/*
    * 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.logging.log4j.core.config;
  
  import java.io.File;
  import java.io.FileInputStream;
  import java.io.FileNotFoundException;
  import java.io.IOException;
  import java.io.InputStream;
  import java.net.MalformedURLException;
  import java.net.URI;
  import java.net.URISyntaxException;
  import java.net.URL;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.List;
  import java.util.Map;
  import java.util.concurrent.locks.Lock;
  import java.util.concurrent.locks.ReentrantLock;
  
  import org.apache.logging.log4j.Level;
  import org.apache.logging.log4j.Logger;
  import org.apache.logging.log4j.core.config.builder.api.ConfigurationBuilderFactory;
  import org.apache.logging.log4j.core.config.plugins.util.PluginManager;
  import org.apache.logging.log4j.core.config.plugins.util.PluginType;
  import org.apache.logging.log4j.core.lookup.Interpolator;
  import org.apache.logging.log4j.core.lookup.StrSubstitutor;
  import org.apache.logging.log4j.core.util.FileUtils;
  import org.apache.logging.log4j.core.util.Loader;
  import org.apache.logging.log4j.core.util.NetUtils;
  import org.apache.logging.log4j.core.util.ReflectionUtil;
  import org.apache.logging.log4j.status.StatusLogger;
  import org.apache.logging.log4j.util.LoaderUtil;
  import org.apache.logging.log4j.util.PropertiesUtil;
  import org.apache.logging.log4j.util.Strings;
  
  /**
   * Factory class for parsed {@link Configuration} objects from a configuration file.
   * ConfigurationFactory allows the configuration implementation to be
   * dynamically chosen in 1 of 3 ways:
   * <ol>
   * <li>A system property named "log4j.configurationFactory" can be set with the
   * name of the ConfigurationFactory to be used.</li>
   * <li>
   * {@linkplain #setConfigurationFactory(ConfigurationFactory)} can be called
   * with the instance of the ConfigurationFactory to be used. This must be called
   * before any other calls to Log4j.</li>
   * <li>
   * A ConfigurationFactory implementation can be added to the classpath and configured as a plugin in the
   * {@link #CATEGORY ConfigurationFactory} category. The {@link Order} annotation should be used to configure the
   * factory to be the first one inspected. See
   * {@linkplain org.apache.logging.log4j.core.config.xml.XmlConfigurationFactory} for an example.</li>
   * </ol>
   *
   * If the ConfigurationFactory that was added returns null on a call to
   * getConfiguration then any other ConfigurationFactories found as plugins will
   * be called in their respective order. DefaultConfiguration is always called
   * last if no configuration has been returned.
   */
  public abstract class ConfigurationFactory extends ConfigurationBuilderFactory {
      /**
       * Allow the ConfigurationFactory class to be specified as a system property.
       */
      public static final String CONFIGURATION_FACTORY_PROPERTY = "log4j.configurationFactory";
  
      /**
       * Allow the location of the configuration file to be specified as a system property.
       */
      public static final String CONFIGURATION_FILE_PROPERTY = "log4j.configurationFile";
  
      /**
       * Plugin category used to inject a ConfigurationFactory {@link org.apache.logging.log4j.core.config.plugins.Plugin}
       * class.
       *
       * @since 2.1
       */
      public static final String CATEGORY = "ConfigurationFactory";
  
      /**
       * Allow subclasses access to the status logger without creating another instance.
       */
      protected static final Logger LOGGER = StatusLogger.getLogger();
  
      /**
      * File name prefix for test configurations.
      */
     protected static final String TEST_PREFIX = "log4j2-test";
 
     /**
      * File name prefix for standard configurations.
      */
     protected static final String DEFAULT_PREFIX = "log4j2";
 
     /**
      * The name of the classloader URI scheme.
      */
     private static final String CLASS_LOADER_SCHEME = "classloader";
 
     /**
      * The name of the classpath URI scheme, synonymous with the classloader URI scheme.
      */
     private static final String CLASS_PATH_SCHEME = "classpath";
 
     private static volatile List<ConfigurationFactory> factories = null;
 
     private static ConfigurationFactory configFactory = new Factory();
 
     protected final StrSubstitutor substitutor = new StrSubstitutor(new Interpolator());
 
     private static final Lock LOCK = new ReentrantLock();
 
