using System.Collections;
using System.Collections.Generic;
using Core;
using Core.Lifecycle;
using UnityEngine;
using UnityEngine.UI;
using Utils;

namespace Minigames.StatueDressup.Controllers
{
    /// <summary>
    /// Manages photo gallery display with optimized memory usage.
    /// Loads photos in pages and caches thumbnails to avoid loading 1000+ photos at once.
    /// Supports grid view with thumbnail preview and enlarged view on selection.
    /// </summary>
    public class StatuePhotoGalleryController : ManagedBehaviour
    {
        public static StatuePhotoGalleryController Instance { get; private set; }
        
        [Header("Gallery UI")]
        [SerializeField] private Transform gridContainer;
        [SerializeField] private PhotoGridItem gridItemPrefab;
        
        [Header("Enlarged View")]
        [SerializeField] private Transform enlargedContainer; // Container for enlarged preview (top layer)
        [SerializeField] private GameObject backdrop; // Dark backdrop for enlarged view
        [SerializeField] private GameObject enlargedPreviewPrefab; // Prefab for enlarged preview (same as grid item)
        
        [Header("Pagination")]
        [SerializeField] private Button previousPageButton;
        [SerializeField] private Button nextPageButton;
        [SerializeField] private Text pageStatusText;
        
        private int currentPage;
        private List<string> allPhotoIds = new List<string>();
        private Dictionary<string, PhotoGridItem> activeGridItems = new Dictionary<string, PhotoGridItem>();
        private Dictionary<string, Texture2D> thumbnailCache = new Dictionary<string, Texture2D>();
        private Dictionary<string, Texture2D> fullPhotoCache = new Dictionary<string, Texture2D>(); // Cache full photos for enlargement
        private Queue<string> thumbnailCacheOrder = new Queue<string>();
        private bool isLoadingPage;
        private PhotoEnlargeController enlargeController;
        
        internal override void OnManagedAwake()
        {
            base.OnManagedAwake();
            
            // Singleton pattern
            if (Instance != null && Instance != this)
            {
                Logging.Warning("[StatuePhotoGalleryController] Duplicate instance detected. Destroying duplicate.");
                Destroy(gameObject);
                return;
            }
            
            Instance = this;
        }
        
        internal override void OnManagedStart()
        {
            base.OnManagedStart();
            
            // Wait for data manager to be ready before initializing
            DecorationDataManager.WhenReady(() =>
            {
                InitializeGallery();
            });
        }
        
        /// <summary>
        /// Initialize gallery once data manager is ready
        /// </summary>
        private void InitializeGallery()
        {
            var settings = DecorationDataManager.Instance?.Settings;
            
            // Initialize enlarge controller
            enlargeController = new PhotoEnlargeController(backdrop, enlargedContainer, 
                settings?.GalleryAnimationDuration ?? StatueDressupConstants.DefaultAnimationDuration);
            
            // Setup page navigation buttons
            if (previousPageButton != null)
                previousPageButton.onClick.AddListener(OnPreviousPageClicked);
            
            if (nextPageButton != null)
                nextPageButton.onClick.AddListener(OnNextPageClicked);
            
            // Hide backdrop initially
            if (backdrop != null)
                backdrop.SetActive(false);
            
            // Clear grid initially (in case there are leftover items from scene setup)
            ClearGrid();
            
            // Load first page
            RefreshGallery();
        }
        
        /// <summary>
        /// Refresh the entire gallery from scratch
        /// </summary>
        public void RefreshGallery()
        {
            // Clear existing items
            ClearGrid();
            
            // Get all photo IDs
            allPhotoIds = PhotoManager.GetAllPhotoIds(CaptureType.StatueMinigame);
            currentPage = 0;
            
            Logging.Debug($"[StatuePhotoGalleryController] Gallery refreshed: {allPhotoIds.Count} photos");
            
            // Display first page
            DisplayCurrentPage();
        }
        
        /// <summary>
        /// Display the current page of photos (clears grid and shows only current page)
        /// </summary>
        private void DisplayCurrentPage()
        {
            if (isLoadingPage) return;
            
            isLoadingPage = true;
            
            // Clear current grid
            ClearGrid();
            
            // Get photos for current page
            int itemsPerPage = DecorationDataManager.Instance?.Settings?.GalleryItemsPerPage ?? StatueDressupConstants.DefaultGalleryItemsPerPage;
            List<string> pagePhotoIds = PhotoManager.GetPhotoIdsPage(CaptureType.StatueMinigame, currentPage, itemsPerPage);
            
            Logging.Debug($"[StatuePhotoGalleryController] Displaying page {currentPage + 1}: {pagePhotoIds.Count} items");
            
