/*
    * Copyright 2012 The Netty Project
    *
    * The Netty Project licenses this file to you under the Apache License,
    * version 2.0 (the "License"); you may not use this file except in compliance
    * with the License. You may obtain a copy of the License at:
    *
    *   http://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
   * License for the specific language governing permissions and limitations
   * under the License.
   */
  package org.jboss.netty.handler.codec.spdy;
  
  import org.jboss.netty.channel.ChannelDownstreamHandler;
  import org.jboss.netty.channel.ChannelEvent;
  import org.jboss.netty.channel.ChannelFuture;
  import org.jboss.netty.channel.ChannelFutureListener;
  import org.jboss.netty.channel.ChannelHandlerContext;
  import org.jboss.netty.channel.Channels;
  import org.jboss.netty.channel.MessageEvent;
  import org.jboss.netty.handler.codec.http.HttpChunk;
  import org.jboss.netty.handler.codec.http.HttpChunkTrailer;
  import org.jboss.netty.handler.codec.http.HttpHeaders;
  import org.jboss.netty.handler.codec.http.HttpMessage;
  import org.jboss.netty.handler.codec.http.HttpRequest;
  import org.jboss.netty.handler.codec.http.HttpResponse;
  
  import java.util.List;
  import java.util.Map;
  
  import static org.jboss.netty.handler.codec.spdy.SpdyCodecUtil.*;
  
  /**
   * Encodes {@link HttpRequest}s, {@link HttpResponse}s, and {@link HttpChunk}s
   * into {@link SpdySynStreamFrame}s and {@link SpdySynReplyFrame}s.
   *
   * <h3>Request Annotations</h3>
   *
   * SPDY specific headers must be added to {@link HttpRequest}s:
   * <table border=1>
   * <tr>
   * <th>Header Name</th><th>Header Value</th>
   * </tr>
   * <tr>
   * <td>{@code "X-SPDY-Stream-ID"}</td>
   * <td>The Stream-ID for this request.
   * Stream-IDs must be odd, positive integers, and must increase monotonically.</td>
   * </tr>
   * <tr>
   * <td>{@code "X-SPDY-Priority"}</td>
   * <td>The priority value for this request.
   * The priority should be between 0 and 7 inclusive.
   * 0 represents the highest priority and 7 represents the lowest.
   * This header is optional and defaults to 0.</td>
   * </tr>
   * </table>
   *
   * <h3>Response Annotations</h3>
   *
   * SPDY specific headers must be added to {@link HttpResponse}s:
   * <table border=1>
   * <tr>
   * <th>Header Name</th><th>Header Value</th>
   * </tr>
   * <tr>
   * <td>{@code "X-SPDY-Stream-ID"}</td>
   * <td>The Stream-ID of the request corresponding to this response.</td>
   * </tr>
   * </table>
   *
   * <h3>Pushed Resource Annotations</h3>
   *
   * SPDY specific headers must be added to pushed {@link HttpResponse}s:
   * <table border=1>
   * <tr>
   * <th>Header Name</th><th>Header Value</th>
   * </tr>
   * <tr>
   * <td>{@code "X-SPDY-Stream-ID"}</td>
   * <td>The Stream-ID for this resource.
   * Stream-IDs must be even, positive integers, and must increase monotonically.</td>
   * </tr>
   * <tr>
   * <td>{@code "X-SPDY-Associated-To-Stream-ID"}</td>
   * <td>The Stream-ID of the request that initiated this pushed resource.</td>
   * </tr>
   * <tr>
   * <td>{@code "X-SPDY-Priority"}</td>
   * <td>The priority value for this resource.
   * The priority should be between 0 and 7 inclusive.
   * 0 represents the highest priority and 7 represents the lowest.
   * This header is optional and defaults to 0.</td>
   * </tr>
   * <tr>
   * <td>{@code "X-SPDY-URL"}</td>
  * <td>The absolute path for the resource being pushed.</td>
  * </tr>
  * </table>
  *
  * <h3>Required Annotations</h3>
  *
  * SPDY requires that all Requests and Pushed Resources contain
  * an HTTP "Host" header.
  *
  * <h3>Optional Annotations</h3>
  *
  * Requests and Pushed Resources must contain a SPDY scheme header.
  * This can be set via the {@code "X-SPDY-Scheme"} header but otherwise
  * defaults to "https" as that is the most common SPDY deployment.
  *
  * <h3>Chunked Content</h3>
  *
  * This encoder associates all {@link HttpChunk}s that it receives
  * with the most recently received 'chunked' {@link HttpRequest}
  * or {@link HttpResponse}.
  *
  * <h3>Pushed Resources</h3>
  *
  * All pushed resources should be sent before sending the response
  * that corresponds to the initial request.
  */
 public class SpdyHttpEncoder implements ChannelDownstreamHandler {
 
