BAEL-1498 Money into words (#3797)

* Add tradukisto library

* Implement MoneyIntoWords

* Update the version of tradukisto library

* Refactor MoneyIntoWords

* Refactor

* Refactor pom.xml

* Refactor pom.xml

* Refactor NumberWordConverter

* BAEL-1498 Small refactoring

* Test edge cases

* BAEL-1498 Additional tests

algorithms/pom.xml

@@ -9,6 +9,7 @@
         <exec-maven-plugin.version>1.5.0</exec-maven-plugin.version>
         <lombok.version>1.16.12</lombok.version>
         <commons-math3.version>3.6.1</commons-math3.version>
+        <tradukisto.version>1.0.1</tradukisto.version>
     </properties>
 
     <parent>
@@ -39,6 +40,11 @@
             <artifactId>jgrapht-core</artifactId>
             <version>1.0.1</version>
         </dependency>
+        <dependency>
+            <groupId>pl.allegro.finance</groupId>
+            <artifactId>tradukisto</artifactId>
+            <version>${tradukisto.version}</version>
+        </dependency>
         <dependency>
             <groupId>org.assertj</groupId>
             <artifactId>assertj-core</artifactId>
@@ -46,7 +52,6 @@
             <scope>test</scope>
         </dependency>
     </dependencies>
-
     <build>
         <pluginManagement>
             <plugins>

algorithms/src/main/java/com/baeldung/algorithms/numberwordconverter/NumberWordConverter.java

@@ -0,0 +1,75 @@
+package com.baeldung.algorithms.numberwordconverter;
+
+import java.math.BigDecimal;
+
+import pl.allegro.finance.tradukisto.MoneyConverters;
+
+public class NumberWordConverter {
+
+    public static final String INVALID_INPUT_GIVEN = "Invalid input given";
+
+    public static final String[] ones = { "", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten", "eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen" };
+
+    public static final String[] tens = {
+      "", // 0
+      "", // 1
+      "twenty", // 2
+      "thirty", // 3
+      "forty", // 4
+      "fifty", // 5
+      "sixty", // 6
+      "seventy", // 7
+      "eighty", // 8
+      "ninety" // 9
+    };
+
+    public static String getMoneyIntoWords(String input) {
+        MoneyConverters converter = MoneyConverters.ENGLISH_BANKING_MONEY_VALUE;
+        return converter.asWords(new BigDecimal(input));
+    }
+
+    public static String getMoneyIntoWords(final double money) {
+        long dollar = (long) money;
+        long cents = Math.round((money - dollar) * 100);
+        if (money == 0D) {
+            return "";
+        }
+        if (money < 0) {
+            return INVALID_INPUT_GIVEN;
+        }
+        String dollarPart = "";
+        if (dollar > 0) {
+            dollarPart = convert(dollar) + " dollar" + (dollar == 1 ? "" : "s");
+        }
+        String centsPart = "";
+        if (cents > 0) {
+            if (dollarPart.length() > 0) {
+                centsPart = " and ";
+            }
+            centsPart += convert(cents) + " cent" + (cents == 1 ? "" : "s");
+        }
+        return dollarPart + centsPart;
+    }
+
+    private static String convert(final long n) {
+        if (n < 0) {
+            return INVALID_INPUT_GIVEN;
+        }
+        if (n < 20) {
+            return ones[(int) n];
+        }
+        if (n < 100) {
+            return tens[(int) n / 10] + ((n % 10 != 0) ? " " : "") + ones[(int) n % 10];
+        }
+        if (n < 1000) {
+            return ones[(int) n / 100] + " hundred" + ((n % 100 != 0) ? " " : "") + convert(n % 100);
+        }
+        if (n < 1_000_000) {
+            return convert(n / 1000) + " thousand" + ((n % 1000 != 0) ? " " : "") + convert(n % 1000);
+        }
+        if (n < 1_000_000_000) {
+            return convert(n / 1_000_000) + " million" + ((n % 1_000_000 != 0) ? " " : "") + convert(n % 1_000_000);
+        }
+        return convert(n / 1_000_000_000) + " billion" + ((n % 1_000_000_000 != 0) ? " " : "") + convert(n % 1_000_000_000);
+    }
+}

algorithms/src/test/java/com/baeldung/algorithms/moneywords/NumberWordConverterTest.java

