Refactor: update sha2 implementations with DigestUtils

Signed-off-by: Yuanchun Shen <yuanchu@amazon.com>

Author: yuancu

core/src/main/java/org/opensearch/sql/expression/function/udf/CryptographicFunction.java

@@ -5,10 +5,7 @@
 
 package org.opensearch.sql.expression.function.udf;
 
-import java.security.MessageDigest;
-import java.security.NoSuchAlgorithmException;
 import java.util.List;
-import java.util.Map;
 import org.apache.calcite.adapter.enumerable.NotNullImplementor;
 import org.apache.calcite.adapter.enumerable.NullPolicy;
 import org.apache.calcite.adapter.enumerable.RexToLixTranslator;
@@ -18,7 +15,9 @@
 import org.apache.calcite.sql.type.ReturnTypes;
 import org.apache.calcite.sql.type.SqlReturnTypeInference;
 import org.apache.calcite.sql.type.SqlTypeTransforms;
+import org.apache.commons.codec.binary.Hex;
 import org.apache.commons.codec.digest.DigestUtils;
+import org.apache.commons.codec.digest.MessageDigestAlgorithms;
 import org.opensearch.sql.expression.function.ImplementorUDF;
 
 public class CryptographicFunction extends ImplementorUDF {
@@ -36,52 +35,24 @@ public SqlReturnTypeInference getReturnTypeInference() {
   }
 
   public static class Sha2Implementor implements NotNullImplementor {
-    private static final ThreadLocal<Map<Integer, MessageDigest>> digests;
-
-    static {
-      digests =
-          ThreadLocal.withInitial(
-              () -> {
-                try {
-                  return Map.of(
-                      224,
-                      MessageDigest.getInstance("SHA-224"),
-                      256,
-                      DigestUtils.getSha256Digest(),
-                      384,
-                      DigestUtils.getSha384Digest(),
-                      512,
-                      DigestUtils.getSha512Digest());
-                } catch (NoSuchAlgorithmException e) {
-                  throw new RuntimeException(e);
-                }
-              });
-    }
-
     @Override
     public Expression implement(
         RexToLixTranslator translator, RexCall call, List<Expression> translatedOperands) {
       return Expressions.call(Sha2Implementor.class, "getDigest", translatedOperands);
     }
 
     public static String getDigest(String input, int algorithm) {
-      if (!digests.get().containsKey(algorithm)) {
-        throw new IllegalArgumentException("Unsupported SHA2 algorithm: " + algorithm);
-      }
-      return getDigest(digests.get().get(algorithm), input);
-    }
-
-    private static String getDigest(MessageDigest digest, String input) {
-      byte[] hash = digest.digest(input.getBytes());
-      StringBuilder hexString = new StringBuilder();
-      for (byte b : hash) {
-        String hex = Integer.toHexString(0xff & b);
-        if (hex.length() == 1) {
-          hexString.append('0');
-        }
-        hexString.append(hex);
-      }
-      return hexString.toString();
+      return switch (algorithm) {
+        case 224 -> Hex.encodeHexString(
+            DigestUtils.getDigest(MessageDigestAlgorithms.SHA_224).digest(input.getBytes()));
+        case 256 -> DigestUtils.sha256Hex(input);
+        case 384 -> DigestUtils.sha384Hex(input);
+        case 512 -> DigestUtils.sha512Hex(input);
+        default -> throw new IllegalArgumentException(
+            String.format(
+                "Unsupported SHA2 algorithm: %d. Only 224, 256, 384, and 512 are supported.",
+                algorithm));
+      };
     }
   }
 }