     private final int spdyVersion;
     private volatile int currentStreamID;
 
     /**
      * Creates a new instance for the SPDY/2 protocol
      */
      @Deprecated
     public SpdyHttpEncoder() {
          this(2);
     }
 
     /**
      * Creates a new instance.
      *
      * @param version the protocol version
      */
     public SpdyHttpEncoder(int version) {
         if (version < SPDY_MIN_VERSION || version > SPDY_MAX_VERSION) {
             throw new IllegalArgumentException(
                     "unsupported version: " + version);
         }
         spdyVersion = version;
     }
 
     public void handleDownstream(ChannelHandlerContext ctx, ChannelEvent evt)
             throws Exception {
         if (!(evt instanceof MessageEvent)) {
             ctx.sendDownstream(evt);
             return;
         }
 
         MessageEvent e = (MessageEvent) evt;
         Object msg = e.getMessage();
 
         if (msg instanceof HttpRequest) {
 
             HttpRequest httpRequest = (HttpRequest) msg;
             SpdySynStreamFrame spdySynStreamFrame = createSynStreamFrame(httpRequest);
             int streamID = spdySynStreamFrame.getStreamId();
             ChannelFuture future = getContentFuture(ctx, e, streamID, httpRequest);
             Channels.write(ctx, future, spdySynStreamFrame, e.getRemoteAddress());
 
         } else if (msg instanceof HttpResponse) {
 
             HttpResponse httpResponse = (HttpResponse) msg;
             if (httpResponse.containsHeader(SpdyHttpHeaders.Names.ASSOCIATED_TO_STREAM_ID)) {
                 SpdySynStreamFrame spdySynStreamFrame = createSynStreamFrame(httpResponse);
                 int streamID = spdySynStreamFrame.getStreamId();
                 ChannelFuture future = getContentFuture(ctx, e, streamID, httpResponse);
                 Channels.write(ctx, future, spdySynStreamFrame, e.getRemoteAddress());
             } else {
                 SpdySynReplyFrame spdySynReplyFrame = createSynReplyFrame(httpResponse);
                 int streamID = spdySynReplyFrame.getStreamId();
                 ChannelFuture future = getContentFuture(ctx, e, streamID, httpResponse);
                 Channels.write(ctx, future, spdySynReplyFrame, e.getRemoteAddress());
             }
 
         } else if (msg instanceof HttpChunk) {
 
             HttpChunk chunk = (HttpChunk) msg;
             SpdyDataFrame spdyDataFrame = new DefaultSpdyDataFrame(currentStreamID);
             spdyDataFrame.setData(chunk.getContent());
             spdyDataFrame.setLast(chunk.isLast());
 
             if (chunk instanceof HttpChunkTrailer) {
                 HttpChunkTrailer trailer = (HttpChunkTrailer) chunk;
                 List<Map.Entry<String, String>> trailers = trailer.getHeaders();
                 if (trailers.isEmpty()) {
                     Channels.write(ctx, e.getFuture(), spdyDataFrame, e.getRemoteAddress());
                 } else {
                     // Create SPDY HEADERS frame out of trailers
                     SpdyHeadersFrame spdyHeadersFrame = new DefaultSpdyHeadersFrame(currentStreamID);
                     for (Map.Entry<String, String> entry: trailers) {
                         spdyHeadersFrame.addHeader(entry.getKey(), entry.getValue());
                     }
 
