/*
 Copyright  2002-2005 MySQL AB, 2008 Sun Microsystems

 This program is free software; you can redistribute it and/or modify
 it under the terms of version 2 of the GNU General Public License as 
 published by the Free Software Foundation.

 There are special exceptions to the terms and conditions of the GPL 
 as it is applied to this software. View the full text of the 
 exception in file EXCEPTIONS-CONNECTOR-J in the directory of this 
 software distribution.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA



 */
package com.mysql.jdbc;

import java.io.UnsupportedEncodingException;
import java.nio.ByteBuffer;
import java.sql.SQLException;

/**
 * Buffer contains code to read and write packets from/to the MySQL server.
 * 
 * @version $Id$
 * @author Mark Matthews
 */
class Buffer {
	static final int MAX_BYTES_TO_DUMP = 512;

	static final int NO_LENGTH_LIMIT = -1;

	static final long NULL_LENGTH = -1;

	private int bufLength = 0;

	private byte[] byteBuffer;

	private int position = 0;

	protected boolean wasMultiPacket = false;

	Buffer(byte[] buf) {
		this.byteBuffer = buf;
		setBufLength(buf.length);
	}

	Buffer(int size) {
		this.byteBuffer = new byte[size];
		setBufLength(this.byteBuffer.length);
		this.position = MysqlIO.HEADER_LENGTH;
	}

	final void clear() {
		this.position = MysqlIO.HEADER_LENGTH;
	}

	final void dump() {
		dump(getBufLength());
	}

	final String dump(int numBytes) {
		return StringUtils.dumpAsHex(getBytes(0,
				numBytes > getBufLength() ? getBufLength() : numBytes),
				numBytes > getBufLength() ? getBufLength() : numBytes);
	}

	final String dumpClampedBytes(int numBytes) {
		int numBytesToDump = numBytes < MAX_BYTES_TO_DUMP ? numBytes
				: MAX_BYTES_TO_DUMP;

		String dumped = StringUtils.dumpAsHex(getBytes(0,
				numBytesToDump > getBufLength() ? getBufLength()
						: numBytesToDump),
				numBytesToDump > getBufLength() ? getBufLength()
						: numBytesToDump);

		if (numBytesToDump < numBytes) {
			return dumped + " ....(packet exceeds max. dump length)";
		}

		return dumped;
	}

	final void dumpHeader() {
		for (int i = 0; i < MysqlIO.HEADER_LENGTH; i++) {
			String hexVal = Integer.toHexString(readByte(i) & 0xff);

			if (hexVal.length() == 1) {
				hexVal = "0" + hexVal; //$NON-NLS-1$
			}

			System.out.print(hexVal + " "); //$NON-NLS-1$
		}
	}

	final void dumpNBytes(int start, int nBytes) {
		StringBuffer asciiBuf = new StringBuffer();

		for (int i = start; (i < (start + nBytes)) && (i < getBufLength()); i++) {
			String hexVal = Integer.toHexString(readByte(i) & 0xff);

			if (hexVal.length() == 1) {
				hexVal = "0" + hexVal; //$NON-NLS-1$
			}

			System.out.print(hexVal + " "); //$NON-NLS-1$

			if ((readByte(i) > 32) && (readByte(i) < 127)) {
				asciiBuf.append((char) readByte(i));
			} else {
				asciiBuf.append("."); //$NON-NLS-1$
			}

			asciiBuf.append(" "); //$NON-NLS-1$
		}

		System.out.println("    " + asciiBuf.toString()); //$NON-NLS-1$
	}

	final void ensureCapacity(int additionalData) throws SQLException {
		if ((this.position + additionalData) > getBufLength()) {
			if ((this.position + additionalData) < this.byteBuffer.length) {
				// byteBuffer.length is != getBufLength() all of the time
				// due to re-using of packets (we don't shrink them)
				//
				// If we can, don't re-alloc, just set buffer length
				// to size of current buffer
				setBufLength(this.byteBuffer.length);
			} else {
				//
				// Otherwise, re-size, and pad so we can avoid
				// allocing again in the near future
				//
				int newLength = (int) (this.byteBuffer.length * 1.25);

				if (newLength < (this.byteBuffer.length + additionalData)) {
					newLength = this.byteBuffer.length
							+ (int) (additionalData * 1.25);
				}

				if (newLength < this.byteBuffer.length) {
					newLength = this.byteBuffer.length + additionalData;
				}

				byte[] newBytes = new byte[newLength];

