/*
    * 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.commons.configuration2.builder.combined;
  
  import static org.apache.commons.configuration2.TempDirUtils.newFile;
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertTrue;
  
  import java.io.File;
  import java.io.FileWriter;
  import java.io.IOException;
  import java.io.PrintWriter;
  import java.text.MessageFormat;
  
  import org.apache.commons.configuration2.BaseHierarchicalConfiguration;
  import org.apache.commons.configuration2.CombinedConfiguration;
  import org.apache.commons.configuration2.Configuration;
  import org.apache.commons.configuration2.XMLConfiguration;
  import org.apache.commons.configuration2.builder.BasicBuilderParameters;
  import org.apache.commons.configuration2.builder.BasicBuilderProperties;
  import org.apache.commons.configuration2.builder.BasicConfigurationBuilder;
  import org.apache.commons.configuration2.builder.CopyObjectDefaultHandler;
  import org.apache.commons.configuration2.builder.FileBasedBuilderParametersImpl;
  import org.apache.commons.configuration2.builder.FileBasedBuilderProperties;
  import org.apache.commons.configuration2.builder.ReloadingDetectorFactory;
  import org.apache.commons.configuration2.builder.ReloadingFileBasedConfigurationBuilder;
  import org.apache.commons.configuration2.builder.fluent.Parameters;
  import org.apache.commons.configuration2.ex.ConfigurationException;
  import org.apache.commons.configuration2.io.FileHandler;
  import org.apache.commons.configuration2.reloading.AlwaysReloadingDetector;
  import org.apache.commons.configuration2.reloading.RandomReloadingDetector;
  import org.apache.commons.configuration2.sync.ReadWriteSynchronizer;
  import org.apache.commons.configuration2.sync.Synchronizer;
  import org.apache.commons.configuration2.tree.MergeCombiner;
  import org.apache.commons.configuration2.tree.xpath.XPathExpressionEngine;
  import org.junit.jupiter.api.BeforeEach;
  import org.junit.jupiter.api.Test;
  import org.junit.jupiter.api.io.TempDir;
  
  /**
   * Test class for {@code ReloadingCombinedConfigurationBuilder} which actually accesses files to be reloaded.
   */
  public class TestReloadingCombinedConfigurationBuilderFileBased {
      /**
       * A test builder class which always returns the same configuration.
       */
      private static final class ConstantConfigurationBuilder extends BasicConfigurationBuilder<BaseHierarchicalConfiguration> {
          private final BaseHierarchicalConfiguration configuration;
  
          public ConstantConfigurationBuilder(final BaseHierarchicalConfiguration conf) {
              super(BaseHierarchicalConfiguration.class);
              configuration = conf;
          }
  
          @Override
          public BaseHierarchicalConfiguration getConfiguration() throws ConfigurationException {
              return configuration;
          }
      }
  
      /**
       * A thread class for testing concurrent reload operations.
       */
      private static final class ReloadThread extends Thread {
          /** The builder to be queried. */
          private final ReloadingCombinedConfigurationBuilder builder;
  
          /** An array for reporting failures. */
          private final int[] failures;
  
          /** The index of this thread in the array with failures. */
          private final int index;
  
          /** The number of test operations. */
          private final int count;
  
          ReloadThread(final ReloadingCombinedConfigurationBuilder bldr, final int[] failures, final int index, final int count) {
              builder = bldr;
              this.failures = failures;
              this.index = index;
              this.count = count;
          }
  
          @Override
          public void run() {
             failures[index] = 0;
             for (int i = 0; i < count; i++) {
                 try {
                     builder.getReloadingController().checkForReloading(null);
                     final String value = builder.getConfiguration().getString("/property[@name='config']/@value");
                     if (value == null || !value.equals("100")) {
                         ++failures[index];
                     }
                 } catch (final Exception ex) {
                     ++failures[index];
                 }
             }
         }
     }
 
     /** Constant for the prefix for XML configuration sources. */
     private static final String PROP_SRC = "override.xml";
 
     /** Constant for the prefix of the reload property. */
     private static final String PROP_RELOAD = "default.xmlReload";
 
     /** Constant for content of a XML configuration for reload tests. */
     private static final String RELOAD_CONTENT = "<config><default><xmlReload{1}>{0}</xmlReload{1}></default></config>";
 
