Merge pull request #9 from Caramel1004/refactor/#8

♻️ [refactor] 송금 수수료 정책 추가, 코드 리팩토리 중

src/main/java/com/moin/remittance/application/service/v2/calculating/ExchangeRateCalculator.java

@@ -0,0 +1,23 @@
+package com.moin.remittance.application.service.v2.calculating;
+
+import com.moin.remittance.application.service.v2.calculating.policy.RemittanceFeePolicy;
+import java.math.BigDecimal;
+import java.math.RoundingMode;
+import java.util.Currency;
+
+public class ExchangeRateCalculator {
+    public static double calculateExchangeRate(long amount, double currencyUnit, double basePrice, String currencyCode) {
+        BigDecimal sourceAmount = new BigDecimal(amount);
+        BigDecimal fee = RemittanceFeePolicy.calculateFee(amount);
+
+        BigDecimal krw = sourceAmount.subtract(fee);
+        BigDecimal targetCurrencyToKrwExchangeRate = new BigDecimal(basePrice / currencyUnit).setScale(4, RoundingMode.HALF_UP);// 소수점 넷째자리에서 반올림
+        System.out.println(targetCurrencyToKrwExchangeRate);
+
+        int decimalPlaces = Currency.getInstance(currencyCode).getDefaultFractionDigits();
+
+        BigDecimal targetAmount = krw.divide(targetCurrencyToKrwExchangeRate, decimalPlaces, BigDecimal.ROUND_HALF_UP);// 자릿수 getDefaultFractionDigits
+
+        return Double.parseDouble(String.valueOf(targetAmount));
+    }
+}

src/main/java/com/moin/remittance/application/service/v2/calculating/policy/RemittanceFeePolicy.java

@@ -0,0 +1,22 @@
+package com.moin.remittance.application.service.v2.calculating.policy;
+
+import java.math.BigDecimal;
+import java.math.RoundingMode;
+
+public class RemittanceFeePolicy {
+
+    public static BigDecimal calculateFee(long amount) {
+        final double HUNDRED_EXCEED_FEE = 3000.0;
+        final double HUNDRED_EXCEED_FEE_RATE = 0.1;
+
+        final double HUNDRED_DOWN_FEE = 1000.0;
+        final double HUNDRED_DOWN_FEE_RATE = 0.2;
+
+        double sourceAmount = (double) amount;
+
+        double targetFee = (sourceAmount > 0.0 && sourceAmount <= 1000000.0)?
+                (sourceAmount * HUNDRED_DOWN_FEE_RATE) + HUNDRED_DOWN_FEE : (sourceAmount * HUNDRED_EXCEED_FEE_RATE) + HUNDRED_EXCEED_FEE;
+
+        return new BigDecimal(targetFee).setScale(1, RoundingMode.HALF_UP);
+    }
+}

src/test/java/com/moin/remittance/util/ExchangeRateCalculatorTest.java → src/test/java/com/moin/remittance/util/ExchangeRateCalculatorCalculatorTest.java

@@ -12,7 +12,7 @@
 
 import static java.lang.Math.round;
 
-public class ExchangeRateCalculatorTest {
+public class ExchangeRateCalculatorCalculatorTest {
     @Test
     @DisplayName("환율 계산")
     public void calculateExchangeRate() {