/*
 * Copyright 2013 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.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandler;
import io.netty.channel.ChannelPipeline;
import io.netty.handler.codec.http.HttpHeaders;

import java.net.URI;
import java.util.List;

This handler does all the heavy lifting for you to run a websocket client. It takes care of websocket handshaking as well as processing of Ping, Pong frames. Text and Binary data frames are passed to the next handler in the pipeline (implemented by you) for processing. Also the close frame is passed to the next handler as you may want inspect it before close the connection if the handleCloseFrames is false, default is true. This implementation will establish the websocket connection once the connection to the remote server was complete. To know once a handshake was done you can intercept the ChannelInboundHandler.userEventTriggered(ChannelHandlerContext, Object) and check if the event was of type ClientHandshakeStateEvent.HANDSHAKE_ISSUED or ClientHandshakeStateEvent.HANDSHAKE_COMPLETE. /**
 * This handler does all the heavy lifting for you to run a websocket client.
 *
 * It takes care of websocket handshaking as well as processing of Ping, Pong frames. Text and Binary
 * data frames are passed to the next handler in the pipeline (implemented by you) for processing.
 * Also the close frame is passed to the next handler as you may want inspect it before close the connection if
 * the {@code handleCloseFrames} is {@code false}, default is {@code true}.
 *
 * This implementation will establish the websocket connection once the connection to the remote server was complete.
 *
 * To know once a handshake was done you can intercept the
 * {@link ChannelInboundHandler#userEventTriggered(ChannelHandlerContext, Object)} and check if the event was of type
 * {@link ClientHandshakeStateEvent#HANDSHAKE_ISSUED} or {@link ClientHandshakeStateEvent#HANDSHAKE_COMPLETE}.
 */
public class WebSocketClientProtocolHandler extends WebSocketProtocolHandler {

    private final WebSocketClientHandshaker handshaker;
    private final boolean handleCloseFrames;

    
Returns the used handshaker
/**
     * Returns the used handshaker
     */
    public WebSocketClientHandshaker handshaker() { return handshaker; }

    
Events that are fired to notify about handshake status
/**
     * Events that are fired to notify about handshake status
     */
    public enum ClientHandshakeStateEvent {
        
The Handshake was started but the server did not response yet to the request
/**
         * The Handshake was started but the server did not response yet to the request
         */
        HANDSHAKE_ISSUED,

        
The Handshake was complete succesful and so the channel was upgraded to websockets
/**
         * The Handshake was complete succesful and so the channel was upgraded to websockets
         */
        HANDSHAKE_COMPLETE
    }

    
Base constructor
Params:
webSocketURL – 
           URL for web socket communications. e.g "ws://myhost.com/mypath". Subsequent web socket frames will be
           sent to this URL.
version – 
           Version of web socket specification to use to connect to the server
subprotocol – 
           Sub protocol request sent to the server.
customHeaders – 
           Map of custom headers to add to the client request
maxFramePayloadLength – 
           Maximum length of a frame's payload
handleCloseFrames –  true if close frames should not be forwarded and just close the channel
performMasking – 
           Whether to mask all written websocket frames. This must be set to true in order to be fully compatible
           with the websocket specifications. Client applications that communicate with a non-standard server
           which doesn't require masking might set this to false to achieve a higher performance.
allowMaskMismatch – 
           When set to true, frames which are not masked properly according to the standard will still be
           accepted./**
     * Base constructor
     *
     * @param webSocketURL
     *            URL for web socket communications. e.g "ws://myhost.com/mypath". Subsequent web socket frames will be
     *            sent to this URL.
     * @param version
     *            Version of web socket specification to use to connect to the server
     * @param subprotocol
     *            Sub protocol request sent to the server.
     * @param customHeaders
     *            Map of custom headers to add to the client request
     * @param maxFramePayloadLength
     *            Maximum length of a frame's payload
     * @param handleCloseFrames
     *            {@code true} if close frames should not be forwarded and just close the channel
     * @param performMasking
     *            Whether to mask all written websocket frames. This must be set to true in order to be fully compatible
     *            with the websocket specifications. Client applications that communicate with a non-standard server
     *            which doesn't require masking might set this to false to achieve a higher performance.
     * @param allowMaskMismatch
     *            When set to true, frames which are not masked properly according to the standard will still be
     *            accepted.
     */
    public WebSocketClientProtocolHandler(URI webSocketURL, WebSocketVersion version, String subprotocol,
                                          boolean allowExtensions, HttpHeaders customHeaders,
                                          int maxFramePayloadLength, boolean handleCloseFrames,
                                          boolean performMasking, boolean allowMaskMismatch) {
        this(WebSocketClientHandshakerFactory.newHandshaker(webSocketURL, version, subprotocol,
                                                            allowExtensions, customHeaders, maxFramePayloadLength,
                                                            performMasking, allowMaskMismatch), handleCloseFrames);
    }

