/*
 Copyright (C) 2007 MySQL AB

 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.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.UnsupportedEncodingException;
import java.sql.Date;
import java.sql.SQLException;
import java.sql.Time;
import java.sql.Timestamp;
import java.sql.Types;
import java.util.Calendar;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.TimeZone;

/**
 * A RowHolder implementation that holds one row packet (which is re-used by the
 * driver, and thus saves memory allocations), and tries when possible to avoid
 * allocations to break out the results as individual byte[]s.
 * 
 * (this isn't possible when doing things like reading floating point values).
 * 
 * @version $Id: $
 */
public class BufferRow extends ResultSetRow {
	private Buffer rowFromServer;

	/**
	 * The beginning of the row packet
	 */
	private int homePosition = 0;
	
	/**
	 * The home position before the is-null bitmask for server-side
	 * prepared statement result sets
	 */
	private int preNullBitmaskHomePosition = 0;

	/**
	 * The last-requested index, used as an optimization, if you ask for the
	 * same index, we won't seek to find it. If you ask for an index that is >
	 * than the last one requested, we start seeking from the last requested
	 * index.
	 */
	private int lastRequestedIndex = -1;

	/**
	 * The position of the last-requested index, optimization in concert with
	 * lastRequestedIndex.
	 */
	private int lastRequestedPos;

	/**
	 * The metadata of the fields of this result set.
	 */
	private Field[] metadata;

	/**
	 * Is this a row from a server-side prepared statement? If so, they're
	 * encoded differently, so we have different ways of finding where each
	 * column is, and unpacking them.
	 */
	private boolean isBinaryEncoded;

	/**
	 * If binary-encoded, the NULL status of each column is at the beginning of
	 * the row, so we
	 */
	private boolean[] isNull;

	private List openStreams;

	public BufferRow(Buffer buf, Field[] fields, boolean isBinaryEncoded)
			throws SQLException {
		this.rowFromServer = buf;
		this.metadata = fields;
		this.isBinaryEncoded = isBinaryEncoded;
		this.homePosition = this.rowFromServer.getPosition();
		this.preNullBitmaskHomePosition = this.homePosition;

		if (fields != null) {
			setMetadata(fields);
		}
	}

	public synchronized void closeOpenStreams() {
		if (this.openStreams != null) {
			// This would've looked slicker in a "for" loop
			// but we want to skip over streams that fail to
			// close (they probably won't ever)
			// to be more robust and close everything we _can_

			Iterator iter = this.openStreams.iterator();

			while (iter.hasNext()) {

				try {
					((InputStream) iter.next()).close();
				} catch (IOException e) {
					// ignore - it can't really happen in this case
				}
			}

			this.openStreams.clear();
		}
	}

	private int findAndSeekToOffset(int index) throws SQLException {
		if (!this.isBinaryEncoded) {

			if (index == 0) {
				this.lastRequestedIndex = 0;
				this.lastRequestedPos = this.homePosition;
				this.rowFromServer.setPosition(this.homePosition);

				return 0;
			}

			if (index == this.lastRequestedIndex) {
				this.rowFromServer.setPosition(this.lastRequestedPos);

				return this.lastRequestedPos;
			}

			int startingIndex = 0;

			if (index > this.lastRequestedIndex) {
				if (this.lastRequestedIndex >= 0) {
					startingIndex = this.lastRequestedIndex;
				} else {
					startingIndex = 0;
				}
				
				this.rowFromServer.setPosition(this.lastRequestedPos);
			} else {
				this.rowFromServer.setPosition(this.homePosition);
			}

			for (int i = startingIndex; i < index; i++) {
				this.rowFromServer.fastSkipLenByteArray();
			}

			this.lastRequestedIndex = index;
			this.lastRequestedPos = this.rowFromServer.getPosition();

			return this.lastRequestedPos;
		}

		return findAndSeekToOffsetForBinaryEncoding(index);
	}

	private int findAndSeekToOffsetForBinaryEncoding(int index)
			throws SQLException {
		if (index == 0) {
			this.lastRequestedIndex = 0;
			this.lastRequestedPos = this.homePosition;
			this.rowFromServer.setPosition(this.homePosition);
			
			return 0;
		}

		if (index == this.lastRequestedIndex) {
			this.rowFromServer.setPosition(this.lastRequestedPos);

			return this.lastRequestedPos;
		}

		int startingIndex = 0;