            // Spawn grid items for this page
            foreach (string photoId in pagePhotoIds)
            {
                SpawnGridItem(photoId);
            }
            
            // Update button states
            UpdatePageButtons();
            
            // Update status text
            int totalPages = Mathf.CeilToInt((float)allPhotoIds.Count / itemsPerPage);
            UpdateStatusText($"Page {currentPage + 1}/{totalPages} ({allPhotoIds.Count} photos)");
            
            isLoadingPage = false;
        }
        
        /// <summary>
        /// Update page navigation button states
        /// </summary>
        private void UpdatePageButtons()
        {
            int itemsPerPage = DecorationDataManager.Instance?.Settings?.GalleryItemsPerPage ?? StatueDressupConstants.DefaultGalleryItemsPerPage;
            int totalPages = Mathf.CeilToInt((float)allPhotoIds.Count / itemsPerPage);
            
            // Enable/disable previous button
            if (previousPageButton != null)
            {
                previousPageButton.interactable = currentPage > 0;
            }
            
            // Enable/disable next button
            if (nextPageButton != null)
            {
                nextPageButton.interactable = currentPage < totalPages - 1;
            }
        }
        
        /// <summary>
        /// Navigate to previous page
        /// </summary>
        private void OnPreviousPageClicked()
        {
            if (currentPage > 0)
            {
                currentPage--;
                DisplayCurrentPage();
                Logging.Debug($"[StatuePhotoGalleryController] Navigated to previous page: {currentPage}");
            }
        }
        
        /// <summary>
        /// Navigate to next page
        /// </summary>
        private void OnNextPageClicked()
        {
            int itemsPerPage = DecorationDataManager.Instance?.Settings?.GalleryItemsPerPage ?? StatueDressupConstants.DefaultGalleryItemsPerPage;
            int totalPages = Mathf.CeilToInt((float)allPhotoIds.Count / itemsPerPage);
            
            if (currentPage < totalPages - 1)
            {
                currentPage++;
                DisplayCurrentPage();
                Logging.Debug($"[StatuePhotoGalleryController] Navigated to next page: {currentPage}");
            }
        }
        
        /// <summary>
        /// Spawn a grid item for a photo
        /// </summary>
        private void SpawnGridItem(string photoId)
        {
            if (activeGridItems.ContainsKey(photoId))
            {
                Logging.Warning($"[StatuePhotoGalleryController] Grid item already exists: {photoId}");
                return;
            }
            
            PhotoGridItem gridItem = Instantiate(gridItemPrefab, gridContainer);
            gridItem.Initialize(photoId, this);
            
            activeGridItems[photoId] = gridItem;
            
            // Load thumbnail asynchronously
            StartCoroutine(LoadThumbnailAsync(photoId, gridItem));
        }
        
        /// <summary>
        /// Load thumbnail for grid item (async to avoid frame hitches)
        /// </summary>
        private IEnumerator LoadThumbnailAsync(string photoId, PhotoGridItem gridItem)
        {
            // Check cache first
            if (thumbnailCache.TryGetValue(photoId, out Texture2D cachedThumbnail))
            {
                gridItem.SetThumbnail(cachedThumbnail);
                yield break;
            }
            
            // Yield to avoid loading all thumbnails in one frame
            yield return null;
            
            // Load full photo
            Texture2D fullPhoto = PhotoManager.LoadPhoto(CaptureType.StatueMinigame, photoId);
            
            if (fullPhoto == null)
            {
                Logging.Warning($"[StatuePhotoGalleryController] Failed to load photo: {photoId}");
                yield break;
            }
            
            // Create thumbnail
            int thumbSize = DecorationDataManager.Instance?.Settings?.GalleryThumbnailSize ?? StatueDressupConstants.DefaultThumbnailSize;
            Texture2D thumbnail = PhotoManager.CreateThumbnail(fullPhoto, thumbSize);
            
            // Destroy full photo immediately (we only need thumbnail)
            Destroy(fullPhoto);
            
            // Cache thumbnail
            CacheThumbnail(photoId, thumbnail);
            
            // Set on grid item
            if (gridItem != null)
            {
                gridItem.SetThumbnail(thumbnail);
            }
        }
        
        /// <summary>
        /// Cache thumbnail with LRU eviction
        /// </summary>
        private void CacheThumbnail(string photoId, Texture2D thumbnail)
        {
            // Add to cache
            thumbnailCache[photoId] = thumbnail;
            thumbnailCacheOrder.Enqueue(photoId);
            
