/*
 * ====================================================================
 * 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */
package org.apache.http.nio.util;

import java.io.IOException;
import java.io.InterruptedIOException;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;

import org.apache.http.annotation.ThreadingBehavior;
import org.apache.http.annotation.Contract;
import org.apache.http.nio.ContentDecoder;
import org.apache.http.nio.IOControl;

Implementation of the ContentInputBuffer interface that can be shared by multiple threads, usually the I/O dispatch of an I/O reactor and a worker thread. 
 The I/O dispatch thread is expect to transfer data from ContentDecoder to the buffer by calling consumeContent(ContentDecoder). 
 The worker thread is expected to read the data from the buffer by calling read() or read(byte[], int, int) methods. 
 In case of an abnormal situation or when no longer needed the buffer must be shut down using shutdown() method. 
Since:
4.0/**
 * Implementation of the {@link ContentInputBuffer} interface that can be
 * shared by multiple threads, usually the I/O dispatch of an I/O reactor and
 * a worker thread.
 * <p>
 * The I/O dispatch thread is expect to transfer data from {@link ContentDecoder} to the buffer
 *   by calling {@link #consumeContent(ContentDecoder)}.
 * <p>
 * The worker thread is expected to read the data from the buffer by calling
 *   {@link #read()} or {@link #read(byte[], int, int)} methods.
 * <p>
 * In case of an abnormal situation or when no longer needed the buffer must be shut down
 * using {@link #shutdown()} method.
 *
 * @since 4.0
 */
@Contract(threading = ThreadingBehavior.SAFE_CONDITIONAL)
public class SharedInputBuffer extends ExpandableBuffer implements ContentInputBuffer {

    private final ReentrantLock lock;
    private final Condition condition;

    private volatile IOControl ioControl;
    private volatile boolean shutdown = false;
    private volatile boolean endOfStream = false;

    
Deprecated:
(4.3) use SharedInputBuffer(int, ByteBufferAllocator)/**
     * @deprecated (4.3) use {@link SharedInputBuffer#SharedInputBuffer(int, ByteBufferAllocator)}
     */
    @Deprecated
    public SharedInputBuffer(final int bufferSize, final IOControl ioControl, final ByteBufferAllocator allocator) {
        super(bufferSize, allocator);
        this.ioControl = ioControl;
        this.lock = new ReentrantLock();
        this.condition = this.lock.newCondition();
    }

    
Since:
4.3/**
     * @since 4.3
     */
    public SharedInputBuffer(final int bufferSize, final ByteBufferAllocator allocator) {
        super(bufferSize, allocator);
        this.lock = new ReentrantLock();
        this.condition = this.lock.newCondition();
    }

    
Since:
4.3/**
     * @since 4.3
     */
    public SharedInputBuffer(final int bufferSize) {
        this(bufferSize, HeapByteBufferAllocator.INSTANCE);
    }

    @Override
    public void reset() {
        if (this.shutdown) {
            return;
        }
        this.lock.lock();
        try {
            clear();
            this.endOfStream = false;
        } finally {
            this.lock.unlock();
        }
    }

    
Deprecated:
(4.3) use consumeContent(ContentDecoder, IOControl)/**
     * @deprecated (4.3) use {@link #consumeContent(ContentDecoder, IOControl)}
     */
    @Override
    @Deprecated
    public int consumeContent(final ContentDecoder decoder) throws IOException {
        return consumeContent(decoder, null);
    }

    
Since:
4.3/**
     * @since 4.3
     */
    public int consumeContent(final ContentDecoder decoder, final IOControl ioControl) throws IOException {
        if (this.shutdown) {
            return -1;
        }
        this.lock.lock();
        try {
            if (ioControl != null) {
                this.ioControl = ioControl;
            }
            setInputMode();
            int totalRead = 0;
            int bytesRead;
            while ((bytesRead = decoder.read(this.buffer)) > 0) {
                totalRead += bytesRead;
            }
            if (bytesRead == -1 || decoder.isCompleted()) {
                this.endOfStream = true;
            }
            if (!this.buffer.hasRemaining()) {
                if (this.ioControl != null) {
                    this.ioControl.suspendInput();
                }
            }
            this.condition.signalAll();

            if (totalRead > 0) {
                return totalRead;
            }
            return this.endOfStream ? -1 : 0;
        } finally {
            this.lock.unlock();
        }
    }

    @Override
    public boolean hasData() {
        this.lock.lock();
        try {
            return super.hasData();
        } finally {
            this.lock.unlock();
        }
    }

    @Override
    public int available() {
        this.lock.lock();
        try {
            return super.available();
        } finally {
            this.lock.unlock();
        }
    }

    @Override
    public int capacity() {
        this.lock.lock();
        try {
            return super.capacity();
        } finally {
            this.lock.unlock();
        }
    }

    @Override
    public int length() {
        this.lock.lock();
        try {
            return super.length();
        } finally {
            this.lock.unlock();
        }
    }

    protected void waitForData() throws IOException {
        this.lock.lock();
        try {
            try {
                while (!super.hasData() && !this.endOfStream) {
                    if (this.shutdown) {
                        throw new InterruptedIOException("Input operation aborted");
                    }
                    if (this.ioControl != null) {
                        this.ioControl.requestInput();
                    }
                    this.condition.await();
                }
            } catch (final InterruptedException ex) {
                throw new IOException("Interrupted while waiting for more data");
            }
        } finally {
            this.lock.unlock();
        }
    }

    public void close() {
        if (this.shutdown) {
            return;
        }
        this.endOfStream = true;
        this.lock.lock();
        try {
            this.condition.signalAll();
        } finally {
            this.lock.unlock();
        }
    }

    public void shutdown() {
        if (this.shutdown) {
            return;
        }
        this.shutdown = true;
        this.lock.lock();
        try {
            this.condition.signalAll();
        } finally {
            this.lock.unlock();
        }
    }

    protected boolean isShutdown() {
        return this.shutdown;
    }

    protected boolean isEndOfStream() {
        return this.shutdown || (!hasData() && this.endOfStream);
    }

    @Override
    public int read() throws IOException {
        if (this.shutdown) {
            return -1;
        }
        this.lock.lock();
        try {
            if (!hasData()) {
                waitForData();
            }
            if (isEndOfStream()) {
                return -1;
            }
            return this.buffer.get() & 0xff;
        } finally {
            this.lock.unlock();
        }
    }

    @Override
    public int read(final byte[] b, final int off, final int len) throws IOException {
        if (this.shutdown) {
            return -1;
        }
        if (b == null) {
            return 0;
        }
        this.lock.lock();
        try {
            if (!hasData()) {
                waitForData();
            }
            if (isEndOfStream()) {
                return -1;
            }
            setOutputMode();
            int chunk = len;
            if (chunk > this.buffer.remaining()) {
                chunk = this.buffer.remaining();
            }
            this.buffer.get(b, off, chunk);
            return chunk;
        } finally {
            this.lock.unlock();
        }
    }

    public int read(final byte[] b) throws IOException {
        if (this.shutdown) {
            return -1;
        }
        if (b == null) {
            return 0;
        }
        return read(b, 0, b.length);
    }

}