/*
    * 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.channel.Channel;
  import io.netty.channel.ChannelFuture;
  import io.netty.channel.ChannelFutureListener;
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.channel.ChannelPipeline;
  import io.netty.channel.ChannelPromise;
  import io.netty.channel.SimpleChannelInboundHandler;
  import io.netty.handler.codec.http.FullHttpRequest;
  import io.netty.handler.codec.http.FullHttpResponse;
  import io.netty.handler.codec.http.HttpClientCodec;
  import io.netty.handler.codec.http.HttpContentDecompressor;
  import io.netty.handler.codec.http.HttpHeaders;
  import io.netty.handler.codec.http.HttpObjectAggregator;
  import io.netty.handler.codec.http.HttpRequestEncoder;
  import io.netty.handler.codec.http.HttpResponse;
  import io.netty.handler.codec.http.HttpResponseDecoder;
  import io.netty.util.NetUtil;
  import io.netty.util.ReferenceCountUtil;
  import io.netty.util.internal.ThrowableUtil;
  
  import java.net.URI;
  import java.nio.channels.ClosedChannelException;
  import java.util.Locale;
  
  /**
   * Base class for web socket client handshake implementations
   */
  public abstract class WebSocketClientHandshaker {
      private static final ClosedChannelException CLOSED_CHANNEL_EXCEPTION = ThrowableUtil.unknownStackTrace(
              new ClosedChannelException(), WebSocketClientHandshaker.class, "processHandshake(...)");
  
      private static final String HTTP_SCHEME_PREFIX = "http://";
      private static final String HTTPS_SCHEME_PREFIX = "https://";
  
      private final URI uri;
  
      private final WebSocketVersion version;
  
      private volatile boolean handshakeComplete;
  
      private final String expectedSubprotocol;
  
      private volatile String actualSubprotocol;
  
      protected final HttpHeaders customHeaders;
  
      private final int maxFramePayloadLength;
  
      /**
       * Base constructor
       *
       * @param uri
       *            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
       */
      protected WebSocketClientHandshaker(URI uri, WebSocketVersion version, String subprotocol,
                                          HttpHeaders customHeaders, int maxFramePayloadLength) {
          this.uri = uri;
          this.version = version;
          expectedSubprotocol = subprotocol;
          this.customHeaders = customHeaders;
          this.maxFramePayloadLength = maxFramePayloadLength;
      }
  
      /**
       * Returns the URI to the web socket. e.g. "ws://myhost.com/path"
       */
      public URI uri() {
          return uri;
      }
  
      /**
       * Version of the web socket specification that is being used
       */
     public WebSocketVersion version() {
         return version;
     }
 
     /**
      * Returns the max length for any frame's payload
      */
     public int maxFramePayloadLength() {
         return maxFramePayloadLength;
     }
 
     /**
      * Flag to indicate if the opening handshake is complete
      */
     public boolean isHandshakeComplete() {
         return handshakeComplete;
     }
 
     private void setHandshakeComplete() {
         handshakeComplete = true;
     }
 
     /**
      * Returns the CSV of requested subprotocol(s) sent to the server as specified in the constructor
      */
     public String expectedSubprotocol() {
         return expectedSubprotocol;
     }
 
     /**
      * Returns the subprotocol response sent by the server. Only available after end of handshake.
      * Null if no subprotocol was requested or confirmed by the server.
      */
     public String actualSubprotocol() {
         return actualSubprotocol;
     }
 
     private void setActualSubprotocol(String actualSubprotocol) {
         this.actualSubprotocol = actualSubprotocol;
     }
 
     /**
      * Begins the opening handshake
      *
      * @param channel
      *            Channel
      */
     public ChannelFuture handshake(Channel channel) {
         if (channel == null) {
             throw new NullPointerException("channel");
         }
         return handshake(channel, channel.newPromise());
     }
 
