/// <summary>
/// start download.
/// </summary>
public async void StartDownload()
{
if (!_cookies.Any())
{
MessageBox.Show(@"未登录中国大学 MOOC.", @"提示", MessageBoxButtons.OK, MessageBoxIcon.Warning);
return;
}
if (string.IsNullOrEmpty(_config.CourseUrl))
{
MessageBox.Show(@"课程链接未输入.", @"提示", MessageBoxButtons.OK, MessageBoxIcon.Warning);
return;
}
var courseUrl = _config.CourseUrl;
if (!_config.IsDownloadDocument &&
!_config.IsDownloadVideo &&
!_config.IsDownloadSubtitle &&
!_config.IsDownloadAttachment) // checked at least one of them
{
MessageBox.Show(@"至少勾选下载视频, 文档, 字幕, 附件其中一种类型.", @"提示", MessageBoxButtons.OK, MessageBoxIcon.Warning);
return;
}
if (MessageBox.Show(@"开始下载?", @"提示", MessageBoxButtons.OKCancel, MessageBoxIcon.Information)
== DialogResult.Cancel)
{
Log("取消下载.");
return;
}
if (!Directory.Exists(_config.CourseSavePath))
{
Log($@"路径: {_config.CourseSavePath} 不存在, 准备创建.");
try
{
Directory.CreateDirectory(_config.CourseSavePath);
Log($@"路径: {_config.CourseSavePath} 创建成功.");
}
catch (Exception exception)
{
Log($@"路径: {_config.CourseSavePath} 创建失败, 原因: {exception.Message}.");
return;
}
}
SetStatus("准备下载");
Log($@"课程将会下载到文件夹: {_config.CourseSavePath}");
SetUIStatus(false);
ResetCurrentBar();
ResetTotalBar();
// 1. initializes a mooc request.
var mooc = new MoocRequest(_cookies, courseUrl);
// 2. get term id.
var termId = await mooc.GetTermIdAsync();
SetStatus("正在下载");
Log($@"提取到课程 ID 是 {termId}");
// 3. get Mooc term JavaScript code.
var moocTermCode = await mooc.GetMocTermJavaScriptCodeAsync(termId);
// 4. evaluate mooc term JavaScript code.
moocTermCode = FixCourseBeanCode(moocTermCode);
var moocTermJSON = EvaluateJavaScriptCode(moocTermCode, COURSE_BEAN_NAME) as string;
// 5. deserialize moocTermJSON.
var course = DeserializeObject <CourseModel>(moocTermJSON ?? string.Empty);
FFmpegWorker.Instance.Start();
for (var chapterIndex = 0; chapterIndex < course.Chapters.Count && !_isCancel; chapterIndex++)
{
var chapter = course.Chapters[chapterIndex];
for (var lessonIndex = 0; lessonIndex < chapter.Lessons.Count && !_isCancel; lessonIndex++)
{
var lesson = chapter.Lessons[lessonIndex];
for (var unitIndex = 0; unitIndex < lesson.Units.Count && !_isCancel; unitIndex++)
{
// update total progress bar.
var totalMax = course.Chapters.Count + chapter.Lessons.Count + lesson.Units.Count;
var totalCurrent = (chapterIndex + 1) + (lessonIndex + 1) + (unitIndex + 1);
UpdateTotalBar(CalculatePercentage(totalCurrent, totalMax));
var unit = lesson.Units[unitIndex];
// create unit save path.
var chapterDir = $@"{chapterIndex + 1:00}-{FixPath(chapter.Name)}";
var lessonDir = $@"{lessonIndex + 1:00}-{FixPath(lesson.Name)}";
var unitPath = Path.Combine(_config.CourseSavePath, course.CourseName, chapterDir, lessonDir);
var unitFileName = $@"{unitIndex + 1:00}-{FixPath(unit.Name)}";
if (!Directory.Exists(unitPath))
{
Directory.CreateDirectory(unitPath);
}
var unitCode = await mooc.GetUnitJavaScriptCodeAsync(
unit.Id, unit.ContentId, unit.TermId, unit.ContentType
);
if (unitCode.Contains("dwr.engine._remoteHandleException"))
{
Console.WriteLine(@"Error: system error.");
break;
}
unitCode = FixCourseBeanCode(unitCode);
var unitJSON = EvaluateJavaScriptCode(unitCode, COURSE_BEAN_NAME) as string;
var unitResult = DeserializeObject <UnitResultModel>(unitJSON ?? string.Empty);
// Parse video / document / attachment link.
