/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at legal-notices/CDDLv1_0.txt
 * or http://forgerock.org/license/CDDLv1.0.html.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at legal-notices/CDDLv1_0.txt.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information:
 *      Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 *
 *
 *      Copyright 2010 Sun Microsystems, Inc.
 *      Portions copyright 2012-2013 ForgeRock AS.
 */
package org.forgerock.opendj.grizzly;

import static com.forgerock.opendj.ldap.CoreMessages.ERR_ASN1_SEQUENCE_WRITE_NOT_STARTED;
import static com.forgerock.opendj.util.StaticUtils.IO_LOG;
import static com.forgerock.opendj.util.StaticUtils.byteToHex;

import java.io.IOException;
import java.nio.ByteBuffer;

import org.forgerock.i18n.LocalizableMessage;
import org.forgerock.opendj.io.ASN1;
import org.forgerock.opendj.io.ASN1Writer;
import org.forgerock.opendj.io.AbstractASN1Writer;
import org.forgerock.opendj.ldap.ByteSequence;
import org.forgerock.opendj.ldap.ByteStringBuilder;
import org.glassfish.grizzly.Buffer;
import org.glassfish.grizzly.Cacheable;
import org.glassfish.grizzly.memory.ByteBufferWrapper;

import com.forgerock.opendj.util.StaticUtils;

/**
 * Grizzly ASN1 writer implementation.
 */
final class ASN1BufferWriter extends AbstractASN1Writer implements Cacheable {
    private class ChildSequenceBuffer implements SequenceBuffer {
        private SequenceBuffer parent;

        private ChildSequenceBuffer child;

        private final ByteStringBuilder buffer = new ByteStringBuilder(BUFFER_INIT_SIZE);

        public SequenceBuffer endSequence() throws IOException {
            writeLength(parent, buffer.length());
            parent.writeByteArray(buffer.getBackingArray(), 0, buffer.length());

            IO_LOG.trace("WRITE ASN.1 END SEQUENCE(length={})", buffer.length());

            return parent;
        }

        public SequenceBuffer startSequence(final byte type) throws IOException {
            if (child == null) {
                child = new ChildSequenceBuffer();
                child.parent = this;
            }

            buffer.append(type);
            child.buffer.clear();

            return child;
        }

        public void writeByte(final byte b) throws IOException {
            buffer.append(b);
        }

        public void writeByteArray(final byte[] bs, final int offset, final int length)
                throws IOException {
            buffer.append(bs, offset, length);
        }
    }

    private static final class RecyclableBuffer extends ByteBufferWrapper {
        private volatile boolean usable = true;

        private RecyclableBuffer() {
            visible = ByteBuffer.allocate(BUFFER_INIT_SIZE);
            allowBufferDispose = true;
        }

        @Override
        public void dispose() {
            usable = true;
        }

        /**
         * Ensures that the specified number of additional bytes will fit in the
         * buffer and resizes it if necessary.
         *
         * @param size
         *            The number of additional bytes.
         */
        public void ensureAdditionalCapacity(final int size) {
            final int newCount = visible.position() + size;
            if (newCount > visible.capacity()) {
                final ByteBuffer newByteBuffer =
                        ByteBuffer.allocate(Math.max(visible.capacity() << 1, newCount));
                visible.flip();
                visible = newByteBuffer.put(visible);
            }
        }
    }

    private class RootSequenceBuffer implements SequenceBuffer {
        private ChildSequenceBuffer child;

        public SequenceBuffer endSequence() throws IOException {
            final LocalizableMessage message = ERR_ASN1_SEQUENCE_WRITE_NOT_STARTED.get();
            throw new IllegalStateException(message.toString());
        }

        public SequenceBuffer startSequence(final byte type) throws IOException {
            if (child == null) {
                child = new ChildSequenceBuffer();
                child.parent = this;
            }

            outBuffer.ensureAdditionalCapacity(1);
            outBuffer.put(type);
            child.buffer.clear();

