/*
 * 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 io.netty.handler.codec.http.websocketx;

import io.netty.buffer.Unpooled;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandler;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.channel.ChannelPipeline;
import io.netty.handler.codec.http.DefaultFullHttpResponse;
import io.netty.handler.codec.http.FullHttpRequest;
import io.netty.handler.codec.http.FullHttpResponse;
import io.netty.handler.codec.http.HttpHeaders;
import io.netty.handler.codec.http.HttpResponseStatus;
import io.netty.util.AttributeKey;

import java.util.List;

import static io.netty.handler.codec.http.HttpVersion.*;

This handler does all the heavy lifting for you to run a websocket server.
It takes care of websocket handshaking as well as processing of control frames (Close, Ping, Pong). Text and Binary
data frames are passed to the next handler in the pipeline (implemented by you) for processing.
See io.netty.example.http.websocketx.html5.WebSocketServer for usage.
The implementation of this handler assumes that you just want to run  a websocket server and not process other types
HTTP requests (like GET and POST). If you wish to support both HTTP requests and websockets in the one server, refer
to the io.netty.example.http.websocketx.server.WebSocketServer example. To know once a handshake was done you can intercept the ChannelInboundHandler.userEventTriggered(ChannelHandlerContext, Object) and check if the event was instance of HandshakeComplete, the event will contain extra information about the handshake such as the request and selected subprotocol. /**
 * This handler does all the heavy lifting for you to run a websocket server.
 *
 * It takes care of websocket handshaking as well as processing of control frames (Close, Ping, Pong). Text and Binary
 * data frames are passed to the next handler in the pipeline (implemented by you) for processing.
 *
 * See <tt>io.netty.example.http.websocketx.html5.WebSocketServer</tt> for usage.
 *
 * The implementation of this handler assumes that you just want to run  a websocket server and not process other types
 * HTTP requests (like GET and POST). If you wish to support both HTTP requests and websockets in the one server, refer
 * to the <tt>io.netty.example.http.websocketx.server.WebSocketServer</tt> example.
 *
 * To know once a handshake was done you can intercept the
 * {@link ChannelInboundHandler#userEventTriggered(ChannelHandlerContext, Object)} and check if the event was instance
 * of {@link HandshakeComplete}, the event will contain extra information about the handshake such as the request and
 * selected subprotocol.
 */
public class WebSocketServerProtocolHandler extends WebSocketProtocolHandler {

    
Events that are fired to notify about handshake status
/**
     * Events that are fired to notify about handshake status
     */
    public enum ServerHandshakeStateEvent {
        
The Handshake was completed successfully and the channel was upgraded to websockets.
Deprecated:
in favor of HandshakeComplete class, it provides extra information about the handshake/**
         * The Handshake was completed successfully and the channel was upgraded to websockets.
         *
         * @deprecated in favor of {@link HandshakeComplete} class,
         * it provides extra information about the handshake
         */
        @Deprecated
        HANDSHAKE_COMPLETE
    }

    
The Handshake was completed successfully and the channel was upgraded to websockets.
/**
     * The Handshake was completed successfully and the channel was upgraded to websockets.
     */
    public static final class HandshakeComplete {
        private final String requestUri;
        private final HttpHeaders requestHeaders;
        private final String selectedSubprotocol;

        HandshakeComplete(String requestUri, HttpHeaders requestHeaders, String selectedSubprotocol) {
            this.requestUri = requestUri;
            this.requestHeaders = requestHeaders;
            this.selectedSubprotocol = selectedSubprotocol;
        }

        public String requestUri() {
            return requestUri;
        }

        public HttpHeaders requestHeaders() {
            return requestHeaders;
        }

        public String selectedSubprotocol() {
            return selectedSubprotocol;
        }
    }

    private static final AttributeKey<WebSocketServerHandshaker> HANDSHAKER_ATTR_KEY =
            AttributeKey.valueOf(WebSocketServerHandshaker.class, "HANDSHAKER");

    private final String websocketPath;
    private final String subprotocols;
    private final boolean allowExtensions;
    private final int maxFramePayloadLength;
    private final boolean allowMaskMismatch;
    private final boolean checkStartsWith;

    public WebSocketServerProtocolHandler(String websocketPath) {
        this(websocketPath, null, false);
    }

