using UnityEngine;
using System.Collections.Generic;

/// <summary>
/// Manages checkpoint saving and loading for respawn system
/// </summary>
public class CheckpointSystem : MonoBehaviour
{
    public static CheckpointSystem Instance { get; private set; }

    [Header("References")]
    public TeamCohesionManager cohesionManager;
    public Transform playerTransform;
    public GridMovement playerMovement;
    
    [Header("Checkpoint Settings")]
    public bool autoSaveOnCheckpoint = true;
    public float checkpointRadius = 3f;
    
    // Saved checkpoint data
    private Vector3 savedPlayerPosition;
    private Quaternion savedPlayerRotation;
    private int savedFloorLevel;
    private List<SavedCharacterData> savedCharacters = new List<SavedCharacterData>();
    private bool hasCheckpoint = false;

    [System.Serializable]
    private class SavedCharacterData
    {
        public CharacterInGroup character;
        public int hp;
        public int fatigue;
        public int mana;
        public int gridX;
        public int gridY;
        
        public SavedCharacterData(CharacterInGroup chara)
        {
            character = chara;
            hp = chara.currentHP;
            fatigue = chara.currentFatigue;
            mana = chara.currentMana;
            gridX = chara.gridX;
            gridY = chara.gridY;
        }
    }

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

    private void Start()
    {
        if (cohesionManager == null)
            cohesionManager = FindFirstObjectByType<TeamCohesionManager>();
        
        if (playerTransform == null)
        {
            GameObject player = GameObject.FindGameObjectWithTag("Player");
            if (player != null)
                playerTransform = player.transform;
        }
        
        if (playerMovement == null)
            playerMovement = FindFirstObjectByType<GridMovement>();
    }

    /// <summary>
    /// Save current game state as a checkpoint
    /// </summary>
    public void SaveCheckpoint()
    {
        if (playerTransform == null)
        {
            Debug.LogWarning("[CheckpointSystem] Cannot save checkpoint: playerTransform is null");
            return;
        }
        
        if (cohesionManager == null)
        {
            Debug.LogWarning("[CheckpointSystem] Cannot save checkpoint: cohesionManager is null");
            return;
        }

        // Save player position and rotation
        savedPlayerPosition = playerTransform.position;
        savedPlayerRotation = playerTransform.rotation;
        
        // Save floor level if available
        if (playerMovement != null)
            savedFloorLevel = playerMovement.currentFloorLevel;
        
        // Save all character data
        savedCharacters.Clear();
        foreach (var character in cohesionManager.groupMembers)
        {
            savedCharacters.Add(new SavedCharacterData(character));
        }
        
        hasCheckpoint = true;
        
        Debug.Log($"[CheckpointSystem] ✓ Checkpoint saved at {savedPlayerPosition} with {savedCharacters.Count} characters");
    }

    /// <summary>
    /// Save checkpoint at specific position
    /// </summary>
    public void SaveCheckpointAt(Vector3 position, Quaternion rotation)
    {
        savedPlayerPosition = position;
        savedPlayerRotation = rotation;
        
        if (playerMovement != null)
            savedFloorLevel = playerMovement.currentFloorLevel;
        
        // Save all character data
        savedCharacters.Clear();
        if (cohesionManager != null)
        {
            foreach (var character in cohesionManager.groupMembers)
            {
                savedCharacters.Add(new SavedCharacterData(character));
            }
        }
        
        hasCheckpoint = true;
        
        Debug.Log($"[CheckpointSystem] Manual checkpoint saved at {savedPlayerPosition}");
    }

    /// <summary>
    /// Load the last checkpoint and restore party
    /// </summary>
    public void LoadCheckpoint()
    {
        if (!hasCheckpoint)
        {
            Debug.LogWarning("[CheckpointSystem] No checkpoint to load, using default spawn");
            LoadDefaultSpawn();
            return;
        }

        Debug.Log("[CheckpointSystem] Loading checkpoint...");

        // Restore player position
        if (playerTransform != null)
        {
            playerTransform.position = savedPlayerPosition;
            playerTransform.rotation = savedPlayerRotation;
        }
        
        // Restore floor level
        if (playerMovement != null)
            playerMovement.currentFloorLevel = savedFloorLevel;

        // Restore all characters
        RestoreCharacters();
        
        Debug.Log($"[CheckpointSystem] Checkpoint loaded: {savedCharacters.Count} characters restored");
    }

    private void RestoreCharacters()
    {
        if (cohesionManager == null)
        {
            Debug.LogError("[CheckpointSystem] CohesionManager not found!");
            return;
        }

        // Clear any dead characters from the current party
        cohesionManager.groupMembers.Clear();

        // Restore all saved characters
        foreach (var saved in savedCharacters)
        {
            CharacterInGroup character = saved.character;
            
            // Restore stats to saved values (full health at checkpoint)
            character.currentHP = character.maxHP; // Always restore to full HP
            character.currentFatigue = character.maxFatigue; // Full stamina
            character.currentMana = character.maxMana; // Full mana
            
            // Restore grid position
            character.gridX = saved.gridX;
            character.gridY = saved.gridY;
            
            // Add back to party
            cohesionManager.groupMembers.Add(character);
            
            Debug.Log($"[CheckpointSystem] Restored character: {character.characterName} with {character.currentHP}/{character.maxHP} HP");
        }

        // Recreate UI for all characters
        RecreatePartyUI();
        
        Debug.Log($"[CheckpointSystem] Finished restoring {savedCharacters.Count} characters");
    }

    /// <summary>
    /// Recreate the party UI after respawn
    /// </summary>
    private void RecreatePartyUI()
    {
        Debug.Log("[CheckpointSystem] Recreating party UI...");
        
        PartyUIManager partyUI = FindFirstObjectByType<PartyUIManager>();
        if (partyUI != null)
        {
            // Rebuild UI for all characters using existing method
            partyUI.DisplayPartyUI();
            Debug.Log("[CheckpointSystem] Party UI recreated successfully");
        }
        else
        {
            Debug.LogWarning("[CheckpointSystem] PartyUIManager not found, cannot recreate UI");
        }
    }

    /// <summary>
    /// Load default spawn point if no checkpoint exists
    /// </summary>
    private void LoadDefaultSpawn()
    {
        // Use current position as default or find a spawn point
        GameObject spawnPoint = GameObject.FindGameObjectWithTag("SpawnPoint");
        
        if (spawnPoint != null && playerTransform != null)
        {
            playerTransform.position = spawnPoint.transform.position;
            playerTransform.rotation = spawnPoint.transform.rotation;
            Debug.Log("[CheckpointSystem] Loaded default spawn point");
        }
        else if (playerTransform != null)
        {
            // Just restore characters at current position
            Debug.Log("[CheckpointSystem] No spawn point, restoring at current position");
        }

        // Restore all party members to full health
        if (cohesionManager != null)
        {
            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);
            }
        }
    }

    /// <summary>
    /// Check if player is near a checkpoint trigger
    /// </summary>
    private void OnTriggerEnter(Collider other)
    {
        if (other.CompareTag("Checkpoint") && autoSaveOnCheckpoint)
        {
            SaveCheckpoint();
            
            // Optional: Show checkpoint saved message
            Debug.Log("[CheckpointSystem] Checkpoint reached!");
        }
    }

    public bool HasCheckpoint() => hasCheckpoint;
    
    public Vector3 GetCheckpointPosition() => savedPlayerPosition;
}