            return child;
        }

        public void writeByte(final byte b) throws IOException {
            outBuffer.ensureAdditionalCapacity(1);
            outBuffer.put(b);
        }

        public void writeByteArray(final byte[] bs, final int offset, final int length)
                throws IOException {
            outBuffer.ensureAdditionalCapacity(length);
            outBuffer.put(bs, offset, length);
        }
    }

    private interface SequenceBuffer {
        public SequenceBuffer endSequence() throws IOException;

        public SequenceBuffer startSequence(byte type) throws IOException;

        public void writeByte(byte b) throws IOException;

        public void writeByteArray(byte[] bs, int offset, int length) throws IOException;
    }

    private static final int BUFFER_INIT_SIZE = 1024;

    /**
     * Reset the writer.
     */
    void reset() {
        if (!outBuffer.usable) {
            // If the output buffer is unusable, create a new one.
            outBuffer = new RecyclableBuffer();
        }
        outBuffer.clear();
    }

    private SequenceBuffer sequenceBuffer;
    private RecyclableBuffer outBuffer;

    private final RootSequenceBuffer rootBuffer;

    /**
     * Creates a new ASN.1 writer that writes to a StreamWriter.
     */
    ASN1BufferWriter() {
        this.sequenceBuffer = this.rootBuffer = new RootSequenceBuffer();
        this.outBuffer = new RecyclableBuffer();
    }

    /**
     * Closes this ASN.1 writer and the underlying outputstream. Any unfinished
     * sequences will be ended.
     *
     * @throws IOException
     *             if an error occurs while closing the stream.
     */
    public void close() throws IOException {
        outBuffer = null;
    }

    /**
     * Flushes the stream.
     *
     * @throws IOException
     *             If an I/O error occurs
     */
    public void flush() throws IOException {
        // Do nothing
    }

    /**
     * Recycle the writer to allow re-use.
     */
    public void recycle() {
        sequenceBuffer = rootBuffer;
        outBuffer.clear();
    }

    /**
     * {@inheritDoc}
     */
    public ASN1Writer writeBoolean(final byte type, final boolean booleanValue) throws IOException {
        sequenceBuffer.writeByte(type);
        writeLength(sequenceBuffer, 1);
        sequenceBuffer.writeByte(booleanValue ? ASN1.BOOLEAN_VALUE_TRUE : ASN1.BOOLEAN_VALUE_FALSE);

        IO_LOG.trace("WRITE ASN.1 BOOLEAN(type=0x{}, length={}, value={})",
                byteToHex(type), 1, String.valueOf(booleanValue));

        return this;
    }

    /**
     * {@inheritDoc}
     */
    public ASN1Writer writeEndSequence() throws IOException {
        sequenceBuffer = sequenceBuffer.endSequence();

        return this;
    }

    /**
     * {@inheritDoc}
     */
    public ASN1Writer writeEndSet() throws IOException {
        return writeEndSequence();
    }

    /**
     * {@inheritDoc}
     */
    public ASN1Writer writeEnumerated(final byte type, final int intValue) throws IOException {
        return writeInteger(type, intValue);
    }

