using System;
using System.Collections;
using AppleHills.Core.Settings;
using Core;
using UnityEngine;
using UnityEngine.UI;

namespace Bootstrap
{
    /// <summary>
    /// Specialized loading screen controller specifically for the initial boot sequence.
    /// This handles the combined progress of bootstrap initialization and main menu loading.
    /// </summary>
    public class InitialLoadingScreen : MonoBehaviour
    {
        [Header("UI References")]
        [SerializeField] private GameObject loadingScreenContainer;
        [SerializeField] private Image progressBarImage;

        [Header("Settings")]
        [SerializeField] private float minimumDisplayTime = 1.0f;
        [SerializeField] private float progressUpdateInterval = 0.1f;
    
        private float _displayStartTime;
        private Coroutine _progressCoroutine;
        private bool _loadingComplete = false;
        private bool _animationComplete = false;
        private Action _onLoadingScreenFullyHidden;
        
        /// <summary>
        /// Event that fires when the loading screen is fully hidden (both loading and animation completed)
        /// </summary>
        public event Action OnLoadingScreenFullyHidden;
        
        /// <summary>
        /// Delegate for providing progress values from different sources
        /// </summary>
        public delegate float ProgressProvider();
        
        /// <summary>
        /// Current progress provider being used for the loading screen
        /// </summary>
        private ProgressProvider _currentProgressProvider;

        private LogVerbosity _logVerbosity = LogVerbosity.Warning;

        /// <summary>
        /// Default progress provider that returns 0 (or 1 if loading is complete)
        /// </summary>
        private float DefaultProgressProvider() => _loadingComplete ? 1f : 0f;
        
        /// <summary>
        /// Check if the loading screen is currently active
        /// </summary>
        public bool IsActive => loadingScreenContainer != null && loadingScreenContainer.activeSelf;
        
        private void Awake()
        {
            if (loadingScreenContainer == null)
                loadingScreenContainer = gameObject;
            
            // Ensure the loading screen is initially hidden
            if (loadingScreenContainer != null)
            {
                loadingScreenContainer.SetActive(false);
            }
        }

        private void Start()
        {
            _logVerbosity = DeveloperSettingsProvider.Instance.GetSettings<DebugSettings>().bootstrapLogVerbosity;
        }

        /// <summary>
        /// Shows the loading screen and resets the progress bar to zero
        /// </summary>
        /// <param name="progressProvider">Optional delegate to provide progress values (0-1). If null, uses default provider.</param>
        /// <param name="onComplete">Optional callback when loading screen is fully hidden</param>
        public void ShowLoadingScreen(ProgressProvider progressProvider = null, Action onComplete = null)
        {
            // Store the completion callback
            _onLoadingScreenFullyHidden = onComplete;
            
            // Set the progress provider, use default if none provided
            _currentProgressProvider = progressProvider ?? DefaultProgressProvider;
            
            // Stop any existing progress coroutine
            if (_progressCoroutine != null)
            {
                StopCoroutine(_progressCoroutine);
                _progressCoroutine = null;
            }
        
            _displayStartTime = Time.time;
            _loadingComplete = false;
            _animationComplete = false;
        
            if (progressBarImage != null)
            {
                progressBarImage.fillAmount = 0f;
            }
        
            if (loadingScreenContainer != null)
            {
                loadingScreenContainer.SetActive(true);
            }
            
            // Start the progress filling coroutine
            _progressCoroutine = StartCoroutine(AnimateProgressBar());
        }
        
        /// <summary>
        /// Animates the progress bar at a steady pace over the minimum display time,
        /// while also checking actual loading progress from the current progress provider
        /// </summary>
        private IEnumerator AnimateProgressBar()
        {
            float startTime = Time.time;
            
            // Continue until both animation and loading are complete
            while (!_animationComplete)
            {
                // Calculate the steady progress based on elapsed time
                float elapsedTime = Time.time - startTime;
                float steadyProgress = Mathf.Clamp01(elapsedTime / minimumDisplayTime);
                
                // Get the actual loading progress from the current provider
                float actualProgress = _currentProgressProvider();
                
                // If loading is complete, actualProgress should be 1.0
                if (_loadingComplete)
                {
                    actualProgress = 1.0f;
                }
                
                // Use the minimum of steady progress and actual progress
                // This ensures we don't show more progress than actual loading
                float displayProgress = Mathf.Min(steadyProgress, actualProgress);
                
                // Log the progress values for debugging
                Logging.Debug($"Progress - Default: {steadyProgress:F2}, Actual: {actualProgress:F2}, Display: {displayProgress:F2}");
                
                // Directly set the progress bar fill amount without smoothing
                if (progressBarImage != null)
                {
                    progressBarImage.fillAmount = displayProgress;
                }
                
                // Check if the animation has completed
                // Animation is complete when we've reached the minimum display time AND we're at 100% progress
                if (steadyProgress >= 1.0f && displayProgress >= 1.0f)
                {
                    _animationComplete = true;
                    Logging.Debug("Animation complete");
                    break;
                }
                
                // Wait for the configured interval before updating again
                yield return new WaitForSeconds(progressUpdateInterval);
            }
            
            // Ensure we end at 100% progress
            if (progressBarImage != null)
            {
                progressBarImage.fillAmount = 1.0f;
                Logging.Debug("Final progress set to 1.0");
            }
            
            // Hide the screen if loading is also complete
            if (_loadingComplete)
            {
                if (loadingScreenContainer != null)
                {
                    loadingScreenContainer.SetActive(false);
                    Logging.Debug("Animation AND loading complete, hiding screen");
                    
                    // Invoke the callback when fully hidden
                    _onLoadingScreenFullyHidden?.Invoke();
                    OnLoadingScreenFullyHidden?.Invoke();
                    _onLoadingScreenFullyHidden = null;
                }
            }
            
            _progressCoroutine = null;
        }
        
        /// <summary>
        /// Called when the actual loading process is complete
        /// </summary>
        public void HideLoadingScreen()
        {
            Logging.Debug("Loading complete, marking loading as finished");
            
            // Mark that loading is complete
            _loadingComplete = true;
            
            // If animation is already complete, we can hide the screen now
            if (_animationComplete)
            {
                if (loadingScreenContainer != null)
                {
                    loadingScreenContainer.SetActive(false);
                    Logging.Debug("Animation already complete, hiding screen immediately");
                    
                    // Invoke the callback when fully hidden
                    _onLoadingScreenFullyHidden?.Invoke();
                    OnLoadingScreenFullyHidden?.Invoke();
                    _onLoadingScreenFullyHidden = null;
                }
            }
            else
            {
                Logging.Debug("Animation still in progress, waiting for it to complete");
                // The coroutine will handle hiding when animation completes
            }
        }
        
        /// <summary>
        /// Waits until the loading screen is fully hidden before continuing
        /// </summary>
        /// <returns>Task that completes when the loading screen is hidden</returns>
        public System.Threading.Tasks.Task WaitForLoadingScreenToHideAsync()
        {
            var tcs = new System.Threading.Tasks.TaskCompletionSource<bool>();
            
            // If the loading screen is not active, complete immediately
            if (!IsActive)
            {
                tcs.SetResult(true);
                return tcs.Task;
            }
            
            // Store existing callback to chain it
            Action existingCallback = _onLoadingScreenFullyHidden;
            
            // Set new callback
            _onLoadingScreenFullyHidden = () => {
                // Call existing callback if any
                existingCallback?.Invoke();
                
                // Complete the task
                tcs.SetResult(true);
            };
            
            return tcs.Task;
        }
    }
}