		if (index > this.lastRequestedIndex) {
			if (this.lastRequestedIndex >= 0) {
				startingIndex = this.lastRequestedIndex;
			} else {
				// First-time "scan"
				startingIndex = 0;
				this.lastRequestedPos = this.homePosition;
			}
			
			this.rowFromServer.setPosition(this.lastRequestedPos);
		} else {
			this.rowFromServer.setPosition(this.homePosition);
		}

		for (int i = startingIndex; i < index; i++) {
			if (this.isNull[i]) {
				continue;
			}

			int curPosition = this.rowFromServer.getPosition();

			switch (this.metadata[i].getMysqlType()) {
			case MysqlDefs.FIELD_TYPE_NULL:
				break; // for dummy binds

			case MysqlDefs.FIELD_TYPE_TINY:

				this.rowFromServer.setPosition(curPosition + 1);
				break;

			case MysqlDefs.FIELD_TYPE_SHORT:
			case MysqlDefs.FIELD_TYPE_YEAR:
				this.rowFromServer.setPosition(curPosition + 2);

				break;
			case MysqlDefs.FIELD_TYPE_LONG:
			case MysqlDefs.FIELD_TYPE_INT24:
				this.rowFromServer.setPosition(curPosition + 4);

				break;
			case MysqlDefs.FIELD_TYPE_LONGLONG:
				this.rowFromServer.setPosition(curPosition + 8);

				break;
			case MysqlDefs.FIELD_TYPE_FLOAT:
				this.rowFromServer.setPosition(curPosition + 4);

				break;
			case MysqlDefs.FIELD_TYPE_DOUBLE:
				this.rowFromServer.setPosition(curPosition + 8);

				break;
			case MysqlDefs.FIELD_TYPE_TIME:
				this.rowFromServer.fastSkipLenByteArray();

				break;
			case MysqlDefs.FIELD_TYPE_DATE:

				this.rowFromServer.fastSkipLenByteArray();

				break;
			case MysqlDefs.FIELD_TYPE_DATETIME:
			case MysqlDefs.FIELD_TYPE_TIMESTAMP:
				this.rowFromServer.fastSkipLenByteArray();

				break;
			case MysqlDefs.FIELD_TYPE_TINY_BLOB:
			case MysqlDefs.FIELD_TYPE_MEDIUM_BLOB:
			case MysqlDefs.FIELD_TYPE_LONG_BLOB:
			case MysqlDefs.FIELD_TYPE_BLOB:
			case MysqlDefs.FIELD_TYPE_VAR_STRING:
			case MysqlDefs.FIELD_TYPE_VARCHAR:
			case MysqlDefs.FIELD_TYPE_STRING:
			case MysqlDefs.FIELD_TYPE_DECIMAL:
			case MysqlDefs.FIELD_TYPE_NEW_DECIMAL:
			case MysqlDefs.FIELD_TYPE_GEOMETRY:
			case MysqlDefs.FIELD_TYPE_BIT:
				this.rowFromServer.fastSkipLenByteArray();

				break;

			default:
				throw SQLError.createSQLException(Messages
						.getString("MysqlIO.97") //$NON-NLS-1$
						+ this.metadata[i].getMysqlType()
						+ Messages.getString("MysqlIO.98")
						+ (i + 1)
						+ Messages.getString("MysqlIO.99") //$NON-NLS-1$ //$NON-NLS-2$
						+ this.metadata.length
						+ Messages.getString("MysqlIO.100"), //$NON-NLS-1$
						SQLError.SQL_STATE_GENERAL_ERROR);
			}
		}

		this.lastRequestedIndex = index;
		this.lastRequestedPos = this.rowFromServer.getPosition();

		return this.lastRequestedPos;
	}

	public synchronized InputStream getBinaryInputStream(int columnIndex)
			throws SQLException {
		if (this.isBinaryEncoded) {
			if (isNull(columnIndex)) {
				return null;
			}
		}
		
		findAndSeekToOffset(columnIndex);

		long length = this.rowFromServer.readFieldLength();
		
		int offset = this.rowFromServer.getPosition();

		if (length == Buffer.NULL_LENGTH) {
			return null;
		}

		InputStream stream = new ByteArrayInputStream(this.rowFromServer
				.getByteBuffer(), offset, (int) length);

		if (this.openStreams == null) {
			this.openStreams = new LinkedList();
		}

		return stream;
	}

	public byte[] getColumnValue(int index) throws SQLException {
		findAndSeekToOffset(index);

