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

/// <summary>
/// 下载器
/// </summary>
public class DownloadHelper : MonoBehaviour
{
    /// <summary>
    /// 单例
    /// </summary>
    private static DownloadHelper _instance;

    /// <summary>
    /// 获得单例
    /// </summary>
    /// <returns>单例</returns>
    public static DownloadHelper GetInstance()
    {
        if (null == _instance)
        {
            GameObject obj = new GameObject("DownloadHelper");
            _instance = obj.AddComponent<DownloadHelper>();
        }

        return _instance;
    }

    /// <summary>
    /// Awake方法
    /// </summary>
    private void Awake()
    {
        _instance = this;
    }

    #region ==========> 资源批量下载临时变量

    /// <summary>
    /// url列表
    /// </summary>
    private List<string> _urls = new List<string>();

    /// <summary>
    /// 总数
    /// </summary>
    private int _count = 0;

    /// <summary>
    /// 当前索引
    /// </summary>
    private int _index = 0;

    /// <summary>
    /// 下载的总字节数
    /// </summary>
    private int _total = 0;

    /// <summary>
    /// 当前www
    /// </summary>
    private WWW _www;

    /// <summary>
    /// 是否中断
    /// </summary>
    private bool _breaking = false;

    /// <summary>
    /// cdn根路径
    /// </summary>
    private string _cdnroot = "http://";

    /// <summary>
    /// 当前WWW组件，用于监听单文件下载进度，有可能为空
    /// </summary>
    public WWW curWWW
    {
        get
        {
            return _www;
        }
    }

    /// <summary>
    /// 当前文件处理流程
    /// </summary>
    public float progress
    {
        get
        {
            return _www == null ? 0 : _www.progress;
        }
    }

    /// <summary>
    /// 递归下载
    /// </summary>
    /// <param name="progress">进程回调</param>
    /// <param name="complete">完成回调</param>
    /// <param name="onError">错误回调</param>
    private void DownLoadItem(ProgressCallback progress, CompleteCallback complete, ErrorCallback onError)
    {
        if (_breaking)
        {
            return;
        }

        string url = _urls[_index];
        DownLoad(_cdnroot, url, (token) =>
        {
            _index++;
            progress.Invoke(_index, _count, _total);
            if (_index >= _count)
            {
                complete.Invoke("complete!");
            }
            else
            {
                DownLoadItem(progress, complete, onError);
            }
        }, onError);
    }
    #endregion

    /// <summary>
    /// 下载资源列表
    /// </summary>
    /// <param name="cdnroot">cnd根目录</param>
    /// <param name="urls">url路径</param>
    /// <param name="progress">进程回调</param>
    /// <param name="complete">完成回调</param>
    /// <param name="onError">错误回调</param>
    public void DownLoadList(string cdnroot, List<string> urls, ProgressCallback progress, CompleteCallback complete, ErrorCallback onError)
    {
        _cdnroot = cdnroot;
        _breaking = false;
        _urls.Clear(); 
        _urls = urls; 
        _count = urls.Count;
        _index = 0; 
        _total = 0;
        DownLoadItem(progress, complete, onError);
    }

    /// <summary>
    /// 中断列表下载（仅适用于列表下载）
    /// </summary>
    public void Break()
    {
        _breaking = true;
    }

    /// <summary>
    /// 单文件下载
    /// </summary>
    /// <param name="cdnroot">cdn根路径</param>
    /// <param name="url">url路径</param>
    /// <param name="callback">完成回调</param>
    /// <param name="onError">错误回调</param>
    public void DownLoad(string cdnroot, string url, CompleteCallback callback, ErrorCallback onError)
    {
        _cdnroot = cdnroot;
        StartCoroutine(IDownload(url, callback, onError));
    }

    /// <summary>
    /// 协同
    /// </summary>
    /// <param name="url">url</param>
    /// <param name="callback">回调</param>
    /// <param name="onError">错误回调</param>
    /// <returns>协同句柄</returns>
    private IEnumerator IDownload(string url, CompleteCallback callback, ErrorCallback onError)
    {
        if (_www != null)
        {
            _www.Dispose();
            _www = null;
        }

        WWW w = new WWW(_cdnroot + url);
        _www = w;

        DateTime start = DateTime.Now;
        /*
        // 超时检测
        while (false == w.isDone)
        {
            if (DateTime.Now - start > TimeSpan.FromSeconds(Const.NetDefaultTimeOut / 1000))
            {
                onError("Time out!!");
                yield break;
            }
            else
            {
                yield return null;
            }
        }
         * */
        yield return w;

        if (w.error != null)
        {
            LogHelper.LogWarning(w.error);
            onError(w.error);
        }
        else
        {
            LogHelper.Log("[DownLoad]::" + url);
            CreateFile(FilePath(url), w.bytes);
            _total += w.size;
            callback("ok!");
        }
    }

    /// <summary>
    /// 创建文件
    /// </summary>
    /// <param name="path">路径</param>
    /// <param name="content">内容</param>
    public static void CreateFile(string path, byte[] content)
    {
        string dir = GetDirectoryByPath(path);
        if (!Directory.Exists(dir))
        {
            Directory.CreateDirectory(dir);
        }

        FileStream fs = new FileStream(path, FileMode.Create);
        fs.Write(content, 0, content.Length);
        fs.Flush();
        fs.Close();
    }

    /// <summary>
    /// 根据文件路径截取目录
    /// </summary>
    /// <param name="path">路径</param>
    /// <returns>目录</returns>
    public static string GetDirectoryByPath(string path)
    {
        string[] temps = path.Split('/');
        string dir = string.Empty;
        for (int i = 0; i < temps.Length - 1; i++)
        {
            dir += temps[i] + "/";
        }

        return dir;
    }

    /// <summary>
    /// 获得文件路径
    /// </summary>
    /// <param name="url">url</param>
    /// <returns>路径</returns>
    private string FilePath(string url)
    {
        return Application.persistentDataPath + "/" + url;
    }
}

/// <summary>
/// 错误回调
/// </summary>
/// <param name="msg">错误消息</param>
public delegate void ErrorCallback(string msg);

/// <summary>
/// 完成回调
/// </summary>
/// <param name="token">token</param>
public delegate void CompleteCallback(object token);

/// <summary>
/// 进程回调
/// </summary>
/// <param name="index">当前索引</param>
/// <param name="count">总数</param>
/// <param name="total">总字节数</param>
public delegate void ProgressCallback(int index, int count, int total);