    public WebSocketServerProtocolHandler(String websocketPath, boolean checkStartsWith) {
        this(websocketPath, null, false, 65536, false, checkStartsWith);
    }

    public WebSocketServerProtocolHandler(String websocketPath, String subprotocols) {
        this(websocketPath, subprotocols, false);
    }

    public WebSocketServerProtocolHandler(String websocketPath, String subprotocols, boolean allowExtensions) {
        this(websocketPath, subprotocols, allowExtensions, 65536);
    }

    public WebSocketServerProtocolHandler(String websocketPath, String subprotocols,
                                          boolean allowExtensions, int maxFrameSize) {
        this(websocketPath, subprotocols, allowExtensions, maxFrameSize, false);
    }

    public WebSocketServerProtocolHandler(String websocketPath, String subprotocols,
            boolean allowExtensions, int maxFrameSize, boolean allowMaskMismatch) {
        this(websocketPath, subprotocols, allowExtensions, maxFrameSize, allowMaskMismatch, false);
    }

    public WebSocketServerProtocolHandler(String websocketPath, String subprotocols,
            boolean allowExtensions, int maxFrameSize, boolean allowMaskMismatch, boolean checkStartsWith) {
        this.websocketPath = websocketPath;
        this.subprotocols = subprotocols;
        this.allowExtensions = allowExtensions;
        maxFramePayloadLength = maxFrameSize;
        this.allowMaskMismatch = allowMaskMismatch;
        this.checkStartsWith = checkStartsWith;
    }

    @Override
    public void handlerAdded(ChannelHandlerContext ctx) {
        ChannelPipeline cp = ctx.pipeline();
        if (cp.get(WebSocketServerProtocolHandshakeHandler.class) == null) {
            // Add the WebSocketHandshakeHandler before this one.
            ctx.pipeline().addBefore(ctx.name(), WebSocketServerProtocolHandshakeHandler.class.getName(),
                    new WebSocketServerProtocolHandshakeHandler(websocketPath, subprotocols,
                            allowExtensions, maxFramePayloadLength, allowMaskMismatch, checkStartsWith));
        }
        if (cp.get(Utf8FrameValidator.class) == null) {
            // Add the UFT8 checking before this one.
            ctx.pipeline().addBefore(ctx.name(), Utf8FrameValidator.class.getName(),
                    new Utf8FrameValidator());
        }
    }

    @Override
    protected void decode(ChannelHandlerContext ctx, WebSocketFrame frame, List<Object> out) throws Exception {
        if (frame instanceof CloseWebSocketFrame) {
            WebSocketServerHandshaker handshaker = getHandshaker(ctx.channel());
            if (handshaker != null) {
                frame.retain();
                handshaker.close(ctx.channel(), (CloseWebSocketFrame) frame);
            } else {
                ctx.writeAndFlush(Unpooled.EMPTY_BUFFER).addListener(ChannelFutureListener.CLOSE);
            }
            return;
        }
        super.decode(ctx, frame, out);
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        if (cause instanceof WebSocketHandshakeException) {
            FullHttpResponse response = new DefaultFullHttpResponse(
                    HTTP_1_1, HttpResponseStatus.BAD_REQUEST, Unpooled.wrappedBuffer(cause.getMessage().getBytes()));
            ctx.channel().writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
        } else {
            ctx.fireExceptionCaught(cause);
            ctx.close();
        }
    }

    static WebSocketServerHandshaker getHandshaker(Channel channel) {
        return channel.attr(HANDSHAKER_ATTR_KEY).get();
    }

    static void setHandshaker(Channel channel, WebSocketServerHandshaker handshaker) {
        channel.attr(HANDSHAKER_ATTR_KEY).set(handshaker);
    }

    static ChannelHandler forbiddenHttpRequestResponder() {
        return new ChannelInboundHandlerAdapter() {
            @Override
            public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
                if (msg instanceof FullHttpRequest) {
                    ((FullHttpRequest) msg).release();
                    FullHttpResponse response =
                            new DefaultFullHttpResponse(HTTP_1_1, HttpResponseStatus.FORBIDDEN);
                    ctx.channel().writeAndFlush(response);
                } else {
                    ctx.fireChannelRead(msg);
                }
            }
        };
    }
}