/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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 org.apache.myfaces.tobago.util;
  
  import org.apache.myfaces.tobago.internal.util.StringUtils;
  import org.junit.jupiter.api.Assertions;
  
  import java.lang.reflect.Field;
  
  public abstract class EnumUnitTest {
  
    protected String getEnumRegexp() {
      return "[a-z][a-zA-Z]*";
    }
  
    protected String constantCaseToEnum(final String constant) {
      return StringUtils.constantToLowerCamelCase(constant);
    }
  
    public <E extends Enum<E>> void testNames(final Class<E> enumType)
        throws NoSuchFieldException, IllegalAccessException {
  
      final Field[] fields = enumType.getFields();
      final E[] values = enumType.getEnumConstants();
  
      Assertions.assertEquals(fields.length, 2 * values.length, "Is for every enum a string constant defined?");
  
      for (final Field field : fields) {
        final Object object = field.get(null);
        final String fieldName = field.getName();
        if (object instanceof String) {
          // case String constant
          final String value = (String) object;
          final String expected = constantCaseToEnum(fieldName);
          Assertions.assertEquals(expected, value);
          Assertions.assertNotNull(enumType.getField(value), "exists");
        } else if (object.getClass().isAssignableFrom(enumType)) {
          // case enum
          Assertions.assertTrue(fieldName.matches(getEnumRegexp()), "value='" + fieldName + "'");
        } else {
          Assertions.fail();
        }
      }
    }
  }