/*
    * 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
    *
    *     https://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.commons.configuration2;
  
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertFalse;
  import static org.junit.jupiter.api.Assertions.assertThrows;
  import static org.junit.jupiter.api.Assertions.assertTrue;
  
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.NoSuchElementException;
  import java.util.Set;
  
  import org.apache.commons.configuration2.builder.FileBasedBuilderParametersImpl;
  import org.apache.commons.configuration2.builder.FileBasedConfigurationBuilder;
  import org.apache.commons.configuration2.ex.ConfigurationException;
  import org.junit.jupiter.api.Test;
  
  /**
   * A test class which tests functionality related to immutable configurations.
   */
  public class TestImmutableConfiguration {
  
      /** Constant for the name of a test properties file. */
      private static final String TEST_FILE = "test.properties";
  
      /**
       * Creates a test configuration object filled with properties.
       *
       * @return the test configuration
       * @throws ConfigurationException if an error occurs
       */
      private static PropertiesConfiguration createTestConfig() throws ConfigurationException {
          return new FileBasedConfigurationBuilder<>(PropertiesConfiguration.class)
              .configure(new FileBasedBuilderParametersImpl().setFile(ConfigurationAssert.getTestFile(TEST_FILE))).getConfiguration();
      }
  
      /**
       * Obtains all keys from the given iteration.
       *
       * @param it the iterator
       * @return a set with all keys
       */
      private static Set<String> fetchKeys(final Iterator<String> it) {
          final Set<String> keys = new HashSet<>();
          while (it.hasNext()) {
              keys.add(it.next());
          }
          return keys;
      }
  
      /**
       * Tests that exceptions thrown by the wrapped configuration are handled correctly.
       */
      @Test
      void testExceptionHandling() {
          final PropertiesConfiguration config = new PropertiesConfiguration();
          final String property = "nonExistingProperty";
          config.setThrowExceptionOnMissing(true);
          final ImmutableConfiguration ic = ConfigurationUtils.unmodifiableConfiguration(config);
          final NoSuchElementException e = assertThrows(NoSuchElementException.class, () -> ic.getString(property));
          assertTrue(e.getMessage().contains(property));
      }
  
      /**
       * Tests whether an immutable subset can be queried.
       */
      @Test
      void testImmutableSubset() throws ConfigurationException {
          final ImmutableConfiguration conf = ConfigurationUtils.unmodifiableConfiguration(createTestConfig());
          final ImmutableConfiguration subset = conf.immutableSubset("test");
          assertFalse(subset.isEmpty());
          assertEquals(1000000, subset.getLong("long"));
      }
  
      /**
       * Tests whether data can be accessed from an unmodifiable configuration.
       */
      @Test
      void testUnmodifiableConfigurationAccess() throws ConfigurationException {
          final Configuration confOrg = createTestConfig();
          final ImmutableConfiguration conf = ConfigurationUtils.unmodifiableConfiguration(confOrg);
          assertFalse(conf.isEmpty());
          for (final Iterator<String> it = confOrg.getKeys(); it.hasNext();) {
             final String key = it.next();
             assertTrue(conf.containsKey(key), "Key not contained: " + key);
             assertEquals(confOrg.getProperty(key), conf.getProperty(key), "Wrong value for " + key);
         }
     }
 
     /**
      * Tests that a cast to a mutable configuration is not possible.
      */
     @Test
     void testUnmodifiableConfigurationCast() throws ConfigurationException {
         final ImmutableConfiguration conf = ConfigurationUtils.unmodifiableConfiguration(createTestConfig());
         assertThrows(ClassCastException.class, () -> ((Configuration) conf).clear());
     }
 
     /**
      * Tests an iteration over the keys of the immutable configuration.
      */
     @Test
     void testUnmodifiableConfigurationIterate() throws ConfigurationException {
         final Configuration confOrg = createTestConfig();
         final ImmutableConfiguration conf = ConfigurationUtils.unmodifiableConfiguration(confOrg);
         assertEquals(fetchKeys(confOrg.getKeys()), fetchKeys(conf.getKeys()));
     }
 
     /**
      * Tests that it is not possible to remove keys using the iterator.
      */
     @Test
     void testUnmodifiableConfigurationIteratorRemove() throws ConfigurationException {
         final ImmutableConfiguration conf = ConfigurationUtils.unmodifiableConfiguration(createTestConfig());
         final Iterator<String> it = conf.getKeys();
         it.next();
         assertThrows(UnsupportedOperationException.class, it::remove);
     }
 
     /**
      * Tests whether an update of the original configuration is visible for the immutable view.
      */
     @Test
     void testUnmodifiableConfigurationLiveUpdate() throws ConfigurationException {
         final Configuration confOrg = createTestConfig();
         final ImmutableConfiguration conf = ConfigurationUtils.unmodifiableConfiguration(confOrg);
         final String key = "new.property";
         final String value = "new value";
         confOrg.addProperty(key, value);
         assertEquals(value, conf.getString(key));
     }
 
     /**
      * Tries to create an immutable configuration from a null object.
      */
     @Test
     void testUnmodifiableConfigurationNull() {
         assertThrows(NullPointerException.class, () -> ConfigurationUtils.unmodifiableConfiguration(null));
     }
 
     /**
      * Tests different access methods for properties.
      */
     @Test
     void testUnmodifiableConfigurationOtherTypes() throws ConfigurationException {
         final ImmutableConfiguration conf = ConfigurationUtils.unmodifiableConfiguration(createTestConfig());
         assertEquals((byte) 10, conf.getByte("test.byte"));
         assertTrue(conf.getBoolean("test.boolean"));
         assertEquals(10.25, conf.getDouble("test.double"), .05);
         assertEquals(20.25f, conf.getFloat("test.float"), .05);
         assertEquals(10, conf.getInt("test.integer"));
         assertEquals(1000000L, conf.getLong("test.long"));
         assertEquals((short) 1, conf.getShort("test.short"));
     }
 
     /**
      * Tests whether an unmodifiable hierarchical configuration can be created.
      */
     @Test
     void testUnmodifiableHierarchicalConfiguration() {
         final HierarchicalConfiguration<?> conf = new BaseHierarchicalConfiguration();
         final String key = "test";
         conf.addProperty(key, Boolean.TRUE);
         final ImmutableHierarchicalConfiguration ihc = ConfigurationUtils.unmodifiableConfiguration(conf);
         assertTrue(ihc.getBoolean(key));
         assertEquals(0, ihc.getMaxIndex(key));
     }
 }