package org.argeo.util;
   
   import java.io.IOException;
   import java.nio.ByteBuffer;
   import java.nio.channels.AsynchronousByteChannel;
   import java.nio.channels.CompletionHandler;
   import java.nio.channels.ReadableByteChannel;
   import java.nio.channels.WritableByteChannel;
   import java.util.concurrent.ExecutorService;
  import java.util.concurrent.Future;
  
  /** An {@link AsynchronousByteChannel} based on an {@link ExecutorService}. */
  public class ServiceChannel implements AsynchronousByteChannel {
  	private final ReadableByteChannel in;
  	private final WritableByteChannel out;
  
  	private boolean open = true;
  
  	private ExecutorService executor;
  
  	public ServiceChannel(ReadableByteChannel in, WritableByteChannel out, ExecutorService executor) {
  		this.in = in;
  		this.out = out;
  		this.executor = executor;
  	}
  
  	@Override
  	public Future<Integer> read(ByteBuffer dst) {
  		return executor.submit(() -> in.read(dst));
  	}
  
  	@Override
  	public <A> void read(ByteBuffer dst, A attachment, CompletionHandler<Integer, ? super A> handler) {
  		try {
  			Future<Integer> res = read(dst);
  			handler.completed(res.get(), attachment);
  		} catch (Exception e) {
  			handler.failed(e, attachment);
  		}
  	}
  
  	@Override
  	public Future<Integer> write(ByteBuffer src) {
  		return executor.submit(() -> out.write(src));
  	}
  
  	@Override
  	public <A> void write(ByteBuffer src, A attachment, CompletionHandler<Integer, ? super A> handler) {
  		try {
  			Future<Integer> res = write(src);
  			handler.completed(res.get(), attachment);
  		} catch (Exception e) {
  			handler.failed(e, attachment);
  		}
  	}
  
  	@Override
  	public synchronized void close() throws IOException {
  		try {
  			in.close();
  		} catch (Exception e) {
  			e.printStackTrace();
  		}
  		try {
  			out.close();
  		} catch (Exception e) {
  			e.printStackTrace();
  		}
  		open = false;
  		notifyAll();
  	}
  
  	@Override
  	public synchronized boolean isOpen() {
  		return open;
  	}
  
  }