public async Task Invoke(HttpContext context)
{
bool useMinification = _options.IsMinificationEnabled() && _minificationManagers.Count > 0;
bool useCompression = _options.IsCompressionEnabled() && _compressionManager != null;
if (!useMinification && !useCompression)
{
await _next.Invoke(context);
return;
}
HttpRequest request = context.Request;
HttpResponse response = context.Response;
using (var cachedStream = new MemoryStream())
{
Stream originalStream = response.Body;
response.Body = cachedStream;
try
{
await _next.Invoke(context);
}
catch (Exception)
{
response.Body = originalStream;
cachedStream.Clear();
throw;
}
byte[] cachedBytes = cachedStream.ToArray();
int cachedByteCount = cachedBytes.Length;
bool isProcessed = false;
response.Body = originalStream;
cachedStream.Clear();
if (request.Method == "GET" && response.StatusCode == 200
&& _options.IsAllowableResponseSize(cachedByteCount))
{
string contentType = response.ContentType;
string mediaType = null;
Encoding encoding = null;
if (contentType != null)
{
MediaTypeHeaderValue mediaTypeHeader;
if (MediaTypeHeaderValue.TryParse(contentType, out mediaTypeHeader))
{
mediaType = mediaTypeHeader.MediaType.ToLowerInvariant();
encoding = mediaTypeHeader.Encoding;
}
}
encoding = encoding ?? Encoding.GetEncoding(0);
string currentUrl = request.Path.Value;
QueryString queryString = request.QueryString;
if (queryString.HasValue)
{
currentUrl += queryString.Value;
}
string content = encoding.GetString(cachedBytes);
string processedContent = content;
IHeaderDictionary responseHeaders = response.Headers;
bool isEncodedContent = responseHeaders.IsEncodedContent();
Action<string, string> appendHttpHeader = (key, value) =>
{
responseHeaders.Append(key, new StringValues(value));
};
if (useMinification)
{
foreach (IMarkupMinificationManager minificationManager in _minificationManagers)
{
if (mediaType != null && minificationManager.IsSupportedMediaType(mediaType)
&& minificationManager.IsProcessablePage(currentUrl))
{
if (isEncodedContent)
{
throw new InvalidOperationException(
string.Format(
AspNetCommonStrings.MarkupMinificationIsNotApplicableToEncodedContent,
responseHeaders["Content-Encoding"]
)
);
}
IMarkupMinifier minifier = minificationManager.CreateMinifier();
MarkupMinificationResult minificationResult = minifier.Minify(processedContent, currentUrl, encoding, false);
if (minificationResult.Errors.Count == 0)
{
processedContent = minificationResult.MinifiedContent;
if (_options.IsPoweredByHttpHeadersEnabled())
{
minificationManager.AppendPoweredByHttpHeader(appendHttpHeader);
}
isProcessed = true;
}
}
if (isProcessed)
{
break;
}
}
}
if (useCompression && !isEncodedContent
&& _compressionManager.IsSupportedMediaType(mediaType))
{
byte[] processedBytes = encoding.GetBytes(processedContent);
using (var inputStream = new MemoryStream(processedBytes))
using (var outputStream = new MemoryStream())
{
string acceptEncoding = request.Headers["Accept-Encoding"];
ICompressor compressor = _compressionManager.CreateCompressor(acceptEncoding);
using (Stream compressedStream = compressor.Compress(outputStream))
{
await inputStream.CopyToAsync(compressedStream);
}
byte[] compressedBytes = outputStream.ToArray();
int compressedByteCount = compressedBytes.Length;
outputStream.Clear();
inputStream.Clear();
responseHeaders["Content-Length"] = compressedByteCount.ToString();
compressor.AppendHttpHeaders(appendHttpHeader);
await originalStream.WriteAsync(compressedBytes, 0, compressedByteCount);
}
isProcessed = true;
}
else
{
if (isProcessed)
{
byte[] processedBytes = encoding.GetBytes(processedContent);
int processedByteCount = processedBytes.Length;
responseHeaders["Content-Length"] = processedByteCount.ToString();
await originalStream.WriteAsync(processedBytes, 0, processedByteCount);
}
}
}
if (!isProcessed)
{
await originalStream.WriteAsync(cachedBytes, 0, cachedByteCount);
}
}
}
/// <summary>
/// Calculatea a size of gzipped code
/// </summary>
/// <param name="bytes">Array of bytes</param>
/// <returns>Size of gzipped code in bytes</returns>
private static long CalculateGzipSize(byte[] bytes)
{
using (var memoryStream = new MemoryStream())
{
// the third parameter tells the GZIP stream to leave the base stream open so it doesn't
// dispose of it when it gets disposed. This is needed because we need to dispose the
// GZIP stream before it will write ANY of its data.
using (var gzipStream = new GZipStream(memoryStream, CompressionMode.Compress, true))
{
gzipStream.Write(bytes, 0, bytes.Length);
}
long compressedByteCount = memoryStream.Position;
memoryStream.Clear();
return compressedByteCount;
}
}
