/*
 * Copyright (c) 2011-2015 EPFL DATA Laboratory
 * Copyright (c) 2014-2015 The Squall Collaboration (see NOTICE)
 *
 * All rights reserved.
 *
 * 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 ch.epfl.data.squall.expressions;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import ch.epfl.data.squall.types.IntegerType;
import ch.epfl.data.squall.types.NumericType;
import ch.epfl.data.squall.types.Type;
import ch.epfl.data.squall.visitors.ValueExpressionVisitor;

/*
 * This class implements Division between any Number type (Integer, Double, Long, etc.).
 * It convert all the value to double, and then return the final result by automatic casting
 *   (i.e. (int)1.0 )
 *
 * Double can store integers exactly in binary representation,
 *   so we won't lose the precision on our integer operations.
 *
 * Having different T types in the constructor arguments
 *   does not result in exception in the constructor,
 *   but rather in eval method.
 */
public class Division implements ValueExpression<Integer> {

    private static final long serialVersionUID = 1L;

    private final List<ValueExpression> _veList = new ArrayList<ValueExpression>();
    private final NumericType<Integer> _wrapper = new IntegerType();

    public Division(ValueExpression ve1, ValueExpression ve2,
	    ValueExpression... veArray) {
	_veList.add(ve1);
	_veList.add(ve2);
	_veList.addAll(Arrays.asList(veArray));
    }

    @Override
    public void accept(ValueExpressionVisitor vev) {
	vev.visit(this);
    }

    @Override
    public void changeValues(int i, ValueExpression<Integer> newExpr) {

    }

    @Override
    public Integer eval(List<String> tuple) {
	final ValueExpression firstVE = _veList.get(0);
	final Object firstObj = firstVE.eval(tuple);
	final NumericType firstType = (NumericType) firstVE.getType();
	double result = firstType.toDouble(firstObj);

	for (int i = 1; i < _veList.size(); i++) {
	    final ValueExpression currentVE = _veList.get(i);
	    final Object currentObj = currentVE.eval(tuple);
	    final NumericType currentType = (NumericType) currentVE.getType();
	    result /= currentType.toDouble(currentObj);
	}
	return _wrapper.fromDouble(result);
    }

    @Override
    public String evalString(List<String> tuple) {
	final Integer result = eval(tuple);
	return _wrapper.toString(result);
    }

    @Override
    public List<ValueExpression> getInnerExpressions() {
	return _veList;
    }

    @Override
    public Type getType() {
	return _wrapper;
    }

    @Override
    public void inverseNumber() {

    }

    @Override
    public boolean isNegative() {
	return false;
    }

    @Override
    public String toString() {
	final StringBuilder sb = new StringBuilder();
	for (int i = 0; i < _veList.size(); i++) {
	    sb.append("(").append(_veList.get(i)).append(")");
	    if (i != _veList.size() - 1)
		sb.append(" / ");
	}
	return sb.toString();
    }

}