/*
 * Copyright 2013 Eediom Inc.
 * 
 * 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 org.araqne.logdb.query.parser;

import java.util.HashMap;
import java.util.Map;

import org.araqne.logdb.AbstractQueryCommandParser;
import org.araqne.logdb.QueryCommand;
import org.araqne.logdb.QueryContext;
import org.araqne.logdb.QueryErrorMessage;
import org.araqne.logdb.QueryParseException;
import org.araqne.logdb.query.command.Evalc;
import org.araqne.logdb.query.expr.Expression;

/**
 * @since 1.7.5
 * @author xeraph
 * 
 */
public class EvalcParser extends AbstractQueryCommandParser {

	private static final String COMMAND = "evalc";

	public EvalcParser() {
		setDescriptions(
				"Evaluate right-hand side expression and assign it to query context as query parameter",
				"우변의 표현식을 평가하여 새로운 쿼리 매개변수를 할당하거나 기존의 쿼리 매개변수 값을 대체합니다. set 쿼리 명령어와 다르게 입력되는 쿼리 실행 시점에 모든 데이터에 대해 평가됩니다. 우변에는 값으로 평가될 수 있는 모든 조합의 표현식을 입력할 수 있습니다.");
	}

	@Override
	public String getCommandName() {
		return COMMAND;
	}

	@Override
	public Map<String, QueryErrorMessage> getErrorMessages() {
		Map<String, QueryErrorMessage> m = new HashMap<String, QueryErrorMessage>();
		m.put("20200", new QueryErrorMessage("assign-token-not-found", "할당자(=) 가 없습니다."));
		m.put("20201", new QueryErrorMessage("constant-name-not-found", "변수 이름이 없습니다."));
		m.put("20202", new QueryErrorMessage("expression-not-found", "표현식이 없습니다."));
		return m;
	}

	@Override
	public QueryCommand parse(QueryContext context, String commandString) {
		// find assignment symbol
		int p = QueryTokenizer.findKeyword(commandString, "=");
		if (p < 0)
			// throw new QueryParseException("assign-token-not-found",
			// commandString.length());
			throw new QueryParseException("20200", COMMAND.length() + 1, commandString.length() - 1, null);

		String constantName = commandString.substring(COMMAND.length(), p).trim();
		String exprToken = commandString.substring(p + 1).trim();

		if (constantName.isEmpty())
			// throw new QueryParseException("constant-name-not-found",
			// commandString.length());
			throw new QueryParseException("20201", COMMAND.length() + 1, p - 1, null);

		if (exprToken.isEmpty())
			// throw new QueryParseException("expression-not-found",
			// commandString.length());
			throw new QueryParseException("20202", p + 1, commandString.length() - 1, null);

		Expression expr = ExpressionParser.parse(context, exprToken, getFunctionRegistry());
		return new Evalc(context, constantName, expr);
	}

}