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

public enum DownloadTaskState
{
    None,
    Downloading,
    DownloadSuccess,
    Error,
}

public class DownloadTask : MonoBehaviour
{


    private UnityWebRequest webRqst;

    public UnityWebRequest WebRqst { get => webRqst; }

    public Action<DownloadTask> Callback { get; set; }

   [SerializeField]
    public DownloadDataEntity CurDownloadEntity { get; set; }

    [SerializeField]
    public float CurLoadProgress { get; private set; }
    public ulong downloadSize;

    private float timeOut;

    private DownloadTaskState state;
    public DownloadTaskState State {
        get => state;
        private set 
        {
            state = value;
            if (CurDownloadEntity != null)
            {
                CurDownloadEntity.State = state;
            }
        }
    }

    public ulong DownLoadSize { get => webRqst.downloadedBytes; }
    
    public DownloadTask()
    {
        //webRqst = new UnityWebRequest();
    }

    public bool SetUrl(string url = "")
    {
        bool ret = true;
        if (string.IsNullOrEmpty(url) && CurDownloadEntity != null)
        {
            webRqst = UnityWebRequest.Get(DownloadMgr.Instance.DownloadUrl + CurDownloadEntity.FullName);
        }
        else if (!string.IsNullOrEmpty(url))
        {
            webRqst = UnityWebRequest.Get(url);
        }
        else
        {
            ret = false;
        }

        return ret;
    }

    public void StartTask()
    {
        StartCoroutine(Task());
    }

    public IEnumerator Task()
    {
        if (State == DownloadTaskState.Downloading)
        {
            yield break;
        }
        State = DownloadTaskState.Downloading;
      
      
        string savePath = DownloadMgr.Instance.LocalFilePath + CurDownloadEntity.FullName;
        //FileStream fs = new FileStream(savePath, FileMode.OpenOrCreate);
        //if (fs == null)
        //{
        //    State = DownloadTaskState.Error;
        //    Callback?.Invoke(this);
        //    yield break;
        //}
       


        UnityWebRequestAsyncOperation asyncOperation = webRqst.SendWebRequest();
        yield return null;
        timeOut = Time.time;
        CurLoadProgress = 0;
        downloadSize = 0;
        while (!webRqst.isDone)
        {
            if (CurLoadProgress < webRqst.downloadProgress)
            {
                timeOut = Time.time;
                CurLoadProgress = webRqst.downloadProgress;

                //int count = (int)(webRqst.downloadedBytes - downloadSize);
                //fs.Write(webRqst.downloadHandler.data,(int)downloadSize, count);

                downloadSize = webRqst.downloadedBytes;
                CurDownloadEntity.UpDateCallback?.Invoke(this);
            }
            if (Time.time - timeOut > DownloadMgr.TimeOut)
            {
                Debug.LogWarning("下载超时！！！");
                //fs.Close();
                State = DownloadTaskState.Error;
                Callback?.Invoke(this);
                yield break;
            }
            yield return null;
        }
        CurLoadProgress = webRqst.downloadProgress;
        downloadSize = webRqst.downloadedBytes;
        CurDownloadEntity.UpDateCallback?.Invoke(this);
        //yield return asyncOperation;
        //fs.Flush();
        //fs.Close();

        if (webRqst != null && webRqst.error == null)
        {
            Debug.Log($"[{CurDownloadEntity.FullName}] 下载完成");
            State = DownloadTaskState.DownloadSuccess;
            //FileHelper.WriteToFileAsync( savePath,webRqst.downloadHandler.data,()=> { Callback?.Invoke(this); });
            FileHelper.WirteToFile( savePath,webRqst.downloadHandler.data);
            Callback?.Invoke(this);
        }
        else
        {
            State = DownloadTaskState.Error;
            Debug.Log($"下载失败；Error = {webRqst.error}   ===  {CurDownloadEntity.FullName} ");
            Callback?.Invoke(this);
        }
    }
}