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

public class LoadAssetBundles : MonoBehaviour
{

    // Use this for initialization
    private static LoadAssetBundles instance;
    private static string localFilePath;
    private AssetBundleManifest manifest;
    private static string ManifestName;
    void Start()
    {

    }

    // Update is called once per frame
    void Update()
    {

    }
    public void GetAssetBundleManifest()
    {
        AssetBundle bundle = AssetBundle.LoadFromFile(localFilePath + ManifestName);
        if (bundle == null)
        {
            Debug.Log("Failed to load AssetBundle!");
        }
        else
        {
            manifest = bundle.LoadAsset<AssetBundleManifest>("AssetBundleManifest");
            bundle.Unload(false);
        }
    }
    public static LoadAssetBundles getInstance()
    {
        if (instance == null)
        {
            instance = new LoadAssetBundles();
            localFilePath = Application.dataPath + "/AssetBundles/";
            ManifestName = "AssetBundles";
        }
        return instance;
    }
    public IEnumerator LoadAssetByName<T>(string fileName, Action<T> callback) where T : UnityEngine.Object
    {
        AssetManager manager=AssetManager.getInstance();
        //先从资源管理器取，如果没有再从资源包中加载
        if (manager.assetObject.ContainsKey(fileName))
        {
            //Debug.Log("从资源管理器中加载了");
            T obj = manager.assetObject[fileName] as T;
            callback(obj);
        }
        else
        {
            //Debug.Log("从资源包加载了");
            if (manifest == null)
            {
                GetAssetBundleManifest();
            }
            string[] dependencies = manifest.GetAllDependencies(fileName);
            AssetBundle[] dpsBundles = new AssetBundle[dependencies.Length];
            for (int i = 0; i < dpsBundles.Length; i++)
            {
                string path = localFilePath + dependencies[i];
                Debug.Log(path);
                dpsBundles[i] = AssetBundle.LoadFromFile(path);
            }
            string mainPath = localFilePath + fileName;
            AssetBundle mainBundle = AssetBundle.LoadFromFile(mainPath);
            if (mainBundle == null)
            {
                Debug.Log("Failed to load AssetBundle!");
                yield return null;
            }

            T obj = mainBundle.LoadAsset<T>(fileName);
            manager.assetObject.Add(fileName, obj);//加入到资源管理器
            callback(obj);
            //yield return new WaitForSeconds(1f);
            mainBundle.Unload(false);
            for (int j = 0; j < dependencies.Length; j++)
            {
                dpsBundles[j].Unload(false);
            }
        }     
    }
    public IEnumerator LoadSceneByName(string fileName, Action callback)
    {
        if (manifest == null)
        {
            GetAssetBundleManifest();
        }
        string[] dependencies = manifest.GetAllDependencies(fileName);
        AssetBundle[] dpsBundles = new AssetBundle[dependencies.Length];
        for (int i = 0; i < dpsBundles.Length; i++)
        {
            string path = localFilePath + dependencies[i];
            dpsBundles[i] = AssetBundle.LoadFromFile(path);
        }
        string mainPath = localFilePath + fileName;
        AssetBundle mainBundle = AssetBundle.LoadFromFile(mainPath);
        if (mainBundle == null)
        {
            Debug.Log("Failed to load AssetBundle!");
            yield return null;
        }

        //mainBundle.LoadAsset<GameObject>(fileName);
        callback();
        yield return new WaitForSeconds(1f);
        mainBundle.Unload(false);
        for (int j = 0; j < dependencies.Length; j++)
        {
            dpsBundles[j].Unload(false);
        }
    }
}