/*
 * Copyright (c) 2008, 2020 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package org.glassfish.grizzly.streams;

import java.io.EOFException;
import java.io.IOException;
import java.nio.BufferUnderflowException;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.logging.Level;
import java.util.logging.Logger;

import org.glassfish.grizzly.Buffer;
import org.glassfish.grizzly.CompletionHandler;
import org.glassfish.grizzly.Connection;
import org.glassfish.grizzly.Grizzly;
import org.glassfish.grizzly.GrizzlyFuture;
import org.glassfish.grizzly.Transformer;
import org.glassfish.grizzly.impl.FutureImpl;
import org.glassfish.grizzly.impl.ReadyFutureImpl;
import org.glassfish.grizzly.impl.SafeFutureImpl;
import org.glassfish.grizzly.utils.CompletionHandlerAdapter;
import org.glassfish.grizzly.utils.ResultAware;
import org.glassfish.grizzly.utils.conditions.Condition;

Each method reads data from the current ByteBuffer. If not enough data is present in the current ByteBuffer, discard
is called on the current ByteBuffer and we advance to the next ByteBuffer, or block if not enough data is present. If
close() is called, all subsequent method calls will throw an IllegalStateException, and any threads blocked waiting
for more data will be unblocked, and continue with an IllegalStateException from the blocking method call.

dataReceived and close may be safely invoked by multiple threads. The other methods must be invoked only by one
thread, which is the reader of this data stream.
Author:
Ken Cavanaugh, Alexey Stashok/**
 * Each method reads data from the current ByteBuffer. If not enough data is present in the current ByteBuffer, discard
 * is called on the current ByteBuffer and we advance to the next ByteBuffer, or block if not enough data is present. If
 * close() is called, all subsequent method calls will throw an IllegalStateException, and any threads blocked waiting
 * for more data will be unblocked, and continue with an IllegalStateException from the blocking method call.
 * <p>
 * dataReceived and close may be safely invoked by multiple threads. The other methods must be invoked only by one
 * thread, which is the reader of this data stream.
 *
 * @author Ken Cavanaugh
 * @author Alexey Stashok
 */
public abstract class AbstractStreamReader implements StreamReader {

    private static final boolean DEBUG = false;
    private static final Logger LOGGER = Grizzly.logger(AbstractStreamReader.class);

    protected final Connection connection;

    protected final Input input;

    protected final AtomicBoolean isClosed = new AtomicBoolean(false);

    private static void msg(final String msg) {
        LOGGER.log(Level.INFO, "READERSTREAM:DEBUG:{0}", msg);
    }

    private static void displayBuffer(final String str, final Buffer wrapper) {
        msg(str);
        msg("\tposition()     = " + wrapper.position());
        msg("\tlimit()        = " + wrapper.limit());
        msg("\tcapacity()     = " + wrapper.capacity());
    }
    // Concurrency considerations:
    // Only one thread (the consumer) may invoke the readXXX methods.
    // dataReceived and close may be invoked by a producer thread.
    // The consumer thread will invoke readXXX methods far more often
    // than a typical producer will call dataReceived or (possibly) close.
    // So buffers must be protected from concurrent access, either by locking
    // or by a wait-free queue. However, volatile is sufficient for current,
    // since we just need to ensure the visibility of the value of current to
    // all threads.
    //

    
Create a new ByteBufferReader.
Params:
connection – the Connection to be associated with this AbstractStreamReader
streamInput – the stream source/**
     * Create a new ByteBufferReader.
     *
     * @param connection the {@link Connection} to be associated with this <code>AbstractStreamReader</code>
     * @param streamInput the stream source
     */
    protected AbstractStreamReader(Connection connection, Input streamInput) {
        this.input = streamInput;
        this.connection = connection;
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public boolean readBoolean() throws IOException {
        return readByte() == 1;
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public byte readByte() throws IOException {
        return input.read();
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public char readChar() throws IOException {
        if (input.isBuffered()) {
            final Buffer buffer = input.getBuffer();
            if (buffer != null && buffer.remaining() >= 2) {
                final char result = buffer.getChar();
                buffer.shrink();
                return result;
            }
        }

        return (char) ((readByte() & 0xff) << 8 | readByte() & 0xff);
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public short readShort() throws IOException {
        if (input.isBuffered()) {
            final Buffer buffer = input.getBuffer();
            if (buffer != null && buffer.remaining() >= 2) {
                final short result = buffer.getShort();
                buffer.shrink();
                return result;
            }
        }

        return (short) ((readByte() & 0xff) << 8 | readByte() & 0xff);
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public int readInt() throws IOException {
        if (input.isBuffered()) {
            final Buffer buffer = input.getBuffer();
            if (buffer != null && buffer.remaining() >= 4) {
                final int result = buffer.getInt();
                buffer.shrink();
                return result;
            }
        }

        return (readShort() & 0xffff) << 16 | readShort() & 0xffff;
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public long readLong() throws IOException {
        if (input.isBuffered()) {
            final Buffer buffer = input.getBuffer();
            if (buffer != null && buffer.remaining() >= 8) {
                final long result = buffer.getLong();
                buffer.shrink();
                return result;
            }
        }

        return (readInt() & 0xffffffffL) << 32 | readInt() & 0xffffffffL;
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    final public float readFloat() throws IOException {
        if (input.isBuffered()) {
            final Buffer buffer = input.getBuffer();
            if (buffer != null && buffer.remaining() >= 4) {
                final float result = buffer.getFloat();
                buffer.shrink();
                return result;
            }
        }

