using UnityEngine;
using System;
using System.Collections.Generic;
using System.IO;

namespace BF
{
    public class AssetBundleObject : AssetObjectBase
    {
        public static Dictionary<string, string> fullpathDict = new Dictionary<string, string>();
        public AssetBundleConfig AssetBundleConfig { get; private set; }

        public AssetBundle Assetbundle { get; private set; }

        private AssetBundleCreateRequest request;

        private BFEvent<AssetBundleObject> loadComplete;

        private BFEvent unloadComplete;

        public float Timeout { get; private set; }  //异步加载的超时机制，保证不会一直卡在这里

        private int recordDependCount;

        private string[] dependAB;

        private AssetBundleLoader assetBundleLoader;

        private bool dependABComplete = false;

        public AssetBundleObject(AssetBundleConfig config, AssetBundleLoader loader) : base(config.assetBundlePath, null)
        {
            AssetBundleConfig = config;
            assetBundleLoader = loader;
            loadComplete = new BFEvent<AssetBundleObject>();
            unloadComplete = new BFEvent();
            dependAB = loader.Manifest.GetAllDependencies(config.assetBundlePath);
            dependABComplete = dependAB.Length == 0;
            recordDependCount = dependAB.Length;
            for (int i = 0; i < dependAB.Length; i++)
            {
                BFLog.LogDebug(BFLog.DEBUG_RESMGR, "green", "[ResMgr] [AssetBundleObject] assetpath : {2} index : {0}, depend : {1}", i, dependAB[i], AssetPath);
                assetBundleLoader.LoadDependBundleAsync(dependAB[i], LoadCompleteDepenedAsset);
            }
        }

        public void LoadBundleAsync(Action<AssetBundleObject> callback)
        {
            ++RefCount;
            if (EAssetLoadStatus.Complete == LoadStatus || EAssetLoadStatus.Error == LoadStatus)
            {
                callback(this);
            }
            else if (EAssetLoadStatus.Unloading == LoadStatus)
            {
                LoadStatus = EAssetLoadStatus.Complete;
                callback(this);
            }
            else
            {
                loadComplete += callback;
            }
        }

        public void StartLoadAsync()
        {
            LoadStatus = EAssetLoadStatus.Loading;

            if (!fullpathDict.TryGetValue(AssetPath, out string fullpath))
            {
                if (AssetBundleConfig.location == 1)
                {
                    fullpath = Path.Combine(Application.persistentDataPath, "update", AssetPath);
                }
                else
                {
                    fullpath = Path.Combine(Application.streamingAssetsPath, AssetPath);
                }
                fullpathDict.Add(AssetPath, fullpath);
            }
            request = AssetBundle.LoadFromFileAsync(fullpath);
            Timeout = ResourceManager.TIME_OUT_LOAD + Time.time;
            BFLog.LogDebug(BFLog.DEBUG_RESMGR, "green", "StartLoadAsync assetpath : {0}. timeout : {1}", fullpath, Timeout);
        }

        public void LoadSync(bool ignoreRefCount = false)
        {
            if (!ignoreRefCount)
            {
                ++RefCount;
            }

            if(EAssetLoadStatus.Complete == LoadStatus)
            {
                return;
            }

            if (EAssetLoadStatus.Loading != LoadStatus)
            {
                for (int i = 0; i < dependAB.Length; i++)
                {
                    assetBundleLoader.LoadDependBundleSync(dependAB[i]);
                }

                if (!fullpathDict.TryGetValue(AssetPath, out string fullpath))
                {
                    if (AssetBundleConfig.location == 1)
                    {
                        fullpath = Path.Combine(Application.persistentDataPath, "update", AssetPath);
                    }
                    else
                    {
                        fullpath = Path.Combine(Application.streamingAssetsPath, AssetPath);
                    }
                    fullpathDict.Add(AssetPath, fullpath);
                }
                var ab = AssetBundle.LoadFromFile(fullpath);
                Complete(ab);
            }
            else
            {
                // 异步过程中转同步
                for (int i = 0; i < dependAB.Length; i++)
                {
                    assetBundleLoader.LoadDependBundleSync(dependAB[i]);
                }
                var ab = request.assetBundle;
                Complete(ab);
            }
        }

        private void LoadCompleteDepenedAsset(AssetBundleObject assetBundleObject)
        {
            recordDependCount--;
            if (recordDependCount == 0)
            {
                dependABComplete = true;
            }

