using System.Collections.Generic;
using System.Linq;
using UnityEngine;

namespace Streamingle.Background
{
    /// <summary>
    /// 런타임 배경 씬 로더 UI (IMGUI)
    /// Inspector에서 설정하거나 단축키로 토글 가능
    /// </summary>
    public class BackgroundSceneLoaderUI : MonoBehaviour
    {
        [Header("설정")]
        [SerializeField] private BackgroundSceneDatabase sceneDatabase;
        [SerializeField] private KeyCode toggleKey = KeyCode.F2;
        [SerializeField] private bool showOnStart = false;

        [Header("UI 설정")]
        [SerializeField] private int windowWidth = 400;
        [SerializeField] private int windowHeight = 500;
        [SerializeField] private int thumbnailSize = 100;

        private bool _showUI;
        private Vector2 _scrollPosition;
        private string _searchFilter = "";
        private string _selectedCategory = "전체";
        private Dictionary<string, List<BackgroundSceneInfo>> _categorizedScenes;
        private Dictionary<string, bool> _categoryFoldouts = new Dictionary<string, bool>();
        private Dictionary<string, Texture2D> _loadedThumbnails = new Dictionary<string, Texture2D>();

        private Rect _windowRect;
        private bool _isDragging;
        private Vector2 _dragOffset;

        private BackgroundSceneLoader _loader;
        private string _statusMessage = "";
        private float _statusTime;

        private GUIStyle _headerStyle;
        private GUIStyle _buttonStyle;
        private GUIStyle _searchStyle;
        private GUIStyle _categoryStyle;
        private bool _stylesInitialized;

        private void Start()
        {
            _showUI = showOnStart;
            _windowRect = new Rect(20, 20, windowWidth, windowHeight);

            if (sceneDatabase != null)
            {
                _categorizedScenes = sceneDatabase.GetScenesByCategory();
                foreach (var category in _categorizedScenes.Keys)
                {
                    _categoryFoldouts[category] = true;
                }

                // 썸네일 로드
                LoadThumbnails();
            }

            // 로더 초기화
            _loader = BackgroundSceneLoader.Instance;
            _loader.Database = sceneDatabase;
            _loader.OnSceneLoadCompleted += OnSceneLoaded;
            _loader.OnSceneUnloaded += OnSceneUnloaded;
            _loader.OnError += OnError;
        }

        private void OnDestroy()
        {
            if (_loader != null)
            {
                _loader.OnSceneLoadCompleted -= OnSceneLoaded;
                _loader.OnSceneUnloaded -= OnSceneUnloaded;
                _loader.OnError -= OnError;
            }
        }

        private void Update()
        {
            if (Input.GetKeyDown(toggleKey))
            {
                _showUI = !_showUI;
            }
        }

        private void LoadThumbnails()
        {
            if (sceneDatabase == null) return;

            foreach (var scene in sceneDatabase.scenes)
            {
                if (string.IsNullOrEmpty(scene.thumbnailPath)) continue;
                if (_loadedThumbnails.ContainsKey(scene.thumbnailPath)) continue;

                // Resources에서 로드 시도 (런타임에서는 Resources 폴더만 가능)
                // 에디터에서만 AssetDatabase 사용 가능
#if UNITY_EDITOR
                var texture = UnityEditor.AssetDatabase.LoadAssetAtPath<Texture2D>(scene.thumbnailPath);
                if (texture != null)
                {
                    _loadedThumbnails[scene.thumbnailPath] = texture;
                    scene.thumbnail = texture;
                }
#endif
            }
        }

        private void InitStyles()
        {
            if (_stylesInitialized) return;

            _headerStyle = new GUIStyle(GUI.skin.box)
            {
                fontSize = 14,
                fontStyle = FontStyle.Bold,
                alignment = TextAnchor.MiddleCenter,
                normal = { textColor = Color.white }
            };

            _buttonStyle = new GUIStyle(GUI.skin.button)
            {
                fontSize = 12
            };

            _searchStyle = new GUIStyle(GUI.skin.textField)
            {
                fontSize = 12
            };