     /**
      * Adds a source for a configuration which can be reloaded to the definition configuration.
      *
      * @param config the definition configuration
      * @param fileName the name of the file
      */
     private static void addReloadSource(final Configuration config, final String fileName) {
         config.addProperty(PROP_SRC + "(-1)[@fileName]", fileName);
         config.addProperty(PROP_SRC + "[@config-reload]", Boolean.TRUE);
     }
 
     /**
      * Returns the name of a test property.
      *
      * @param idx the index of the property
      * @return the test property with this index
      */
     private static String testProperty(final int idx) {
         return PROP_RELOAD + idx;
     }
 
     /**
      * Helper method for writing a file.
      *
      * @param file the file to be written
      * @param content the file's content
      * @throws IOException if an error occurs
      */
     private static void writeFile(final File file, final String content) throws IOException {
         try (PrintWriter out = new PrintWriter(new FileWriter(file))) {
             out.print(content);
         }
     }
 
     /** A folder for temporary files. */
     @TempDir
     public File tempFolder;
 
     /** A helper object for creating builder parameters. */
     private Parameters parameters;
 
     /** The builder to be tested. */
     private ReloadingCombinedConfigurationBuilder builder;
 
     /**
      * Helper method for testing whether the builder's definition file can be reloaded. This method expects that the test
      * builder has been fully initialized.
      *
      * @param defFile the path to the definition file
      * @throws IOException if an I/O error occurs.
      * @throws ConfigurationException if a configuration-related error occurs
      * @throws InterruptedException if waiting is interrupted
      */
     private void checkReloadDefinitionFile(final File defFile) throws IOException, ConfigurationException, InterruptedException {
         final File src1 = writeReloadFile(null, 1, 0);
         final File src2 = writeReloadFile(null, 1, 1);
         writeDefinitionFile(defFile, src1);
         CombinedConfiguration config = builder.getConfiguration();
         assertEquals(0, config.getInt(testProperty(1)));
 
         // No change definition file
         boolean reloaded = false;
         for (int attempts = 0; attempts < 50 && !reloaded; attempts++) {
             writeDefinitionFile(defFile, src2);
             reloaded = builder.getReloadingController().checkForReloading(null);
             if (!reloaded) {
                 Thread.sleep(100);
             }
         }
         assertTrue(reloaded);
         config = builder.getConfiguration();
         assertEquals(1, config.getInt(testProperty(1)));
     }
 
     @BeforeEach
     public void setUp() throws Exception {
         parameters = new Parameters();
         builder = new ReloadingCombinedConfigurationBuilder();
     }
 
     /**
      * Tests concurrent access to a reloading builder for combined configurations.
      */
     @Test
     public void testConcurrentGetAndReload() throws Exception {
         final int threadCount = 4;
         final int loopCount = 100;
         final ReloadingDetectorFactory detectorFactory = (handler, params) -> new RandomReloadingDetector();
         final BaseHierarchicalConfiguration defConf = new BaseHierarchicalConfiguration();
         defConf.addProperty("header.result.nodeCombiner[@config-class]", MergeCombiner.class.getName());
         defConf.addProperty("header.result.expressionEngine[@config-class]", XPathExpressionEngine.class.getName());
         addReloadSource(defConf, "configA.xml");
         addReloadSource(defConf, "configB.xml");
         final Synchronizer sync = new ReadWriteSynchronizer();
         builder.configure(parameters.combined().setDefinitionBuilder(new ConstantConfigurationBuilder(defConf)).setSynchronizer(sync)
             .registerChildDefaultsHandler(BasicBuilderProperties.class, new CopyObjectDefaultHandler(new BasicBuilderParameters().setSynchronizer(sync)))
             .registerChildDefaultsHandler(FileBasedBuilderProperties.class,
                 new CopyObjectDefaultHandler(new FileBasedBuilderParametersImpl().setReloadingDetectorFactory(detectorFactory))));
 
         assertEquals("100", builder.getConfiguration().getString("/property[@name='config']/@value"));
 
         final Thread[] testThreads = new Thread[threadCount];
         final int[] failures = new int[threadCount];
 
         for (int i = 0; i < testThreads.length; ++i) {
             testThreads[i] = new ReloadThread(builder, failures, i, loopCount);
             testThreads[i].start();
         }
 
         int totalFailures = 0;
         for (int i = 0; i < testThreads.length; ++i) {
             testThreads[i].join();
             totalFailures += failures[i];
         }
         assertEquals(0, totalFailures);
     }
 