     /**
      * Begins the opening handshake
      *
      * @param channel
      *            Channel
      * @param promise
      *            the {@link ChannelPromise} to be notified when the opening handshake is sent
      */
     public final ChannelFuture handshake(Channel channel, final ChannelPromise promise) {
         FullHttpRequest request =  newHandshakeRequest();
 
         HttpResponseDecoder decoder = channel.pipeline().get(HttpResponseDecoder.class);
         if (decoder == null) {
             HttpClientCodec codec = channel.pipeline().get(HttpClientCodec.class);
             if (codec == null) {
                promise.setFailure(new IllegalStateException("ChannelPipeline does not contain " +
                        "a HttpResponseDecoder or HttpClientCodec"));
                return promise;
             }
         }
 
         channel.writeAndFlush(request).addListener(new ChannelFutureListener() {
             @Override
             public void operationComplete(ChannelFuture future) {
                 if (future.isSuccess()) {
                     ChannelPipeline p = future.channel().pipeline();
                     ChannelHandlerContext ctx = p.context(HttpRequestEncoder.class);
                     if (ctx == null) {
                         ctx = p.context(HttpClientCodec.class);
                     }
                     if (ctx == null) {
                         promise.setFailure(new IllegalStateException("ChannelPipeline does not contain " +
                                 "a HttpRequestEncoder or HttpClientCodec"));
                         return;
                     }
                     p.addAfter(ctx.name(), "ws-encoder", newWebSocketEncoder());
 
                     promise.setSuccess();
                 } else {
                     promise.setFailure(future.cause());
                 }
             }
         });
         return promise;
     }
 
     /**
      * Returns a new {@link FullHttpRequest) which will be used for the handshake.
      */
     protected abstract FullHttpRequest newHandshakeRequest();
 
     /**
      * Validates and finishes the opening handshake initiated by {@link #handshake}}.
      *
      * @param channel
      *            Channel
      * @param response
      *            HTTP response containing the closing handshake details
      */
     public final void finishHandshake(Channel channel, FullHttpResponse response) {
         verify(response);
 
         // Verify the subprotocol that we received from the server.
         // This must be one of our expected subprotocols - or null/empty if we didn't want to speak a subprotocol
         String receivedProtocol = response.headers().get(HttpHeaders.Names.SEC_WEBSOCKET_PROTOCOL);
         receivedProtocol = receivedProtocol != null ? receivedProtocol.trim() : null;
         String expectedProtocol = expectedSubprotocol != null ? expectedSubprotocol : "";
         boolean protocolValid = false;
 
         if (expectedProtocol.isEmpty() && receivedProtocol == null) {
             // No subprotocol required and none received
             protocolValid = true;
             setActualSubprotocol(expectedSubprotocol); // null or "" - we echo what the user requested
         } else if (!expectedProtocol.isEmpty() && receivedProtocol != null && !receivedProtocol.isEmpty()) {
             // We require a subprotocol and received one -> verify it
             for (String protocol : expectedProtocol.split(",")) {
                 if (protocol.trim().equals(receivedProtocol)) {
                     protocolValid = true;
                     setActualSubprotocol(receivedProtocol);
                     break;
                 }
             }
         } // else mixed cases - which are all errors
 
         if (!protocolValid) {
             throw new WebSocketHandshakeException(String.format(
                     "Invalid subprotocol. Actual: %s. Expected one of: %s",
                     receivedProtocol, expectedSubprotocol));
         }
 
         setHandshakeComplete();
 
         final ChannelPipeline p = channel.pipeline();
         // Remove decompressor from pipeline if its in use
         HttpContentDecompressor decompressor = p.get(HttpContentDecompressor.class);
         if (decompressor != null) {
             p.remove(decompressor);
         }
 
         // Remove aggregator if present before
         HttpObjectAggregator aggregator = p.get(HttpObjectAggregator.class);
         if (aggregator != null) {
             p.remove(aggregator);
         }
 
