using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using UnityEngine;
using UnityEngine.UIElements;
using PrimeTween;
using OnlyScove.Scripts;
#if UNITY_EDITOR
using UnityEditor;
using UnityEditor.Build;
#endif

namespace Hallucinate.UI
{
    [RequireComponent(typeof(UIDocument))]
    public class UIManager : MonoBehaviour
    {
        public static UIManager Instance { get; private set; }

        private UIDocument _uiDocument;
        private VisualElement _rootElement;
        public VisualElement Root => _rootElement;
        private VisualElement _cursorLayer;
        private VisualElement _mainCursor;

        private readonly Dictionary<Type, BaseUIController> _controllers = new Dictionary<Type, BaseUIController>();
        private readonly Stack<BaseUIController> _history = new Stack<BaseUIController>();

        [Header("References")]
        [SerializeField] private InputReader inputReader;
        public InputReader InputReader => inputReader;

        [Header("Game Metadata")]
        [SerializeField] private Texture2D gameIcon;

        [Header("Cursor & Effects Settings")]
        [SerializeField] private Sprite cursorSprite; 
        [SerializeField] private Sprite cursorTrailSprite;
        [SerializeField, Range(10f, 150f)] private float cursorSize = 40f;
        [SerializeField, Range(5, 50)] private int trailLength = 20;
        [SerializeField, Range(1, 10)] private int trailSpacing = 2; 
        [SerializeField] private bool enableRipples = true;
        [SerializeField] private Color rippleColor = new Color(1, 1, 1, 0.4f);

        [Header("UI Templates")]
        [SerializeField] private VisualTreeAsset loginTemplate;
        [SerializeField] private VisualTreeAsset mainMenuTemplate;
        [SerializeField] private VisualTreeAsset lobbyTemplate;
        [SerializeField] private VisualTreeAsset roomItemTemplate;
        [SerializeField] private VisualTreeAsset profileTemplate;
        [SerializeField] private VisualTreeAsset settingsTemplate;
        [SerializeField] private VisualTreeAsset hudTemplate;
        
        private LoginController _loginController;
        private MainMenuController _mainMenuController;
        private LobbyController _lobbyController;
        private SettingsController _settingsController;
        private List<VisualElement> _trailSegments = new List<VisualElement>();
        private List<Vector2> _posHistory = new List<Vector2>();

        private Vector2 _lastMousePos;
        private float _trailOpacity = 1f;
        private bool _isSettingsOpen = false;
        public bool IsSettingsOpen => _isSettingsOpen;

        private const string UI_SCALE_KEY = "UIScale";

        [Header("Development Settings")]
        [SerializeField] private bool allowMultipleInstances = true;

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

            // Single instance guard
            if (!Application.isEditor && !allowMultipleInstances)
            {
                var currentProcess = System.Diagnostics.Process.GetCurrentProcess();
                var processes = System.Diagnostics.Process.GetProcessesByName(currentProcess.ProcessName);
                if (processes.Length > 1)
                {
                    Debug.LogError("[UIManager] Another instance is already running. Quitting to prevent save conflict.");
                    Application.Quit();
                    return;
                }
            }

            _uiDocument = GetComponent<UIDocument>();
            UnityEngine.Cursor.visible = false;
            
            ApplySavedUIScale();
        }

        public void OnGameStarted()
        {
            _ = Push<HUDController>();
        }

        public void OnBackToMenu()
        {
            _ = Push<MainMenuController>();
        }

        public void SetUIScale(float scale)
        {
            if (_uiDocument == null || _uiDocument.panelSettings == null) return;