    
Base constructor
Params:
webSocketURL – 
           URL for web socket communications. e.g "ws://myhost.com/mypath". Subsequent web socket frames will be
           sent to this URL.
version – 
           Version of web socket specification to use to connect to the server
subprotocol – 
           Sub protocol request sent to the server.
customHeaders – 
           Map of custom headers to add to the client request
maxFramePayloadLength – 
           Maximum length of a frame's payload
handleCloseFrames –  true if close frames should not be forwarded and just close the channel/**
     * Base constructor
     *
     * @param webSocketURL
     *            URL for web socket communications. e.g "ws://myhost.com/mypath". Subsequent web socket frames will be
     *            sent to this URL.
     * @param version
     *            Version of web socket specification to use to connect to the server
     * @param subprotocol
     *            Sub protocol request sent to the server.
     * @param customHeaders
     *            Map of custom headers to add to the client request
     * @param maxFramePayloadLength
     *            Maximum length of a frame's payload
     * @param handleCloseFrames
     *            {@code true} if close frames should not be forwarded and just close the channel
     */
    public WebSocketClientProtocolHandler(URI webSocketURL, WebSocketVersion version, String subprotocol,
                                                   boolean allowExtensions, HttpHeaders customHeaders,
                                                   int maxFramePayloadLength, boolean handleCloseFrames) {
        this(webSocketURL, version, subprotocol, allowExtensions, customHeaders, maxFramePayloadLength,
             handleCloseFrames, true, false);
    }

    
Base constructor
Params:
webSocketURL – 
           URL for web socket communications. e.g "ws://myhost.com/mypath". Subsequent web socket frames will be
           sent to this URL.
version – 
           Version of web socket specification to use to connect to the server
subprotocol – 
           Sub protocol request sent to the server.
customHeaders – 
           Map of custom headers to add to the client request
maxFramePayloadLength – 
           Maximum length of a frame's payload/**
     * Base constructor
     *
     * @param webSocketURL
     *            URL for web socket communications. e.g "ws://myhost.com/mypath". Subsequent web socket frames will be
     *            sent to this URL.
     * @param version
     *            Version of web socket specification to use to connect to the server
     * @param subprotocol
     *            Sub protocol request sent to the server.
     * @param customHeaders
     *            Map of custom headers to add to the client request
     * @param maxFramePayloadLength
     *            Maximum length of a frame's payload
     */
    public WebSocketClientProtocolHandler(URI webSocketURL, WebSocketVersion version, String subprotocol,
                                          boolean allowExtensions, HttpHeaders customHeaders,
                                          int maxFramePayloadLength) {
        this(webSocketURL, version, subprotocol,
                allowExtensions, customHeaders, maxFramePayloadLength, true);
    }

    
Base constructor
Params:
handshaker –  The WebSocketClientHandshaker which will be used to issue the handshake once the connection was established to the remote peer.
handleCloseFrames –  true if close frames should not be forwarded and just close the channel/**
     * Base constructor
     *
     * @param handshaker
     *            The {@link WebSocketClientHandshaker} which will be used to issue the handshake once the connection
     *            was established to the remote peer.
     * @param handleCloseFrames
     *            {@code true} if close frames should not be forwarded and just close the channel
     */
    public WebSocketClientProtocolHandler(WebSocketClientHandshaker handshaker, boolean handleCloseFrames) {
        this.handshaker = handshaker;
        this.handleCloseFrames = handleCloseFrames;
    }

    
Base constructor
Params:
handshaker –  The WebSocketClientHandshaker which will be used to issue the handshake once the connection was established to the remote peer./**
     * Base constructor
     *
     * @param handshaker
     *            The {@link WebSocketClientHandshaker} which will be used to issue the handshake once the connection
     *            was established to the remote peer.
     */
    public WebSocketClientProtocolHandler(WebSocketClientHandshaker handshaker) {
        this(handshaker, true);
    }

    @Override
    protected void decode(ChannelHandlerContext ctx, WebSocketFrame frame, List<Object> out) throws Exception {
        if (handleCloseFrames && frame instanceof CloseWebSocketFrame) {
            ctx.close();
            return;
        }
        super.decode(ctx, frame, out);
    }

    @Override
    public void handlerAdded(ChannelHandlerContext ctx) {
        ChannelPipeline cp = ctx.pipeline();
        if (cp.get(WebSocketClientProtocolHandshakeHandler.class) == null) {
            // Add the WebSocketClientProtocolHandshakeHandler before this one.
            ctx.pipeline().addBefore(ctx.name(), WebSocketClientProtocolHandshakeHandler.class.getName(),
                    new WebSocketClientProtocolHandshakeHandler(handshaker));
        }
        if (cp.get(Utf8FrameValidator.class) == null) {
            // Add the UFT8 checking before this one.
            ctx.pipeline().addBefore(ctx.name(), Utf8FrameValidator.class.getName(),
                    new Utf8FrameValidator());
        }
    }
}