/**
 * Copyright (C) 2009-2013 FoundationDB, LLC
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package com.foundationdb.server.rowdata;

import com.foundationdb.ais.model.TableName;
import com.foundationdb.server.AkServerUtil;
import com.foundationdb.server.error.UnsupportedCharsetException;

import java.io.UnsupportedEncodingException;

final class ConversionHelper {
    // "public" methods

    /**
     * Writes a VARCHAR or CHAR: inserts the correct-sized PREFIX for MySQL
     * VARCHAR. Can be used temporarily for
     * the BLOB types as well.
     *
     * @param string Othe string to put in
     * @param bytes Buffer to write bytes into
     * @param offset Position within bytes to write at
     * @param fieldDef Corresponding field
     * @return How many positions in bytes were used
     */
    public static int encodeString(String string, final byte[] bytes, final int offset, final FieldDef fieldDef) {
        assert string != null;
        final byte[] b;
        String charsetName = fieldDef.column().getCharsetName();
        if (charsetName == null) {
            // For instance, a BLOB, which does no have a charset of its own.
            charsetName = fieldDef.column().getTable().getDefaultedCharsetName();
        }
        try {
            b = string.getBytes(charsetName);
        } catch (UnsupportedEncodingException e) {
            TableName table = fieldDef.column().getTable().getName();
            throw new UnsupportedCharsetException(charsetName);
        }
        return putByteArray(b, 0, b.length, bytes, offset, fieldDef);
    }

    public static int putByteArray(final byte[] src, final int srcOffset, final int srcLength,
                                   final byte[] dst, final int dstOffset, final FieldDef fieldDef) {
        int prefixSize = fieldDef.getPrefixSize();
        AkServerUtil.putIntegerByWidth(dst, dstOffset, prefixSize, srcLength);
        System.arraycopy(src, srcOffset, dst, dstOffset + prefixSize, srcLength);
        return prefixSize + srcLength;

    }

    // for use in this class

    private ConversionHelper() {}
}