feat: parameterized length for CUID version 2

Resolves: #4
Signed-off-by: Thibault Meyer <meyer.thibault@gmail.com>

Author: thibaultmeyer

src/main/java/io/github/thibaultmeyer/cuid/CUID.java

@@ -50,26 +50,18 @@ public static CUID randomCUID2() {
         return randomCUID2(CUIDv2.LENGTH_STANDARD);
     }
 
-    /**
-     * Generates a new random CUID (Version 2).
-     *
-     * @param withBigLength {@code true} to generate a long CUID (Version 2), otherwise, {@code false}
-     * @return Newly generated CUID (Version 2)
-     * @since 2.0.0
-     */
-    public static CUID randomCUID2(final boolean withBigLength) {
-
-        return randomCUID2(withBigLength ? CUIDv2.LENGTH_BIG : CUIDv2.LENGTH_STANDARD);
-    }
-
     /**
      * Generates a new random CUID (Version 2).
      *
      * @param length requested CUID length
      * @return Newly generated CUID (Version 2)
-     * @since 2.0.0
+     * @since 2.0.1
      */
-    private static CUID randomCUID2(final int length) {
+    public static CUID randomCUID2(final int length) {
+
+        if (length <= 0) {
+            throw new CUIDGenerationException("the length must be at least 1");
+        }
 
         final String time = Long.toString(System.currentTimeMillis(), NUMBER_BASE);
         final char firstLetter = CUIDv2.ALPHABET_ARRAY[Math.abs(Common.nextIntValue()) % CUIDv2.ALPHABET_ARRAY.length];
@@ -123,7 +115,7 @@ public static boolean isValid(final String cuidAsString) {
 
         return cuidAsString != null
             && (cuidAsString.length() == CUIDv1.LENGTH_STANDARD && cuidAsString.startsWith(CUIDv1.START_CHARACTER) // Version 1
-            || (cuidAsString.length() == CUIDv2.LENGTH_STANDARD || cuidAsString.length() == CUIDv2.LENGTH_BIG)) // Version 2
+            || (cuidAsString.length() > 0)) // Version 2
             && cuidAsString.chars()
             .filter(c -> !((c >= '0' && c <= '9') || (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z')))
             .count() == 0;
@@ -247,7 +239,6 @@ private static final class CUIDv2 {
 
         // CUID configuration
         private static final int LENGTH_STANDARD = 24;
-        private static final int LENGTH_BIG = 32;
 
         // Counter
         private static int counter = Integer.MAX_VALUE;

src/main/java/io/github/thibaultmeyer/cuid/exception/CUIDGenerationException.java

@@ -17,4 +17,15 @@ public CUIDGenerationException(final Throwable cause) {
 
         super("CUID generation failure", cause);
     }
+
+    /**
+     * Creates a new instance.
+     *
+     * @param cause Cause of the exception
+     * @since 2.0.1
+     */
+    public CUIDGenerationException(final String cause) {
+
+        super("CUID generation failure: " + cause);
+    }
 }

src/test/java/io/github/thibaultmeyer/cuid/CUIDv2Test.java

@@ -1,5 +1,6 @@
 package io.github.thibaultmeyer.cuid;
 
+import io.github.thibaultmeyer.cuid.exception.CUIDGenerationException;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.MethodOrderer;
 import org.junit.jupiter.api.Test;
@@ -57,7 +58,7 @@ void randomCUIDv2() {
     void randomCUIDv2BigLength() {
 
         // Act
-        final CUID cuid = CUID.randomCUID2(true);
+        final CUID cuid = CUID.randomCUID2(32);
 
         // Assert
         Assertions.assertNotNull(cuid);
@@ -105,6 +106,30 @@ void compareToSame() {
         Assertions.assertEquals(0, result);
     }
 
+    @Test
+    void parameterizedLength() {
+
+        // Act
+        final CUID cuid = CUID.randomCUID2(2);
+
+        // Assert
+        Assertions.assertNotNull(cuid);
+        Assertions.assertEquals(2, cuid.toString().length());
+    }
+
+    @Test
+    void parameterizedLengthInvalidSize() {
+
+        // Act
+        final CUIDGenerationException exception = Assertions.assertThrows(
+            CUIDGenerationException.class,
+            () -> CUID.randomCUID2(-1));
+
+        // Assert
+        Assertions.assertNotNull(exception);
+        Assertions.assertEquals("CUID generation failure: the length must be at least 1", exception.getMessage());
+    }
+
     @Test
     void unicityOver500000() {
 

src/test/java/io/github/thibaultmeyer/cuid/PerformanceTest.java

@@ -74,13 +74,13 @@ void speedCUIDv2Standard() {
     @Test
     void speedCUIDv2Big() {
         for (int i = 0; i < 10; i += 1) {
-            CUID.randomCUID2(true);
+            CUID.randomCUID2(32);
         }
 
         final List<CUID> cuidList = new ArrayList<>();
         final long start = System.nanoTime();
         for (int i = 0; i < 1_000_000; i += 1) {
-            cuidList.add(CUID.randomCUID2(true));
+            cuidList.add(CUID.randomCUID2(32));
         }
         final long end = System.nanoTime();