package emissary.core.channels;
   
   import org.apache.commons.compress.utils.SeekableInMemoryByteChannel;
   import org.apache.commons.lang3.Validate;
   
   import java.nio.channels.SeekableByteChannel;
   
   /**
    * Provide an in-memory backed implementation for streaming data to a consumer
   */
  public final class InMemoryChannelFactory {
      private InMemoryChannelFactory() {}
  
      /**
       * Create a new instance of the factory using the provided byte array
       * 
       * @param bytes containing the data to provide to consumers in an immutable manner
       * @return a new instance
       */
      public static SeekableByteChannelFactory create(final byte[] bytes) {
          return ImmutableChannelFactory.create(new InMemoryChannelFactoryImpl(bytes));
      }
  
      /**
       * Private class to hide implementation details from callers
       */
      private static final class InMemoryChannelFactoryImpl implements SeekableByteChannelFactory {
          /**
           * The byte array this SeekableByteChannel is to represent.
           */
          private final byte[] bytes;
  
          private InMemoryChannelFactoryImpl(final byte[] bytes) {
              Validate.notNull(bytes, "Required: bytes not null");
  
              this.bytes = bytes;
          }
  
          /**
           * Create an immutable byte channel to the existing byte array (no copy in/out regardless of how many channels are
           * created)
           * 
           * @return the new channel instance
           */
          @Override
          public SeekableByteChannel create() {
              return new SeekableInMemoryByteChannel(bytes);
          }
      }
  }