            _categoryStyle = new GUIStyle(GUI.skin.label)
            {
                fontSize = 13,
                fontStyle = FontStyle.Bold
            };

            _stylesInitialized = true;
        }

        private void OnGUI()
        {
            if (!_showUI) return;

            InitStyles();

            // 드래그 처리
            HandleDrag();

            // 윈도우 그리기
            _windowRect = GUI.Window(GetInstanceID(), _windowRect, DrawWindow, "");
        }

        private void HandleDrag()
        {
            Event e = Event.current;
            Rect titleBar = new Rect(_windowRect.x, _windowRect.y, _windowRect.width, 30);

            if (e.type == EventType.MouseDown && titleBar.Contains(e.mousePosition))
            {
                _isDragging = true;
                _dragOffset = e.mousePosition - new Vector2(_windowRect.x, _windowRect.y);
                e.Use();
            }
            else if (e.type == EventType.MouseUp)
            {
                _isDragging = false;
            }
            else if (e.type == EventType.MouseDrag && _isDragging)
            {
                _windowRect.position = e.mousePosition - _dragOffset;
                e.Use();
            }
        }

        private void DrawWindow(int windowID)
        {
            // 타이틀 바
            GUI.Box(new Rect(0, 0, _windowRect.width, 30), "배경 씬 로더", _headerStyle);

            // 닫기 버튼
            if (GUI.Button(new Rect(_windowRect.width - 25, 5, 20, 20), "X"))
            {
                _showUI = false;
            }

            GUILayout.Space(35);

            // 현재 씬 상태
            GUILayout.BeginHorizontal();
            string currentSceneName = _loader?.CurrentSceneName ?? "없음";
            GUILayout.Label($"현재: {currentSceneName}", GUILayout.Width(200));

            bool hasLoadedScene = _loader != null &&
                                  _loader.CurrentBackgroundScene.HasValue &&
                                  _loader.CurrentBackgroundScene.Value.IsValid() &&
                                  _loader.CurrentBackgroundScene.Value.isLoaded;

            if (hasLoadedScene && GUILayout.Button("언로드", GUILayout.Width(60)))
            {
                _loader.UnloadCurrentScene();
            }
            GUILayout.EndHorizontal();

            // 검색
            GUILayout.BeginHorizontal();
            GUILayout.Label("검색:", GUILayout.Width(40));
            _searchFilter = GUILayout.TextField(_searchFilter, _searchStyle, GUILayout.Width(150));
            if (GUILayout.Button("X", GUILayout.Width(25)))
            {
                _searchFilter = "";
            }
            GUILayout.EndHorizontal();

            // 카테고리 선택
            GUILayout.BeginHorizontal();
            GUILayout.Label("카테고리:", GUILayout.Width(60));

            var categories = new List<string> { "전체" };
            if (_categorizedScenes != null)
            {
                categories.AddRange(_categorizedScenes.Keys.OrderBy(x => x));
            }

            int currentIndex = categories.IndexOf(_selectedCategory);
            if (currentIndex < 0) currentIndex = 0;

            // 간단한 드롭다운 대체
            if (GUILayout.Button(_selectedCategory, GUILayout.Width(100)))
            {
                currentIndex = (currentIndex + 1) % categories.Count;
                _selectedCategory = categories[currentIndex];
            }
            GUILayout.EndHorizontal();

            GUILayout.Space(10);

            // 씬 목록
            _scrollPosition = GUILayout.BeginScrollView(_scrollPosition);

            if (_categorizedScenes != null)
            {
                var filteredScenes = GetFilteredScenes();
                DrawSceneList(filteredScenes);
            }

            GUILayout.EndScrollView();

            // 상태 메시지
            if (Time.time - _statusTime < 3f && !string.IsNullOrEmpty(_statusMessage))
            {
                GUILayout.Label(_statusMessage);
            }

