/*
 *  Copyright 2017-2025 Adobe.
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *          http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package com.adobe.testing.s3mock.util;

import org.jspecify.annotations.Nullable;

public final class EtagUtil {

  private EtagUtil() {
    // private constructor for utility classes
  }

  /**
   * Returns etag in normalized form with surrounding quotes.
   * This normalized form is persisted so that S3Mock can conform to RFC2616 / RFC7232.
   * <a href="https://www.rfc-editor.org/rfc/rfc2616#section-14.19">RFC2616</a>
   * <a href="https://www.rfc-editor.org/rfc/rfc7232">RFC7232</a>
   */
  @Nullable
  public static String normalizeEtag(@Nullable String etag) {
    if (etag == null) {
      return null;
    } else if (etag.startsWith("\"") && etag.endsWith("\"")) {
      return etag;
    } else {
      return String.format("\"%s\"", etag);
    }
  }
}
