/*
* Copyright 2015 Netflix, Inc.
*
* Licensed 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 io.reactivex.netty.protocol.http.sse.server;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelOutboundHandlerAdapter;
import io.netty.channel.ChannelPromise;
import io.netty.handler.codec.http.HttpResponse;
import io.netty.util.ByteProcessor;
import io.reactivex.netty.protocol.http.sse.ServerSentEvent;
import static io.netty.handler.codec.http.HttpHeaderNames.*;
/**
* An encoder to handle {@link io.reactivex.netty.protocol.http.sse.ServerSentEvent} encoding for an HTTP server.
*
* This encoder will encode any {@link io.reactivex.netty.protocol.http.sse.ServerSentEvent} to {@link ByteBuf} and also set the appropriate HTTP Response
* headers required for <a href="http://www.w3.org/TR/eventsource/">SSE</a>
*/
@ChannelHandler.Sharable
public class ServerSentEventEncoder extends ChannelOutboundHandlerAdapter {
private static final byte[] EVENT_PREFIX_BYTES = "event: ".getBytes();
private static final byte[] NEW_LINE_AS_BYTES = "\n".getBytes();
private static final byte[] ID_PREFIX_AS_BYTES = "id: ".getBytes();
private static final byte[] DATA_PREFIX_AS_BYTES = "data: ".getBytes();
private final boolean splitSseData;
public ServerSentEventEncoder() {
this(false);
}
/**
* Splits the SSE data on new line and create multiple "data" events if {@code splitSseData} is {@code true}
*
* @param splitSseData {@code true} if the SSE data is to be splitted on new line to create multiple "data" events.
*/
public ServerSentEventEncoder(boolean splitSseData) {
this.splitSseData = splitSseData;
}
@Override
public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) throws Exception {
Object msgToWriteFurther = msg;
if (msg instanceof HttpResponse) {
HttpResponse response = (HttpResponse) msg;
/*Set the content-type for SSE*/
response.headers().set(CONTENT_TYPE, "text/event-stream");
} else if (msg instanceof ServerSentEvent) {
final ServerSentEvent serverSentEvent = (ServerSentEvent) msg;
final ByteBuf out = ctx.alloc().buffer();
msgToWriteFurther = out;
if (serverSentEvent.hasEventType()) { // Write event type, if available
out.writeBytes(EVENT_PREFIX_BYTES);
out.writeBytes(serverSentEvent.getEventType());
out.writeBytes(NEW_LINE_AS_BYTES);
}
if (serverSentEvent.hasEventId()) { // Write event id, if available
out.writeBytes(ID_PREFIX_AS_BYTES);
out.writeBytes(serverSentEvent.getEventId());
out.writeBytes(NEW_LINE_AS_BYTES);
}
final ByteBuf content;
if (serverSentEvent.hasDataAsString()) {
/*Allocate ByteBuf only in the eventloop*/
content = ctx.alloc().buffer().writeBytes(serverSentEvent.contentAsString().getBytes());
} else {
content = serverSentEvent.content();
}
if (splitSseData) {
while (content.isReadable()) { // Scan the buffer and split on new line into multiple data lines.
final int readerIndexAtStart = content.readerIndex();
int newLineIndex = content.forEachByte(new ByteProcessor() {
@Override
public boolean process(byte value) throws Exception {
return (char) value != '\n';
}
});
if (-1 == newLineIndex) { // No new line, write the buffer as is.
out.writeBytes(DATA_PREFIX_AS_BYTES);
out.writeBytes(content);
out.writeBytes(NEW_LINE_AS_BYTES);
} else { // Write the buffer till the new line and then iterate this loop
out.writeBytes(DATA_PREFIX_AS_BYTES);
out.writeBytes(content, newLineIndex - readerIndexAtStart);
content.readerIndex(content.readerIndex() + 1);
out.writeBytes(NEW_LINE_AS_BYTES);
}
}
} else { // write the buffer with data prefix and new line post fix.
out.writeBytes(DATA_PREFIX_AS_BYTES);
out.writeBytes(content);
out.writeBytes(NEW_LINE_AS_BYTES);
}
}
ctx.write(msgToWriteFurther, promise);
}
}