                     // Write HEADERS frame and append Data Frame
                     ChannelFuture future = Channels.future(e.getChannel());
                     future.addListener(new SpdyFrameWriter(ctx, e, spdyDataFrame));
                     Channels.write(ctx, future, spdyHeadersFrame, e.getRemoteAddress());
                 }
             } else {
                 Channels.write(ctx, e.getFuture(), spdyDataFrame, e.getRemoteAddress());
             }
         } else {
             // Unknown message type
             ctx.sendDownstream(evt);
         }
     }
 
     private static ChannelFuture getContentFuture(
             ChannelHandlerContext ctx, MessageEvent e, int streamID, HttpMessage httpMessage) {
         if (httpMessage.getContent().readableBytes() == 0) {
             return e.getFuture();
         }
 
         // Create SPDY Data Frame out of message content
         SpdyDataFrame spdyDataFrame = new DefaultSpdyDataFrame(streamID);
         spdyDataFrame.setData(httpMessage.getContent());
         spdyDataFrame.setLast(true);
 
         // Create new future and add listener
         ChannelFuture future = Channels.future(e.getChannel());
         future.addListener(new SpdyFrameWriter(ctx, e, spdyDataFrame));
 
         return future;
     }
 
     private static class SpdyFrameWriter implements ChannelFutureListener {
 
         private final ChannelHandlerContext ctx;
         private final MessageEvent e;
         private final Object spdyFrame;
 
         SpdyFrameWriter(ChannelHandlerContext ctx, MessageEvent e, Object spdyFrame) {
             this.ctx = ctx;
             this.e = e;
             this.spdyFrame = spdyFrame;
         }
 
         public void operationComplete(ChannelFuture future) throws Exception {
             if (future.isSuccess()) {
                 Channels.write(ctx, e.getFuture(), spdyFrame, e.getRemoteAddress());
             } else if (future.isCancelled()) {
                 e.getFuture().cancel();
             } else {
                 e.getFuture().setFailure(future.getCause());
             }
         }
     }
 
     private SpdySynStreamFrame createSynStreamFrame(HttpMessage httpMessage)
             throws Exception {
         boolean chunked = httpMessage.isChunked();
 
         // Get the Stream-ID, Associated-To-Stream-ID, Priority, URL, and scheme from the headers
         int streamID = SpdyHttpHeaders.getStreamId(httpMessage);
         int associatedToStreamID = SpdyHttpHeaders.getAssociatedToStreamId(httpMessage);
         byte priority = SpdyHttpHeaders.getPriority(httpMessage);
         String URL = SpdyHttpHeaders.getUrl(httpMessage);
         String scheme = SpdyHttpHeaders.getScheme(httpMessage);
         SpdyHttpHeaders.removeStreamId(httpMessage);
         SpdyHttpHeaders.removeAssociatedToStreamId(httpMessage);
         SpdyHttpHeaders.removePriority(httpMessage);
         SpdyHttpHeaders.removeUrl(httpMessage);
         SpdyHttpHeaders.removeScheme(httpMessage);
 
         // The Connection, Keep-Alive, Proxy-Connection, and Transfer-Encoding
         // headers are not valid and MUST not be sent.
         httpMessage.removeHeader(HttpHeaders.Names.CONNECTION);
         httpMessage.removeHeader("Keep-Alive");
         httpMessage.removeHeader("Proxy-Connection");
         httpMessage.removeHeader(HttpHeaders.Names.TRANSFER_ENCODING);
 
