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

namespace TModule.Runtime
{
    public class DownloadRoutine
    {
        /// <summary>
        /// 下载路径
        /// </summary>
        public string DownLoadUrl { get; set; }

        /// <summary>
        /// 文件保存路径
        /// </summary>
        public string FileSavePath { get; set; }

        /// <summary>
        /// 是否空闲
        /// </summary>
        public bool IsLeisure { get; set; } = true;

        /// <summary>
        /// 下载总大小
        /// </summary>
        private long _totalSzie;

        public long TotalSize => _totalSzie;

        /// <summary>
        /// 已下载大小
        /// </summary>
        private long _currentDownloadSize;

        public long CurrentDownloadSize => _currentDownloadSize;

        //停止下载
        private bool _isStop;

        public bool IsStop
        {
            get => _isStop ||
#if UNITY_EDITOR 
                !UnityEditor.EditorApplication.isPlaying

#else
            !Application.isPlaying
#endif
                ;
            set => _isStop = value;
        }

        public Action onDownloadOver;

        /// <summary>
        /// 下载中事件 下载进度 总大小 已下载大小
        /// </summary>
        public Action<float,long,long> onProgress;

        public Action<string> onError;

        /// <summary>
        /// 开始下载
        /// </summary>
        /// <param name="url"></param>
        /// <returns></returns>
        public async Task StartDownload(string url,string fileSavePath)
        {
            DownLoadUrl = url;
            FileSavePath = fileSavePath;
            IsStop = false;
            _currentDownloadSize = 0;
            IsLeisure = false;
            UnityWebRequest webRequest = UnityWebRequest.Head(DownLoadUrl);
            await webRequest.SendWebRequest();
            if (webRequest.result == UnityWebRequest.Result.ConnectionError || webRequest.result == UnityWebRequest.Result.ProtocolError)
            {
                onError?.Invoke(webRequest.error);
                Debug.Log(webRequest.error); //出现错误 输出错误信息
            }
            else
            {
                string info = webRequest.GetResponseHeader("Content-Length");
                _totalSzie = long.Parse(info);
                await DownloadFile();
            }
        }

        public void StopDownload()
        {
            IsStop = true;
        }

        public async Task ContinueDownload()
        {
            if (IsLeisure) return;
            IsStop = false;
            await DownloadFile();
        }

        async Task DownloadFile()
        {
            string dirPath = Path.GetDirectoryName(FileSavePath);
            if (!Directory.Exists(dirPath))
                Directory.CreateDirectory(dirPath);
            using (FileStream fs = new FileStream(FileSavePath, FileMode.OpenOrCreate, FileAccess.Write,FileShare.ReadWrite))
            {
                _currentDownloadSize = fs.Length;

                if (_currentDownloadSize < _totalSzie)
                {
                    fs.Seek(_currentDownloadSize, SeekOrigin.Begin);
                    UnityWebRequest request = UnityWebRequest.Get(DownLoadUrl);
                    request.SetRequestHeader("Range", $"bytes={_currentDownloadSize}-");
                    request.SendWebRequest();
                    if (request.result == UnityWebRequest.Result.ConnectionError || request.result == UnityWebRequest.Result.ProtocolError)
                    {
                        onError?.Invoke(request.error);
                        Debug.Log(request.error); //出现错误 输出错误信息
                    }
                    else
                    {
                        long index = 0;
                        while (_currentDownloadSize < _totalSzie)
                        {
                            if (IsStop) break;
                            byte[] data = request.downloadHandler.data;
                            if (data != null)
                            {
                                long length = data.Length - index;
                                fs.Write(data, (int)index, (int)length);
                                index += length;
                                _currentDownloadSize += length;
                                onProgress?.Invoke((float)Math.Round((double)_currentDownloadSize / _totalSzie,2), _totalSzie, _currentDownloadSize);
                                if (_currentDownloadSize >= _totalSzie)
                                {
                                    //下载完成
                                    IsLeisure = true;
                                    onDownloadOver?.Invoke();
                                    break;
                                }
                            }
                            await Task.Yield();
                        }
                    }
                }
            }
        }
    }
}