/*
 * Copyright 2013 Future Systems
 * 
 * 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.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
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.TimeSpan;
import org.araqne.logdb.TimeUnit;
import org.araqne.logdb.query.aggregator.AggregationField;
import org.araqne.logdb.query.command.Timechart;

public class TimechartParser extends AbstractQueryCommandParser {
	private static final String COMMAND = "timechart";
	private static final String BY = "by";

	public TimechartParser() {
		setDescriptions("Evaluate aggregatation function per time span. If you specify by-clause, fields are generated by group.",
				"지정된 시간 단위마다 집계 함수의 결과를 계산합니다. by 절을 이용하여 그룹 필드를 지정하는 경우, 그룹 필드 값으로 필드가 생성되면서 필드별 통계 값을 계산합니다.");

		setOptions("span", true,
				"Time span. You should use s(second), m(minute), h(hour), d(day), mon(month) time unit. For example, `10s` means 10 seconds interval.",
				"시간 단위. s(초), m(분), h(시), d(일), mon(월) 단위로 지정할 수 있습니다. 예를 들면, 10s의 경우 10초 단위로 통계를 생성합니다.");
	}

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

	@Override
	public Map<String, QueryErrorMessage> getErrorMessages() {
		Map<String, QueryErrorMessage> m = new HashMap<String, QueryErrorMessage>();
		m.put("21800", new QueryErrorMessage("need-aggregation-field", "필드를 입력하십시오."));
		return m;
	}

	@Override
	public QueryCommand parse(QueryContext context, String commandString) {
		// timechart <options> <aggregation functions> by <clause>
		ParseResult r = QueryTokenizer.parseOptions(context, commandString, COMMAND.length(), Arrays.asList("span", "pivot"),
				getFunctionRegistry());

		@SuppressWarnings("unchecked")
		Map<String, String> options = (Map<String, String>) r.value;

		String argsPart = commandString.substring(r.next);
		String aggsPart = argsPart;

		List<String> clauses = new ArrayList<String>();

		// parse clauses
		int byPos = QueryTokenizer.findKeyword(argsPart, BY, 0, true);
		if (byPos > 0) {
			aggsPart = argsPart.substring(0, byPos);
			String clausePart = argsPart.substring(byPos + BY.length());
			clauses = Arrays.asList(clausePart.split(","));
		}

		// parse aggregations
		List<String> aggTerms = QueryTokenizer.parseByComma(aggsPart);
		List<AggregationField> fields = new ArrayList<AggregationField>();

		for (String aggTerm : aggTerms) {
			AggregationField field = AggregationParser.parse(context, aggTerm, getFunctionRegistry());
			fields.add(field);
		}

		if (fields.size() == 0)
			// throw new QueryParseException("need-aggregation-field",
			// COMMAND.length());
			throw new QueryParseException("21800", COMMAND.length() + 1, commandString.length() - 1, null);

		// parse timespan option
		TimeSpan timeSpan = null;
		if (options.containsKey("span"))
			timeSpan = TimeSpan.parse(options.get("span"));

		if (timeSpan == null)
			timeSpan = new TimeSpan(1, TimeUnit.Day);

		boolean pivot = false;
		if (options.containsKey("pivot") && CommandOptions.parseBoolean(options.get("pivot")))
			pivot = true;

		String clause = null;
		if (!clauses.isEmpty())
			clause = clauses.get(0).trim();

		return new Timechart(fields, clause, timeSpan, pivot);
	}
}