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

// 和资源有关的管理器都将继承自此类
public class IAssetManager 
{
    // 管理器所管理的资源列表，实际上是引用列表
    protected List<string> lstRefAsset = new List<string>();

    // 增加引用的资源
    public virtual void RefAsset(string name)
    {}

    // 以一定的策略卸载资源
    public virtual bool UnloadAsset()
    { return true; }

}

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

public class ResourceManager
{
    // 已解压的Asset列表 [prefabPath, asset]
    private Dictionary<string, Object> dicAsset = new Dictionary<string, Object>();
    // "正在"加载的资源列表 [prefabPath, www]
    private Dictionary<string, WWW> dicLoadingReq = new Dictionary<string, WWW>();

    public Object GetResource(string name)
    {
        Object obj = null;
        if (dicAsset.TryGetValue(name, out obj) == false)
        {
            Debug.LogWarning("<GetResource Failed> Res not exist, res.Name = " + name);
            if (dicLoadingReq.ContainsKey(name))
            {
                Debug.LogWarning("<GetResource Failed> The res is still loading");
            }
        }
        return obj;
    }

    // name表示prefabPath，eg:Prefab/Pet/ABC
    public void LoadAsync(string name)
    {
        LoadAsync(name, typeof(Object));
    }

    // name表示prefabPath，eg:Prefab/Pet/ABC
    public void LoadAsync(string name, System.Type type)
    {
        // 如果已经下载，则返回
        if (dicAsset.ContainsKey(name))
            return;

        // 如果正在下载，则返回
        if (dicLoadingReq.ContainsKey(name))
            return;

        // 添加引用
        RefAsset(name);
        // 如果没下载，则开始下载
        CoroutineProvider.Instance().StartCoroutine(AsyncLoadCoroutine(name, type));
    }

    private IEnumerator AsyncLoadCoroutine(string name, System.Type type)
    {
        string assetBundleName = GlobalSetting.ConvertToAssetBundleName(name);
        string url = GlobalSetting.ConverToFtpPath(assetBundleName);
        int verNum = GameApp.GetVersionManager().GetVersionNum(assetBundleName);

        Debug.Log("WWW AsyncLoad name =" + assetBundleName + " versionNum = " + verNum);
        if (Caching.IsVersionCached(url, verNum) == false)
            Debug.Log("Version Is not Cached, which will download from net!");

        WWW www = WWW.LoadFromCacheOrDownload(url,verNum);
        dicLoadingReq.Add(name, www);
        while (www.isDone == false)
            yield return null;

        AssetBundleRequest req = www.assetBundle.LoadAsync(GetAssetName(name), type);
        while (req.isDone == false)
            yield return null;

        dicAsset.Add(name, req.asset);
        dicLoadingReq.Remove(name);
        www.assetBundle.Unload(false);
        www = null;
        // Debug.Log("WWW AsyncLoad Finished " + assetBundleName + " versionNum = " + verNum);
    }

    public bool IsResLoading(string name)
    {
        return dicLoadingReq.ContainsKey(name);
    }

    public bool IsResLoaded(string name)
    {
        return dicAsset.ContainsKey(name);
    }

    public WWW GetLoadingWWW(string name)
    {
        WWW www = null;
        dicLoadingReq.TryGetValue(name, out www);
        return www;
    }

    // 移除Asset资源的引用，name表示prefabPath
    public void UnrefAsset(string name)
    {
        dicAsset.Remove(name);
    }

    private string GetAssetName(string ResName)
    {
        int index = ResName.LastIndexOf('/');
        return ResName.Substring(index + 1, ResName.Length - index - 1);
    }

    public void UnloadUnusedAsset()
    {
        bool effectNeedUnload = GameApp.GetEffectManager().UnloadAsset();
        bool worldNeedUnload = GameApp.GetWorldManager().UnloadAsset();
        bool sceneNeedUnload = GameApp.GetSceneManager().UnloadAsset();
        if (effectNeedUnload || worldNeedUnload || sceneNeedUnload)
        {
            Resources.UnloadUnusedAssets();
        }
    }

    // 根据资源路径添加资源引用，每个管理器管理自己的引用
    private void RefAsset(string name)
    {
        // 模型之类的
        if (name.Contains(GlobalSetting.CharacterPath))
            GameApp.GetWorldManager().RefAsset(name);
        // 图片之类的
        else if (name.Contains(GlobalSetting.TexturePath))
            GameApp.GetUIManager().RefPTexture(name);// 特效之类的
        else if (name.Contains(GlobalSetting.EffectPath))
            GameApp.GetEffectManager().RefAsset(name);
　　　　 ......
　　　　 else
            Debug.LogWarning("<Res not ref> name = " + name);
    }

}