/*
 * Copyright 1999-2012 Alibaba Group.
 *  
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *  
 *      http://www.apache.org/licenses/LICENSE-2.0
 *  
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.alibaba.cobar.manager.response;

import java.nio.ByteBuffer;
import java.util.HashMap;
import java.util.Map;

import com.alibaba.cobar.config.Fields;
import com.alibaba.cobar.manager.ManagerConnection;
import com.alibaba.cobar.mysql.PacketUtil;
import com.alibaba.cobar.net.mysql.EOFPacket;
import com.alibaba.cobar.net.mysql.FieldPacket;
import com.alibaba.cobar.net.mysql.ResultSetHeaderPacket;
import com.alibaba.cobar.net.mysql.RowDataPacket;
import com.alibaba.cobar.util.StringUtil;

/**
 * @author wenfeng.cenwf 2011-4-25
 */
public final class ShowVariables {

    private static final int FIELD_COUNT = 2;
    private static final ResultSetHeaderPacket header = PacketUtil.getHeader(FIELD_COUNT);
    private static final FieldPacket[] fields = new FieldPacket[FIELD_COUNT];
    private static final EOFPacket eof = new EOFPacket();
    static {
        int i = 0;
        byte packetId = 0;
        header.packetId = ++packetId;

        fields[i] = PacketUtil.getField("VARIABLE_NAME", Fields.FIELD_TYPE_VAR_STRING);
        fields[i++].packetId = ++packetId;

        fields[i] = PacketUtil.getField("VALUE", Fields.FIELD_TYPE_VAR_STRING);
        fields[i++].packetId = ++packetId;

        eof.packetId = ++packetId;
    }

    public static void execute(ManagerConnection c) {
        ByteBuffer buffer = c.allocate();

        // write header
        buffer = header.write(buffer, c);

        // write fields
        for (FieldPacket field : fields) {
            buffer = field.write(buffer, c);
        }

        // write eof
        buffer = eof.write(buffer, c);

        // write rows
        byte packetId = eof.packetId;
        for (Map.Entry<String, String> e : variables.entrySet()) {
            RowDataPacket row = getRow(e.getKey(), e.getValue(), c.getCharset());
            row.packetId = ++packetId;
            buffer = row.write(buffer, c);
        }

        // write lastEof
        EOFPacket lastEof = new EOFPacket();
        lastEof.packetId = ++packetId;
        buffer = lastEof.write(buffer, c);

        // write buffer
        c.write(buffer);
    }

    private static RowDataPacket getRow(String name, String value, String charset) {
        RowDataPacket row = new RowDataPacket(FIELD_COUNT);
        row.add(StringUtil.encode(name, charset));
        row.add(StringUtil.encode(value, charset));
        return row;
    }

    private static final Map<String, String> variables = new HashMap<String, String>();
    static {
        variables.put("character_set_client", "utf8");
        variables.put("character_set_connection", "utf8");
        variables.put("character_set_results", "utf8");
        variables.put("character_set_server", "utf8");
        variables.put("init_connect", "");
        variables.put("interactive_timeout", "172800");
        variables.put("lower_case_table_names", "1");
        variables.put("max_allowed_packet", "16777216");
        variables.put("net_buffer_length", "8192");
        variables.put("net_write_timeout", "60");
        variables.put("query_cache_size", "0");
        variables.put("query_cache_type", "OFF");
        variables.put("sql_mode", "STRICT_TRANS_TABLES");
        variables.put("system_time_zone", "CST");
        variables.put("time_zone", "SYSTEM");
        variables.put("lower_case_table_names", "1");
        variables.put("tx_isolation", "REPEATABLE-READ");
        variables.put("wait_timeout", "172800");
    }

}