         ChannelHandlerContext ctx = p.context(HttpResponseDecoder.class);
         if (ctx == null) {
             ctx = p.context(HttpClientCodec.class);
             if (ctx == null) {
                 throw new IllegalStateException("ChannelPipeline does not contain " +
                         "a HttpRequestEncoder or HttpClientCodec");
             }
             final HttpClientCodec codec =  (HttpClientCodec) ctx.handler();
             // Remove the encoder part of the codec as the user may start writing frames after this method returns.
             codec.removeOutboundHandler();
 
             p.addAfter(ctx.name(), "ws-decoder", newWebsocketDecoder());
 
             // Delay the removal of the decoder so the user can setup the pipeline if needed to handle
             // WebSocketFrame messages.
             // See https://github.com/netty/netty/issues/4533
             channel.eventLoop().execute(new Runnable() {
                 @Override
                 public void run() {
                     p.remove(codec);
                 }
             });
         } else {
             if (p.get(HttpRequestEncoder.class) != null) {
                 // Remove the encoder part of the codec as the user may start writing frames after this method returns.
                 p.remove(HttpRequestEncoder.class);
             }
             final ChannelHandlerContext context = ctx;
             p.addAfter(context.name(), "ws-decoder", newWebsocketDecoder());
 
             // Delay the removal of the decoder so the user can setup the pipeline if needed to handle
             // WebSocketFrame messages.
             // See https://github.com/netty/netty/issues/4533
             channel.eventLoop().execute(new Runnable() {
                 @Override
                 public void run() {
                     p.remove(context.handler());
                 }
             });
         }
     }
 
     /**
      * Process the opening handshake initiated by {@link #handshake}}.
      *
      * @param channel
      *            Channel
      * @param response
      *            HTTP response containing the closing handshake details
      * @return future
      *            the {@link ChannelFuture} which is notified once the handshake completes.
      */
     public final ChannelFuture processHandshake(final Channel channel, HttpResponse response) {
         return processHandshake(channel, response, channel.newPromise());
     }
 
     /**
      * Process the opening handshake initiated by {@link #handshake}}.
      *
      * @param channel
      *            Channel
      * @param response
      *            HTTP response containing the closing handshake details
      * @param promise
      *            the {@link ChannelPromise} to notify once the handshake completes.
      * @return future
      *            the {@link ChannelFuture} which is notified once the handshake completes.
      */
     public final ChannelFuture processHandshake(final Channel channel, HttpResponse response,
                                                 final ChannelPromise promise) {
         if (response instanceof FullHttpResponse) {
             try {
                 finishHandshake(channel, (FullHttpResponse) response);
                 promise.setSuccess();
             } catch (Throwable cause) {
                 promise.setFailure(cause);
             }
         } else {
             ChannelPipeline p = channel.pipeline();
             ChannelHandlerContext ctx = p.context(HttpResponseDecoder.class);
             if (ctx == null) {
                 ctx = p.context(HttpClientCodec.class);
                 if (ctx == null) {
                     return promise.setFailure(new IllegalStateException("ChannelPipeline does not contain " +
                             "a HttpResponseDecoder or HttpClientCodec"));
                 }
             }
             // Add aggregator and ensure we feed the HttpResponse so it is aggregated. A limit of 8192 should be more
             // then enough for the websockets handshake payload.
             //
             // TODO: Make handshake work without HttpObjectAggregator at all.
             String aggregatorName = "httpAggregator";
             p.addAfter(ctx.name(), aggregatorName, new HttpObjectAggregator(8192));
             p.addAfter(aggregatorName, "handshaker", new SimpleChannelInboundHandler<FullHttpResponse>() {
                 @Override
                 protected void channelRead0(ChannelHandlerContext ctx, FullHttpResponse msg) throws Exception {
                     // Remove ourself and do the actual handshake
                     ctx.pipeline().remove(this);
                     try {
                         finishHandshake(channel, msg);
                         promise.setSuccess();
                     } catch (Throwable cause) {
                         promise.setFailure(cause);
                     }
                 }
 
                 @Override
                 public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
                     // Remove ourself and fail the handshake promise.
                     ctx.pipeline().remove(this);
                     promise.setFailure(cause);
                 }
 