@@ -0,0 +1,84 @@
+package com.baeldung.algorithms.moneywords;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.Test;
+
+import com.baeldung.algorithms.numberwordconverter.NumberWordConverter;
+
+public class NumberWordConverterTest {
+
+    @Test
+    public void whenMoneyNegative_thenReturnInvalidInput() {
+        assertEquals(NumberWordConverter.INVALID_INPUT_GIVEN, NumberWordConverter.getMoneyIntoWords(-13));
+    }
+
+    @Test
+    public void whenZeroDollarsGiven_thenReturnEmptyString() {
+        assertEquals("", NumberWordConverter.getMoneyIntoWords(0));
+    }
+
+    @Test
+    public void whenOnlyDollarsGiven_thenReturnWords() {
+        assertEquals("one dollar", NumberWordConverter.getMoneyIntoWords(1));
+    }
+
+    @Test
+    public void whenOnlyCentsGiven_thenReturnWords() {
+        assertEquals("sixty cents", NumberWordConverter.getMoneyIntoWords(0.6));
+    }
+    
+    @Test
+    public void whenAlmostAMillioDollarsGiven_thenReturnWords() {
+        String expectedResult = "nine hundred ninety nine thousand nine hundred ninety nine dollars";
+        assertEquals(expectedResult, NumberWordConverter.getMoneyIntoWords(999_999));
+    }
+    
+    @Test
+    public void whenThirtyMillionDollarsGiven_thenReturnWords() {
+        String expectedResult = "thirty three million three hundred forty eight thousand nine hundred seventy eight dollars";
+        assertEquals(expectedResult, NumberWordConverter.getMoneyIntoWords(33_348_978));
+    }
+    
+    @Test
+    public void whenTwoBillionDollarsGiven_thenReturnWords() {
+        String expectedResult = "two billion one hundred thirty three million two hundred forty seven thousand eight hundred ten dollars";
+        assertEquals(expectedResult, NumberWordConverter.getMoneyIntoWords(2_133_247_810));
+    }
+
+    @Test
+    public void whenGivenDollarsAndCents_thenReturnWords() {
+        String expectedResult = "nine hundred twenty four dollars and sixty cents";
+        assertEquals(expectedResult, NumberWordConverter.getMoneyIntoWords(924.6));
+    }
+
+    @Test
+    public void whenOneDollarAndNoCents_thenReturnDollarSingular() {
+        assertEquals("one dollar", NumberWordConverter.getMoneyIntoWords(1));
+    }
+
+    @Test
+    public void whenNoDollarsAndOneCent_thenReturnCentSingular() {
+        assertEquals("one cent", NumberWordConverter.getMoneyIntoWords(0.01));
+    }
+
+    @Test
+    public void whenNoDollarsAndTwoCents_thenReturnCentsPlural() {
+        assertEquals("two cents", NumberWordConverter.getMoneyIntoWords(0.02));
+    }
+
+    @Test
+    public void whenNoDollarsAndNinetyNineCents_thenReturnWords() {
+        assertEquals("ninety nine cents", NumberWordConverter.getMoneyIntoWords(0.99));
+    }
+
+    @Test
+    public void whenNoDollarsAndNineFiveNineCents_thenCorrectRounding() {
+        assertEquals("ninety six cents", NumberWordConverter.getMoneyIntoWords(0.959));
+    }
+
+    @Test
+    public void whenGivenDollarsAndCents_thenReturnWordsVersionTwo() {
+        assertEquals("three hundred ten £ 00/100", NumberWordConverter.getMoneyIntoWords("310"));
+    }
+}