		if (!this.isBinaryEncoded) {
			return this.rowFromServer.readLenByteArray(0);
		}

		if (this.isNull[index]) {
			return null;
		}

		switch (this.metadata[index].getMysqlType()) {
		case MysqlDefs.FIELD_TYPE_NULL:
			return null;

		case MysqlDefs.FIELD_TYPE_TINY:
			return new byte[] { this.rowFromServer.readByte() };

		case MysqlDefs.FIELD_TYPE_SHORT:
		case MysqlDefs.FIELD_TYPE_YEAR:
			return this.rowFromServer.getBytes(2);

		case MysqlDefs.FIELD_TYPE_LONG:
		case MysqlDefs.FIELD_TYPE_INT24:
			return this.rowFromServer.getBytes(4);

		case MysqlDefs.FIELD_TYPE_LONGLONG:
			return this.rowFromServer.getBytes(8);

		case MysqlDefs.FIELD_TYPE_FLOAT:
			return this.rowFromServer.getBytes(4);

		case MysqlDefs.FIELD_TYPE_DOUBLE:
			return this.rowFromServer.getBytes(8);

		case MysqlDefs.FIELD_TYPE_TIME:
		case MysqlDefs.FIELD_TYPE_DATE:
		case MysqlDefs.FIELD_TYPE_DATETIME:
		case MysqlDefs.FIELD_TYPE_TIMESTAMP:
		case MysqlDefs.FIELD_TYPE_TINY_BLOB:
		case MysqlDefs.FIELD_TYPE_MEDIUM_BLOB:
		case MysqlDefs.FIELD_TYPE_LONG_BLOB:
		case MysqlDefs.FIELD_TYPE_BLOB:
		case MysqlDefs.FIELD_TYPE_VAR_STRING:
		case MysqlDefs.FIELD_TYPE_VARCHAR:
		case MysqlDefs.FIELD_TYPE_STRING:
		case MysqlDefs.FIELD_TYPE_DECIMAL:
		case MysqlDefs.FIELD_TYPE_NEW_DECIMAL:
		case MysqlDefs.FIELD_TYPE_GEOMETRY:
		case MysqlDefs.FIELD_TYPE_BIT:
			return this.rowFromServer.readLenByteArray(0);

		default:
			throw SQLError.createSQLException(Messages.getString("MysqlIO.97") //$NON-NLS-1$
					+ this.metadata[index].getMysqlType()
					+ Messages.getString("MysqlIO.98")
					+ (index + 1)
					+ Messages.getString("MysqlIO.99") //$NON-NLS-1$ //$NON-NLS-2$
					+ this.metadata.length + Messages.getString("MysqlIO.100"), //$NON-NLS-1$
					SQLError.SQL_STATE_GENERAL_ERROR);
		}
	}

	public int getInt(int columnIndex) throws SQLException {

		findAndSeekToOffset(columnIndex);

		long length = this.rowFromServer.readFieldLength();
		
		int offset = this.rowFromServer.getPosition();

		if (length == Buffer.NULL_LENGTH) {
			return 0;
		}

		return StringUtils.getInt(this.rowFromServer.getByteBuffer(), offset,
				offset + (int) length);
	}

	public long getLong(int columnIndex) throws SQLException {
		findAndSeekToOffset(columnIndex);

		long length = this.rowFromServer.readFieldLength();
		
		int offset = this.rowFromServer.getPosition();
		
		if (length == Buffer.NULL_LENGTH) {
			return 0;
		}

		return StringUtils.getLong(this.rowFromServer.getByteBuffer(), offset,
				offset + (int) length);
	}

	public double getNativeDouble(int columnIndex) throws SQLException {
		if (isNull(columnIndex)) {
			return 0;
		}
		
		findAndSeekToOffset(columnIndex);
	
		int offset = this.rowFromServer.getPosition();

		return getNativeDouble(this.rowFromServer.getByteBuffer(), offset);
	}

	public float getNativeFloat(int columnIndex) throws SQLException {
		if (isNull(columnIndex)) {
			return 0;
		}
		
		findAndSeekToOffset(columnIndex);

		int offset = this.rowFromServer.getPosition();

		return getNativeFloat(this.rowFromServer.getByteBuffer(), offset);
	}

	public int getNativeInt(int columnIndex) throws SQLException {
		if (isNull(columnIndex)) {
			return 0;
		}
		
