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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 {@link MathContext} to does the rounding operations. The implementation will use the precision, in other words, the total number of digits in a number
 * The derived class will implements the {@link RoundedMoney} with this rounding monetary operator
 *   *   {@code
 *
 *     MathContext mathContext = new MathContext(4, RoundingMode.HALF_EVEN);
 *     MonetaryOperator monetaryOperator = PrecisionContextRoundedOperator.of(mathContext);
 *     CurrencyUnit real = Monetary.getCurrency("BRL");
 *     MonetaryAmount money = Money.of(BigDecimal.valueOf(35.34567), real);
 *     MonetaryAmount result = monetaryOperator.apply(money); // BRL 35.35
 *
 *    }
* 
* Case the parameter in {@link MonetaryOperator#apply(MonetaryAmount)} be null, the apply will return a {@link NullPointerException}
 * @author Otavio Santana
 * @see PrecisionContextRoundedOperator#of(MathContext)
 * @see RoundedMoney
 * @see MonetaryOperator
 * @see BigDecimal#precision()
 */
public final class PrecisionContextRoundedOperator implements MonetaryOperator {

	private final MathContext mathContext;

	private PrecisionContextRoundedOperator(MathContext mathContext) {
		this.mathContext = mathContext;
	}

	/**
	 * Creates the rounded Operator from mathContext
	 * @param mathContext the math context, not null.
	 * @return the {@link MonetaryOperator} using the {@link MathContext} used in parameter
	 * @throws NullPointerException when the {@link MathContext} is null
	 * @throws IllegalArgumentException when the {@link MathContext#getPrecision()} is lesser than zero
	 * @throws IllegalArgumentException when the mathContext is {@link MathContext#getRoundingMode()} is {@link RoundingMode#UNNECESSARY}
	 * @see MathContext
	 */
	public static PrecisionContextRoundedOperator of(MathContext mathContext) {

		Objects.requireNonNull(mathContext);

		if(RoundingMode.UNNECESSARY.equals(mathContext.getRoundingMode())) {
			   throw new IllegalArgumentException("To create the MathContextRoundedOperator you cannot use the RoundingMode.UNNECESSARY on MathContext");
		}

		if(mathContext.getPrecision() <= 0) {
				throw new IllegalArgumentException("To create the MathContextRoundedOperator you cannot use the zero precision on MathContext");
		}

		return new PrecisionContextRoundedOperator(mathContext);
	}

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

	public MathContext getMathContext() {
		return mathContext;
	}

	@Override
	public String toString() {
		return PrecisionContextRoundedOperator.class.getName() + '{' +
                "mathContext:" + mathContext + '}';
	}

}