				System.arraycopy(this.byteBuffer, 0, newBytes, 0,
						this.byteBuffer.length);
				this.byteBuffer = newBytes;
				setBufLength(this.byteBuffer.length);
			}
		}
	}

	/**
	 * Skip over a length-encoded string
	 * 
	 * @return The position past the end of the string
	 */
	public int fastSkipLenString() {
		long len = this.readFieldLength();

		this.position += len;

		return (int) len;
	}

	public void fastSkipLenByteArray() {
		long len = this.readFieldLength();

		if (len == NULL_LENGTH || len == 0) {
			return;
		}
		
		this.position += len;
	}
	
	protected final byte[] getBufferSource() {
		return this.byteBuffer;
	}

	int getBufLength() {
		return this.bufLength;
	}

	/**
	 * Returns the array of bytes this Buffer is using to read from.
	 * 
	 * @return byte array being read from
	 */
	public byte[] getByteBuffer() {
		return this.byteBuffer;
	}

	final byte[] getBytes(int len) {
		byte[] b = new byte[len];
		System.arraycopy(this.byteBuffer, this.position, b, 0, len);
		this.position += len; // update cursor

		return b;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see com.mysql.jdbc.Buffer#getBytes(int, int)
	 */
	byte[] getBytes(int offset, int len) {
		byte[] dest = new byte[len];
		System.arraycopy(this.byteBuffer, offset, dest, 0, len);

		return dest;
	}

	int getCapacity() {
		return this.byteBuffer.length;
	}

	public ByteBuffer getNioBuffer() {
		throw new IllegalArgumentException(Messages
				.getString("ByteArrayBuffer.0")); //$NON-NLS-1$
	}

	/**
	 * Returns the current position to write to/ read from
	 * 
	 * @return the current position to write to/ read from
	 */
	public int getPosition() {
		return this.position;
	}

	// 2000-06-05 Changed
	final boolean isLastDataPacket() {
		return ((getBufLength() < 9) && ((this.byteBuffer[0] & 0xff) == 254));
	}

	final long newReadLength() {
		int sw = this.byteBuffer[this.position++] & 0xff;

		switch (sw) {
		case 251:
			return 0;

		case 252:
			return readInt();

		case 253:
			return readLongInt();

		case 254: // changed for 64 bit lengths
			return readLongLong();

		default:
			return sw;
		}
	}

	final byte readByte() {
		return this.byteBuffer[this.position++];
	}

	final byte readByte(int readAt) {
		return this.byteBuffer[readAt];
	}

	final long readFieldLength() {
		int sw = this.byteBuffer[this.position++] & 0xff;

		switch (sw) {
		case 251:
			return NULL_LENGTH;

		case 252:
			return readInt();

		case 253:
			return readLongInt();

		case 254:
			return readLongLong();

		default:
			return sw;
		}
	}

	// 2000-06-05 Changed
	final int readInt() {
		byte[] b = this.byteBuffer; // a little bit optimization

		return (b[this.position++] & 0xff) | ((b[this.position++] & 0xff) << 8);
	}

	final int readIntAsLong() {
		byte[] b = this.byteBuffer;

		return (b[this.position++] & 0xff) | ((b[this.position++] & 0xff) << 8)
				| ((b[this.position++] & 0xff) << 16)
				| ((b[this.position++] & 0xff) << 24);
	}

	final byte[] readLenByteArray(int offset) {
		long len = this.readFieldLength();

		if (len == NULL_LENGTH) {
			return null;
		}

		if (len == 0) {
			return Constants.EMPTY_BYTE_ARRAY;
		}

		this.position += offset;

		return getBytes((int) len);
	}

	final long readLength() {
		int sw = this.byteBuffer[this.position++] & 0xff;

		switch (sw) {
		case 251:
			return 0;

		case 252:
			return readInt();

		case 253:
			return readLongInt();

		case 254:
			return readLong();

		default:
			return sw;
		}
	}

	// 2000-06-05 Fixed
	final long readLong() {
		byte[] b = this.byteBuffer;

		return ((long) b[this.position++] & 0xff)
				| (((long) b[this.position++] & 0xff) << 8)
				| ((long) (b[this.position++] & 0xff) << 16)
				| ((long) (b[this.position++] & 0xff) << 24);
	}

	// 2000-06-05 Changed
	final int readLongInt() {
		byte[] b = this.byteBuffer;

		return (b[this.position++] & 0xff) | ((b[this.position++] & 0xff) << 8)
				| ((b[this.position++] & 0xff) << 16);
	}