		findAndSeekToOffset(columnIndex);

		int offset = this.rowFromServer.getPosition();

		return getNativeInt(this.rowFromServer.getByteBuffer(), offset);
	}

	public long getNativeLong(int columnIndex) throws SQLException {
		if (isNull(columnIndex)) {
			return 0;
		}
		
		findAndSeekToOffset(columnIndex);

		int offset = this.rowFromServer.getPosition();

		return getNativeLong(this.rowFromServer.getByteBuffer(), offset);
	}

	public short getNativeShort(int columnIndex) throws SQLException {
		if (isNull(columnIndex)) {
			return 0;
		}
		
		findAndSeekToOffset(columnIndex);

		int offset = this.rowFromServer.getPosition();

		return getNativeShort(this.rowFromServer.getByteBuffer(), offset);
	}

	public Timestamp getNativeTimestamp(int columnIndex,
			Calendar targetCalendar, TimeZone tz, boolean rollForward,
			ConnectionImpl conn, ResultSetImpl rs) throws SQLException {
		if (isNull(columnIndex)) {
			return null;
		}
		
		findAndSeekToOffset(columnIndex);

		long length = this.rowFromServer.readFieldLength();
		
		int offset = this.rowFromServer.getPosition();

		return getNativeTimestamp(this.rowFromServer.getByteBuffer(), offset,
				(int) length, targetCalendar, tz, rollForward, conn, rs);
	}

	public Reader getReader(int columnIndex) throws SQLException {
		InputStream stream = getBinaryInputStream(columnIndex);

		if (stream == null) {
			return null;
		}

		try {
			return new InputStreamReader(stream, this.metadata[columnIndex]
					.getCharacterSet());
		} catch (UnsupportedEncodingException e) {
			SQLException sqlEx = SQLError.createSQLException("");

			sqlEx.initCause(e);

			throw sqlEx;
		}
	}

	public String getString(int columnIndex, String encoding, ConnectionImpl conn)
			throws SQLException {
		if (this.isBinaryEncoded) {
			if (isNull(columnIndex)) {
				return null;
			}
		}
		
		findAndSeekToOffset(columnIndex);

		long length = this.rowFromServer.readFieldLength();

		if (length == Buffer.NULL_LENGTH) {
			return null;
		}

		if (length == 0) {
			return "";
		}

		// TODO: I don't like this, would like to push functionality back
		// to the buffer class somehow

		int offset = this.rowFromServer.getPosition();

		return getString(encoding, conn, this.rowFromServer.getByteBuffer(),
				offset, (int) length);
	}

	public Time getTimeFast(int columnIndex, Calendar targetCalendar,
			TimeZone tz, boolean rollForward, ConnectionImpl conn,
			ResultSetImpl rs) throws SQLException {
		if (isNull(columnIndex)) {
			return null;
		}

		findAndSeekToOffset(columnIndex);

		long length = this.rowFromServer.readFieldLength();
		
		int offset = this.rowFromServer.getPosition();

		return getTimeFast(columnIndex, this.rowFromServer.getByteBuffer(),
				offset, (int)length, targetCalendar, tz, rollForward, conn, rs);
	}

	public Timestamp getTimestampFast(int columnIndex, Calendar targetCalendar,
			TimeZone tz, boolean rollForward, ConnectionImpl conn,
			ResultSetImpl rs) throws SQLException {
		if (isNull(columnIndex)) {
			return null;
		}

		findAndSeekToOffset(columnIndex);

		long length = this.rowFromServer.readFieldLength();
		
		int offset = this.rowFromServer.getPosition();

		return getTimestampFast(columnIndex,
				this.rowFromServer.getByteBuffer(), offset, (int)length, targetCalendar, tz,
				rollForward, conn, rs);
	}

	public boolean isFloatingPointNumber(int index) throws SQLException {
		if (this.isBinaryEncoded) {
			switch (this.metadata[index].getSQLType()) {
			case Types.FLOAT:
			case Types.DOUBLE:
			case Types.DECIMAL:
			case Types.NUMERIC:
				return true;
			default:
				return false;
			}
		}

		findAndSeekToOffset(index);

		long length = this.rowFromServer.readFieldLength();

		if (length == Buffer.NULL_LENGTH) {
			return false;
		}

		if (length == 0) {
			return false;
		}

		for (int i = 0; i < (int) length; i++) {
			char c = (char) this.rowFromServer.readByte();

