamera();
            }
        }

        public override void OnNetworkDespawn()
        {
            currentState.OnValueChanged -= HandleGameStateChanged;

            // 네트워크 씬 로드 이벤트 구독 해제
            if (NetworkManager.Singleton.SceneManager != null)
            {
                NetworkManager.Singleton.SceneManager.OnLoadEventCompleted -= OnSceneLoadCompleted;
            }

            // UI 정리
            CleanupUI();

            if (IsServer)
            {
                UnsubscribeFromPlayerEvents();
                UnsubscribeFromBossEvents();
            }
        }

        #region UI Management































        /// <summary>
        /// UI 프리팹 인스턴스화
        /// </summary>
        private void SpawnUI()
        {
            // Canvas 찾기 또는 생성
            Canvas canvas = FindOrCreateCanvas();

            // 게임 오버 UI
            if (gameOverUIPrefab != null)
            {
                gameOverUIInstance = Instantiate(gameOverUIPrefab, canvas.transform);
                gameOverUIInstance.name = "GameOverUI";
                gameOverUIInstance.SetActive(false);

                if (debugMode)
                {
                    Debug.Log("[GameManager] GameOverUI instantiated");
                }
            }

            // 승리 UI
            if (victoryUIPrefab != null)
            {
                victoryUIInstance = Instantiate(victoryUIPrefab, canvas.transform);
                victoryUIInstance.name = "VictoryUI";
                victoryUIInstance.SetActive(false);

                if (debugMode)
                {
                    Debug.Log("[GameManager] VictoryUI instantiated");
                }
            }

            // 승리 연출 이펙트
            if (victoryEffectPrefab != null)
            {
                victoryEffectInstance = Instantiate(victoryEffectPrefab);
                victoryEffectInstance.name = "VictoryEffect";
                victoryEffectInstance.SetActive(false);

                if (debugMode)
                {
                    Debug.Log("[GameManager] VictoryEffect instantiated");
                }
            }
        }

        /// <summary>
        /// Canvas 찾기 또는 생성
        /// </summary>
        private Canvas FindOrCreateCanvas()
        {
            // 기존 Canvas 찾기
            Canvas canvas = FindFirstObjectByType<Canvas>();

            if (canvas == null)
            {
                // 새 Canvas 생성
                var canvasObject = new GameObject("GameUI Canvas");
                canvas = canvasObject.AddComponent<Canvas>();
                canvas.renderMode = RenderMode.ScreenSpaceOverlay;
                canvasObject.AddComponent<UnityEngine.UI.CanvasScaler>();
                canvasObject.AddComponent<UnityEngine.UI.GraphicRaycaster>();

                if (debugMode)
                {
                    Debug.Log("[GameManager] Created new Canvas");
                }
            }

            return canvas;
        }

        /// <summary>
        /// UI 정리
        /// </summary>
        private void CleanupUI()
        {
            if (gameOverUIInstance != null)
            {
                Destroy(gameOverUIInstance);
            }

            if (victoryUIInstance != null)
            {
                Destroy(victoryUIInstance);
            }

            if (victoryEffectInstance != null)
            {
                Destroy(victoryEffectInstance);
            }
        }

        #endregion

        private void HandleGameStateChanged(GameState oldValue, GameState newValue)
        {
            OnGameStateChanged?.Invoke(newValue);

            // UI 활성화/비활성화
            UpdateUIVisibility(newValue);

            if (debugMode)
            {
                Debug.Log($"[GameManager] State changed: {oldValue} -> {newValue}");
            }
        }

        private void UpdateUIVisibility(GameState state)
        {
            // 게임 오버 UI
            if (gameOverUIInstance != null)
            {
                gameOverUIInstance.SetActive(state == GameState.GameOver);
            }

            // 승리 UI
            if (victoryUIInstance != null)
            {
                victoryUIInstance.SetActive(state == GameState.Victory);
            }

            // 승리 연출
            if (victoryEffectInstance != null && state == GameState.Victory)
            {
                victoryEffectInstance.SetActive(true);
            }
        }

        #region Player Death Tracking

        private List<PlayerNetworkController> alivePlayers = new List<PlayerNetworkController>();

        private IEnumerator WaitForPlayersAndSubscribe()
        {
            // 플레이어들이 스폰될 때까지 대기
            yield return new WaitForSeconds(1f);

            SubscribeToPlayerEvents();

