/// <summary>
/// Downloads the file.
/// </summary>
public async Task <Stream> DownloadFile(string fileName)
{
Log($"{fileName} is requested by the client.");
string cachedFileLocation = Path.Combine(CommonConstants.CacheFilesLocation, $"{fileName}");
bool fileWasCached = CommonFunctionality.DoesFileExist(cachedFileLocation);
if (fileWasCached)
{
Log($"{fileName} was previously cached.");
byte[] allCachedBytes = System.IO.File.ReadAllBytes(cachedFileLocation);
FileCurrentVersionStatus fileCurrentVersionStatus;
using (ServerServiceClient serverServiceClient = new ServerServiceClient())
{
fileCurrentVersionStatus = await serverServiceClient.IsCurrentVersionOfFileAsync(fileName, allCachedBytes.CalculateSha256Hash());
if (fileCurrentVersionStatus == FileCurrentVersionStatus.Modified)
{
Log($"{fileName} has been modified on the main server.");
Stream downloadFile = await UpdateCachedFile(fileName, allCachedBytes, serverServiceClient, cachedFileLocation);
MarkFileAsCached(fileName);
return(downloadFile);
}
}
if (fileCurrentVersionStatus == FileCurrentVersionStatus.UpToDate)
{
MarkFileAsCached(fileName);
return(new MemoryStream(allCachedBytes));
}
throw new FileNotFoundException();
}
// File hasn't been cached before.
using (ServerServiceClient serverServiceClient = new ServerServiceClient())
{
Log($"{fileName} hasn't been cached before. Downloading it from the main server for the first time.");
Stream downloadedFile = await serverServiceClient.DownloadFileAsync(fileName);
byte[] fileContent = CommonFunctionality.ReadFully(downloadedFile);
SaveToNewFile(fileContent, cachedFileLocation);
MarkFileAsCached(fileName);
return(new MemoryStream(fileContent));
}
}