     /**
      * Returns the ConfigurationFactory.
      * @return the ConfigurationFactory.
      */
     public static ConfigurationFactory getInstance() {
         // volatile works in Java 1.6+, so double-checked locking also works properly
         //noinspection DoubleCheckedLocking
         if (factories == null) {
             LOCK.lock();
             try {
                 if (factories == null) {
                     final List<ConfigurationFactory> list = new ArrayList<>();
                     final String factoryClass = PropertiesUtil.getProperties().getStringProperty(CONFIGURATION_FACTORY_PROPERTY);
                     if (factoryClass != null) {
                         addFactory(list, factoryClass);
                     }
                     final PluginManager manager = new PluginManager(CATEGORY);
                     manager.collectPlugins();
                     final Map<String, PluginType<?>> plugins = manager.getPlugins();
                     final List<Class<? extends ConfigurationFactory>> ordered = new ArrayList<>(plugins.size());
                     for (final PluginType<?> type : plugins.values()) {
                         try {
                             ordered.add(type.getPluginClass().asSubclass(ConfigurationFactory.class));
                         } catch (final Exception ex) {
                             LOGGER.warn("Unable to add class {}", type.getPluginClass(), ex);
                         }
                     }
                     Collections.sort(ordered, OrderComparator.getInstance());
                     for (final Class<? extends ConfigurationFactory> clazz : ordered) {
                         addFactory(list, clazz);
                     }
                     // see above comments about double-checked locking
                     //noinspection NonThreadSafeLazyInitialization
                     factories = Collections.unmodifiableList(list);
                 }
             } finally {
                 LOCK.unlock();
             }
         }
 
         LOGGER.debug("Using configurationFactory {}", configFactory);
         return configFactory;
     }
 
     private static void addFactory(final Collection<ConfigurationFactory> list, final String factoryClass) {
         try {
             addFactory(list, LoaderUtil.loadClass(factoryClass).asSubclass(ConfigurationFactory.class));
         } catch (final Exception ex) {
             LOGGER.error("Unable to load class {}", factoryClass, ex);
         }
     }
 
     private static void addFactory(final Collection<ConfigurationFactory> list,
                                    final Class<? extends ConfigurationFactory> factoryClass) {
         try {
             list.add(ReflectionUtil.instantiate(factoryClass));
         } catch (final Exception ex) {
             LOGGER.error("Unable to create instance of {}", factoryClass.getName(), ex);
         }
     }
 
     /**
      * Set the configuration factory. This method is not intended for general use and may not be thread safe.
      * @param factory the ConfigurationFactory.
      */
     public static void setConfigurationFactory(final ConfigurationFactory factory) {
         configFactory = factory;
     }
 
     /**
      * Reset the ConfigurationFactory to the default. This method is not intended for general use and may
      * not be thread safe.
      */
     public static void resetConfigurationFactory() {
         configFactory = new Factory();
     }
 
     /**
      * Remove the ConfigurationFactory. This method is not intended for general use and may not be thread safe.
      * @param factory The factory to remove.
      */
     public static void removeConfigurationFactory(final ConfigurationFactory factory) {
         if (configFactory == factory) {
             configFactory = new Factory();
         }
     }
 
     protected abstract String[] getSupportedTypes();
 
     protected boolean isActive() {
         return true;
     }
 
     public abstract Configuration getConfiguration(ConfigurationSource source);
 
     /**
      * Returns the Configuration.
      * @param name The configuration name.
      * @param configLocation The configuration location.
      * @return The Configuration.
      */
     public Configuration getConfiguration(final String name, final URI configLocation) {
         if (!isActive()) {
             return null;
         }
         if (configLocation != null) {
             final ConfigurationSource source = getInputFromUri(configLocation);
             if (source != null) {
                 return getConfiguration(source);
             }
         }
         return null;
     }
 
     /**
      * Returns the Configuration obtained using a given ClassLoader.
      *
      * @param name The configuration name.
      * @param configLocation A URI representing the location of the configuration.
      * @param loader The default ClassLoader to use. If this is {@code null}, then the
      *               {@linkplain LoaderUtil#getThreadContextClassLoader() default ClassLoader} will be used.
      * @return The Configuration.
      * @since 2.1
      */
     public Configuration getConfiguration(final String name, final URI configLocation, final ClassLoader loader) {
         if (!isActive()) {
             return null;
         }
         if (loader == null) {
             return getConfiguration(name, configLocation);
         }
         if (isClassLoaderUri(configLocation)) {
             final String path = extractClassLoaderUriPath(configLocation);
             final ConfigurationSource source = getInputFromResource(path, loader);
             if (source != null) {
                 final Configuration configuration = getConfiguration(source);
                 if (configuration != null) {
                     return configuration;
                 }
             }
         }
         return getConfiguration(name, configLocation);
     }
 