    /**
     * {@inheritDoc}
     */
    public ASN1Writer writeInteger(final byte type, final int intValue) throws IOException {
        sequenceBuffer.writeByte(type);
        if (((intValue < 0) && ((intValue & 0xFFFFFF80) == 0xFFFFFF80))
                || ((intValue & 0x0000007F) == intValue)) {
            writeLength(sequenceBuffer, 1);
            sequenceBuffer.writeByte((byte) (intValue & 0xFF));
            IO_LOG.trace("WRITE ASN.1 INTEGER(type=0x{}, length={}, value={})", byteToHex(type), 1, intValue);
        } else if (((intValue < 0) && ((intValue & 0xFFFF8000) == 0xFFFF8000))
                || ((intValue & 0x00007FFF) == intValue)) {
            writeLength(sequenceBuffer, 2);
            sequenceBuffer.writeByte((byte) ((intValue >> 8) & 0xFF));
            sequenceBuffer.writeByte((byte) (intValue & 0xFF));
            IO_LOG.trace("WRITE ASN.1 INTEGER(type=0x{}, length={}, value={})", byteToHex(type), 2, intValue);
        } else if (((intValue < 0) && ((intValue & 0xFF800000) == 0xFF800000))
                || ((intValue & 0x007FFFFF) == intValue)) {
            writeLength(sequenceBuffer, 3);
            sequenceBuffer.writeByte((byte) ((intValue >> 16) & 0xFF));
            sequenceBuffer.writeByte((byte) ((intValue >> 8) & 0xFF));
            sequenceBuffer.writeByte((byte) (intValue & 0xFF));
            IO_LOG.trace("WRITE ASN.1 INTEGER(type=0x{}, length={}, value={})", byteToHex(type), 3, intValue);
        } else {
            writeLength(sequenceBuffer, 4);
            sequenceBuffer.writeByte((byte) ((intValue >> 24) & 0xFF));
            sequenceBuffer.writeByte((byte) ((intValue >> 16) & 0xFF));
            sequenceBuffer.writeByte((byte) ((intValue >> 8) & 0xFF));
            sequenceBuffer.writeByte((byte) (intValue & 0xFF));
            IO_LOG.trace("WRITE ASN.1 INTEGER(type=0x{}, length={}, value={})", byteToHex(type), 4, intValue);
        }
        return this;
    }

