cleanup

README.md

@@ -101,6 +101,8 @@ Inspiration
 * https://github.com/lucamarrocco/timeandmoney/blob/master/lib/money.rb
 * http://joda-money.sourceforge.net/
 * http://en.wikipedia.org/wiki/Currency_pair
+* https://github.com/RubyMoney/eu_central_bank
+* http://en.wikipedia.org/wiki/ISO_4217
 
 Bibliography
 ============
@@ -109,9 +111,3 @@ Bibliography
 Fowler, M., D. Rice, M. Foemmel, E. Hieatt, R. Mee, and R. Stafford, Patterns of Enterprise Application Architecture, Addison-Wesley, 2002.
 http://martinfowler.com/books.html#eaa
 
-http://en.wikipedia.org/wiki/ISO_4217
-
-Todo
-====
-
-* https://github.com/RubyMoney/eu_central_bank
\ No newline at end of file

lib/Verraes/Money/CurrencyPair.php

+<?php
+/**
+ * This file is part of the Verraes\Money library
+ *
+ * Copyright (c) 2011 Mathias Verraes
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Verraes\Money;
+
+/** @see http://en.wikipedia.org/wiki/Currency_pair */
+class CurrencyPair
+{
+	/** @var Currency */
+	private $counterCurrency;
+
+	/** @var Currency */
+	private $baseCurrency;
+
+	/** @var float */
+	private $ratio;
+
+	public function __construct(Currency $counterCurrency, Currency $baseCurrency, $ratio)
+	{
+		$this->counterCurrency = $counterCurrency;
+		$this->baseCurrency = $baseCurrency;
+		$this->ratio = $ratio;
+	}
+
+	/** @return Money */
+	public function convert(Money $money)
+	{
+		if(!$money->getCurrency()->equals($this->counterCurrency)) {
+			throw new InvalidArgumentException("The Money has the wrong currency");
+		}
+
+		// @todo add rounding mode?
+		return new Money((int) round($money->getUnits() * $this->ratio), $this->baseCurrency);
+	}
+
+	/** @return Currency */
+	public function getCounterCurrency()
+	{
+		return $this->counterCurrency;
+	}
+
+	/** @return Currency */
+	public function getBaseCurrency()
+	{
+		return $this->baseCurrency;
+	}
+
+	/** @return float */
+	public function getRatio()
+	{
+		return $this->ratio;
+	}
+}
\ No newline at end of file

tests/CurrencyPairTest.php

+<?php
+/**
+ * This file is part of the Verraes\Money library
+ *
+ * Copyright (c) 2011 Mathias Verraes
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+require_once 'bootstrap.php';
+
+use Verraes\Money\Money;
+use Verraes\Money\Currency;
+use Verraes\Money\CurrencyPair;
+
+class CurrencyPairTest extends PHPUnit_Framework_TestCase
+{
+	/** @test */
+	public function ConvertsEurToUsdAndBack()
+	{
+		$eur = Money::EUR(100);
+
+		$pair = new CurrencyPair(new Currency('EUR'), new Currency('USD'), 1.2500);
+		$usd = $pair->convert($eur);
+		$this->assertEquals(Money::USD(125), $usd);
+
+		$pair = new CurrencyPair(new Currency('USD'), new Currency('EUR'), 0.8000);
+		$eur = $pair->convert($usd);
+		$this->assertEquals(Money::EUR(100), $eur);
+	}
+
+
+}
\ No newline at end of file

tests/bootstrap.php

@@ -10,6 +10,7 @@
 
 require_once 'PHPUnit/Framework/TestCase.php';
 require_once __DIR__.'/../lib/Verraes/Money/Currency.php';
+require_once __DIR__.'/../lib/Verraes/Money/CurrencyPair.php';
 require_once __DIR__.'/../lib/Verraes/Money/Exception.php';
 require_once __DIR__.'/../lib/Verraes/Money/InvalidArgumentException.php';
 require_once __DIR__.'/../lib/Verraes/Money/UnknownCurrencyException.php';