     /**
      * Load the configuration from a URI.
      * @param configLocation A URI representing the location of the configuration.
      * @return The ConfigurationSource for the configuration.
      */
     protected ConfigurationSource getInputFromUri(final URI configLocation) {
         final File configFile = FileUtils.fileFromUri(configLocation);
         if (configFile != null && configFile.exists() && configFile.canRead()) {
             try {
                 return new ConfigurationSource(new FileInputStream(configFile), configFile);
             } catch (final FileNotFoundException ex) {
                 LOGGER.error("Cannot locate file {}", configLocation.getPath(), ex);
             }
         }
         if (isClassLoaderUri(configLocation)) {
             final ClassLoader loader = LoaderUtil.getThreadContextClassLoader();
             final String path = extractClassLoaderUriPath(configLocation);
             final ConfigurationSource source = getInputFromResource(path, loader);
             if (source != null) {
                 return source;
             }
         }
         if (!configLocation.isAbsolute()) { // LOG4J2-704 avoid confusing error message thrown by uri.toURL()
             LOGGER.error("File not found in file system or classpath: {}", configLocation.toString());
             return null;
         }
         try {
             return new ConfigurationSource(configLocation.toURL().openStream(), configLocation.toURL());
         } catch (final MalformedURLException ex) {
             LOGGER.error("Invalid URL {}", configLocation.toString(), ex);
         } catch (final Exception ex) {
             LOGGER.error("Unable to access {}", configLocation.toString(), ex);
         }
         return null;
     }
 
     private static boolean isClassLoaderUri(final URI uri) {
         if (uri == null) {
             return false;
         }
         final String scheme = uri.getScheme();
         return scheme == null || scheme.equals(CLASS_LOADER_SCHEME) || scheme.equals(CLASS_PATH_SCHEME);
     }
 
     private static String extractClassLoaderUriPath(final URI uri) {
         return uri.getScheme() == null ? uri.getPath() : uri.getSchemeSpecificPart();
     }
 
     /**
      * Load the configuration from the location represented by the String.
      * @param config The configuration location.
      * @param loader The default ClassLoader to use.
      * @return The InputSource to use to read the configuration.
      */
     protected ConfigurationSource getInputFromString(final String config, final ClassLoader loader) {
         try {
             final URL url = new URL(config);
             return new ConfigurationSource(url.openStream(), FileUtils.fileFromUri(url.toURI()));
         } catch (final Exception ex) {
             final ConfigurationSource source = getInputFromResource(config, loader);
             if (source == null) {
                 try {
                     final File file = new File(config);
                     return new ConfigurationSource(new FileInputStream(file), file);
                 } catch (final FileNotFoundException fnfe) {
                     // Ignore the exception
                     LOGGER.catching(Level.DEBUG, fnfe);
                 }
             }
             return source;
         }
     }
 
     /**
      * Retrieve the configuration via the ClassLoader.
      * @param resource The resource to load.
      * @param loader The default ClassLoader to use.
      * @return The ConfigurationSource for the configuration.
      */
     protected ConfigurationSource getInputFromResource(final String resource, final ClassLoader loader) {
         final URL url = Loader.getResource(resource, loader);
         if (url == null) {
             return null;
         }
         InputStream is = null;
         try {
             is = url.openStream();
         } catch (final IOException ioe) {
             LOGGER.catching(Level.DEBUG, ioe);
             return null;
         }
         if (is == null) {
             return null;
         }
 
         if (FileUtils.isFile(url)) {
             try {
                 return new ConfigurationSource(is, FileUtils.fileFromUri(url.toURI()));
             } catch (final URISyntaxException ex) {
                 // Just ignore the exception.
                 LOGGER.catching(Level.DEBUG, ex);
             }
         }
         return new ConfigurationSource(is, url);
     }
 
     /**
      * Default Factory.
      */
     private static class Factory extends ConfigurationFactory {
 
