package org.apidesign.apifest08.currency;

import java.math.BigDecimal;

import java.util.Currency;

/**

 * An amount of a currency.

 * Immutable.

 * @author jdvorak

 */

public class MonetaryAmount {

    private final BigDecimal amount;

    private final Currency currency;

    /**

     * A new amount.

     * @param amount the quantity of the currency; must not be null

     * @param currency the currency; must not be null

     */

    public MonetaryAmount( final BigDecimal amount, final Currency currency ) {

        this.amount = amount;

        this.currency = currency;

        if ( amount == null ) {

            throw new NullPointerException( "The amount" );

        }

        if ( currency == null ) {

            throw new NullPointerException( "The currency" );

        }

    }

    /**

     * A new amount.

     * @param amount the quantity of the currency; must not be null

     * @param currency the currency; must not be null

     */

    public MonetaryAmount( final double amount, final Currency currency ) {

        this( new BigDecimal( amount ), currency );

    }

    /**

     * The amount.

     * @return the amount

     */

    public BigDecimal getAmount() {

        return amount;

    }

    /**

     * The currency.

     * @return the currency

     */

    public Currency getCurrency() {

        return currency;

    }

    /**

     * The string representation of the monetary amount.

     * @return the amount, a non-breakable space, the currency

     */

    @Override

    public String toString() {

        return amount.toPlainString() + "\u00a0" + currency.toString();

    }

    /**

     * Two monetary amounts are equal to each other iff they have equal amounts of equal currencies.

     * @param other the other object

     * @return equality

     */

    @Override

    public boolean equals( final Object other ) {

        if ( other instanceof MonetaryAmount ) {

            final MonetaryAmount otherMonetaryAmount = (MonetaryAmount) other;

            return getAmount().equals( otherMonetaryAmount.getAmount() ) && getCurrency().equals( otherMonetaryAmount.getCurrency() );

        }

        return false;

    }

    /**

     * The hash code combines the hash codes of the amount and of the currency.

     * @return hash code

     */

    @Override

    public int hashCode() {

        return amount.hashCode() * 37 + currency.hashCode();

    }

}