    /**
     * {@inheritDoc}
     */
    public ASN1Writer writeInteger(final byte type, final long longValue) throws IOException {
        sequenceBuffer.writeByte(type);
        if (((longValue < 0) && ((longValue & 0xFFFFFFFFFFFFFF80L) == 0xFFFFFFFFFFFFFF80L))
                || ((longValue & 0x000000000000007FL) == longValue)) {
            writeLength(sequenceBuffer, 1);
            sequenceBuffer.writeByte((byte) (longValue & 0xFF));
            IO_LOG.trace("WRITE ASN.1 INTEGER(type=0x{}, length={}, value={})", byteToHex(type), 1, longValue);
        } else if (((longValue < 0) && ((longValue & 0xFFFFFFFFFFFF8000L) == 0xFFFFFFFFFFFF8000L))
                || ((longValue & 0x0000000000007FFFL) == longValue)) {
            writeLength(sequenceBuffer, 2);
            sequenceBuffer.writeByte((byte) ((longValue >> 8) & 0xFF));
            sequenceBuffer.writeByte((byte) (longValue & 0xFF));
            IO_LOG.trace("WRITE ASN.1 INTEGER(type=0x{}, length={}, value={})", byteToHex(type), 2, longValue);
        } else if (((longValue < 0) && ((longValue & 0xFFFFFFFFFF800000L) == 0xFFFFFFFFFF800000L))
                || ((longValue & 0x00000000007FFFFFL) == longValue)) {
            writeLength(sequenceBuffer, 3);
            sequenceBuffer.writeByte((byte) ((longValue >> 16) & 0xFF));
            sequenceBuffer.writeByte((byte) ((longValue >> 8) & 0xFF));
            sequenceBuffer.writeByte((byte) (longValue & 0xFF));
            IO_LOG.trace("WRITE ASN.1 INTEGER(type=0x{}, length={}, value={})", byteToHex(type), 3, longValue);
        } else if (((longValue < 0) && ((longValue & 0xFFFFFFFF80000000L) == 0xFFFFFFFF80000000L))
                || ((longValue & 0x000000007FFFFFFFL) == longValue)) {
            writeLength(sequenceBuffer, 4);
            sequenceBuffer.writeByte((byte) ((longValue >> 24) & 0xFF));
            sequenceBuffer.writeByte((byte) ((longValue >> 16) & 0xFF));
            sequenceBuffer.writeByte((byte) ((longValue >> 8) & 0xFF));
            sequenceBuffer.writeByte((byte) (longValue & 0xFF));
            IO_LOG.trace("WRITE ASN.1 INTEGER(type=0x{}, length={}, value={})", byteToHex(type), 4, longValue);
        } else if (((longValue < 0) && ((longValue & 0xFFFFFF8000000000L) == 0xFFFFFF8000000000L))
                || ((longValue & 0x0000007FFFFFFFFFL) == longValue)) {
            writeLength(sequenceBuffer, 5);
            sequenceBuffer.writeByte((byte) ((longValue >> 32) & 0xFF));
            sequenceBuffer.writeByte((byte) ((longValue >> 24) & 0xFF));
            sequenceBuffer.writeByte((byte) ((longValue >> 16) & 0xFF));
            sequenceBuffer.writeByte((byte) ((longValue >> 8) & 0xFF));
            sequenceBuffer.writeByte((byte) (longValue & 0xFF));
            IO_LOG.trace("WRITE ASN.1 INTEGER(type=0x{}, length={}, value={})", byteToHex(type), 5, longValue);
        } else if (((longValue < 0) && ((longValue & 0xFFFF800000000000L) == 0xFFFF800000000000L))
                || ((longValue & 0x00007FFFFFFFFFFFL) == longValue)) {
            writeLength(sequenceBuffer, 6);
            sequenceBuffer.writeByte((byte) ((longValue >> 40) & 0xFF));
            sequenceBuffer.writeByte((byte) ((longValue >> 32) & 0xFF));
            sequenceBuffer.writeByte((byte) ((longValue >> 24) & 0xFF));
            sequenceBuffer.writeByte((byte) ((longValue >> 16) & 0xFF));
            sequenceBuffer.writeByte((byte) ((longValue >> 8) & 0xFF));
            sequenceBuffer.writeByte((byte) (longValue & 0xFF));
            IO_LOG.trace("WRITE ASN.1 INTEGER(type=0x{}, length={}, value={})", byteToHex(type), 6, longValue);
        } else if (((longValue < 0) && ((longValue & 0xFF80000000000000L) == 0xFF80000000000000L))
                || ((longValue & 0x007FFFFFFFFFFFFFL) == longValue)) {
            writeLength(sequenceBuffer, 7);
            sequenceBuffer.writeByte((byte) ((longValue >> 48) & 0xFF));
            sequenceBuffer.writeByte((byte) ((longValue >> 40) & 0xFF));
            sequenceBuffer.writeByte((byte) ((longValue >> 32) & 0xFF));
            sequenceBuffer.writeByte((byte) ((longValue >> 24) & 0xFF));
            sequenceBuffer.writeByte((byte) ((longValue >> 16) & 0xFF));
            sequenceBuffer.writeByte((byte) ((longValue >> 8) & 0xFF));
            sequenceBuffer.writeByte((byte) (longValue & 0xFF));
            IO_LOG.trace("WRITE ASN.1 INTEGER(type=0x{}, length={}, value={})", byteToHex(type), 7, longValue);
        } else {
            writeLength(sequenceBuffer, 8);
            sequenceBuffer.writeByte((byte) ((longValue >> 56) & 0xFF));
            sequenceBuffer.writeByte((byte) ((longValue >> 48) & 0xFF));
            sequenceBuffer.writeByte((byte) ((longValue >> 40) & 0xFF));
            sequenceBuffer.writeByte((byte) ((longValue >> 32) & 0xFF));
            sequenceBuffer.writeByte((byte) ((longValue >> 24) & 0xFF));
            sequenceBuffer.writeByte((byte) ((longValue >> 16) & 0xFF));
            sequenceBuffer.writeByte((byte) ((longValue >> 8) & 0xFF));
            sequenceBuffer.writeByte((byte) (longValue & 0xFF));
            IO_LOG.trace("WRITE ASN.1 INTEGER(type=0x{}, length={}, value={})", byteToHex(type), 8, longValue);
        }
        return this;
    }

    /**
     * {@inheritDoc}
     */
    public ASN1Writer writeNull(final byte type) throws IOException {
        sequenceBuffer.writeByte(type);
        writeLength(sequenceBuffer, 0);

