/**
 *                                                                            
 * Copyright (c) 2011, 2016 - Loetz GmbH&Co.KG (69115 Heidelberg, Germany)
 *                                                                            
 * All rights reserved. This program and the accompanying materials           
 * are made available under the terms of the Eclipse Public License v1.0       
 * which accompanies this distribution, and is available at                  
 * http://www.eclipse.org/legal/epl-v10.html                                 
 *                                                                            
 * Contributors:   
 * Christophe Loetz (Loetz GmbH&Co.KG) - initial implementation 
 */
package org.eclipse.osbp.utils.currency;

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

import org.joda.money.CurrencyUnit;
import org.joda.money.Money;
import org.joda.time.DateTime;


/**
 *  Currency Conversion
 */
public class CurrencyConverter {

	private final Locale fLocalLocale;
	private final CurrencyUnit fLocalCurrencyUnit;
	private final BigDecimal fReferenceRateEuroToLocal;
	private final Locale fForeignLocale;
	private final CurrencyUnit fForeignCurrencyUnit;
	private final BigDecimal fReferenceRateEuroToForeign;
	private final DateTime fReferenceDate;
	private final boolean fSameCurrencyUnit;

	/**
	 * @param localLocale the local Locale
	 * @param foreignLocale the foreign Locale
	 * @param referenceDate the reference date used for reference rates
	 */
	public CurrencyConverter(final Locale localLocale, final Locale foreignLocale, final DateTime referenceDate) {
		this(localLocale, null, foreignLocale, null, referenceDate);
	}
	
	/**
	 * @param localLocale the local Locale
	 * @param foreignCurrency the foreign Locale
	 * This constructor will use the actual reference dates aka "now"
	 */
	public CurrencyConverter(final Locale localLocale, final Locale foreignLocale) {
		this(localLocale, foreignLocale, DateTime.now());
	}
	
	/**
	 * @param localLocale the local Locale
	 * @param localCurrency the local currency unit
	 * @param foreignLocale the foreign Locale
	 * @param foreignCurrency the foreign currency unit
	 * @param referenceDate the reference date used for reference rates
	 */
	public CurrencyConverter(final CurrencyUnit localCurrency, final CurrencyUnit foreignCurrency, final DateTime referenceDate) {
		this(null, localCurrency, null, foreignCurrency, referenceDate);
	}
	
	/**
	 * @param localCurrency the local currency
	 * @param foreignCurrency the foreign currency
	 * This constructor will use the actual reference dates aka "now"
	 */
	public CurrencyConverter(final CurrencyUnit localUnit, final CurrencyUnit foreignCurrency) {
		this(localUnit, foreignCurrency, DateTime.now());
	}

	private  CurrencyConverter(final Locale localLocale, final CurrencyUnit localCurrency, final Locale foreignLocale, final CurrencyUnit foreignCurrency, final DateTime referenceDate) {
		fLocalCurrencyUnit = currencyUnitOf(localLocale, localCurrency);
		fLocalLocale = localeOf(localLocale, localCurrency);
		fForeignCurrencyUnit = currencyUnitOf(foreignLocale, foreignCurrency);
		fForeignLocale = localeOf(foreignLocale, foreignCurrency);
		fSameCurrencyUnit = fLocalCurrencyUnit.equals(fForeignCurrencyUnit);
		fReferenceDate = referenceDate;
		fReferenceRateEuroToLocal = EuroBasedExchangeReferenceRates.getReferenceRate(fLocalCurrencyUnit, fReferenceDate);
		fReferenceRateEuroToForeign = EuroBasedExchangeReferenceRates.getReferenceRate(fForeignCurrencyUnit, fReferenceDate);
	}

	/**
	 * @param locale
	 * @param currencyUnit
	 * @return the currency unit depending on either the currencyUnit or the locale
	 */
	public static CurrencyUnit currencyUnitOf(final Locale locale, final CurrencyUnit currencyUnit) {
		if	(currencyUnit == null) {
			return CurrencyUnit.of(locale);
		}
		else {
			return currencyUnit;
		}
	}
	
