/// <summary>
/// Initializes a new instance of the <see cref="DownloadedAsset" /> class.
/// </summary>
/// <param name="fileName">Name of the file.</param>
/// <param name="apiAsset"></param>
/// <param name="info"></param>
/// <param name="stream">The stream.</param>
/// <exception cref="ArgumentNullException">fileName or stream is null.</exception>
public DownloadedAsset(string fileName, ApiAsset apiAsset, DownloadInfo info, Stream stream)
{
if (fileName == null) throw new ArgumentNullException(nameof(fileName));
if (apiAsset == null) throw new ArgumentNullException(nameof(apiAsset));
if (stream == null) throw new ArgumentNullException(nameof(stream));
FileName = fileName;
ApiAsset = apiAsset;
Info = info;
Stream = stream;
}
/// <summary>
/// Downloads the asset.
/// </summary>
/// <param name="asset">The asset.</param>
/// <returns></returns>
/// <exception cref="ArgumentNullException"></exception>
/// <exception cref="Exception">the specified asset id is invalid</exception>
public async Task<IDownloadedAsset> DownloadAsset(ApiAsset asset)
{
if (asset == null) throw new ArgumentNullException(nameof(asset));
var downloadInfo = ResolveDownloadInfo(asset);
using (var webClient = _webClientFactory.CreateWebClient(asset.Type != AssetType.Mod))
{
using (var stream = await webClient.OpenReadTaskAsync(downloadInfo.Url))
{
// Read content information from the headers.
var contentDispositionHeader = webClient.ResponseHeaders.Get("Content-Disposition");
var contentLengthHeader = webClient.ResponseHeaders.Get("Content-Length");
var contentTypeHeader = webClient.ResponseHeaders.Get("Content-Type");
// Ensure the required content headers exist.
if (string.IsNullOrWhiteSpace(contentDispositionHeader) ||
string.IsNullOrWhiteSpace(contentTypeHeader))
throw new Exception("invalid headers");
// Parse the content length header to an integer.
var contentLength = 0;
if (contentLengthHeader != null && !int.TryParse(contentLengthHeader, out contentLength))
throw new Exception("invalid headers");
// Get asset information for the asset type specified in the url.
var assetInfo = asset.Type.GetCustomAttribute<AssetInfoAttribute>();
// Ensure the type of the received content matches the expected content type.
if (assetInfo == null || assetInfo.ContentType != contentTypeHeader.Split(';').FirstOrDefault())
throw new Exception("invalid response type");
// Extract the filename of the asset from the content disposition header.
var fileNameMatch = Regex.Match(contentDispositionHeader, @"attachment; filename=(""?)(.*)\1");
if (fileNameMatch == null || !fileNameMatch.Success)
throw new Exception("invalid headers");
var fileName = fileNameMatch.Groups[2].Value;
// Copy the contents of the downloaded stream to a memory stream.
var memoryStream = new MemoryStream();
await stream.CopyToAsync(memoryStream);
// Verify we received all content.
if (contentLengthHeader != null && memoryStream.Length != contentLength)
throw new Exception("unexpected end of stream");
// Create an instance of ParkitectAsset with the received content and data.
return new DownloadedAsset(fileName, asset, downloadInfo, memoryStream);
}
}
}
private DownloadInfo ResolveDownloadInfo(ApiAsset asset)
{
if (asset == null) throw new ArgumentNullException(nameof(asset));
switch (asset.Type)
{
case AssetType.Blueprint:
case AssetType.Savegame:
return new DownloadInfo(asset.Resource.Data.Url, null, null);
case AssetType.Mod:
var repoUrl = asset.Resource.Data.Source;
var repoUrlParts = repoUrl.Split("/".ToCharArray(), StringSplitOptions.RemoveEmptyEntries);
var repo = $"{repoUrlParts[repoUrlParts.Length - 2]}/{repoUrlParts[repoUrlParts.Length - 1]}";
if (asset.Resource.Data.ZipBall == null)
throw new Exception("mod has not yet been released(tagged)");
return new DownloadInfo(asset.Resource.Data.ZipBall, repo, asset.Resource.Data.Version);
default:
throw new Exception("unsupported mod type");
}
}
