RVRNEXT-6 add ExchangeRateCalculator

src/Finance/ExchangeRateCalculator.php

@@ -0,0 +1,52 @@
+<?php namespace RVR\Finance;
+
+use DateTime;
+use RVR\PersistentData\Model\Currency;
+use RVR\PersistentData\Model\CurrencyExchangeRate;
+use RVR\Repository\CurrencyExchangeRateRepository;
+
+class ExchangeRateCalculator
+{
+    private Currency $mainCurrency;
+
+    private CurrencyExchangeRateRepository $currencyExchangeRateRepository;
+
+    private array $exchangeRates = [];
+
+    public function __construct(Currency $mainCurrency)
+    {
+        $this->mainCurrency = $mainCurrency;
+        $this->currencyExchangeRateRepository = new CurrencyExchangeRateRepository();
+    }
+
+    public function calculate(float $sumInCurrency, Currency $currency, DateTime $time): float
+    {
+        if ($currency->getId() === $this->mainCurrency->getId()) {
+            return $sumInCurrency;
+        }
+
+        $currentExchangeRate = $this->getCurrentExchangeRate($currency, $time);
+        if ($currentExchangeRate === null) {
+            return 0.0;
+        }
+
+        return $sumInCurrency * $currentExchangeRate->getExchangeRate();
+    }
+
+    private function getCurrentExchangeRate(Currency $currency, DateTime $time): ?CurrencyExchangeRate
+    {
+        if (!isset($this->exchangeRates[$currency->getId()])) {
+            $this->exchangeRates[$currency->getId()] = iterator_to_array($this->currencyExchangeRateRepository->getAllByCurrency($currency));
+        }
+
+        $currentExchangeRate = null;
+        foreach ($this->exchangeRates[$currency->getId()] as $exchangeRate) {
+            if ($exchangeRate->getValidFrom() > $time) {
+                break;
+            }
+            $currentExchangeRate = $exchangeRate;
+        }
+
+        return $currentExchangeRate;
+    }
+}