var unitType = (UnitType)(unit.ContentType ?? 0);
switch (unitType)
{
case UnitType.Other: // type is null.
break;
case UnitType.Video: // video type.
{
if (!_config.IsDownloadVideo)
{
break;
}
// get access token.
var tokenJSON = await mooc.GetResourceTokenJsonAsync(
$"{unit.Id}", $@"{unit.TermId}", $"{unit.ContentType}"
);
var tokenObject = JObject.Parse(tokenJSON);
var signature = tokenObject["result"]?["videoSignDto"]?["signature"]?.ToString();
var videoJSON = await mooc.GetVideoJsonAsync($@"{unit.ContentId}", signature);
var video = DeserializeObject <VideoResponseModel>(videoJSON);
var courseVideo = new CourseVideoInfo
{
SavePath = unitPath,
VideoFileName = $@"{unitFileName}.mp4",
MergeListFile = $@"{unitFileName}.text"
};
Log($@"下载视频: {unitFileName}");
// subtitles
if (_config.IsDownloadSubtitle)
{
foreach (var caption in video.Result.SrtCaptions)
{
// subtitle file. E.g:
// 01-第一节 Java明天 视频.zh.srt
// 01-第一节 Java明天 视频.en.srt
var srtName = $@"{unitFileName}.{caption.LanguageCode}.srt";
var srtContent = await mooc.DownloadSubtitleAsync(caption.Url);
File.WriteAllBytes(Path.Combine(unitPath, srtName), srtContent);
}
}
var videoInfo = video.Result.Videos.FirstOrDefault(
v => v.Quality.HasValue &&
(VideoQuality)v.Quality == _config.VideoQuality
);
if (videoInfo != null)
{
var videoUrl = new Uri(videoInfo.VideoUrl); // video url.
var baseUrl = $@"{videoUrl.Scheme}://{videoUrl.Host}" +
string.Join("", videoUrl.Segments.Take(videoUrl.Segments.Length - 1));
Configuration.Default.BaseUri = new Uri(baseUrl, UriKind.Absolute);
var m3u8List = await mooc.DownloadM3U8ListAsync(videoUrl);
using var reader = new M3UFileReader(m3u8List);
var m3u8Info = reader.Read();
var merger = new StringBuilder();
for (var i = 0; i < m3u8Info.MediaFiles.Count && !_isCancel; i++)
{
UpdateCurrentBar(CalculatePercentage(i + 1, m3u8Info.MediaFiles.Count));
var tsSavedName = $@"{unitFileName}-{i:00}.ts";
for (var j = 0; j < MAX_TIMES; j++)
{
var tsBytes = await mooc.DownloadM3U8TSAsync(m3u8Info.MediaFiles[i].Uri);
if (tsBytes is null)
{
await Task.Delay(TimeSpan.FromSeconds(Math.Pow(2, j + 1)));
}
else
{
File.WriteAllBytes(Path.Combine(unitPath, tsSavedName), tsBytes);
break;
}
}
merger.AppendLine(
$@"file '{Path.Combine(unitPath, tsSavedName)}'"
); // combine ts file path and add to list.
courseVideo.TSFiles.Add(tsSavedName);
}
Log($@"课程 {unitFileName} 已下载完成.");
File.WriteAllText(
Path.Combine(unitPath, $@"{courseVideo.MergeListFile}"), merger.ToString()
);
FFmpegWorker.Instance.Enqueue(courseVideo);
}
}
break;
case UnitType.Document: // document type. E.g pdf.