                 @Override
                 public void channelInactive(ChannelHandlerContext ctx) throws Exception {
                     // Fail promise if Channel was closed
                     promise.tryFailure(CLOSED_CHANNEL_EXCEPTION);
                     ctx.fireChannelInactive();
                 }
             });
             try {
                 ctx.fireChannelRead(ReferenceCountUtil.retain(response));
             } catch (Throwable cause) {
                 promise.setFailure(cause);
             }
         }
         return promise;
     }
 
     /**
      * Verify the {@link FullHttpResponse} and throws a {@link WebSocketHandshakeException} if something is wrong.
      */
     protected abstract void verify(FullHttpResponse response);
 
     /**
      * Returns the decoder to use after handshake is complete.
      */
     protected abstract WebSocketFrameDecoder newWebsocketDecoder();
 
     /**
      * Returns the encoder to use after the handshake is complete.
      */
     protected abstract WebSocketFrameEncoder newWebSocketEncoder();
 
     /**
      * Performs the closing handshake
      *
      * @param channel
      *            Channel
      * @param frame
      *            Closing Frame that was received
      */
     public ChannelFuture close(Channel channel, CloseWebSocketFrame frame) {
         if (channel == null) {
             throw new NullPointerException("channel");
         }
         return close(channel, frame, channel.newPromise());
     }
 
     /**
      * Performs the closing handshake
      *
      * @param channel
      *            Channel
      * @param frame
      *            Closing Frame that was received
      * @param promise
      *            the {@link ChannelPromise} to be notified when the closing handshake is done
      */
     public ChannelFuture close(Channel channel, CloseWebSocketFrame frame, ChannelPromise promise) {
         if (channel == null) {
             throw new NullPointerException("channel");
         }
         return channel.writeAndFlush(frame, promise);
     }
 
     /**
      * Return the constructed raw path for the give {@link URI}.
      */
     static String rawPath(URI wsURL) {
         String path = wsURL.getRawPath();
         String query = wsURL.getRawQuery();
         if (query != null && !query.isEmpty()) {
             path = path + '?' + query;
         }
 
         return path == null || path.isEmpty() ? "/" : path;
     }
 
     static CharSequence websocketHostValue(URI wsURL) {
         int port = wsURL.getPort();
         if (port == -1) {
             return wsURL.getHost();
         }
         String host = wsURL.getHost();
         if (port == 80) {
             return "http".equals(wsURL.getScheme())
                     || "ws".equals(wsURL.getScheme()) ?
                     host : NetUtil.toSocketAddressString(host, 80);
         }
         if (port == 443) {
             return "https".equals(wsURL.getScheme())
                     || "wss".equals(wsURL.getScheme()) ?
                     host : NetUtil.toSocketAddressString(host, 443);
         }
 
         // if the port is not standard (80/443) its needed to add the port to the header.
         // See http://tools.ietf.org/html/rfc6454#section-6.2
         return NetUtil.toSocketAddressString(host, port);
     }
 
     static CharSequence websocketOriginValue(URI wsURL) {
         String scheme = wsURL.getScheme();
         final String schemePrefix;
         int port = wsURL.getPort();
         final int defaultPort;
         if ("wss".equals(scheme)
             || "https".equals(scheme)
             || (scheme == null && port == 443)) {
 
             schemePrefix = HTTPS_SCHEME_PREFIX;
             defaultPort = 443;
         } else {
             schemePrefix = HTTP_SCHEME_PREFIX;
             defaultPort = 80;
         }
 
         // Convert uri-host to lower case (by RFC 6454, chapter 4 "Origin of a URI")
         String host = wsURL.getHost().toLowerCase(Locale.US);
 
         if (port != defaultPort && port != -1) {
             // if the port is not standard (80/443) its needed to add the port to the header.
             // See http://tools.ietf.org/html/rfc6454#section-6.2
             return schemePrefix + NetUtil.toSocketAddressString(host, port);
         }
         return schemePrefix + host;
     }
 }