content: /*
   * Copyright (C) 2014 Glyptodon LLC
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this software and associated documentation files (the "Software"), to deal
   * in the Software without restriction, including without limitation the rights
   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   * copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
   * THE SOFTWARE.
   */
  
  package org.glyptodon.guacamole.protocol;
  
  import org.glyptodon.guacamole.GuacamoleException;
  import org.glyptodon.guacamole.GuacamoleServerException;
  import org.glyptodon.guacamole.io.GuacamoleWriter;
  
  /**
   * GuacamoleWriter which applies a given GuacamoleFilter to observe or alter
   * all written instructions. Instructions may also be dropped or denied by
   * the filter.
   *
   * @author Michael Jumper
   */
  public class FilteredGuacamoleWriter implements GuacamoleWriter {
  
      /**
       * The wrapped GuacamoleWriter.
       */
      private final GuacamoleWriter writer;
  
      /**
       * The filter to apply when writing instructions.
       */
      private final GuacamoleFilter filter;
  
      /**
       * Parser for reading instructions prior to writing, such that they can be
       * passed on to the filter.
       */
      private final GuacamoleParser parser = new GuacamoleParser();
      
      /**
       * Wraps the given GuacamoleWriter, applying the given filter to all written 
       * instructions. Future writes will only write instructions which pass
       * the filter.
       *
       * @param writer The GuacamoleWriter to wrap.
       * @param filter The filter which dictates which instructions are written,
       *               and how.
       */
      public FilteredGuacamoleWriter(GuacamoleWriter writer, GuacamoleFilter filter) {
          this.writer = writer;
          this.filter = filter;
      }
   
      @Override
      public void write(char[] chunk, int offset, int length) throws GuacamoleException {
  
          // Write all data in chunk
          while (length > 0) {
  
              // Pass as much data through the parser as possible
              int parsed;
              while ((parsed = parser.append(chunk, offset, length)) != 0) {
                  offset += parsed;
                  length -= parsed;
              }
  
              // If no instruction is available, it must be incomplete
              if (!parser.hasNext())
                  throw new GuacamoleServerException("Filtered write() contained an incomplete instruction.");
  
              // Write single instruction through filter
              writeInstruction(parser.next());
  
          }
          
      }
  
      @Override
      public void write(char[] chunk) throws GuacamoleException {
          write(chunk, 0, chunk.length);
      }
  
      @Override
      public void writeInstruction(GuacamoleInstruction instruction) throws GuacamoleException {
  
          // Write instruction only if not dropped
          GuacamoleInstruction filteredInstruction = filter.filter(instruction);
          if (filteredInstruction != null)
              writer.writeInstruction(filteredInstruction);
  
      }
  
  }
  