            // 로딩 표시
            if (_loader != null && _loader.IsLoading)
            {
                GUILayout.Label("로딩 중...");
            }
        }

        private Dictionary<string, List<BackgroundSceneInfo>> GetFilteredScenes()
        {
            var result = new Dictionary<string, List<BackgroundSceneInfo>>();

            foreach (var kvp in _categorizedScenes)
            {
                if (_selectedCategory != "전체" && kvp.Key != _selectedCategory)
                    continue;

                var scenes = kvp.Value;

                if (!string.IsNullOrEmpty(_searchFilter))
                {
                    scenes = scenes.Where(s =>
                        s.sceneName.ToLower().Contains(_searchFilter.ToLower()) ||
                        s.categoryName.ToLower().Contains(_searchFilter.ToLower())
                    ).ToList();
                }

                if (scenes.Count > 0)
                {
                    result[kvp.Key] = scenes;
                }
            }

            return result;
        }

        private void DrawSceneList(Dictionary<string, List<BackgroundSceneInfo>> scenes)
        {
            foreach (var kvp in scenes.OrderBy(x => x.Key))
            {
                string category = kvp.Key;
                var sceneList = kvp.Value;

                if (!_categoryFoldouts.ContainsKey(category))
                    _categoryFoldouts[category] = true;

                // 카테고리 헤더
                GUILayout.BeginHorizontal();
                _categoryFoldouts[category] = GUILayout.Toggle(_categoryFoldouts[category],
                    $"{(_categoryFoldouts[category] ? "▼" : "▶")} {category} ({sceneList.Count})",
                    _categoryStyle);
                GUILayout.EndHorizontal();

                if (!_categoryFoldouts[category]) continue;

                // 씬 목록
                foreach (var sceneInfo in sceneList)
                {
                    DrawSceneItem(sceneInfo);
                }

                GUILayout.Space(5);
            }
        }

        private void DrawSceneItem(BackgroundSceneInfo sceneInfo)
        {
            string currentName = _loader?.CurrentSceneName ?? "";
            bool isCurrentScene = !string.IsNullOrEmpty(currentName) &&
                                  currentName != "없음" &&
                                  currentName == sceneInfo.sceneName;

            GUILayout.BeginHorizontal(GUI.skin.box);

            // 썸네일
            if (sceneInfo.thumbnail != null)
            {
                GUILayout.Box(sceneInfo.thumbnail, GUILayout.Width(50), GUILayout.Height(50));
            }
            else
            {
                GUILayout.Box("No\nImg", GUILayout.Width(50), GUILayout.Height(50));
            }

            // 씬 정보
            GUILayout.BeginVertical();
            GUIStyle nameStyle = isCurrentScene ? new GUIStyle(GUI.skin.label) { fontStyle = FontStyle.Bold } : GUI.skin.label;
            GUILayout.Label(sceneInfo.sceneName, nameStyle);
            GUILayout.Label(sceneInfo.categoryName, new GUIStyle(GUI.skin.label) { fontSize = 10 });
            GUILayout.EndVertical();

            GUILayout.FlexibleSpace();

            // 로드 버튼
            if (GUILayout.Button(isCurrentScene ? "로드됨" : "로드", _buttonStyle, GUILayout.Width(60), GUILayout.Height(40)))
            {
                if (!isCurrentScene)
                {
                    _loader?.LoadScene(sceneInfo);
                }
            }

            GUILayout.EndHorizontal();
        }

        private void OnSceneLoaded(BackgroundSceneInfo sceneInfo)
        {
            _statusMessage = $"로드 완료: {sceneInfo.sceneName}";
            _statusTime = Time.time;
        }

        private void OnSceneUnloaded(string sceneName)
        {
            _statusMessage = $"언로드 완료: {sceneName}";
            _statusTime = Time.time;
        }

        private void OnError(string error)
        {
            _statusMessage = $"오류: {error}";
            _statusTime = Time.time;
            UnityEngine.Debug.LogError(error);
        }

        /// <summary>
        /// UI 표시 토글
        /// </summary>
        public void ToggleUI()
        {
            _showUI = !_showUI;
        }

        /// <summary>
        /// UI 표시 설정
        /// </summary>
        public void SetUIVisible(bool visible)
        {
            _showUI = visible;
        }
    }
}