         /**
          * Default Factory Constructor.
          * @param name The configuration name.
          * @param configLocation The configuration location.
          * @return The Configuration.
          */
         @Override
         public Configuration getConfiguration(final String name, final URI configLocation) {
 
             if (configLocation == null) {
                 final String configLocationStr = this.substitutor.replace(PropertiesUtil.getProperties()
                         .getStringProperty(CONFIGURATION_FILE_PROPERTY));
                 if (configLocationStr != null) {
                     ConfigurationSource source = null;
                     try {
                         source = getInputFromUri(NetUtils.toURI(configLocationStr));
                     } catch (final Exception ex) {
                         // Ignore the error and try as a String.
                         LOGGER.catching(Level.DEBUG, ex);
                     }
                     if (source == null) {
                         final ClassLoader loader = LoaderUtil.getThreadContextClassLoader();
                         source = getInputFromString(configLocationStr, loader);
                     }
                     if (source != null) {
                         for (final ConfigurationFactory factory : getFactories()) {
                             final String[] types = factory.getSupportedTypes();
                             if (types != null) {
                                 for (final String type : types) {
                                     if (type.equals("*") || configLocationStr.endsWith(type)) {
                                         final Configuration config = factory.getConfiguration(source);
                                         if (config != null) {
                                             return config;
                                         }
                                     }
                                 }
                             }
                         }
                     }
                 } else {
                     for (final ConfigurationFactory factory : getFactories()) {
                         final String[] types = factory.getSupportedTypes();
                         if (types != null) {
                             for (final String type : types) {
                                 if (type.equals("*")) {
                                     final Configuration config = factory.getConfiguration(name, configLocation);
                                     if (config != null) {
                                         return config;
                                     }
                                 }
                             }
                         }
                     }
                 }
             } else {
                 // configLocation != null
                 final String configLocationStr = configLocation.toString();
                 for (final ConfigurationFactory factory : getFactories()) {
                     final String[] types = factory.getSupportedTypes();
                     if (types != null) {
                         for (final String type : types) {
                             if (type.equals("*") || configLocationStr.endsWith(type)) {
                                 final Configuration config = factory.getConfiguration(name, configLocation);
                                 if (config != null) {
                                     return config;
                                 }
                             }
                         }
                     }
                 }
             }
 
             Configuration config = getConfiguration(true, name);
             if (config == null) {
                 config = getConfiguration(true, null);
                 if (config == null) {
                     config = getConfiguration(false, name);
                     if (config == null) {
                         config = getConfiguration(false, null);
                     }
                 }
             }
             if (config != null) {
                 return config;
             }
             LOGGER.error("No log4j2 configuration file found. Using default configuration: logging only errors to the console.");
             return new DefaultConfiguration();
         }
 
         private Configuration getConfiguration(final boolean isTest, final String name) {
             final boolean named = Strings.isNotEmpty(name);
             final ClassLoader loader = LoaderUtil.getThreadContextClassLoader();
             for (final ConfigurationFactory factory : getFactories()) {
                 String configName;
                 final String prefix = isTest ? TEST_PREFIX : DEFAULT_PREFIX;
                 final String [] types = factory.getSupportedTypes();
                 if (types == null) {
                     continue;
                 }
 
                 for (final String suffix : types) {
                     if (suffix.equals("*")) {
                         continue;
                     }
                     configName = named ? prefix + name + suffix : prefix + suffix;
 
                     final ConfigurationSource source = getInputFromResource(configName, loader);
                     if (source != null) {
                         return factory.getConfiguration(source);
                     }
                 }
             }
             return null;
         }
 
         @Override
         public String[] getSupportedTypes() {
             return null;
         }
 
         @Override
         public Configuration getConfiguration(final ConfigurationSource source) {
             if (source != null) {
                 final String config = source.getLocation();
                 for (final ConfigurationFactory factory : getFactories()) {
                     final String[] types = factory.getSupportedTypes();
                     if (types != null) {
                         for (final String type : types) {
                             if (type.equals("*") || config != null && config.endsWith(type)) {
                                 final Configuration c = factory.getConfiguration(source);
                                 if (c != null) {
                                     LOGGER.debug("Loaded configuration from {}", source);
                                     return c;
                                 }
                                 LOGGER.error("Cannot determine the ConfigurationFactory to use for {}", config);
                                 return null;
                             }
                         }
                     }
                 }
             }
             LOGGER.error("Cannot process configuration, input source is null");
             return null;
         }
     }
 
     static List<ConfigurationFactory> getFactories() {
         return factories;
     }
 }