/* Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF 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 org.apache.harmony.nio.internal;

import java.io.Closeable;
import java.io.FileDescriptor;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.Pipe;
import java.nio.channels.spi.SelectorProvider;
import libcore.io.IoUtils;
import org.apache.harmony.luni.platform.FileDescriptorHandler;

/*
 * Implements {@link java.nio.channels.Pipe}.
 */
final class PipeImpl extends Pipe {
	private final PipeSinkChannel sink;
	private final PipeSourceChannel source;

	public PipeImpl() throws IOException {
		int[] fds = new int[2];
		IoUtils.pipe(fds);
		// Which fd is used for which channel is important. Unix pipes are only
		// guaranteed to be
		// unidirectional, and indeed are only unidirectional on Linux. See
		// IoUtils.pipe.
		this.sink = new PipeSinkChannel(fds[1]);
		this.source = new PipeSourceChannel(fds[0]);
	}

	@Override
	public SinkChannel sink() {
		return sink;
	}

	@Override
	public SourceChannel source() {
		return source;
	}

	/**
	 * FileChannelImpl doesn't close its fd itself; it calls close on the object
	 * it's given.
	 */
	private static class FdCloser implements Closeable {
		private final FileDescriptor fd;

		private FdCloser(FileDescriptor fd) {
			this.fd = fd;
		}

		public void close() throws IOException {
			IoUtils.close(fd);
		}
	}

	private class PipeSourceChannel extends Pipe.SourceChannel implements
			FileDescriptorHandler {
		private final FileDescriptor fd;
		private final FileChannelImpl channel;

		private PipeSourceChannel(int fd) throws IOException {
			super(SelectorProvider.provider());
			this.fd = IoUtils.newFileDescriptor(fd);
			this.channel = new ReadOnlyFileChannel(new FdCloser(this.fd), fd);
		}

		@Override
		protected void implCloseSelectableChannel() throws IOException {
			channel.close();
		}

		@Override
		protected void implConfigureBlocking(boolean blocking)
				throws IOException {
			IoUtils.setBlocking(getFD(), blocking);
		}

		public int read(ByteBuffer buffer) throws IOException {
			return channel.read(buffer);
		}

		public long read(ByteBuffer[] buffers) throws IOException {
			return channel.read(buffers);
		}

		public long read(ByteBuffer[] buffers, int offset, int length)
				throws IOException {
			return channel.read(buffers, offset, length);
		}

		public FileDescriptor getFD() {
			return fd;
		}
	}

	private class PipeSinkChannel extends Pipe.SinkChannel implements
			FileDescriptorHandler {
		private final FileDescriptor fd;
		private final FileChannelImpl channel;

		private PipeSinkChannel(int fd) throws IOException {
			super(SelectorProvider.provider());
			this.fd = IoUtils.newFileDescriptor(fd);
			this.channel = new WriteOnlyFileChannel(new FdCloser(this.fd), fd);
		}

		@Override
		protected void implCloseSelectableChannel() throws IOException {
			channel.close();
		}

		@Override
		protected void implConfigureBlocking(boolean blocking)
				throws IOException {
			IoUtils.setBlocking(getFD(), blocking);
		}

		public int write(ByteBuffer buffer) throws IOException {
			return channel.write(buffer);
		}

		public long write(ByteBuffer[] buffers) throws IOException {
			return channel.write(buffers);
		}

		public long write(ByteBuffer[] buffers, int offset, int length)
				throws IOException {
			return channel.write(buffers, offset, length);
		}

		public FileDescriptor getFD() {
			return fd;
		}
	}
}
