/*
 * Copyright 2002-2018 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 java.math.BigInteger;

import org.springframework.asm.MethodVisitor;
import org.springframework.expression.EvaluationException;
import org.springframework.expression.Operation;
import org.springframework.expression.TypedValue;
import org.springframework.expression.spel.CodeFlow;
import org.springframework.expression.spel.ExpressionState;
import org.springframework.util.Assert;
import org.springframework.util.NumberUtils;

Implements the multiply operator. 
Conversions and promotions are handled as defined in
Section 5.6.2 of the
Java Language Specification, with the addiction of BigDecimal/BigInteger management: 
If any of the operands is of a reference type, unboxing conversion (Section 5.1.8)
is performed. Then:
 If either operand is of type BigDecimal, the other is converted to BigDecimal.

If either operand is of type double, the other is converted to double.

Otherwise, if either operand is of type float, the other is converted to float.
 If either operand is of type BigInteger, the other is converted to BigInteger.

Otherwise, if either operand is of type long, the other is converted to long.

Otherwise, both operands are converted to type int.
Author:
Andy Clement, Juergen Hoeller, Sam Brannen, Giovanni Dall'Oglio Risso
Since:
3.0/**
 * Implements the {@code multiply} operator.
 *
 * <p>Conversions and promotions are handled as defined in
 * <a href="http://java.sun.com/docs/books/jls/third_edition/html/conversions.html">Section 5.6.2 of the
 * Java Language Specification</a>, with the addiction of {@code BigDecimal}/{@code BigInteger} management:
 *
 * <p>If any of the operands is of a reference type, unboxing conversion (Section 5.1.8)
 * is performed. Then:<br>
 * If either operand is of type {@code BigDecimal}, the other is converted to {@code BigDecimal}.<br>
 * If either operand is of type double, the other is converted to double.<br>
 * Otherwise, if either operand is of type float, the other is converted to float.<br>
 * If either operand is of type {@code BigInteger}, the other is converted to {@code BigInteger}.<br>
 * Otherwise, if either operand is of type long, the other is converted to long.<br>
 * Otherwise, both operands are converted to type int.
 *
 * @author Andy Clement
 * @author Juergen Hoeller
 * @author Sam Brannen
 * @author Giovanni Dall'Oglio Risso
 * @since 3.0
 */
public class OpMultiply extends Operator {

	public OpMultiply(int pos, SpelNodeImpl... operands) {
		super("*", pos, operands);
	}


	
Implements the multiply operator directly here for certain types of supported operands and otherwise delegates to any registered overloader for types not supported here. 
Supported operand types:

numbers
String and int ('abc' * 2 == 'abcabc')

/**
	 * Implements the {@code multiply} operator directly here for certain types
	 * of supported operands and otherwise delegates to any registered overloader
	 * for types not supported here.
	 * <p>Supported operand types:
	 * <ul>
	 * <li>numbers
	 * <li>String and int ('abc' * 2 == 'abcabc')
	 * </ul>
	 */
	@Override
	public TypedValue getValueInternal(ExpressionState state) throws EvaluationException {
		Object leftOperand = getLeftOperand().getValueInternal(state).getValue();
		Object rightOperand = getRightOperand().getValueInternal(state).getValue();

		if (leftOperand instanceof Number && rightOperand instanceof Number) {
			Number leftNumber = (Number) leftOperand;
			Number rightNumber = (Number) rightOperand;

			if (leftNumber instanceof BigDecimal || rightNumber instanceof BigDecimal) {
				BigDecimal leftBigDecimal = NumberUtils.convertNumberToTargetClass(leftNumber, BigDecimal.class);
				BigDecimal rightBigDecimal = NumberUtils.convertNumberToTargetClass(rightNumber, BigDecimal.class);
				return new TypedValue(leftBigDecimal.multiply(rightBigDecimal));
			}
			else if (leftNumber instanceof Double || rightNumber instanceof Double) {
				this.exitTypeDescriptor = "D";
				return new TypedValue(leftNumber.doubleValue() * rightNumber.doubleValue());
			}
			else if (leftNumber instanceof Float || rightNumber instanceof Float) {
				this.exitTypeDescriptor = "F";
				return new TypedValue(leftNumber.floatValue() * rightNumber.floatValue());
			}
			else if (leftNumber instanceof BigInteger || rightNumber instanceof BigInteger) {
				BigInteger leftBigInteger = NumberUtils.convertNumberToTargetClass(leftNumber, BigInteger.class);
				BigInteger rightBigInteger = NumberUtils.convertNumberToTargetClass(rightNumber, BigInteger.class);
				return new TypedValue(leftBigInteger.multiply(rightBigInteger));
			}
			else if (leftNumber instanceof Long || rightNumber instanceof Long) {
				this.exitTypeDescriptor = "J";
				return new TypedValue(leftNumber.longValue() * rightNumber.longValue());
			}
			else if (CodeFlow.isIntegerForNumericOp(leftNumber) || CodeFlow.isIntegerForNumericOp(rightNumber)) {
				this.exitTypeDescriptor = "I";
				return new TypedValue(leftNumber.intValue() * rightNumber.intValue());
			}
			else {
				// Unknown Number subtypes -> best guess is double multiplication
				return new TypedValue(leftNumber.doubleValue() * rightNumber.doubleValue());
			}
		}

		if (leftOperand instanceof String && rightOperand instanceof Integer) {
			int repeats = (Integer) rightOperand;
			StringBuilder result = new StringBuilder();
			for (int i = 0; i < repeats; i++) {
				result.append(leftOperand);
			}
			return new TypedValue(result.toString());
		}

		return state.operate(Operation.MULTIPLY, leftOperand, rightOperand);
	}

	@Override
	public boolean isCompilable() {
		if (!getLeftOperand().isCompilable()) {
			return false;
		}
		if (this.children.length > 1) {
			if (!getRightOperand().isCompilable()) {
				return false;
			}
		}
		return (this.exitTypeDescriptor != null);
	}

	@Override
	public void generateCode(MethodVisitor mv, CodeFlow cf) {
		getLeftOperand().generateCode(mv, cf);
		String leftDesc = getLeftOperand().exitTypeDescriptor;
		String exitDesc = this.exitTypeDescriptor;
		Assert.state(exitDesc != null, "No exit type descriptor");
		char targetDesc = exitDesc.charAt(0);
		CodeFlow.insertNumericUnboxOrPrimitiveTypeCoercion(mv, leftDesc, targetDesc);
		if (this.children.length > 1) {
			cf.enterCompilationScope();
			getRightOperand().generateCode(mv, cf);
			String rightDesc = getRightOperand().exitTypeDescriptor;
			cf.exitCompilationScope();
			CodeFlow.insertNumericUnboxOrPrimitiveTypeCoercion(mv, rightDesc, targetDesc);
			switch (targetDesc) {
				case 'I':
					mv.visitInsn(IMUL);
					break;
				case 'J':
					mv.visitInsn(LMUL);
					break;
				case 'F':
					mv.visitInsn(FMUL);
					break;
				case 'D':
					mv.visitInsn(DMUL);
					break;
				default:
					throw new IllegalStateException(
							"Unrecognized exit type descriptor: '" + this.exitTypeDescriptor + "'");
			}
		}
		cf.pushDescriptor(this.exitTypeDescriptor);
	}

}