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JSR 354 provides an API for representing, transporting, and performing comprehensive calculations with Money and Currency. This module implements JSR 354.

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/*
  Copyright (c) 2012, 2014, Credit Suisse (Anatole Tresch), Werner Keil and others by the @author tag.

  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.javamoney.moneta.function;

import java.math.BigDecimal;
import java.math.MathContext;
import java.math.RoundingMode;
import java.util.Objects;

import javax.money.MonetaryAmount;
import javax.money.MonetaryOperator;

import org.javamoney.moneta.RoundedMoney;

/**
 * This implementation uses a scale and {@link RoundingMode} to does the rounding operations. The implementation will use the scale, in other words, the number of digits to the right of the decimal point
 * The derived class will implements the {@link RoundedMoney} with this rounding monetary operator
 *   *   {@code
 *
 *     MonetaryOperator monetaryOperator = ScaleRoundedOperator.of(scale, RoundingMode.HALF_EVEN);
 *     CurrencyUnit real = Monetary.getCurrency("BRL");
 *     MonetaryAmount money = Money.of(BigDecimal.valueOf(35.34567), real);
 *     MonetaryAmount result = monetaryOperator.apply(money); // BRL 35.3457
 *
 *    }
* 
 * Case the parameter in {@link MonetaryOperator#apply(MonetaryAmount)} be null, the apply will return a {@link NullPointerException}
 * @author Otavio Santana
 * @see #ScaleRoundedOperator(int, RoundingMode)
 * @see RoundedMoney
 * @see MonetaryOperator
 * @see BigDecimal#scale()
 */
public final class ScaleRoundedOperator implements MonetaryOperator {

	private final int scale;

	private final RoundingMode roundingMode;

	private ScaleRoundedOperator(int scale, RoundingMode roundingMode) {
		this.scale = scale;
		this.roundingMode = roundingMode;
	}

	/**
	 * Creates the rounded Operator from scale and roundingMode
	 * @param scale the scale to be used
	 * @param roundingMode the rounding mode to be used
	 * @return the {@link MonetaryOperator} using the scale and {@link RoundingMode} used in parameter
	 * @throws NullPointerException when the {@link MathContext} is null
	 * @see RoundingMode
	 */
	public static ScaleRoundedOperator of(int scale, RoundingMode roundingMode) {

		Objects.requireNonNull(roundingMode);

		if(RoundingMode.UNNECESSARY.equals(roundingMode)) {
		   throw new IllegalStateException("To create the ScaleRoundedOperator you cannot use the RoundingMode.UNNECESSARY");
		}
		return new ScaleRoundedOperator(scale, roundingMode);
	}

	@Override
	public MonetaryAmount apply(MonetaryAmount amount) {
		RoundedMoney roundedMoney = RoundedMoney.from(Objects.requireNonNull(amount));
		BigDecimal numberValue = roundedMoney.getNumber().numberValue(BigDecimal.class);
		BigDecimal numberRounded = numberValue.setScale(scale, roundingMode);
		return RoundedMoney.of(numberRounded, roundedMoney.getCurrency(), this);
	}

	public int getScale() {
		return scale;
	}

	public RoundingMode getRoundingMode() {
		return roundingMode;
	}

	@Override
	public String toString() {
		return ScaleRoundedOperator.class.getName() + '{' +
                "scale:" + Integer.toString(scale) + ',' +
                "roundingMode:" + roundingMode + '}';
	}

}