Get streaming approach to work after all

Sources/GzipMiddleware/GzipMiddleware.swift

@@ -3,15 +3,6 @@ import Vapor
 import Foundation
 import ZIPFoundation
 
-private extension Data {
-    mutating func appendLittleEndian(_ word: UInt32) {
-        self.append(UInt8(word & 0xFF))
-        self.append(UInt8((word >> 8) & 0xFF))
-        self.append(UInt8((word >> 16) & 0xFF))
-        self.append(UInt8((word >> 24) & 0xFF))
-    }
-}
-
 /// Server Gzip middlere:
 /// 1. checks if the "Accept-Encoding" header contains "gzip"
 /// 2. if so, compresses the body and sets the response header "Content-Encoding" to "gzip",
@@ -39,22 +30,35 @@ public struct GzipServerMiddleware: Middleware, ServiceType {
             var headers = response.http.headers
             headers.replaceOrAdd(name: .contentEncoding, value: "gzip")
             return response.http.body.consumeData(on: request).map { data in
-                var buffer  = Data()
+                let stream  = HTTPChunkedStream(on: request)
+                let bufSize = 4096
+                var buffer  = ByteBufferAllocator().buffer(capacity: 16)
                 let header  : [UInt8] = [0x1f, 0x8b, 0x08, 0x00]
                 let header2 : [UInt8] = [0x00, 0x03]
-                buffer.append(contentsOf: header)
-                buffer.appendLittleEndian(UInt32(Date().timeIntervalSince1970))
-                buffer.append(contentsOf: header2)
-                let crc32   = try Data.compress(size: data.count, bufferSize: 4096,
+                buffer.write(bytes: header)
+                buffer.write(integer: UInt32(Date().timeIntervalSince1970), endianness: .little)
+                buffer.write(bytes: header2)
+                var write   = stream.write(.chunk(buffer))
+                let crc32   = try Data.compress(size: data.count, bufferSize: bufSize,
                     provider: {(offset, readSize) -> Data in
                         return data.subdata(in: offset..<offset+readSize)
                     },
                     consumer: { data -> Void in
-                        buffer.append(data)
+                        var buffer  = ByteBufferAllocator().buffer(capacity: bufSize)
+                        buffer.write(bytes: data)
+                        write = write.flatMap {
+                            return stream.write(.chunk(buffer))
+                        }
                     })
-                buffer.appendLittleEndian(crc32)
-                buffer.appendLittleEndian(UInt32(data.count))
-                let httpResponse = HTTPResponse(status: response.http.status, headers: headers, body: buffer)
+                write.always {
+                    buffer.clear()
+                    buffer.write(integer: crc32, endianness: .little)
+                    buffer.write(integer: UInt32(data.count), endianness: .little)
+                    stream.write(.chunk(buffer)).always {
+                        _ = stream.write(.end)
+                    }
+                }
+                let httpResponse = HTTPResponse(status: response.http.status, headers: headers, body: stream)
                 return request.response(http: httpResponse)
             }
         }