using System.Collections;
using System.Collections.Generic;
using System.Security.Cryptography;
using System.IO;
using UnityEngine;
using UnityEngine.UI;
using MEC;

public class ResManager {

  private struct BundleInfo{
    public long size;
    public string hash;
  }

  public static ResManager Instance
  {
    get
    {
      if (_instance == null)
        _instance = new ResManager();
      return _instance;
    }
  }
  static ResManager _instance;

  Test test;
  string Content;

  static string BundleRoot = "PackData";
  static string ManifestBundleName = "PackData";
  static string ManifestFileResName = "bundles"; // under Resources/bundles.manifest
  static string ManifesteRemotePath = "bundles.manifest";
#if UNITY_STANDALONE_WIN
	static string cdnAddress = "http://localhost/bundles/"; // PC
#elif UNITY_ANDROID
	static string cdnAddress = "http://10.0.2.2/bundles/"; // AndroidEmu
#endif

  Dictionary<string, AssetBundle> CachedBundles = new Dictionary<string, AssetBundle>();
  Dictionary<string, string> FileMapping = new Dictionary<string, string>();
  AssetBundleManifest Manifest;

#region 更新相关
  // 本地streamingAssetsPath下的bundles数据，从固化的bundles.manifest中读取
  Dictionary<string, BundleInfo> localBundles = new Dictionary<string, BundleInfo>();
  // CDN上的bundles数据
  Dictionary<string, BundleInfo> remoteBundles = new Dictionary<string, BundleInfo>();
#endregion

  public void Init(Test test)
  {
    this.test = test;
    LoadLocalBundlesInfo();
    Timing.Instance.RunCoroutineOnInstance(DownloadManifest());
  }

  void Print(string content , bool alert = false)
  {
    test.Print(content, alert);
  }

  public string ResContent(string path)
  {
    TextAsset text = Resources.Load(path) as TextAsset;
    if (text == null)
      return null;
    return text.text;
  }

  public void ReadFileMapping()
  {
    AssetBundle bundle = LoadBundle("bundle00.ab"); // 不可以省略后缀
    if (bundle == null)
    {
      string path = PathHelper.GetStreamingFullFilePath(BundleRoot + "/bundle00.ab");
      Print("Bundle 为空, path = " + path, true);
      return;
    }
    TextAsset text = bundle.LoadAsset<TextAsset>("fileMapping");
    if (text == null)
      return;
    string content = text.text;
    content = content.Replace("\r", string.Empty);
    string[] lines = content.Split('\n');
    Print("Load FileMapping:");
    foreach (string line in lines)
    {
      string[] part = line.Split(',');
      FileMapping.Add(part[0], part[1]);
      Print(part[0] + "      " + part[1]);
    }
  }

  /// <summary>
  /// 刚开始进入游戏的时候要写入.manifest，用来后续对比更新
  /// </summary>
  public void LoadManifest()
  {
    AssetBundle bundle = LoadBundle(ManifestBundleName);
    if (bundle == null)
    {
      Print("没有Manifest", true);
      return;
    }
    Manifest = bundle.LoadAsset<AssetBundleManifest>("AssetBundleManifest");
    if (Manifest == null)
    {
      Print("AssetBundleManifest", true);
      return;
    }
    Print("All bundles:");
    string[] bundleNames = Manifest.GetAllAssetBundles();
    foreach (var bundleName in bundleNames)
    {
      Print(bundleName);
    }
  }

  public AssetBundle LoadBundle(string name)
  {
    AssetBundle bundle;
    if (CachedBundles.TryGetValue(name, out bundle))
    {
      return bundle;
    }
    string path = PathHelper.GetPersistentFullFilePath(BundleRoot + "/" + name);
    Print(path);
    if (!File.Exists(path))
    {
      Print("不在persistent里");
      path = PathHelper.GetStreamingFullFilePath(BundleRoot + "/" + name);
    }
    bundle = AssetBundle.LoadFromFile(path);
    if(bundle == null)
      Print("是空的");
    CachedBundles.Add(name, bundle);
    return bundle;
  }

  public string GetBundleName(string assetName)
  {
    string bundleName;
    FileMapping.TryGetValue(assetName, out bundleName);
    return bundleName;
  }

  public string BundleContent(string resName)
  {
    string bundleName = GetBundleName(resName);
    if (bundleName == null)
      return null;
    AssetBundle bundle = LoadBundle(bundleName);
    if (bundle == null)
      return null;
    TextAsset text = bundle.LoadAsset<TextAsset>(resName);
    if (text == null)
      return null;
    return text.text;
  }

