/*
 * Copyright 1999-2015 dangdang.com.
 * <p>
 * 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.
 * </p>
 */

package com.dangdang.ddframe.rdb.sharding.parsing.parser.dialect.postgresql;

import com.dangdang.ddframe.rdb.sharding.api.rule.ShardingRule;
import com.dangdang.ddframe.rdb.sharding.parsing.lexer.LexerEngine;
import com.dangdang.ddframe.rdb.sharding.parsing.lexer.dialect.postgresql.PostgreSQLKeyword;
import com.dangdang.ddframe.rdb.sharding.parsing.lexer.token.DefaultKeyword;
import com.dangdang.ddframe.rdb.sharding.parsing.lexer.token.Keyword;
import com.dangdang.ddframe.rdb.sharding.parsing.parser.exception.SQLParsingUnsupportedException;
import com.dangdang.ddframe.rdb.sharding.parsing.parser.sql.AbstractOrderBySQLParser;
import com.dangdang.ddframe.rdb.sharding.parsing.parser.sql.DistinctSQLParser;
import com.dangdang.ddframe.rdb.sharding.parsing.parser.sql.GroupBySQLParser;
import com.dangdang.ddframe.rdb.sharding.parsing.parser.sql.HavingSQLParser;
import com.dangdang.ddframe.rdb.sharding.parsing.parser.sql.SelectListSQLParser;
import com.dangdang.ddframe.rdb.sharding.parsing.parser.sql.WhereSQLParser;
import com.dangdang.ddframe.rdb.sharding.parsing.parser.statement.dql.select.AbstractSelectParser;
import com.dangdang.ddframe.rdb.sharding.parsing.parser.statement.dql.select.SelectStatement;

/**
 * PostgreSQL Select语句解析器.
 *
 * @author zhangliang
 */
public final class PostgreSQLSelectParser extends AbstractSelectParser {
    
    private final DistinctSQLParser distinctSQLParser;
    
    private final SelectListSQLParser selectListSQLParser;
    
    private final GroupBySQLParser groupBySQLParser;
    
    private final HavingSQLParser havingSQLParser;
    
    private final AbstractOrderBySQLParser orderBySQLParser;
    
    private  final PostgreSQLLimitSQLParser limitSQLParser;
    
    public PostgreSQLSelectParser(final ShardingRule shardingRule, final LexerEngine lexerEngine) {
        super(shardingRule, lexerEngine, new WhereSQLParser(lexerEngine));
        distinctSQLParser = new DistinctSQLParser(lexerEngine);
        selectListSQLParser = new SelectListSQLParser(shardingRule, lexerEngine);
        groupBySQLParser = new GroupBySQLParser(lexerEngine);
        havingSQLParser = new HavingSQLParser(lexerEngine);
        orderBySQLParser = new PostgreSQLOrderBySQLParser(lexerEngine);
        limitSQLParser = new PostgreSQLLimitSQLParser(lexerEngine);
    }
    
    @Override
    protected void parseInternal(final SelectStatement selectStatement) {
        distinctSQLParser.parse();
        selectListSQLParser.parse(selectStatement, getItems());
        parseFrom(selectStatement);
        parseWhere(selectStatement);
        groupBySQLParser.parse(selectStatement);
        havingSQLParser.parse();
        orderBySQLParser.parse(selectStatement);
        limitSQLParser.parse(selectStatement);
        parseFor();
        parseRest();
    }
    
    private void parseFor() {
        if (!getLexerEngine().skipIfEqual(DefaultKeyword.FOR)) {
            return;
        }
        getLexerEngine().skipIfEqual(DefaultKeyword.UPDATE, PostgreSQLKeyword.SHARE);
        if (getLexerEngine().equalAny(DefaultKeyword.OF)) {
            throw new SQLParsingUnsupportedException(DefaultKeyword.OF);
        }
        getLexerEngine().skipIfEqual(PostgreSQLKeyword.NOWAIT);
    }
    
    @Override
    protected Keyword[] getUnsupportedKeywordsRest() {
        return new Keyword[] {PostgreSQLKeyword.WINDOW, DefaultKeyword.FETCH};
    }
}