/*
 * 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.aggregator;

import java.util.List;

import org.araqne.logdb.QueryParseException;
import org.araqne.logdb.Row;
import org.araqne.logdb.query.expr.Expression;

public class Count extends AbstractAggregationFunction {
	private Expression expr;
	private long result = 0;

	public Count(List<Expression> exprs) {
		super(exprs);

		if (exprs.size() > 1)
			// throw new QueryParseException("invalid-count-args", -1);
			throw new QueryParseException("91010", -1, -1, null);

		if (exprs.size() == 1)
			this.expr = exprs.get(0);
	}

	@Override
	public String getName() {
		return "count";
	}

	@Override
	public void apply(Row map) {
		if (expr == null)
			result++;
		else if (expr.eval(map) != null)
			result++;
	}

	@Override
	public Object eval() {
		return result;
	}

	@Override
	public void clean() {
		result = 0;
	}

	@Override
	public AggregationFunction clone() {
		Count c = new Count(exprs);
		c.result = result;
		return c;
	}

	@Override
	public void merge(AggregationFunction func) {
		Count c = (Count) func;
		this.result += c.result;
	}

	@Override
	public void deserialize(Object[] values) {
		result = (Long) values[0];
	}

	@Override
	public Object[] serialize() {
		Object[] l = new Object[1];
		l[0] = result;
		return l;
	}

	@Override
	public String toString() {
		if (expr == null)
			return "count";
		return "count(" + expr + ")";
	}

	@Override
	public boolean canBeDistributed() {
		return true;
	}

	@Override
	public AggregationFunction mapper(List<Expression> exprs) {
		return new Count(exprs);
	}

	@Override
	public AggregationFunction reducer(List<Expression> exprs) {
		return new Sum(exprs);
	}
}