Add function for money almost all

src/main/kotlin/com/example/demo/DemoApplication.kt

@@ -17,12 +17,20 @@ class DemoApplication : CommandLineRunner {
         //
         // println(result)
 
-        val config = "USD=1,KHR=4000,EUR=0.99"
-        val result = MoneyConfig.parse(config)
-        println(result)
+        // val config = "USD=1,KHR=4000,EUR=0.99"
+        // val result = MoneyConfig.parse(config)
+        // println(result)
 
-        val value1 = MoneyDyn()
-        value1.setConfig(config)
+        MoneyConfig.parse("USD=1,KHR=4000,EUR=0.99")
+
+        val value1 = MoneyDyn(value = 2.0, currency = "USD")
+        val value2 = MoneyDyn(value = 20000.0, currency = "KHR")
+        val value3 = MoneyDyn(value = 0.99, currency = "EUR")
+        value1.addMoney(value2)
+        value1.addMoney(value3)
+
+        // val result = value1.exchange("KHR")
+        println(value1.exchangeTo("KHR")) // 7
     }
 }
 

src/main/kotlin/com/example/demo/domain/MoneyConfig.kt

@@ -4,6 +4,12 @@ object MoneyConfig {
     private const val SPLIT_ORD_1 = ','
     private const val SPLIT_ORD_2 = '='
 
+    /**
+     * Key is the currency
+     * Value is the rate
+     */
+    private val config = mutableMapOf<String, Double>()
+
     fun parse(config: String): Map<String, Double> {
         val result = mutableMapOf<String, Double>()
         val rates = config.split(SPLIT_ORD_1)
@@ -20,11 +26,22 @@ object MoneyConfig {
             if (temp.size == 2) {
                 val currency = temp[0]
                 val value = temp[1].toDouble()
-                result.put(currency, value)
+                result.put(currency.toUpperCase(), value)
             } else {
                 throw IllegalArgumentException("invalid value!")
             }
         }
+
+        // if you want to use all set currencies without remove from memory, we should remove this line
+        this.config.clear()
+        this.config.putAll(result)
         return result
     }
+
+    // all currencies with its rate
+    fun getConfig() = this.config
+
+    fun getRate(currency: String): Double {
+        return getConfig()[currency.toUpperCase()] ?: throw IllegalArgumentException("currency not found")
+    }
 }

src/main/kotlin/com/example/demo/domain/MoneyDyn.kt

@@ -4,14 +4,38 @@ class MoneyDyn (
     var value: Double = 0.0,
     var currency: String = "USD"
 ) {
+
+    fun addMoney(other: MoneyDyn): MoneyDyn {
+        this.value = this.value.plus(exchange(other, this.currency))
+        return this
+    }
+
+    fun exchange(fromMoney: MoneyDyn, exchangeCurrency: String): Double {
+        if (!fromMoney.currency.equals(exchangeCurrency, ignoreCase = true)) {
+            val rateFrom = MoneyConfig.getRate(fromMoney.currency)
+            val rateTo = MoneyConfig.getRate(exchangeCurrency)
+            return computeRate(amountFrom = fromMoney.value, rateFrom = rateFrom, rateTo = rateTo)
+        }
+        return fromMoney.value
+    }
+
+    fun exchangeTo(toCurrency: String): MoneyDyn {
+        return MoneyDyn(value = exchange(this, toCurrency))
+    }
+
+    private fun computeRate(
+        amountFrom: Double = 1.0,
+        baseRate: Double = 1.0,
+        rateFrom: Double,
+        rateTo: Double
+    ): Double {
+        return amountFrom * ((baseRate / rateFrom) / (baseRate / rateTo))
+    }
+
+    private fun isEqualCurrency(other: MoneyDyn) =
+        this.currency.equals(other.currency, ignoreCase = true)
+
     override fun toString(): String {
         return "MoneyDyn(value=$value, currency='$currency')"
     }
-
-    private var config = mapOf<String, Double>()
-    fun setConfig(config: String) {
-        this.config = MoneyConfig.parse(config)
-    }
-
-
 }