	// 2000-06-05 Fixed
	final long readLongLong() {
		byte[] b = this.byteBuffer;

		return (b[this.position++] & 0xff)
				| ((long) (b[this.position++] & 0xff) << 8)
				| ((long) (b[this.position++] & 0xff) << 16)
				| ((long) (b[this.position++] & 0xff) << 24)
				| ((long) (b[this.position++] & 0xff) << 32)
				| ((long) (b[this.position++] & 0xff) << 40)
				| ((long) (b[this.position++] & 0xff) << 48)
				| ((long) (b[this.position++] & 0xff) << 56);
	}

	final int readnBytes() {
		int sw = this.byteBuffer[this.position++] & 0xff;

		switch (sw) {
		case 1:
			return this.byteBuffer[this.position++] & 0xff;

		case 2:
			return this.readInt();

		case 3:
			return this.readLongInt();

		case 4:
			return (int) this.readLong();

		default:
			return 255;
		}
	}

	//
	// Read a null-terminated string
	//
	// To avoid alloc'ing a new byte array, we
	// do this by hand, rather than calling getNullTerminatedBytes()
	//
	final String readString() {
		int i = this.position;
		int len = 0;
		int maxLen = getBufLength();

		while ((i < maxLen) && (this.byteBuffer[i] != 0)) {
			len++;
			i++;
		}

		String s = new String(this.byteBuffer, this.position, len);
		this.position += (len + 1); // update cursor

		return s;
	}

	final String readString(String encoding) throws SQLException {
		int i = this.position;
		int len = 0;
		int maxLen = getBufLength();

		while ((i < maxLen) && (this.byteBuffer[i] != 0)) {
			len++;
			i++;
		}

		try {
			return new String(this.byteBuffer, this.position, len, encoding);
		} catch (UnsupportedEncodingException uEE) {
			throw SQLError.createSQLException(Messages.getString("ByteArrayBuffer.1") //$NON-NLS-1$
					+ encoding + "'", SQLError.SQL_STATE_ILLEGAL_ARGUMENT); //$NON-NLS-1$
		} finally {
			this.position += (len + 1); // update cursor
		}
	}

	void setBufLength(int bufLengthToSet) {
		this.bufLength = bufLengthToSet;
	}

	/**
	 * Sets the array of bytes to use as a buffer to read from.
	 * 
	 * @param byteBuffer
	 *            the array of bytes to use as a buffer
	 */
	public void setByteBuffer(byte[] byteBufferToSet) {
		this.byteBuffer = byteBufferToSet;
	}

	/**
	 * Set the current position to write to/ read from
	 * 
	 * @param position
	 *            the position (0-based index)
	 */
	public void setPosition(int positionToSet) {
		this.position = positionToSet;
	}

	/**
	 * Sets whether this packet was part of a multipacket
	 * 
	 * @param flag
	 *            was this packet part of a multipacket?
	 */
	public void setWasMultiPacket(boolean flag) {
		this.wasMultiPacket = flag;
	}

	public String toString() {
		return dumpClampedBytes(getPosition());
	}

	public String toSuperString() {
		return super.toString();
	}

	/**
	 * Was this packet part of a multipacket?
	 * 
	 * @return was this packet part of a multipacket?
	 */
	public boolean wasMultiPacket() {
		return this.wasMultiPacket;
	}

	final void writeByte(byte b) throws SQLException {
		ensureCapacity(1);

		this.byteBuffer[this.position++] = b;
	}

	// Write a byte array
	final void writeBytesNoNull(byte[] bytes) throws SQLException {
		int len = bytes.length;
		ensureCapacity(len);
		System.arraycopy(bytes, 0, this.byteBuffer, this.position, len);
		this.position += len;
	}

	// Write a byte array with the given offset and length
	final void writeBytesNoNull(byte[] bytes, int offset, int length)
			throws SQLException {
		ensureCapacity(length);
		System.arraycopy(bytes, offset, this.byteBuffer, this.position, length);
		this.position += length;
	}

	final void writeDouble(double d) throws SQLException {
		long l = Double.doubleToLongBits(d);
		writeLongLong(l);
	}

	final void writeFieldLength(long length) throws SQLException {
		if (length < 251) {
			writeByte((byte) length);
		} else if (length < 65536L) {
			ensureCapacity(3);
			writeByte((byte) 252);
			writeInt((int) length);
		} else if (length < 16777216L) {
			ensureCapacity(4);
			writeByte((byte) 253);
			writeLongInt((int) length);
		} else {
			ensureCapacity(9);
			writeByte((byte) 254);
			writeLongLong(length);
		}
	}

	final void writeFloat(float f) throws SQLException {
		ensureCapacity(4);

		int i = Float.floatToIntBits(f);
		byte[] b = this.byteBuffer;
		b[this.position++] = (byte) (i & 0xff);
		b[this.position++] = (byte) (i >>> 8);
		b[this.position++] = (byte) (i >>> 16);
		b[this.position++] = (byte) (i >>> 24);
	}