            // 게임 시작
            SetGameState(GameState.Playing);
        }

        private void SubscribeToPlayerEvents()
        {
            var players = FindObjectsByType<PlayerNetworkController>(FindObjectsSortMode.None);
            foreach (var player in players)
            {
                player.OnDeath += HandlePlayerDeath;
                if (!player.IsDead)
                {
                    alivePlayers.Add(player);
                }
            }

            if (debugMode)
            {
                Debug.Log($"[GameManager] Subscribed to {players.Length} players, {alivePlayers.Count} alive");
            }
        }

        private void UnsubscribeFromPlayerEvents()
        {
            var players = FindObjectsByType<PlayerNetworkController>(FindObjectsSortMode.None);
            foreach (var player in players)
            {
                player.OnDeath -= HandlePlayerDeath;
            }
            alivePlayers.Clear();
        }

        private void HandlePlayerDeath(PlayerNetworkController player)
        {
            alivePlayers.Remove(player);

            if (debugMode)
            {
                Debug.Log($"[GameManager] Player died. Alive: {alivePlayers.Count}");
            }

            // 모든 플레이어 사망 체크
            if (alivePlayers.Count == 0)
            {
                TriggerGameOver();
            }
        }

        #endregion

        #region Boss Death Tracking

        private void SubscribeToBossEvents()
        {
            BossEnemy.OnBossSpawned += HandleBossSpawned;

            // 이미 스폰된 보스가 있는지 확인
            if (BossEnemy.ActiveBoss != null)
            {
                SubscribeToBossDeath(BossEnemy.ActiveBoss);
            }
        }

        private void UnsubscribeFromBossEvents()
        {
            BossEnemy.OnBossSpawned -= HandleBossSpawned;
        }

        private void HandleBossSpawned(BossEnemy boss)
        {
            SubscribeToBossDeath(boss);

            if (debugMode)
            {
                Debug.Log($"[GameManager] Boss spawned: {boss.name}");
            }
        }

        private void SubscribeToBossDeath(BossEnemy boss)
        {
            boss.OnDeath += HandleBossDeath;
        }

        private void HandleBossDeath()
        {
            if (debugMode)
            {
                Debug.Log("[GameManager] Boss died!");
            }

            TriggerVictory();
        }

        #endregion

        #region Game State Management

        private void SetGameState(GameState newState)
        {
            if (!IsServer) return;

            currentState.Value = newState;
        }

        /// <summary>
        /// 게임 오버 처리 (서버에서만 실행)
        /// </summary>
        public void TriggerGameOver()
        {
            if (!IsServer || currentState.Value != GameState.Playing) return;

            SetGameState(GameState.GameOver);
            OnGameOver?.Invoke();

            if (debugMode)
            {
                Debug.Log("[GameManager] Game Over!");
            }

            // N초 후 씬 재시작
            StartCoroutine(RestartSceneAfterDelay(gameOverRestartDelay));
        }

        /// <summary>
        /// 승리 처리 (서버에서만 실행)
        /// </summary>
        public void TriggerVictory()
        {
            if (!IsServer || currentState.Value != GameState.Playing) return;

            SetGameState(GameState.Victory);
            OnVictory?.Invoke();

            if (debugMode)
            {
                Debug.Log("[GameManager] Victory!");
            }

            // N초 후 씬 재시작 (또는 로비로 이동)
            StartCoroutine(RestartSceneAfterDelay(victoryToLobbyDelay));
        }

        private IEnumerator RestartSceneAfterDelay(float delay)
        {
            yield return new WaitForSeconds(delay);

            // 현재 씬 다시 로드
            string currentScene = SceneManager.GetActiveScene().name;

            if (IsServer)
            {
                // 네트워크 씬 관리 사용
                NetworkManager.Singleton.SceneManager.LoadScene(currentScene, LoadSceneMode.Single);
            }
        }

        #endregion

        #region Utility

        /// <summary>
        /// 살아있는 플레이어 목록 반환
        /// </summary>
        public List<PlayerNetworkController> GetAlivePlayers()
        {
            return alivePlayers.Where(p => p != null && !p.IsDead).ToList();
        }

        /// <summary>
        /// 랜덤한 살아있는 플레이어 반환 (관전용)
        /// </summary>
        public PlayerNetworkController GetRandomAlivePlayer()
        {
            var alive = GetAlivePlayers();
            if (alive.Count == 0) return null;

            return alive[UnityEngine.Random.Range(0, alive.Count)];
        }

        #endregion
    }
}