        IO_LOG.trace("WRITE ASN.1 NULL(type=0x{}, length={})", byteToHex(type), 0);

        return this;
    }

    /**
     * {@inheritDoc}
     */
    public ASN1Writer writeOctetString(final byte type, final byte[] value, final int offset,
            final int length) throws IOException {
        sequenceBuffer.writeByte(type);
        writeLength(sequenceBuffer, length);
        sequenceBuffer.writeByteArray(value, offset, length);

        IO_LOG.trace("WRITE ASN.1 OCTETSTRING(type=0x{}, length={})", byteToHex(type), length);
        return this;
    }

    /**
     * {@inheritDoc}
     */
    public ASN1Writer writeOctetString(final byte type, final ByteSequence value)
            throws IOException {
        sequenceBuffer.writeByte(type);
        writeLength(sequenceBuffer, value.length());
        // TODO: Is there a more efficient way to do this?
        for (int i = 0; i < value.length(); i++) {
            sequenceBuffer.writeByte(value.byteAt(i));
        }

        IO_LOG.trace("WRITE ASN.1 OCTETSTRING(type=0x{}, length={})", byteToHex(type), value.length());
        return this;
    }

    /**
     * {@inheritDoc}
     */
    public ASN1Writer writeOctetString(final byte type, final String value) throws IOException {
        sequenceBuffer.writeByte(type);

        if (value == null) {
            writeLength(sequenceBuffer, 0);
            return this;
        }

        final byte[] bytes = StaticUtils.getBytes(value);
        writeLength(sequenceBuffer, bytes.length);
        sequenceBuffer.writeByteArray(bytes, 0, bytes.length);

        IO_LOG.trace("WRITE ASN.1 OCTETSTRING(type=0x{}, length={}, value={})", byteToHex(type),
                    bytes.length, value);
        return this;
    }

    /**
     * {@inheritDoc}
     */
    public ASN1Writer writeStartSequence(final byte type) throws IOException {
        // Get a child sequence buffer
        sequenceBuffer = sequenceBuffer.startSequence(type);

        IO_LOG.trace("WRITE ASN.1 START SEQUENCE(type=0x{})", byteToHex(type));
        return this;
    }

    /**
     * {@inheritDoc}
     */
    public ASN1Writer writeStartSet(final byte type) throws IOException {
        // From an implementation point of view, a set is equivalent to a
        // sequence.
        return writeStartSequence(type);
    }

    Buffer getBuffer() {
        outBuffer.usable = false;
        return outBuffer.flip();
    }

    /**
     * Writes the provided value for use as the length of an ASN.1 element.
     *
     * @param buffer
     *            The sequence buffer to write to.
     * @param length
     *            The length to encode for use in an ASN.1 element.
     * @throws IOException
     *             if an error occurs while writing.
     */
    private void writeLength(final SequenceBuffer buffer, final int length) throws IOException {
        if (length < 128) {
            buffer.writeByte((byte) length);
        } else if ((length & 0x000000FF) == length) {
            buffer.writeByte((byte) 0x81);
            buffer.writeByte((byte) (length & 0xFF));
        } else if ((length & 0x0000FFFF) == length) {
            buffer.writeByte((byte) 0x82);
            buffer.writeByte((byte) ((length >> 8) & 0xFF));
            buffer.writeByte((byte) (length & 0xFF));
        } else if ((length & 0x00FFFFFF) == length) {
            buffer.writeByte((byte) 0x83);
            buffer.writeByte((byte) ((length >> 16) & 0xFF));
            buffer.writeByte((byte) ((length >> 8) & 0xFF));
            buffer.writeByte((byte) (length & 0xFF));
        } else {
            buffer.writeByte((byte) 0x84);
            buffer.writeByte((byte) ((length >> 24) & 0xFF));
            buffer.writeByte((byte) ((length >> 16) & 0xFF));
            buffer.writeByte((byte) ((length >> 8) & 0xFF));
            buffer.writeByte((byte) (length & 0xFF));
        }
    }
}