            // Unity UI Toolkit dùng panelSettings để điều khiển tỉ lệ
            // Chúng ta thay đổi scale multiplier. Mặc định 1.0 sẽ tương ứng với visual scale là 1.3
            _uiDocument.panelSettings.scale = scale * 1.3f;
            PlayerPrefs.SetFloat(UI_SCALE_KEY, scale);
            PlayerPrefs.Save();
        }

        private void ApplySavedUIScale()
        {
            float savedScale = PlayerPrefs.GetFloat(UI_SCALE_KEY, 1.0f);
            SetUIScale(savedScale);
        }
        private void Start()
        {
            if (_uiDocument == null) _uiDocument = GetComponent<UIDocument>();
            if (_uiDocument == null)
            {
                Debug.LogError("[UIManager] UIDocument component missing!");
                return;
            }

            _rootElement = _uiDocument.rootVisualElement;
            if (_rootElement == null)
            {
                Debug.LogError("[UIManager] Root VisualElement is null!");
                return;
            }

            _cursorLayer = new VisualElement();
            _cursorLayer.name = "CursorLayer";
            _cursorLayer.style.position = Position.Absolute;
            _cursorLayer.style.width = Length.Percent(100);
            _cursorLayer.style.height = Length.Percent(100);
            _cursorLayer.pickingMode = PickingMode.Ignore;
            _rootElement.Add(_cursorLayer);

            SetupVirtualCursor();

            _rootElement.RegisterCallback<PointerDownEvent>(OnGlobalClick, TrickleDown.TrickleDown);

            if (inputReader != null)
            {
                inputReader.OnToggleSettingsEvent += ToggleSettings;
                inputReader.OnCancelEvent += HandleCancel;
            }

#if UNITY_EDITOR
            if (gameIcon == null)
            {
                var icons = PlayerSettings.GetIcons(NamedBuildTarget.Unknown, IconKind.Any);
                if (icons != null && icons.Length > 0) gameIcon = icons[0];
            }
#endif
            InitializeControllers();
            CheckLoginStatus();
        }

        private void CheckLoginStatus()
        {
            string savedName = PlayerPrefs.GetString("Username", "");
            if (string.IsNullOrEmpty(savedName))
            {
                _ = Push<LoginController>();
            }
            else
            {
                Debug.Log($"[UIManager] Welcome back, {savedName}!");
                _ = Push<MainMenuController>();
            }
        }

        public void OnLoginSuccess()
        {
            _ = Push<MainMenuController>();
        }

        private void OnDestroy()
        {
            if (inputReader != null)
            {
                inputReader.OnToggleSettingsEvent -= ToggleSettings;
                inputReader.OnCancelEvent -= HandleCancel;
            }
        }

        private void HandleCancel()
        {
            if (_isSettingsOpen) ToggleSettings();
        }

        public async void ToggleSettings()
        {
            if (_settingsController == null) return;

            if (!_isSettingsOpen)
            {
                _isSettingsOpen = true;
                _settingsController.Root.BringToFront();
                _cursorLayer.BringToFront();
                await _settingsController.PlayTransitionIn();
            }
            else
            {
                _isSettingsOpen = false;
                await _settingsController.PlayTransitionOut();
            }
        }

        private void Update()
        {
            if (_history.Count > 0) _history.Peek().Update();
            UpdateCursorAndTrail();
        }

        private void SetupVirtualCursor()
        {
            if (_cursorLayer == null) return;

            _cursorLayer.Clear();
            _trailSegments.Clear();
            _posHistory.Clear();

            if (cursorTrailSprite != null)
            {
                for (int i = 0; i < trailLength; i++)
                {
                    var segment = new VisualElement();
                    segment.style.position = Position.Absolute;
                    segment.style.width = cursorSize;
                    segment.style.height = cursorSize;
                    segment.style.backgroundImage = new StyleBackground(Background.FromSprite(cursorTrailSprite));
                    
                    float ratio = 1f - ((float)i / trailLength);
                    segment.style.opacity = 0f;
                    segment.style.scale = new StyleScale(new Scale(new Vector3(ratio, ratio, 1f)));
                    segment.style.translate = new StyleTranslate(new Translate(Length.Percent(-50), Length.Percent(-50)));
                    segment.pickingMode = PickingMode.Ignore;
                    