     /**
      * Tests whether the default definition builder is capable of detecting a change in the definition configuration.
      */
     @Test
     public void testReloadDefinitionFileDefaultBuilder() throws ConfigurationException, IOException, InterruptedException {
         final File defFile = newFile(tempFolder);
         builder.configure(parameters.combined().setDefinitionBuilderParameters(parameters.xml().setReloadingRefreshDelay(0L).setFile(defFile)));
         checkReloadDefinitionFile(defFile);
     }
 
     /**
      * Tests whether a change in the definition file is detected and causes a reload if a specific builder for the
      * definition configuration is provided.
      */
     @Test
     public void testReloadDefinitionFileExplicitBuilder() throws ConfigurationException, IOException, InterruptedException {
         final File defFile = newFile(tempFolder);
         builder.configure(parameters.combined().setDefinitionBuilder(
             new ReloadingFileBasedConfigurationBuilder<>(XMLConfiguration.class).configure(parameters.xml().setReloadingRefreshDelay(0L).setFile(defFile))));
         checkReloadDefinitionFile(defFile);
     }
 
     /**
      * Tests whether a changed file is detected on disk.
      */
     @Test
     public void testReloadFromFile() throws ConfigurationException, IOException {
         final File xmlConf1 = writeReloadFile(null, 1, 0);
         final File xmlConf2 = writeReloadFile(null, 2, 0);
         final ReloadingDetectorFactory detectorFactory = (handler, params) -> new AlwaysReloadingDetector();
         final BaseHierarchicalConfiguration defConf = new BaseHierarchicalConfiguration();
         addReloadSource(defConf, xmlConf1.getAbsolutePath());
         addReloadSource(defConf, xmlConf2.getAbsolutePath());
         builder.configure(parameters.combined().setDefinitionBuilder(new ConstantConfigurationBuilder(defConf)).registerChildDefaultsHandler(
             FileBasedBuilderProperties.class, new CopyObjectDefaultHandler(new FileBasedBuilderParametersImpl().setReloadingDetectorFactory(detectorFactory))));
         CombinedConfiguration config = builder.getConfiguration();
         assertEquals(0, config.getInt(testProperty(1)));
         assertEquals(0, config.getInt(testProperty(2)));
 
         writeReloadFile(xmlConf1, 1, 1);
         builder.getReloadingController().checkForReloading(null);
         config = builder.getConfiguration();
         assertEquals(1, config.getInt(testProperty(1)));
         assertEquals(0, config.getInt(testProperty(2)));
 
         writeReloadFile(xmlConf2, 2, 2);
         builder.getReloadingController().checkForReloading(null);
         config = builder.getConfiguration();
         assertEquals(1, config.getInt(testProperty(1)));
         assertEquals(2, config.getInt(testProperty(2)));
     }
 
     /**
      * Writes a configuration definition file that refers to the specified file source.
      *
      * @param defFile the target definition file
      * @param src the configuration source file to be referenced
      * @throws ConfigurationException if an error occurs
      */
     private void writeDefinitionFile(final File defFile, final File src) throws ConfigurationException {
         final XMLConfiguration defConf = new XMLConfiguration();
         addReloadSource(defConf, src.getAbsolutePath());
         new FileHandler(defConf).save(defFile);
     }
 
     /**
      * Writes a file for testing reload operations.
      *
      * @param f the file to be written or <b>null</b> for creating a new one
      * @param tagIdx the index of the tag
      * @param value the value of the reload test property
      * @return the file that was written
      * @throws IOException if an error occurs
      */
     private File writeReloadFile(final File f, final int tagIdx, final int value) throws IOException {
         return writeReloadFile(f, MessageFormat.format(RELOAD_CONTENT, value, tagIdx));
     }
 
     /**
      * Helper method for writing a test file for reloading. The file will be created in the test directory. It is also
      * scheduled for automatic deletion after the test.
      *
      * @param f the file to be written or <b>null</b> for creating a new one
      * @param content the content of the file
      * @return the {@code File} object for the test file
      * @throws IOException if an error occurs
      */
     private File writeReloadFile(final File f, final String content) throws IOException {
         final File file = f != null ? f : newFile(tempFolder);
         writeFile(file, content);
         return file;
     }
 }