using System;
using Core;
using UnityEngine;
using UnityEngine.SceneManagement;
using Bootstrap;
using UI.Core;
using Pixelplacement;

namespace UI
{
    public class PauseMenu : UIPage
    {
        private static PauseMenu _instance;

        /// <summary>
        /// Singleton instance of the PauseMenu. No longer creates an instance if one doesn't exist.
        /// </summary>
        public static PauseMenu Instance => _instance;
        
        [Header("UI References")]
        [SerializeField] private GameObject pauseMenuPanel;
        [SerializeField] private GameObject pauseButton;
        [SerializeField] private CanvasGroup canvasGroup;

        
        private void Awake()
        {
            _instance = this;
            
            // Ensure we have a CanvasGroup for transitions
            if (canvasGroup == null)
                canvasGroup = GetComponent<CanvasGroup>();
            if (canvasGroup == null)
                canvasGroup = gameObject.AddComponent<CanvasGroup>();
            canvasGroup.alpha = 0f;
            canvasGroup.interactable = false;
            canvasGroup.blocksRaycasts = false;
            gameObject.SetActive(false);
            
            // Register for post-boot initialization
            BootCompletionService.RegisterInitAction(InitializePostBoot);
        }

        private void InitializePostBoot()
        {
            // Subscribe to scene loaded events
            SceneManagerService.Instance.SceneLoadCompleted += SetPauseMenuByLevel;
            
            // Also react to global UI hide/show events from the page controller
            if (UIPageController.Instance != null)
            {
                UIPageController.Instance.OnAllUIHidden += HandleAllUIHidden;
                UIPageController.Instance.OnAllUIShown += HandleAllUIShown;
            }

            // SceneManagerService subscription moved to InitializePostBoot
            
            // Set initial state based on current scene
            SetPauseMenuByLevel(SceneManager.GetActiveScene().name);
    
            Logging.Debug("[PauseMenu] Subscribed to SceneManagerService events");
        }

        private void OnDestroy()
        {
            // Unsubscribe when destroyed
            if (SceneManagerService.Instance != null)
            {
                SceneManagerService.Instance.SceneLoadCompleted -= SetPauseMenuByLevel;
            }
            if (UIPageController.Instance != null)
            {
                UIPageController.Instance.OnAllUIHidden -= HandleAllUIHidden;
                UIPageController.Instance.OnAllUIShown -= HandleAllUIShown;
            }
        }
        
        /// <summary>
        /// Sets the pause menu game object active or inactive based on the current level
        /// </summary>
        /// <param name="levelName">The name of the level/scene</param>
        public void SetPauseMenuByLevel(string levelName)
        {
            HidePauseMenu();
            // TODO: Implement level-based pause menu visibility logic if needed
            /*if (string.IsNullOrEmpty(levelName))
                return;
                
            bool isStartingLevel = levelName.ToLower().Contains("startingscene");
            
            if(isStartingLevel)
                HidePauseMenu(false); // Ensure menu is hidden when switching to a game level
            
            Logging.Debug($"[PauseMenu] Setting pause menu active: {!isStartingLevel} for scene: {levelName}");*/
        }

        /// <summary>
        /// Shows the pause menu and hides the pause button. Sets input mode to UI.
        /// </summary>
        public void ShowPauseMenu()
        {
            if (UIPageController.Instance != null)
            {
                UIPageController.Instance.PushPage(this);
            }
            else
            {
                // Fallback if no controller, just show
                if (pauseMenuPanel != null)
                    pauseMenuPanel.SetActive(true);
                gameObject.SetActive(true);
                BeginPauseSideEffects();
                // no animation fallback
                if (canvasGroup != null)
                {
                    canvasGroup.alpha = 1f;
                    canvasGroup.interactable = true;
                    canvasGroup.blocksRaycasts = true;
                }
            }
        }

        /// <summary>
        /// Hides the pause menu and shows the pause button. Sets input mode to Game.
        /// </summary>
        public void HidePauseMenu()
        {
            if (!GameManager.Instance.IsPaused)
            {
                // Ensure UI is hidden if somehow active without state
                if (pauseMenuPanel != null) pauseMenuPanel.SetActive(false);
                gameObject.SetActive(false);
                return;
            }
            if (UIPageController.Instance != null && UIPageController.Instance.CurrentPage == this)
            {
                UIPageController.Instance.PopPage();
            }
            else
            {
                // Fallback if no controller, just hide
                if (pauseMenuPanel != null)
                    pauseMenuPanel.SetActive(false);
                if (pauseButton != null)
                    pauseButton.SetActive(true);
                if (canvasGroup != null)
                {
                    canvasGroup.alpha = 0f;
                    canvasGroup.interactable = false;
                    canvasGroup.blocksRaycasts = false;
                }
                gameObject.SetActive(false);
            }
        }

        public void HidePauseMenuAndResumeGame()
        {
            HidePauseMenu();
            EndPauseSideEffects();
        }
        