            BFLog.LogDebug(BFLog.DEBUG_RESMGR, "green", "[AssetBundleObject] [LoadCompleteDepenedAsset] : {0}, record dependent count : {1}", assetBundleObject.AssetPath, recordDependCount);
        }

        /// <summary>
        /// 加载完成，返回true, 否则返回false. 超时机制确保不会无法结束
        /// </summary>
        /// <returns></returns>
        public override bool Tick()
        {
            try
            {
                if (EAssetLoadStatus.Loading == LoadStatus)
                {
                    if (request != null && request.isDone && dependABComplete)
                    {
                        Complete(request.assetBundle);
                        return true;
                    }
                    else
                    {
                        if (Timeout < Time.time) //超时机制
                        {
                            BFLog.LogError("[ResMgr] bundlepath : {0}, timeout ! assetbunle is null = {1}", AssetPath, (null == Assetbundle));
                            Timeout += ResourceManager.TIME_OUT_LOAD;
                            return false;
                        }
                    }
                }
                else if (EAssetLoadStatus.Complete == LoadStatus)
                {
                    return true;
                }
                return false;
            }
            catch (Exception ex) //需要测试!!!! 尝试捕获异常，保证单个资源加载出错不卡住游戏。比如异步过程中被同步调用等。
            {
                BFLog.LogError("[ResMgr] loading exception! assetpath : {0}, exception : {1}", AssetPath, ex.ToString());
                return true;
            }
        }

        public void Complete(AssetBundle ab)
        {
            Assetbundle = ab;
            LoadStatus = ab == null ? EAssetLoadStatus.Error : EAssetLoadStatus.Complete;
            request = null;
            loadComplete.Invoke(this);
            loadComplete.Clear();
        }

        public void AddUnloadCallback(Action unloadCallback)
        {
            unloadComplete += unloadCallback;
        }

        public override bool Unload(bool immediately)
        {
            BFLog.LogDebug(BFLog.DEBUG_RESMGR, "green", "[ResMgr] assetBundleobject base unload assetpath : {0}, refcount : {1}", AssetPath, RefCount);
            if (RefCount == 0)
                return false;

            --RefCount;
            if (RefCount == 0)
            {
                loadComplete.Clear();
                LoadStatus = EAssetLoadStatus.Unloading;
                BFLog.LogDebug(BFLog.DEBUG_RESMGR, "green", "[ResMgr] assetobject unloaded immediately");
                UnloadCountdown(true);  // assetbundle目前都是立即卸载
                return false;
            }
            return false;
        }

        protected override bool OnUnloadComplete()
        {
            BFLog.LogDebug(BFLog.DEBUG_RESMGR, "green", "[ResMgr] AssetBundleObject OnUnloadComplete start LoadStatus : {0}", LoadStatus);
            if (EAssetLoadStatus.Complete == LoadStatus)
            {
                return false;
            }

            if (!ReferenceEquals(null, request))
            {
                var assetbundle = request.assetBundle;
                assetbundle.Unload(true);
                request = null;
            }

            if (!ReferenceEquals(null, Assetbundle))
            {
                Assetbundle.Unload(true);
                Assetbundle = null;
            }

            LoadStatus = EAssetLoadStatus.Unloaded;
            assetBundleLoader.RemoveCache(this);
            unloadComplete.Invoke();
            unloadComplete.Clear();
            for (int i = 0; i < dependAB.Length; i++)
            {
                assetBundleLoader.UnLoadBundle(dependAB[i], true);
            }
            BFLog.LogDebug(BFLog.DEBUG_RESMGR, "green", "[ResMgr] OnUnloadComplete end ");
            return true;
        }
    }
}