/*
    * 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.appender.db.jpa;
  
  import java.lang.reflect.Constructor;
  
  import org.apache.logging.log4j.core.Filter;
  import org.apache.logging.log4j.core.LogEvent;
  import org.apache.logging.log4j.core.appender.AbstractAppender;
  import org.apache.logging.log4j.core.appender.db.AbstractDatabaseAppender;
  import org.apache.logging.log4j.core.config.plugins.Plugin;
  import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
  import org.apache.logging.log4j.core.config.plugins.PluginElement;
  import org.apache.logging.log4j.core.config.plugins.PluginFactory;
  import org.apache.logging.log4j.core.util.Booleans;
  import org.apache.logging.log4j.core.util.Loader;
  import org.apache.logging.log4j.util.Strings;
  
  /**
   * This Appender writes logging events to a relational database using the Java Persistence API. It requires a
   * pre-configured JPA persistence unit and a concrete implementation of the abstract
   * {@link AbstractLogEventWrapperEntity} class decorated with JPA annotations.
   *
   * @see AbstractLogEventWrapperEntity
   */
  @Plugin(name = "JPA", category = "Core", elementType = "appender", printObject = true)
  public final class JpaAppender extends AbstractDatabaseAppender<JpaDatabaseManager> {
      private static final long serialVersionUID = 1L;
  
      private final String description;
  
      private JpaAppender(final String name, final Filter filter, final boolean ignoreExceptions,
              final JpaDatabaseManager manager) {
          super(name, filter, ignoreExceptions, manager);
          this.description = this.getName() + "{ manager=" + this.getManager() + " }";
      }
  
      @Override
      public String toString() {
          return this.description;
      }
  
      /**
       * Factory method for creating a JPA appender within the plugin manager.
       *
       * @param name The name of the appender.
       * @param ignore If {@code "true"} (default) exceptions encountered when appending events are logged; otherwise
       *               they are propagated to the caller.
       * @param filter The filter, if any, to use.
       * @param bufferSize If an integer greater than 0, this causes the appender to buffer log events and flush whenever
       *                   the buffer reaches this size.
       * @param entityClassName The fully qualified name of the concrete {@link AbstractLogEventWrapperEntity}
       *                        implementation that has JPA annotations mapping it to a database table.
       * @param persistenceUnitName The name of the JPA persistence unit that should be used for persisting log events.
       * @return a new JPA appender.
       */
      @PluginFactory
      public static JpaAppender createAppender(
              @PluginAttribute("name") final String name,
              @PluginAttribute("ignoreExceptions") final String ignore,
              @PluginElement("Filter") final Filter filter,
              @PluginAttribute("bufferSize") final String bufferSize,
              @PluginAttribute("entityClassName") final String entityClassName,
              @PluginAttribute("persistenceUnitName") final String persistenceUnitName) {
          if (Strings.isEmpty(entityClassName) || Strings.isEmpty(persistenceUnitName)) {
              LOGGER.error("Attributes entityClassName and persistenceUnitName are required for JPA Appender.");
              return null;
          }
  
          final int bufferSizeInt = AbstractAppender.parseInt(bufferSize, 0);
          final boolean ignoreExceptions = Booleans.parseBoolean(ignore, true);
  
          try {
              @SuppressWarnings("unchecked")
              final Class<? extends AbstractLogEventWrapperEntity> entityClass =
                      (Class<? extends AbstractLogEventWrapperEntity>) Loader.loadClass(entityClassName);
  
              if (!AbstractLogEventWrapperEntity.class.isAssignableFrom(entityClass)) {
                  LOGGER.error("Entity class [{}] does not extend AbstractLogEventWrapperEntity.", entityClassName);
                  return null;
              }
  
              try {
                  entityClass.getConstructor();
              } catch (final NoSuchMethodException e) {
                 LOGGER.error("Entity class [{}] does not have a no-arg constructor. The JPA provider will reject it.",
                         entityClassName);
                 return null;
             }
 
             final Constructor<? extends AbstractLogEventWrapperEntity> entityConstructor =
                     entityClass.getConstructor(LogEvent.class);
 
             final String managerName = "jpaManager{ description=" + name + ", bufferSize=" + bufferSizeInt
                     + ", persistenceUnitName=" + persistenceUnitName + ", entityClass=" + entityClass.getName() + '}';
 
             final JpaDatabaseManager manager = JpaDatabaseManager.getJPADatabaseManager(
                     managerName, bufferSizeInt, entityClass, entityConstructor, persistenceUnitName
             );
             if (manager == null) {
                 return null;
             }
 
             return new JpaAppender(name, filter, ignoreExceptions, manager);
         } catch (final ClassNotFoundException e) {
             LOGGER.error("Could not load entity class [{}].", entityClassName, e);
             return null;
         } catch (final NoSuchMethodException e) {
             LOGGER.error("Entity class [{}] does not have a constructor with a single argument of type LogEvent.",
                     entityClassName);
             return null;
         }
     }
 }