        /// <summary>
        /// Resumes the game by hiding the pause menu.
        /// </summary>
        public void ResumeGame()
        {
            HidePauseMenuAndResumeGame();
        }

        private void BeginPauseSideEffects()
        {
            if (pauseButton != null) pauseButton.SetActive(false);
            GameManager.Instance.RequestPause(this);
            Logging.Debug("[PauseMenu] Game Paused");
        }

        private void EndPauseSideEffects()
        {
            if (pauseButton != null) pauseButton.SetActive(true);
            GameManager.Instance.ReleasePause(this);
            Logging.Debug("[PauseMenu] Game Resumed");
        }

        protected override void DoTransitionIn(Action onComplete)
        {
            // Ensure the panel root is active
            if (pauseMenuPanel != null) pauseMenuPanel.SetActive(true);
            // Pause side effects should run immediately (hide button, set input mode, etc.).
            // The tween itself must run in unscaled time so it still animates while the game is paused.
            BeginPauseSideEffects();

            if (canvasGroup != null)
            {
                canvasGroup.interactable = true;
                canvasGroup.blocksRaycasts = true;
                canvasGroup.alpha = 0f;
                // pass obeyTimescale = false so this tween runs even when Time.timeScale == 0
                Tween.Value(0f, 1f, (v) =>
                {
                    Logging.Debug($"[PauseMenu] Tweening pause menu alpha: {v}");
                    canvasGroup.alpha = v;
                }, transitionDuration, 0f, Tween.EaseInOut, Tween.LoopType.None, null,  () =>
                {
                    Logging.Debug("[PauseMenu] Finished tweening pause menu in.");
                    onComplete?.Invoke();
                }, false);
            }
            else
            {
                onComplete?.Invoke();
            }
        }

        protected override void DoTransitionOut(Action onComplete)
        {
            if (canvasGroup != null)
            {
                canvasGroup.interactable = false;
                canvasGroup.blocksRaycasts = false;
                // Run out-tween in unscaled time as well so the fade completes while paused.
                Tween.Value(canvasGroup.alpha, 0f, v => canvasGroup.alpha = v, transitionDuration, 0f, Tween.EaseInOut, Tween.LoopType.None, null, () =>
                 {
                     EndPauseSideEffects();
                     if (pauseMenuPanel != null) pauseMenuPanel.SetActive(false);
                     onComplete?.Invoke();
                }, false);
            }
            else
            {
                EndPauseSideEffects();
                if (pauseMenuPanel != null) pauseMenuPanel.SetActive(false);
                onComplete?.Invoke();
            }
        }

        /// <summary>
        /// Exits to the main menu scene.
        /// </summary>
        public async void ExitToAppleHills()
        {
            // Replace with the actual scene name as set in Build Settings
            var progress = new Progress<float>(p => Logging.Debug($"Loading progress: {p * 100:F0}%"));
            await SceneManagerService.Instance.SwitchSceneAsync("AppleHillsOverworld", progress);
        }

        /// <summary>
        /// Exits the application.
        /// </summary>
        public void ExitGame()
        {
#if UNITY_EDITOR
            UnityEditor.EditorApplication.isPlaying = false;
#else
            Application.Quit();
#endif
        }

        public async void ReloadLevel()
        {
            var progress = new Progress<float>(p => Logging.Debug($"Loading progress: {p * 100:F0}%"));
            await SceneManagerService.Instance.ReloadCurrentScene(progress);
        }
        
        /// <summary>
        /// Loads a level based on the selection from a dropdown menu.
        /// Connect this to a Dropdown's onValueChanged event and pass the selected option text.
        /// </summary>
        /// <param name="levelSelection">The selected level name or identifier from the dropdown</param>
        public async void LoadLevel(int levelSelection)
        {
            // Hide the pause menu before loading a new level
            HidePauseMenuAndResumeGame();
            
            // Replace with the actual scene name as set in Build Settings
            var progress = new Progress<float>(p => Logging.Debug($"Loading progress: {p * 100:F0}%"));
            switch (levelSelection)
            {
                case 0:
                    await SceneManagerService.Instance.SwitchSceneAsync("AppleHillsOverworld", progress);
                    break;
                case 1:
                    await SceneManagerService.Instance.SwitchSceneAsync("Quarry", progress);
                    break;
                case 2:
                    await SceneManagerService.Instance.SwitchSceneAsync("DivingForPictures", progress);
                    break;
            }
        }
        
        // Handlers for UI controller hide/show events — make these safe with respect to transitions and pause state
        private void HandleAllUIHidden()
        {
            var parent = transform.parent?.gameObject ?? gameObject;

            // If we're currently transitioning, wait for the transition out to complete before deactivating
            if (_isTransitioning)
            {
                Action handler = null;
                handler = () =>
                {
                    OnTransitionOutCompleted -= handler;
                    parent.SetActive(false);
                };
                OnTransitionOutCompleted += handler;
                return;
            }

            // If this page is visible, request a proper hide so transition/out side-effects run (e.g. releasing pause)
            if (_isVisible)
            {
                HidePauseMenu();
                return;
            }

            // Otherwise it's safe to immediately deactivate
            parent.SetActive(false);
        }

        private void HandleAllUIShown()
        {
            var parent = transform.parent?.gameObject ?? gameObject;

            // Just ensure the parent is active. Do not force pause or transitions here.
            parent.SetActive(true);
        }
    }
}