using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using Core;
using UnityEngine.AddressableAssets;
using UnityEngine.ResourceManagement.AsyncOperations;

namespace Utils
{
    /// <summary>
    /// Utility class for common Addressables operations.
    /// Provides generic methods for loading assets by label and creating lookup dictionaries.
    /// </summary>
    public static class AddressablesUtility
    {
        /// <summary>
        /// Load all assets with a specific label and create a dictionary indexed by a key selector.
        /// </summary>
        /// <typeparam name="TAsset">Type of asset to load</typeparam>
        /// <typeparam name="TKey">Type of key for dictionary</typeparam>
        /// <param name="label">Addressables label to filter by</param>
        /// <param name="keySelector">Function to extract key from asset (e.g., asset => asset.Id)</param>
        /// <param name="onProgress">Optional callback for progress updates (0-1)</param>
        /// <returns>Dictionary of assets indexed by key, and operation handle for cleanup</returns>
        public static async Task<(Dictionary<TKey, TAsset> dictionary, AsyncOperationHandle<IList<TAsset>> handle)> 
            LoadAssetsByLabelAsync<TAsset, TKey>(
                string label, 
                Func<TAsset, TKey> keySelector,
                Action<float> onProgress = null)
        {
            Dictionary<TKey, TAsset> dictionary = new Dictionary<TKey, TAsset>();
            
            // Load all assets with the specified label
            AsyncOperationHandle<IList<TAsset>> handle = Addressables.LoadAssetsAsync<TAsset>(
                label,
                asset =>
                {
                    // This callback is invoked for each asset as it loads
                    if (asset != null)
                    {
                        TKey key = keySelector(asset);
                        if (key != null && !dictionary.ContainsKey(key))
                        {
                            dictionary[key] = asset;
                        }
                    }
                });
            
            // Report progress if callback provided
            while (!handle.IsDone)
            {
                onProgress?.Invoke(handle.PercentComplete);
                await Task.Yield();
            }
            
            // Final progress update
            onProgress?.Invoke(1f);
            
            // Check if load was successful
            if (handle.Status != AsyncOperationStatus.Succeeded)
            {
                Logging.Error($"[AddressablesUtility] Failed to load assets with label '{label}': {handle.OperationException?.Message}");
                return (dictionary, handle);
            }
            
            Logging.Debug($"[AddressablesUtility] Loaded {dictionary.Count} assets with label '{label}'");
            
            return (dictionary, handle);
        }
        
        /// <summary>
        /// Load a single asset by address
        /// </summary>
        /// <typeparam name="TAsset">Type of asset to load</typeparam>
        /// <param name="address">Addressable address/key</param>
        /// <returns>Loaded asset and operation handle for cleanup</returns>
        public static async Task<(TAsset asset, AsyncOperationHandle<TAsset> handle)> LoadAssetAsync<TAsset>(string address)
        {
            AsyncOperationHandle<TAsset> handle = Addressables.LoadAssetAsync<TAsset>(address);
            
            await handle.Task;
            
            if (handle.Status != AsyncOperationStatus.Succeeded)
            {
                Logging.Warning($"[AddressablesUtility] Failed to load asset '{address}': {handle.OperationException?.Message}");
                return (default(TAsset), handle);
            }
            
            return (handle.Result, handle);
        }
        
        /// <summary>
        /// Safely release an Addressables handle
        /// </summary>
        public static void ReleaseHandle<T>(AsyncOperationHandle<T> handle)
        {
            if (handle.IsValid())
            {
                Addressables.Release(handle);
            }
        }
    }
}