{
if (!_config.IsDownloadDocument)
{
break;
}
var documentUrl = unitResult.TextOrigUrl;
var fileName = $@"{unitFileName}.pdf";
Log($@"准备下载文档: {fileName}");
for (var i = 0; i < MAX_TIMES; i++)
{
var document = await mooc.DownloadDocumentAsync(documentUrl);
if (document is null)
{
await Task.Delay(TimeSpan.FromSeconds(Math.Pow(2, i + 1)));
}
else
{
File.WriteAllBytes(Path.Combine(unitPath, fileName), document);
Log($@"文档 {fileName} 已下载完成.");
break;
}
}
}
break;
case UnitType.Attachment: // attachment type. E.g source code.
{
if (!_config.IsDownloadAttachment)
{
break;
}
const string attachmentBaseUrl = "https://www.icourse163.org/course/attachment.htm";
var content = JObject.Parse(unit.JsonContent);
var nosKey = content["nosKey"]?.ToString();
var fileName = content["fileName"]?.ToString();
var attachmentUrl = $@"{attachmentBaseUrl}?fileName={fileName}&nosKey={nosKey}";
Log($@"准备下载附件: {fileName}");
for (var i = 0; i < MAX_TIMES; i++)
{
var attachment = await mooc.DownloadAttachmentAsync(attachmentUrl);
if (attachment is null)
{
await Task.Delay(TimeSpan.FromSeconds(Math.Pow(2, i + 1)));
}
else
{
File.WriteAllBytes(
Path.Combine(unitPath, $@"{unitFileName}-{FixPath(fileName)}"), attachment
);
Log($@"附件 {fileName} 已下载完成.");
break;
}
}
}
break;
default: // not recognized type
throw new ArgumentOutOfRangeException();
}
}
}
}
SetUIStatus(true);
if (_isCancel)
{
Log("已取消下载.");
}
else
{
UpdateTotalBar(100);
UpdateCurrentBar(100);
SetStatus("下载完成");
Log("下载完成!");
}
}
private async Task DownloadAttachmentAsync(UnitModel unit, MoocRequest mooc, string unitPath,
string unitFileName)
{
if (!_config.IsDownloadAttachment)
{
return;
}
const string attachmentBaseUrl = "https://www.icourse163.org/course/attachment.htm";
if (string.IsNullOrEmpty(unit.JsonContent))
{
WriteLog($"附件 {unit.Name} 下载链接为空, 跳过下载.");
return;
}
var content = JObject.Parse(unit.JsonContent);
var nosKey = content["nosKey"]?.ToString();
var fileName = content["fileName"]?.ToString();
var attachmentUrl = $@"{attachmentBaseUrl}?fileName={fileName}&nosKey={nosKey}";
var downloadAttSuccess = false;
var attachSavePath = Path.Combine(unitPath, $@"{unitFileName}-{FixPath(fileName)}");
if (File.Exists(attachSavePath)) // exist attachment, skip.
{
WriteLog($@"附件 {fileName} 已下载, 跳过.");
return;
}
WriteLog($@"准备下载附件: {fileName}");
for (var i = 0; i < MAX_TIMES; i++)
{
try
{
var attachment = await mooc.DownloadAttachmentAsync(attachmentUrl);
if (attachment is null)
{
WriteLog($"下载附件 {fileName} 失败, 准备重试, 当前重试第 {i + 1} 次.");
await Task.Delay(TimeSpan.FromSeconds(Math.Pow(2, i)));
}
else
{
File.WriteAllBytes(attachSavePath, attachment);
downloadAttSuccess = true;
WriteLog($@"附件 {fileName} 已下载完成.");
break;
}
}
catch (Exception exception)
{
await Task.Delay(TimeSpan.FromSeconds(Math.Pow(2, i)));
WriteLog($@"下载附件 {fileName} 发生错误, 原因: {exception.Message}, 准备重试, 当前重试第 {i + 1} 次.");
}
}
if (!downloadAttSuccess)
{
WriteLog($"下载附件 {fileName} 失败, 已跳过.");
}
}