        return Float.intBitsToFloat(readInt());
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    final public double readDouble() throws IOException {
        if (input.isBuffered()) {
            final Buffer buffer = input.getBuffer();
            if (buffer != null && buffer.remaining() >= 8) {
                final double result = buffer.getDouble();
                buffer.shrink();
                return result;
            }
        }

        return Double.longBitsToDouble(readLong());
    }

    private void arraySizeCheck(final int sizeInBytes) {
        if (sizeInBytes > available()) {
            throw new BufferUnderflowException();
        }
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public void readBooleanArray(boolean[] data) throws IOException {
        arraySizeCheck(data.length);
        for (int ctr = 0; ctr < data.length; ctr++) {
            data[ctr] = readBoolean();
        }
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public void readByteArray(final byte[] data) throws IOException {
        readByteArray(data, 0, data.length);
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public void readByteArray(byte[] data, int offset, int length) throws IOException {
        arraySizeCheck(length);
        if (input.isBuffered()) {
            final Buffer buffer = input.getBuffer();
            buffer.get(data, offset, length);
            buffer.shrink();
        } else {
            for (int i = offset; i < length; i++) {
                data[i] = input.read();
            }
        }

    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public void readBytes(final Buffer buffer) throws IOException {
        if (!buffer.hasRemaining()) {
            return;
        }

        arraySizeCheck(buffer.remaining());
        if (input.isBuffered()) {
            final Buffer inputBuffer = input.getBuffer();
            final int diff = buffer.remaining() - inputBuffer.remaining();
            if (diff >= 0) {
                buffer.put(inputBuffer);
            } else {
                final int save = inputBuffer.limit();
                inputBuffer.limit(save + diff);
                buffer.put(inputBuffer);
                inputBuffer.limit(save);
            }

            inputBuffer.shrink();
        } else {
            while (buffer.hasRemaining()) {
                buffer.put(input.read());
            }
        }
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public void readCharArray(final char[] data) throws IOException {
        arraySizeCheck(2 * data.length);
        for (int i = 0; i < data.length; i++) {
            data[i] = readChar();
        }
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public void readShortArray(final short[] data) throws IOException {
        arraySizeCheck(2 * data.length);
        for (int i = 0; i < data.length; i++) {
            data[i] = readShort();
        }
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public void readIntArray(final int[] data) throws IOException {
        arraySizeCheck(4 * data.length);
        for (int i = 0; i < data.length; i++) {
            data[i] = readInt();
        }
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public void readLongArray(final long[] data) throws IOException {
        arraySizeCheck(8 * data.length);
        for (int i = 0; i < data.length; i++) {
            data[i] = readLong();
        }
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public void readFloatArray(final float[] data) throws IOException {
        arraySizeCheck(4 * data.length);
        for (int i = 0; i < data.length; i++) {
            data[i] = readFloat();
        }
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public void readDoubleArray(final double[] data) throws IOException {
        arraySizeCheck(8 * data.length);
        for (int i = 0; i < data.length; i++) {
            data[i] = readDouble();
        }

    }

    @Override
    public void skip(int length) {
        input.skip(length);
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public <E> GrizzlyFuture<E> decode(Transformer<Stream, E> decoder) {
        return decode(decoder, null);
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public <E> GrizzlyFuture<E> decode(Transformer<Stream, E> decoder, CompletionHandler<E> completionHandler) {
        final FutureImpl<E> future = SafeFutureImpl.create();

        final DecodeCompletionHandler<E, Integer> completionHandlerWrapper = new DecodeCompletionHandler<>(future, completionHandler);

        notifyCondition(new StreamDecodeCondition<>(this, decoder, completionHandlerWrapper), completionHandlerWrapper);

        return future;
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public GrizzlyFuture<Integer> notifyAvailable(int size) {
        return notifyAvailable(size, null);
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public GrizzlyFuture<Integer> notifyAvailable(final int size, CompletionHandler<Integer> completionHandler) {
        return notifyCondition(new Condition() {
            @Override
            public boolean check() {
                return available() >= size;
            }
        }, completionHandler);
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public GrizzlyFuture<Integer> notifyCondition(Condition condition) {
        return notifyCondition(condition, null);
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public synchronized GrizzlyFuture<Integer> notifyCondition(final Condition condition, final CompletionHandler<Integer> completionHandler) {
        if (isClosed()) {
            EOFException exception = new EOFException();
            if (completionHandler != null) {
                completionHandler.failed(exception);
            }

            return ReadyFutureImpl.create(exception);
        }

        return input.notifyCondition(condition, completionHandler);
    }

    
Closes the StreamReader and causes all subsequent method calls on this object to throw
IllegalStateException.
/**
     * Closes the <tt>StreamReader</tt> and causes all subsequent method calls on this object to throw
     * IllegalStateException.
     */
    @Override
    public void close() {
        if (isClosed.compareAndSet(false, true)) {
            if (input != null) {
                try {
                    input.close();
                } catch (IOException ignored) {
                }
            }
        }
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public boolean isClosed() {
        return isClosed.get();
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public final boolean hasAvailable() {
        return available() > 0;
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public int available() {
        return input.size();
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public boolean isSupportBufferWindow() {
        return input.isBuffered();
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public Buffer getBufferWindow() {
        return input.getBuffer();
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public Buffer takeBufferWindow() {
        return input.takeBuffer();
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public Connection getConnection() {
        return connection;
    }

    private static class DecodeCompletionHandler<A, B> extends CompletionHandlerAdapter<A, B> implements ResultAware<A> {

        private volatile A result;

        public DecodeCompletionHandler(FutureImpl<A> future, CompletionHandler<A> completionHandler) {
            super(future, completionHandler);
        }

        @Override
        public void setResult(A result) {
            this.result = result;
        }

        @Override
        protected A adapt(B result) {
            return this.result;
        }
    }
}