/*
 * Copyright 2002-2014 the original author or authors.
 *
 * 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.springframework.expression.spel.ast;

import java.math.BigDecimal;

import org.springframework.expression.spel.ExpressionState;
import org.springframework.util.ClassUtils;
import org.springframework.util.NumberUtils;
import org.springframework.util.ObjectUtils;

/**
 * Common supertype for operators that operate on either one or two operands.
 * In the case of multiply or divide there would be two operands, but for
 * unary plus or minus, there is only one.
 *
 * @author Andy Clement
 * @author Juergen Hoeller
 * @author Giovanni Dall'Oglio Risso
 * @since 3.0
 */
public abstract class Operator extends SpelNodeImpl {

	private final String operatorName;


	public Operator(String payload,int pos,SpelNodeImpl... operands) {
		super(pos, operands);
		this.operatorName = payload;
	}


	public SpelNodeImpl getLeftOperand() {
		return this.children[0];
	}

	public SpelNodeImpl getRightOperand() {
		return this.children[1];
	}

	public final String getOperatorName() {
		return this.operatorName;
	}

	/**
	 * String format for all operators is the same '(' [operand] [operator] [operand] ')'
	 */
	@Override
	public String toStringAST() {
		StringBuilder sb = new StringBuilder();
		sb.append("(");
		sb.append(getChild(0).toStringAST());
		for (int i = 1; i < getChildCount(); i++) {
			sb.append(" ").append(getOperatorName()).append(" ");
			sb.append(getChild(i).toStringAST());
		}
		sb.append(")");
		return sb.toString();
	}


	protected boolean equalityCheck(ExpressionState state, Object left, Object right) {
		if (left instanceof Number && right instanceof Number) {
			Number leftNumber = (Number) left;
			Number rightNumber = (Number) right;

			if (leftNumber instanceof BigDecimal || rightNumber instanceof BigDecimal) {
				BigDecimal leftBigDecimal = NumberUtils.convertNumberToTargetClass(leftNumber, BigDecimal.class);
				BigDecimal rightBigDecimal = NumberUtils.convertNumberToTargetClass(rightNumber, BigDecimal.class);
				return (leftBigDecimal == null ? rightBigDecimal == null : leftBigDecimal.compareTo(rightBigDecimal) == 0);
			}

			if (leftNumber instanceof Double || rightNumber instanceof Double) {
				return (leftNumber.doubleValue() == rightNumber.doubleValue());
			}

			if (leftNumber instanceof Float || rightNumber instanceof Float) {
				return (leftNumber.floatValue() == rightNumber.floatValue());
			}

			if (leftNumber instanceof Long || rightNumber instanceof Long) {
				return (leftNumber.longValue() == rightNumber.longValue());
			}

			return (leftNumber.intValue() == rightNumber.intValue());
		}

		if (left instanceof CharSequence && right instanceof CharSequence) {
			return left.toString().equals(right.toString());
		}

		if (ObjectUtils.nullSafeEquals(left, right)) {
			return true;
		}

		if (left instanceof Comparable && right instanceof Comparable) {
			Class<?> ancestor = ClassUtils.determineCommonAncestor(left.getClass(), right.getClass());
			if (ancestor != null && Comparable.class.isAssignableFrom(ancestor)) {
				return (state.getTypeComparator().compare(left, right) == 0);
			}
		}

		return false;
	}

}