         SpdySynStreamFrame spdySynStreamFrame =
                 new DefaultSpdySynStreamFrame(streamID, associatedToStreamID, priority);
 
         // Unfold the first line of the message into name/value pairs
         if (httpMessage instanceof HttpRequest) {
             HttpRequest httpRequest = (HttpRequest) httpMessage;
             SpdyHeaders.setMethod(spdyVersion, spdySynStreamFrame, httpRequest.getMethod());
             SpdyHeaders.setUrl(spdyVersion, spdySynStreamFrame, httpRequest.getUri());
             SpdyHeaders.setVersion(spdyVersion, spdySynStreamFrame, httpMessage.getProtocolVersion());
         }
         if (httpMessage instanceof HttpResponse) {
             HttpResponse httpResponse = (HttpResponse) httpMessage;
             SpdyHeaders.setStatus(spdyVersion, spdySynStreamFrame, httpResponse.getStatus());
             SpdyHeaders.setUrl(spdyVersion, spdySynStreamFrame, URL);
             SpdyHeaders.setVersion(spdyVersion, spdySynStreamFrame, httpMessage.getProtocolVersion());
             spdySynStreamFrame.setUnidirectional(true);
         }
 
         // Replace the HTTP host header with the SPDY host header
         if (spdyVersion >= 3) {
             String host = HttpHeaders.getHost(httpMessage);
             httpMessage.removeHeader(HttpHeaders.Names.HOST);
             SpdyHeaders.setHost(spdySynStreamFrame, host);
         }
 
         // Set the SPDY scheme header
         if (scheme == null) {
             scheme = "https";
         }
         SpdyHeaders.setScheme(spdyVersion, spdySynStreamFrame, scheme);
 
         // Transfer the remaining HTTP headers
         for (Map.Entry<String, String> entry: httpMessage.getHeaders()) {
             spdySynStreamFrame.addHeader(entry.getKey(), entry.getValue());
         }
 
         if (chunked) {
             currentStreamID = streamID;
             spdySynStreamFrame.setLast(false);
         } else {
             spdySynStreamFrame.setLast(httpMessage.getContent().readableBytes() == 0);
         }
 
         return spdySynStreamFrame;
     }
 
     private SpdySynReplyFrame createSynReplyFrame(HttpResponse httpResponse)
             throws Exception {
         boolean chunked = httpResponse.isChunked();
 
         // Get the Stream-ID from the headers
         int streamID = SpdyHttpHeaders.getStreamId(httpResponse);
         SpdyHttpHeaders.removeStreamId(httpResponse);
 
         // The Connection, Keep-Alive, Proxy-Connection, and Transfer-ENcoding
         // headers are not valid and MUST not be sent.
         httpResponse.removeHeader(HttpHeaders.Names.CONNECTION);
         httpResponse.removeHeader("Keep-Alive");
         httpResponse.removeHeader("Proxy-Connection");
         httpResponse.removeHeader(HttpHeaders.Names.TRANSFER_ENCODING);
 
         SpdySynReplyFrame spdySynReplyFrame = new DefaultSpdySynReplyFrame(streamID);
 
         // Unfold the first line of the response into name/value pairs
         SpdyHeaders.setStatus(spdyVersion, spdySynReplyFrame, httpResponse.getStatus());
         SpdyHeaders.setVersion(spdyVersion, spdySynReplyFrame, httpResponse.getProtocolVersion());
 
         // Transfer the remaining HTTP headers
         for (Map.Entry<String, String> entry: httpResponse.getHeaders()) {
             spdySynReplyFrame.addHeader(entry.getKey(), entry.getValue());
         }
 
         if (chunked) {
             currentStreamID = streamID;
             spdySynReplyFrame.setLast(false);
         } else {
             spdySynReplyFrame.setLast(httpResponse.getContent().readableBytes() == 0);
         }
 
         return spdySynReplyFrame;
     }
 }