            // Evict oldest if over limit
            int maxCached = DecorationDataManager.Instance?.Settings?.GalleryMaxCachedThumbnails ?? StatueDressupConstants.DefaultMaxCachedThumbnails;
            while (thumbnailCache.Count > maxCached && thumbnailCacheOrder.Count > 0)
            {
                string oldestId = thumbnailCacheOrder.Dequeue();
                
                if (thumbnailCache.TryGetValue(oldestId, out Texture2D oldThumbnail))
                {
                    Destroy(oldThumbnail);
                    thumbnailCache.Remove(oldestId);
                    Logging.Debug($"[StatuePhotoGalleryController] Evicted thumbnail from cache: {oldestId}");
                }
            }
        }
        
        /// <summary>
        /// Enlarge a photo (called by PhotoGridItem)
        /// </summary>
        public void OnGridItemClicked(PhotoGridItem gridItem, string photoId)
        {
            if (enlargeController == null)
            {
                Logging.Error("[StatuePhotoGalleryController] Enlarge controller not initialized");
                return;
            }
            
            // If already enlarged, shrink it
            if (enlargeController.IsPhotoEnlarged)
            {
                enlargeController.ShrinkPhoto();
                return;
            }
            
            Logging.Debug($"[StatuePhotoGalleryController] Enlarging photo: {photoId}");
            
            float enlargedScale = DecorationDataManager.Instance?.Settings?.GalleryEnlargedScale ?? StatueDressupConstants.DefaultEnlargedScale;
            
            // Check cache first
            if (fullPhotoCache.TryGetValue(photoId, out Texture2D fullPhoto))
            {
                // Use cached photo
                enlargeController.EnlargePhoto(gridItem, enlargedPreviewPrefab != null ? enlargedPreviewPrefab : gridItem.gameObject, fullPhoto, enlargedScale);
            }
            else
            {
                // Load full-size photo
                fullPhoto = PhotoManager.LoadPhoto(CaptureType.StatueMinigame, photoId);
                
                if (fullPhoto == null)
                {
                    Logging.Error($"[StatuePhotoGalleryController] Failed to load photo: {photoId}");
                    return;
                }
                
                // Cache it (limited cache)
                if (fullPhotoCache.Count < 10) // Keep only recent 10 full photos
                {
                    fullPhotoCache[photoId] = fullPhoto;
                }
                
                enlargeController.EnlargePhoto(gridItem, enlargedPreviewPrefab != null ? enlargedPreviewPrefab : gridItem.gameObject, fullPhoto, enlargedScale);
            }
        }
        
        /// <summary>
        /// Cleanup when gallery is closed
        /// </summary>
        public void CleanupGallery()
        {
            if (enlargeController != null)
            {
                enlargeController.Cleanup();
            }
            
            // Clean up cached full photos
            foreach (var photo in fullPhotoCache.Values)
            {
                if (photo != null)
                {
                    Destroy(photo);
                }
            }
            fullPhotoCache.Clear();
        }
        
        /// <summary>
        /// Update status text
        /// </summary>
        private void UpdateStatusText(string message)
        {
            if (pageStatusText != null)
                pageStatusText.text = message;
            
            Logging.Debug($"[StatuePhotoGalleryController] Status: {message}");
        }
        
        /// <summary>
        /// Clear only the grid items (used when switching pages)
        /// </summary>
        private void ClearGrid()
        {
            // Destroy grid items
            foreach (var gridItem in activeGridItems.Values)
            {
                if (gridItem != null)
                    Destroy(gridItem.gameObject);
            }
            activeGridItems.Clear();
            
            Logging.Debug("[StatuePhotoGalleryController] Grid cleared");
        }
        
        /// <summary>
        /// Clear all grid items and cached data (full cleanup)
        /// </summary>
        private void ClearGallery()
        {
            ClearGrid();
            
            // Clear thumbnail cache
            foreach (var thumbnail in thumbnailCache.Values)
            {
                if (thumbnail != null)
                    Destroy(thumbnail);
            }
            thumbnailCache.Clear();
            thumbnailCacheOrder.Clear();
            
            Logging.Debug("[StatuePhotoGalleryController] Gallery fully cleared");
        }
        
        internal override void OnManagedDestroy()
        {
            base.OnManagedDestroy();
            
            // Singleton cleanup
            if (Instance == this)
            {
                Instance = null;
            }
            
            // Clean up cached textures
            ClearGallery();
            CleanupGallery();
            
            // Unsubscribe buttons
            if (previousPageButton != null)
                previousPageButton.onClick.RemoveListener(OnPreviousPageClicked);
            
            if (nextPageButton != null)
                nextPageButton.onClick.RemoveListener(OnNextPageClicked);
        }
    }
}