using System;
using System.Collections.Generic;

namespace BF
{
    public class AssetLoader : LoaderBase
    {
        private List<AssetObject> delayUnload;

        public AssetLoader() : base()
        {
            delayUnload = new List<AssetObject>();
        }

        public override AssetObject LoadAssetAsync(string assetPath, Type type, Action<string, UnityEngine.Object> complete)
        {
            var aob = new AssetObject(assetPath, type);

#if UNITY_EDITOR
            string path = char.ToUpper(assetPath[0]) + assetPath.Substring(1);
            var asset = UnityEditor.AssetDatabase.LoadAssetAtPath(path, type);
            if (ReferenceEquals(asset, null))
            {
                throw new Exception("加载资源为空 " + path);
            }
            BFMain.Instance.OneShotManager.AddOneShot(() => { aob.AssetDataBaseLoadEnd(asset); }); // 延缓一帧执行
#endif
            return aob;
        }

        public override AssetObject LoadAssetSync(string assetPath, Type type)
        {
            var aob = new AssetObject(assetPath, type, true);
#if UNITY_EDITOR
            string path = char.ToUpper(assetPath[0]) + assetPath.Substring(1);
            var asset = UnityEditor.AssetDatabase.LoadAssetAtPath(path, type);
            aob.LoadComplete(asset);
#endif
            return aob;
        }

        public override void LoadAssetSync(AssetObject assetObject)
        {
#if UNITY_EDITOR
            var asset = UnityEditor.AssetDatabase.LoadAssetAtPath(assetObject.AssetPath, assetObject.AssetType);
            assetObject.LoadComplete(asset);
            assetObject.LoadSync();
#endif
        }

        public override void Unload(AssetObject asset, bool immediately)
        {
            if (EAssetLoadStatus.Unloading == asset.LoadStatus)
            {
                return;
            }

            if (EAssetLoadStatus.Unloaded == asset.LoadStatus)
            {
                resMgr.RemoveAsset(asset.AssetPath);
            }
            else if (asset.Unload(immediately))
            {
                delayUnload.Add(asset);
            }
        }

        public override string GetSceneLoadPath(string assetBundlePath)
        {
            return assetBundlePath;
        }

        public override void LoadSceneAsync(string assetBundlePath, Action<AssetBundleObject> complete)
        {
        }

        public override void UnloadScene(string assetBundlePath)
        {
        }

        public override void Tick()
        {
            TickDelayUnload(false);
        }

        void TickDelayUnload(bool immediately)
        {
            var length = delayUnload.Count;
            for (int i = 0; i < length;)
            {
                var asset = delayUnload[i];
                asset.UnloadCountdown(immediately);
                //卸载完成，或者卸载过程中，重新被加载使用
                if (EAssetLoadStatus.Unloaded == asset.LoadStatus || EAssetLoadStatus.Unloading != asset.LoadStatus)
                {
                    delayUnload.RemoveAt(i);
                    --length;
                }
                else
                {
                    ++i;
                }
            }
        }

        public override void UnloadAllDelayAssets()
        {
            TickDelayUnload(true);
        }

        public override void Clear()
        {
        }

        public override bool ContainsAsset(string assetPath)
        {
            return System.IO.File.Exists(assetPath);
        }
    }
}