/*
 * JBoss, Home of Professional Open Source.
 * Copyright 2014 Red Hat, Inc., and individual contributors
 * as indicated by the @author tags.
 *
 * 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.netty.handler.ssl;

import java.io.ByteArrayOutputStream;

import javax.net.ssl.SSLEngine;

/**
 * Super hacky class that allows the client and server hello message to be modified and the corresponding hash generated
 * at runtime.
 *
 *
 * @author Stuart Douglas
 */
class ALPNHackClientByteArrayOutputStream extends ByteArrayOutputStream {

   private final SSLEngine sslEngine;
   private boolean ready = true;
   /**
    * the server hello that was sent over the wire, before we messed with it
    */
   private byte[] receivedServerHello;
   private byte[] sentClientHello;

   ALPNHackClientByteArrayOutputStream(SSLEngine sslEngine) {
      this.sslEngine = sslEngine;
   }

   @Override
   public void write(byte[] b, int off, int len) {
      if(ready) {
         if(b[off] == 2) { // server hello
            ready = false; //we are done processing
            byte[] newData;
            if(receivedServerHello != null) {
               int b1 = b[off + 1];
               int b2 = b[off + 2];
               int b3 = b[off + 3];
               int length = (b1 & 0xFF) << 16 | (b2 & 0xFF) << 8 | b3 & 0xFF;
               if(length + 4 == len) {
                  newData = receivedServerHello;
               } else {
                  newData = new byte[receivedServerHello.length + len - 4 - length];
                  System.arraycopy(receivedServerHello, 0, newData, 0, receivedServerHello.length);
                  System.arraycopy(b, length + 4, newData, receivedServerHello.length, len - 4 -length);
               }
            } else {
               newData = new byte[len];
               System.arraycopy(b, off, newData, 0, len);
            }
            ALPNHackSSLEngine.regenerateHashes(sslEngine, this, sentClientHello, newData);
            return;
         }
      }
      super.write(b, off, len);
   }

   byte[] getSentClientHello() {
      return sentClientHello;
   }

   void setSentClientHello(byte[] sentClientHello) {
      this.sentClientHello = sentClientHello;
   }

   byte[] getReceivedServerHello() {
      return receivedServerHello;
   }

   void setReceivedServerHello(byte[] receivedServerHello) {
      this.receivedServerHello = receivedServerHello;
   }
}
