Quantity.fromNumericalAmount, the inverse of getNumericalAmount

CHANGELOG.md

@@ -19,6 +19,7 @@
 * Fix #4975: exposing scale operations for all Resources
 * Fix #4992: Optimize Quantity parsing to avoid regex overhead
 * Fix #4998: removing the internal usage of the Serialization yaml mapper
+* Fix #5052: add Quantity.fromNumericalAmount, the inverse of getNumericalAmount
 
 #### Dependency Upgrade
 * Fix #5006: Bump BouncyCastle to 1.72

kubernetes-model-generator/kubernetes-model-core/src/main/java/io/fabric8/kubernetes/api/model/Quantity.java

@@ -110,7 +110,7 @@ public void setFormat(String format) {
    * If this is a memory Quantity, the result will represent bytes.<br>
    * If this is a cpu Quantity, the result will represent cores.
    *
-   * @return the formated amount as a number
+   * @return the formatted amount as a number
    * @throws ArithmeticException
    */
   @JsonIgnore
@@ -145,13 +145,39 @@ public static BigDecimal getAmountInBytes(Quantity quantity) throws ArithmeticEx
 
     Quantity amountFormatPair = parse(value);
     String formatStr = amountFormatPair.getFormat();
+
+    BigDecimal digit = new BigDecimal(amountFormatPair.getAmount());
+    BigDecimal multiple = getMultiple(formatStr);
+
+    return digit.multiply(multiple);
+  }
+
+  /**
+   * Constructs a new Quantity from the provided amountInBytes. This amount is converted
+   * to a value with the unit provided in desiredFormat.
+   * 
+   * @param amountInBytes
+   * @param desiredFormat
+   * @see #getNumericalAmount()
+   * @return a new Quantity with the value of amountInBytes with units desiredFormat
+   */
+  public static Quantity fromNumericalAmount(BigDecimal amountInBytes, String desiredFormat) {
+    if (desiredFormat == null || desiredFormat.isEmpty()) {
+      return new Quantity(amountInBytes.stripTrailingZeros().toPlainString());
+    }
+
+    BigDecimal scaledToDesiredFormat = amountInBytes.divide(getMultiple(desiredFormat), MathContext.DECIMAL64);
+
+    return new Quantity(scaledToDesiredFormat.stripTrailingZeros().toPlainString(), desiredFormat);
+  }
+
+  private static BigDecimal getMultiple(String formatStr) {
     // Handle Decimal exponent case
     if (containsAtLeastOneDigit(formatStr) && formatStr.length() > 1) {
       int exponent = Integer.parseInt(formatStr.substring(1));
-      return new BigDecimal("10").pow(exponent, MathContext.DECIMAL64).multiply(new BigDecimal(amountFormatPair.getAmount()));
+      return new BigDecimal("10").pow(exponent, MathContext.DECIMAL64);
     }
 
-    BigDecimal digit = new BigDecimal(amountFormatPair.getAmount());
     BigDecimal multiple = new BigDecimal("1");
     BigDecimal binaryFactor = new BigDecimal("2");
     BigDecimal decimalFactor = new BigDecimal("10");
@@ -207,8 +233,7 @@ public static BigDecimal getAmountInBytes(Quantity quantity) throws ArithmeticEx
       default:
         throw new IllegalArgumentException("Invalid quantity format passed to parse");
     }
-
-    return digit.multiply(multiple);
+    return multiple;
   }
 
   /**

kubernetes-model-generator/kubernetes-model-core/src/test/java/io/fabric8/kubernetes/api/model/QuantityTest.java

@@ -19,6 +19,8 @@
 import com.fasterxml.jackson.databind.ObjectMapper;
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
 
 import java.math.BigDecimal;
 
@@ -198,4 +200,14 @@ public void testIndexOfUnit() {
     assertEquals(4, Quantity.indexOfUnit("123 K"));
     assertEquals(4, Quantity.indexOfUnit("123c"));
   }
+
+  @ParameterizedTest
+  @ValueSource(strings = {
+      "129e6", "129e+6", "1234567890", "8Ki", "7Mi", "6Gi", "5Ti", "4Pi", "3Ei", "5n", "4u", "3m",
+      "9", "8k", "50k", "7M", "6G", "5T", "40T", "300T", "2P", "1E", ".5Mi", "0.5e-1", "1.1E-5" })
+  @DisplayName("Test fromAmountInBytes method")
+  void testFromAmountInBytes(String amount) {
+    Quantity quantity = new Quantity(amount);
+    assertEquals(quantity, Quantity.fromNumericalAmount(quantity.getNumericalAmount(), quantity.getFormat()));
+  }
 }