	// 2000-06-05 Changed
	final void writeInt(int i) throws SQLException {
		ensureCapacity(2);

		byte[] b = this.byteBuffer;
		b[this.position++] = (byte) (i & 0xff);
		b[this.position++] = (byte) (i >>> 8);
	}

	// Write a String using the specified character
	// encoding
	final void writeLenBytes(byte[] b) throws SQLException {
		int len = b.length;
		ensureCapacity(len + 9);
		writeFieldLength(len);
		System.arraycopy(b, 0, this.byteBuffer, this.position, len);
		this.position += len;
	}

	// Write a String using the specified character
	// encoding
	final void writeLenString(String s, String encoding, String serverEncoding,
			SingleByteCharsetConverter converter, boolean parserKnowsUnicode,
			ConnectionImpl conn)
			throws UnsupportedEncodingException, SQLException {
		byte[] b = null;

		if (converter != null) {
			b = converter.toBytes(s);
		} else {
			b = StringUtils.getBytes(s, encoding, serverEncoding,
					parserKnowsUnicode, conn);
		}

		int len = b.length;
		ensureCapacity(len + 9);
		writeFieldLength(len);
		System.arraycopy(b, 0, this.byteBuffer, this.position, len);
		this.position += len;
	}

	// 2000-06-05 Changed
	final void writeLong(long i) throws SQLException {
		ensureCapacity(4);

		byte[] b = this.byteBuffer;
		b[this.position++] = (byte) (i & 0xff);
		b[this.position++] = (byte) (i >>> 8);
		b[this.position++] = (byte) (i >>> 16);
		b[this.position++] = (byte) (i >>> 24);
	}

	// 2000-06-05 Changed
	final void writeLongInt(int i) throws SQLException {
		ensureCapacity(3);
		byte[] b = this.byteBuffer;
		b[this.position++] = (byte) (i & 0xff);
		b[this.position++] = (byte) (i >>> 8);
		b[this.position++] = (byte) (i >>> 16);
	}

	final void writeLongLong(long i) throws SQLException {
		ensureCapacity(8);
		byte[] b = this.byteBuffer;
		b[this.position++] = (byte) (i & 0xff);
		b[this.position++] = (byte) (i >>> 8);
		b[this.position++] = (byte) (i >>> 16);
		b[this.position++] = (byte) (i >>> 24);
		b[this.position++] = (byte) (i >>> 32);
		b[this.position++] = (byte) (i >>> 40);
		b[this.position++] = (byte) (i >>> 48);
		b[this.position++] = (byte) (i >>> 56);
	}

	// Write null-terminated string
	final void writeString(String s) throws SQLException {
		ensureCapacity((s.length() * 2) + 1);
		writeStringNoNull(s);
		this.byteBuffer[this.position++] = 0;
	}
	
	//	 Write null-terminated string in the given encoding
	final void writeString(String s, String encoding, ConnectionImpl conn) throws SQLException {
		ensureCapacity((s.length() * 2) + 1);
		try {
			writeStringNoNull(s, encoding, encoding, false, conn);
		} catch (UnsupportedEncodingException ue) {
			throw new SQLException(ue.toString(), SQLError.SQL_STATE_GENERAL_ERROR);
		}
		
		this.byteBuffer[this.position++] = 0;
	}

	// Write string, with no termination
	final void writeStringNoNull(String s) throws SQLException {
		int len = s.length();
		ensureCapacity(len * 2);
		System.arraycopy(s.getBytes(), 0, this.byteBuffer, this.position, len);
		this.position += len;

		// for (int i = 0; i < len; i++)
		// {
		// this.byteBuffer[this.position++] = (byte)s.charAt(i);
		// }
	}

	// Write a String using the specified character
	// encoding
	final void writeStringNoNull(String s, String encoding,
			String serverEncoding, boolean parserKnowsUnicode, ConnectionImpl conn)
			throws UnsupportedEncodingException, SQLException {
		byte[] b = StringUtils.getBytes(s, encoding, serverEncoding,
				parserKnowsUnicode, conn);

		int len = b.length;
		ensureCapacity(len);
		System.arraycopy(b, 0, this.byteBuffer, this.position, len);
		this.position += len;
	}
}