			if ((c == 'e') || (c == 'E')) {
				return true;
			}
		}

		return false;
	}

	public boolean isNull(int index) throws SQLException {
		if (!this.isBinaryEncoded) {
			findAndSeekToOffset(index);

			return this.rowFromServer.readFieldLength() == Buffer.NULL_LENGTH;
		}

		return this.isNull[index];
	}

	public long length(int index) throws SQLException {
		findAndSeekToOffset(index);

		long length = this.rowFromServer.readFieldLength();

		if (length == Buffer.NULL_LENGTH) {
			return 0;
		}

		return length;
	}

	public void setColumnValue(int index, byte[] value) throws SQLException {
		throw new OperationNotSupportedException();
	}

	public ResultSetRow setMetadata(Field[] f) throws SQLException {
		super.setMetadata(f);

		if (this.isBinaryEncoded) {
			setupIsNullBitmask();
		}
		
		return this;
	}

	/**
	 * Unpacks the bitmask at the head of the row packet that tells us what
	 * columns hold null values, and sets the "home" position directly after the
	 * bitmask.
	 */
	private void setupIsNullBitmask() throws SQLException {
		if (this.isNull != null) {
			return; // we've already done this
		}
		
		this.rowFromServer.setPosition(this.preNullBitmaskHomePosition);
		
		int nullCount = (this.metadata.length + 9) / 8;

		byte[] nullBitMask = new byte[nullCount];

		for (int i = 0; i < nullCount; i++) {
			nullBitMask[i] = this.rowFromServer.readByte();
		}

		this.homePosition = this.rowFromServer.getPosition();

		this.isNull = new boolean[this.metadata.length];

		int nullMaskPos = 0;
		int bit = 4; // first two bits are reserved for future use

		for (int i = 0; i < this.metadata.length; i++) {

			this.isNull[i] = ((nullBitMask[nullMaskPos] & bit) != 0);

			if (((bit <<= 1) & 255) == 0) {
				bit = 1; /* To next byte */

				nullMaskPos++;
			}
		}
	}

	public Date getDateFast(int columnIndex, ConnectionImpl conn,
			ResultSetImpl rs, Calendar targetCalendar) throws SQLException {
		if (isNull(columnIndex)) {
			return null;
		}

		findAndSeekToOffset(columnIndex);

		long length = this.rowFromServer.readFieldLength();
		
		int offset = this.rowFromServer.getPosition();

		return getDateFast(columnIndex, this.rowFromServer.getByteBuffer(),
				offset, (int)length, conn, rs, targetCalendar);
	}

	public java.sql.Date getNativeDate(int columnIndex, ConnectionImpl conn,
			ResultSetImpl rs) throws SQLException {
		if (isNull(columnIndex)) {
			return null;
		}
		
		findAndSeekToOffset(columnIndex);

		long length = this.rowFromServer.readFieldLength();
		
		int offset = this.rowFromServer.getPosition();
		
		return getNativeDate(columnIndex, this.rowFromServer.getByteBuffer(),
				offset, (int) length, conn, rs);
	}

	public Object getNativeDateTimeValue(int columnIndex, Calendar targetCalendar,
			int jdbcType, int mysqlType, TimeZone tz,
			boolean rollForward, ConnectionImpl conn, ResultSetImpl rs)
			throws SQLException {
		if (isNull(columnIndex)) {
			return null;
		}
		
		findAndSeekToOffset(columnIndex);

		long length = this.rowFromServer.readFieldLength();
		
		int offset = this.rowFromServer.getPosition();

		return getNativeDateTimeValue(columnIndex, this.rowFromServer
				.getByteBuffer(), offset, (int) length, targetCalendar, jdbcType,
				mysqlType, tz, rollForward, conn, rs);
	}

	public Time getNativeTime(int columnIndex, Calendar targetCalendar,
			TimeZone tz, boolean rollForward, ConnectionImpl conn,
			ResultSetImpl rs) throws SQLException {
		if (isNull(columnIndex)) {
			return null;
		}
		
		findAndSeekToOffset(columnIndex);

		long length = this.rowFromServer.readFieldLength();
		
		int offset = this.rowFromServer.getPosition();
		
		return getNativeTime(columnIndex, this.rowFromServer.getByteBuffer(),
				offset, (int) length, targetCalendar, tz, rollForward, conn, rs);
	}
}