                    _cursorLayer.Add(segment);
                    _trailSegments.Add(segment);
                }
            }

            _mainCursor = new VisualElement();
            _mainCursor.style.position = Position.Absolute;
            _mainCursor.style.width = cursorSize;
            _mainCursor.style.height = cursorSize;
            _mainCursor.style.backgroundImage = new StyleBackground(Background.FromSprite(cursorSprite != null ? cursorSprite : cursorTrailSprite));
            _mainCursor.style.translate = new StyleTranslate(new Translate(Length.Percent(-50), Length.Percent(-50)));
            _mainCursor.pickingMode = PickingMode.Ignore;
            _cursorLayer.Add(_mainCursor);

            Vector2 startPos = new Vector2(Input.mousePosition.x, Screen.height - Input.mousePosition.y);
            _lastMousePos = startPos;
            for (int i = 0; i < trailLength * trailSpacing + 1; i++) _posHistory.Add(startPos);
        }

        private float GetCurrentScale()
        {
            if (_uiDocument != null && _uiDocument.panelSettings != null)
                return _uiDocument.panelSettings.scale;
            return 1.0f;
        }

        private void OnGlobalClick(PointerDownEvent evt)
        {
            if (!enableRipples || _cursorLayer == null) return;

            var ripple = new VisualElement();
            ripple.style.position = Position.Absolute;
            ripple.style.width = cursorSize;
            ripple.style.height = cursorSize;
            ripple.style.translate = new StyleTranslate(new Translate(Length.Percent(-50), Length.Percent(-50)));
            
            var radius = new StyleLength(new Length(50, LengthUnit.Percent));
            ripple.style.borderTopLeftRadius = radius;
            ripple.style.borderTopRightRadius = radius;
            ripple.style.borderBottomLeftRadius = radius;
            ripple.style.borderBottomRightRadius = radius;
            
            ripple.style.borderTopColor = rippleColor;
            ripple.style.borderBottomColor = rippleColor;
            ripple.style.borderLeftColor = rippleColor;
            ripple.style.borderRightColor = rippleColor;
            ripple.style.borderTopWidth = 2;
            ripple.style.borderBottomWidth = 2;
            ripple.style.borderLeftWidth = 2;
            ripple.style.borderRightWidth = 2;
            
            // PointerDownEvent.localPosition đã được Unity tự động scale theo Panel
            ripple.style.left = evt.localPosition.x;
            ripple.style.top = evt.localPosition.y;
            ripple.pickingMode = PickingMode.Ignore;

            _cursorLayer.Add(ripple);

            // Correct Fluent API for PrimeTween
            Tween.Custom(Vector3.one, Vector3.one * 2.5f, duration: 0.4f, 
                onValueChange: val => ripple.style.scale = new StyleScale(new Scale(val)),
                ease: Ease.OutQuad);
            
            Tween.Custom(1f, 0f, duration: 0.4f, onValueChange: val => ripple.style.opacity = val)
                .OnComplete(() => ripple.RemoveFromHierarchy());
        }

        private void UpdateCursorAndTrail()
        {
            if (!Application.isFocused || _cursorLayer == null)
            {
                if (_cursorLayer != null) _cursorLayer.style.display = DisplayStyle.None;
                return;
            }

            Vector3 mousePos = Input.mousePosition;
            bool isMouseInWindow = mousePos.x >= 0 && mousePos.x <= Screen.width && mousePos.y >= 0 && mousePos.y <= Screen.height;

            if (!isMouseInWindow)
            {
                _cursorLayer.style.display = DisplayStyle.None;
                return;
            }

            _cursorLayer.style.display = DisplayStyle.Flex;

