private async Task ManageES5Conversion(HttpContext context)
{
//If this return true here, this mean this is a subsequent call to a file
//and that the file has already been cached in the internal dictionary
//Otherwise we must try to seek the file hash of the current request and see
//if it has been converted at least once in the app lifetime
if (ES5CacheHelper.HasES5FileInCacheByPath(context.Request.Path))
{
var fileCache = ES5CacheHelper.GetES5FileFromCache(context.Request.Path);
//Manage request specificity
await HttpRequestManager.ManageRequest(context, fileCache.ES5Path, fileCache.ETag, fileCache.ContentLength);
return;
}
//Here we are tricking the StaticFile handler by modifying the Body Stream type before it try to write in it.
//Using a MemoryStream in order to be able to catch and modify the content afterward
var originalResponseStream = context.Response.Body;
using (var fakeResponseStream = new MemoryStream())
{
context.Response.Body = fakeResponseStream;
//Awaiting StaticFile to fill the content
await _next(context);
//If the requested file return 304 status code, we should not try to cache / resolve this file
//as StaticFileMiddleware does not return the data in this case
//Same as if there is any other behavior that is not a success (not 200) we must retrieve and return the initial stream modified by the other context
//without any alteration
if (context.Response.StatusCode != 200)
{
//Restoring the original response WriteOnly Stream
context.Response.Body = await CopyStreamAsync(fakeResponseStream, originalResponseStream);
return;
}
var response = await ExtractResponseAsync(context.Request, context.Response);
RequestFileCacheMetadata _cacheMetadata = null;
//From here we must see if we have a corresponding hash for this fetched resource in the cache store. Subsequent call will short-circuit at the top of this method because
//the cache entry dictionary will be populated. If the data is not present we will have
//to cache the file in disk
if (ES5CacheHelper.HasES5FileInCacheWithChecksum(context.Request.Path, response.SourceCheckSum))
{
_cacheMetadata = ES5CacheHelper.GetES5FileFromCache(context.Request.Path);
}
else
{
//Convert to ES5 the current response
var fileContent = ES5Convert(response);
if (fileContent == null)
{
//If here that mean that conversion failed.
//We will take the original object but will add
//current content as ES5 even if not
fileContent = response;
fileContent.ES5Content = fileContent.SourceContent;
}
_cacheMetadata = ES5CacheHelper.SetES5FileInCache(fileContent);
}
//As we have interverted the original Http Stream in our 'using' above, we
//must restore it in order to make the thing work normally
context.Response.Body = originalResponseStream;
//Manage request specificity
await HttpRequestManager.ManageRequest(context, _cacheMetadata.ES5Path, _cacheMetadata.ETag, _cacheMetadata.ContentLength);
}
}