	/**
	 * @param locale
	 * @param currencyUnit
	 * @return the locale depending on either the locale or the currencyUnit
	 */
	public static Locale localeOf(final Locale locale, final CurrencyUnit currencyUnit) {
		if	(locale == null) {
			if	(currencyUnit.getCountryCodes().size() == 1) {
				return new Locale("", currencyUnit.getCountryCodes().iterator().next());
			}
			else {
				return null;
			}
		}
		else {
			return locale;
		}
	}
	
	/**
	 * @return the local Locale; may be null
	 */
	public Locale getLocalLocale() {
		return fLocalLocale;
	}
	
	/**
	 * @return the local currency unit
	 */
	public CurrencyUnit getLocalCurrencyUnit() {
		return fLocalCurrencyUnit;
	}
	
	/**
	 * @return the foreign Locale; may be null
	 */
	public Locale getForeignLocale() {
		return fForeignLocale;
	}

	/**
	 * @return the foreign currency unit
	 */
	public CurrencyUnit getForeignCurrencyUnit() {
		return fForeignCurrencyUnit;
	}

	/**
	 * @return the reference date used for reference rates
	 */
	public DateTime getReferenceDate() {
		return fReferenceDate;
	}

	/**
	 * @return the rate from local to foreign currency
	 */
	public double getLocalToForeignReferenceRateAsDouble() {
		return getLocalToForeignReferenceRate().doubleValue();
	}
	
	/**
	 * @return the rate from local to foreign currency
	 */
	public BigDecimal getLocalToForeignReferenceRate() {
		return getReferenceRate(false);
	}

	/**
	 * @return the rate from foreign to local currency
	 */
	public double getForeignToLocalReferenceRateAsDouble() {
		return getForeignToLocalReferenceRate().doubleValue();
	}
	
	/**
	 * @return the rate from foreign to local currency
	 */
	public BigDecimal getForeignToLocalReferenceRate() {
		return getReferenceRate(true);
	}
	
	public final static MathContext BASIC_DIVIDE_RATES_MATHCONTEXT = new MathContext(8);
	
	private BigDecimal getReferenceRate(boolean backward) {
		if	(backward) {
			return fReferenceRateEuroToLocal.divide(fReferenceRateEuroToForeign, BASIC_DIVIDE_RATES_MATHCONTEXT);
		}
		else {
			return fReferenceRateEuroToForeign.divide(fReferenceRateEuroToLocal, BASIC_DIVIDE_RATES_MATHCONTEXT);
		}
	}

	/**
	 * @param localAmount
	 * @return the exchanged foreign amount
	 */
	public double exchangeToDouble(double localAmount) {
		return exchangeToDouble(localAmount, false);
	}

	/**
	 * @param amount
	 * @param backward false if exchange from local to foreign currency, true vice versa
	 * @return the exchanged amount
	 */
	public double exchangeToDouble(double amount, boolean backward) {
		return exchange(BigDecimal.valueOf(amount), backward).doubleValue();
	}
	
	/**
	 * @param localAmount
	 * @return the exchanged foreign amount
	 */
	public BigDecimal exchange(BigDecimal base) {
		return exchange(base, false);
	}
	
	/**
	 * @param amount
	 * @param backward false if exchange from local to foreign currency, true vice versa
	 * @return the exchanged amount
	 */
	public BigDecimal exchange(BigDecimal base, boolean backward) {
		if	(fSameCurrencyUnit) {
			return base;
		}
		else {
			Money result;
			if	(backward) {
				result = Money.of(
					fLocalCurrencyUnit, 
					base
						.multiply(fReferenceRateEuroToLocal)
						.divide(fReferenceRateEuroToForeign, RoundingMode.HALF_EVEN),
					RoundingMode.HALF_EVEN
				);
			}
			else {
				result = Money.of(
					fForeignCurrencyUnit, 
					base
						.multiply(fReferenceRateEuroToForeign)
						.divide(fReferenceRateEuroToLocal, RoundingMode.HALF_EVEN),
					RoundingMode.HALF_EVEN
				);
			}
			return result.getAmount();
		}
	}
}