            // QUAN TRỌNG: Chia tọa độ pixel cho scale của UI để có tọa độ local chính xác
            float scale = GetCurrentScale();
            Vector2 uiPos = new Vector2(mousePos.x / scale, (Screen.height - mousePos.y) / scale);

            float mouseSpeed = Vector2.Distance(uiPos, _lastMousePos);
            _lastMousePos = uiPos;

            if (mouseSpeed > 0.1f) _trailOpacity = Mathf.MoveTowards(_trailOpacity, 1f, Time.deltaTime * 5f);
            else _trailOpacity = Mathf.MoveTowards(_trailOpacity, 0f, Time.deltaTime * 3f);

            _posHistory.Insert(0, uiPos);
            if (_posHistory.Count > trailLength * trailSpacing + 1)
                _posHistory.RemoveAt(_posHistory.Count - 1);

            if (_mainCursor != null)
            {
                _mainCursor.style.left = uiPos.x;
                _mainCursor.style.top = uiPos.y;
            }

            for (int i = 0; i < _trailSegments.Count; i++)
            {
                int historyIndex = (i + 1) * trailSpacing;
                if (historyIndex < _posHistory.Count)
                {
                    _trailSegments[i].style.left = _posHistory[historyIndex].x;
                    _trailSegments[i].style.top = _posHistory[historyIndex].y;
                    float baseRatio = 1f - ((float)i / trailLength);
                    _trailSegments[i].style.opacity = baseRatio * 0.5f * _trailOpacity;
                }
            }
        }

        private void InitializeControllers()
        {
            try 
            {
                _mainMenuController = RegisterController<MainMenuController>(mainMenuTemplate);
                if (_mainMenuController != null && gameIcon != null) _mainMenuController.SetGameIcon(gameIcon);

                _lobbyController = RegisterController<LobbyController>(lobbyTemplate);
                if (_lobbyController != null) _lobbyController.SetRoomTemplate(roomItemTemplate);

                RegisterController<ProfileController>(profileTemplate);
                _settingsController = RegisterController<SettingsController>(settingsTemplate);
                RegisterController<HUDController>(hudTemplate);

                _loginController = RegisterController<LoginController>(loginTemplate);
            }
            catch (Exception e)
            {
                Debug.LogError($"[UIManager] Failed to initialize controllers: {e}");
            }
        }

        private T RegisterController<T>(VisualTreeAsset template) where T : BaseUIController
        {
            if (template == null)
            {
                Debug.LogWarning($"[UIManager] Template for {typeof(T).Name} is missing in Inspector.");
                return null;
            }

            if (_rootElement == null) return null;

            VisualElement instance = null;
            try 
            {
                instance = template.Instantiate();
            }
            catch (Exception e)
            {
                Debug.LogError($"[UIManager] Failed to instantiate template for {typeof(T).Name}: {e.Message}");
                return null;
            }

            if (instance == null) return null;

            instance.style.flexGrow = 1;
            instance.style.position = Position.Absolute;
            instance.style.width = Length.Percent(100);
            instance.style.height = Length.Percent(100);
            instance.style.display = DisplayStyle.None;
            
            _rootElement.Add(instance);
            if (_cursorLayer != null) _cursorLayer.BringToFront();

            var controller = ScriptableObject.CreateInstance<T>();
            controller.Initialize(instance, this);
            _controllers[typeof(T)] = controller;
            return controller;
        }

        public async Task Push<T>() where T : BaseUIController
        {
            if (!_controllers.TryGetValue(typeof(T), out var newScreen)) return;
            if (_history.Count > 0 && _history.Peek() == newScreen) return;
            if (_history.Count > 0) await _history.Peek().PlayTransitionOut();

            _history.Push(newScreen);
            await newScreen.PlayTransitionIn();
            if (_cursorLayer != null) _cursorLayer.BringToFront();
        }

        public async Task Pop()
        {
            if (_history.Count <= 1) return;
            await _history.Pop().PlayTransitionOut();
            if (_history.Count > 0) await _history.Peek().PlayTransitionIn();
            if (_cursorLayer != null) _cursorLayer.BringToFront();
        }
    }
}