  /// <summary>
  /// 根据Resources/bundles.manifest读取本地bundle数据
  /// </summary>
  private void LoadLocalBundlesInfo()
  {
    TextAsset manifest = Resources.Load<TextAsset>(ManifestFileResName);
    if(manifest == null)
    {
      Debug.LogError("本地Resources目录下没有bundles.manifest");
      return;
    }
    string[] bundles = manifest.text.Replace("\r", string.Empty).Split('\n');
    string[] info;
    foreach(string bundle in bundles)
    {
      info = bundle.Split(',');
      if (info.Length != 3)
        continue;
      BundleInfo bi = new BundleInfo();
      bi.size = long.Parse(info[1]);
      bi.hash = info[2];
      localBundles.Add(info[0], bi);
    }
  }

  IEnumerator<float> DownloadManifest()
  {
    WWW www = new WWW(cdnAddress + ManifesteRemotePath);
    while(!www.isDone)
    {
      yield return Timing.WaitForSeconds(0.01f);
    }
    string content = www.text;
    string[] bundles = content.Replace("\r", string.Empty).Split('\n');
    string[] info;
    foreach (string bundle in bundles)
    {
      info = bundle.Split(',');
      if (info.Length != 3)
        continue;
      BundleInfo bi = new BundleInfo();
      bi.size = long.Parse(info[1]);
      bi.hash = info[2];
      remoteBundles.Add(info[0], bi);
    }
    // Download bundles
    Timing.Instance.RunCoroutineOnInstance(DownloadBundles());
  }

  IEnumerator<float> DownloadBundles()
  {
    List<string> downloadBundles = new List<string>();
    foreach(var b in remoteBundles)
    {
      string bundleName = b.Key;
      long size = b.Value.size;
      string hash = b.Value.hash;
      BundleInfo localInfo;
      //1. 剔除首包中就有的
      if (localBundles.TryGetValue(bundleName, out localInfo) && localInfo.hash == hash)
        continue;
      //2. 剔除上次小版本更新下载下来的
      string persistentPath = PathHelper.GetPersistentFullFilePath(BundleRoot + "/" + bundleName);
      if(File.Exists(persistentPath))
      {
        long lastsize = new FileInfo(persistentPath).Length;
        if(lastsize == size)
        {
          string lasthash = FileUtil.GetMD5Hash(persistentPath);
          if (lasthash == "")
          {
            Debug.LogError("计算md5出错");
          }
          else if (lasthash == hash)
            continue;
        }
      }
      downloadBundles.Add(bundleName);
    }
    //3. 下载
    foreach (string bundle in downloadBundles)
    {
      WWW www = new WWW(cdnAddress + bundle);
      while(!www.isDone)
      {
        yield return Timing.WaitForSeconds(0.01f);
      }
      // save to persistentDataPath
      Print("->下载" + bundle + "完毕");
      byte[] data = www.bytes;
			string folder = PathHelper.GetPersistentFullFilePath(BundleRoot);
			if (!Directory.Exists(folder))
				Directory.CreateDirectory(folder);
      File.WriteAllBytes(folder + "/" + bundle, data);
    }

    Print("Bundle 下载完毕，共下载" + downloadBundles.Count + "个");
    Print("------------------------------------------------------------------------");
    // test test
    ResManager.Instance.ReadFileMapping();
    ResManager.Instance.LoadManifest();
    // Done 
    OnDownloaded();
  }

  void OnDownloaded()
  {
    if (test != null)
      test.Testing();
  }

}