using UnityEngine;
using System.Collections;

/// <summary>
/// Central manager for game state, death, and respawn logic.
/// Handles party wipe detection, death sequence, and respawn coordination.
/// </summary>
public class GameManager : MonoBehaviour
{
    public static GameManager Instance { get; private set; }

    [Header("References")]
    public TeamCohesionManager cohesionManager;
    public CheckpointSystem checkpointSystem;
    public DeathScreenUI deathScreenUI;
    public GridMovement playerMovement;
    
    [Header("Death & Respawn Settings")]
    public float deathDelay = 2f;
    public float respawnFadeTime = 1f;
    public bool resetMonstersOnRespawn = false;
    
    [Header("Optional Penalties")]
    public bool applyGoldPenalty = false;
    public float goldPenaltyPercent = 0f;
    
    private bool isPlayerDead = false;
    private CanvasGroup fadeCanvasGroup;

    #region Initialization

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

    private void Start()
    {
        FindReferences();
        ValidateSetup();
    }

    private void FindReferences()
    {
        if (cohesionManager == null)
            cohesionManager = FindFirstObjectByType<TeamCohesionManager>();
        
        if (checkpointSystem == null)
            checkpointSystem = FindFirstObjectByType<CheckpointSystem>();
            
        if (deathScreenUI == null)
            deathScreenUI = FindFirstObjectByType<DeathScreenUI>();
            
        if (playerMovement == null)
            playerMovement = FindFirstObjectByType<GridMovement>();
    }
    
    private void ValidateSetup()
    {
        bool hasAllReferences = cohesionManager != null && checkpointSystem != null && 
                                deathScreenUI != null && playerMovement != null;
        
        if (!hasAllReferences)
        {
            Debug.LogError("[GameManager] Missing references! Respawn system may not work.");
        }
    }

    #endregion

    #region Death & Respawn

    public void OnPartyWiped()
    {
        if (isPlayerDead) return;
        
        isPlayerDead = true;
        StartCoroutine(HandleDeathSequence());
    }

    private IEnumerator HandleDeathSequence()
    {
        if (playerMovement != null)
            playerMovement.enabled = false;
        
        StopAllMonsterAttacks();
        
        yield return new WaitForSeconds(deathDelay);
        yield return StartCoroutine(FadeToBlack(respawnFadeTime));
        
        if (deathScreenUI != null)
        {
            deathScreenUI.Show();
        }
        else
        {
            Debug.LogWarning("[GameManager] Death Screen UI not found, auto-respawning");
            RespawnParty();
        }
    }

    public void RespawnParty()
    {
        StartCoroutine(RespawnSequence());
    }

    private IEnumerator RespawnSequence()
    {
        if (deathScreenUI != null)
            deathScreenUI.Hide();
        
        yield return new WaitForSeconds(0.2f);
        
        if (checkpointSystem != null)
        {
            checkpointSystem.LoadCheckpoint();
        }
        else
        {
            Debug.LogWarning("[GameManager] CheckpointSystem not found, basic respawn");
            BasicRespawn();
        }
        
        if (applyGoldPenalty && goldPenaltyPercent > 0)
            ApplyGoldPenalty();
        
        if (resetMonstersOnRespawn)
            ResetMonsters();
        
        yield return new WaitForSeconds(0.3f);
        yield return StartCoroutine(FadeFromBlack(respawnFadeTime));
        
        if (playerMovement != null)
            playerMovement.enabled = true;
        
        isPlayerDead = false;
    }

    private void BasicRespawn()
    {
        if (cohesionManager == null || cohesionManager.groupMembers == null) return;
        
        foreach (var character in cohesionManager.groupMembers)
        {
            character.currentHP = character.maxHP;
            character.currentFatigue = character.maxFatigue;
            character.currentMana = character.maxMana;
            
            UIUpdater.Instance?.UpdateCharacterHP(character);
            UIUpdater.Instance?.UpdateCharacterFatigue(character);
        }
    }

    #endregion

    #region Monster Management

    private void StopAllMonsterAttacks()
    {
        MonsterFormationGroup[] monsterGroups = FindObjectsByType<MonsterFormationGroup>(FindObjectsSortMode.None);
        
        foreach (var group in monsterGroups)
        {
            group.StopAllCoroutines();
            group.isChasing = false;
            group.hasDetectedPlayer = false;
            
            foreach (var monster in group.frontRow)
            {
                if (monster != null)
                    monster.StopMove();
            }
            
            foreach (var monster in group.backRow)
            {
                if (monster != null)
                    monster.StopMove();
            }
        }
    }
    
    private void ResetMonsters()
    {
        MonsterFormationGroup[] monsterGroups = FindObjectsByType<MonsterFormationGroup>(FindObjectsSortMode.None);
        
        foreach (var group in monsterGroups)
        {
            group.StopAllCoroutines();
            group.isChasing = false;
            group.hasDetectedPlayer = false;
        }
    }

    private void ApplyGoldPenalty()
    {
        // TODO: Implement gold penalty when currency system exists
    }

    #endregion

    #region Fade Effects
    
    private void CreateFadeOverlay()
    {
        GameObject fadeObj = new GameObject("FadeOverlay");
        fadeObj.transform.SetParent(transform);
        
        Canvas canvas = fadeObj.AddComponent<Canvas>();
        canvas.renderMode = RenderMode.ScreenSpaceOverlay;
        canvas.sortingOrder = 100;
        
        fadeCanvasGroup = fadeObj.AddComponent<CanvasGroup>();
        fadeCanvasGroup.alpha = 0f;
        fadeCanvasGroup.interactable = false;
        fadeCanvasGroup.blocksRaycasts = false;
        
        GameObject panel = new GameObject("BlackPanel");
        panel.transform.SetParent(fadeObj.transform, false);
        
        UnityEngine.UI.Image image = panel.AddComponent<UnityEngine.UI.Image>();
        image.color = Color.black;
        
        RectTransform rect = panel.GetComponent<RectTransform>();
        rect.anchorMin = Vector2.zero;
        rect.anchorMax = Vector2.one;
        rect.sizeDelta = Vector2.zero;
    }

    private IEnumerator FadeToBlack(float duration)
    {
        float elapsed = 0f;
        while (elapsed < duration)
        {
            elapsed += Time.deltaTime;
            fadeCanvasGroup.alpha = Mathf.Lerp(0f, 1f, elapsed / duration);
            yield return null;
        }
        fadeCanvasGroup.alpha = 1f;
    }

    private IEnumerator FadeFromBlack(float duration)
    {
        float elapsed = 0f;
        while (elapsed < duration)
        {
            elapsed += Time.deltaTime;
            fadeCanvasGroup.alpha = Mathf.Lerp(1f, 0f, elapsed / duration);
            yield return null;
        }
        fadeCanvasGroup.alpha = 0f;
    }
    
    #endregion

    #region Public API

    public bool IsPlayerDead() => isPlayerDead;

    #endregion
}