/*
    * 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.jdbc;
  
  import java.io.PrintWriter;
  import java.lang.reflect.Method;
  import java.sql.Connection;
  import java.sql.SQLException;
  
  import javax.sql.DataSource;
  
  import org.apache.logging.log4j.Logger;
  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.PluginFactory;
  import org.apache.logging.log4j.core.util.Loader;
  import org.apache.logging.log4j.status.StatusLogger;
  import org.apache.logging.log4j.util.Strings;
  
  /**
   * A {@link JdbcAppender} connection source that uses a public static factory method to obtain a {@link Connection} or
   * {@link DataSource}.
   */
  @Plugin(name = "ConnectionFactory", category = "Core", elementType = "connectionSource", printObject = true)
  public final class FactoryMethodConnectionSource implements ConnectionSource {
      private static final Logger LOGGER = StatusLogger.getLogger();
  
      private final DataSource dataSource;
      private final String description;
  
      private FactoryMethodConnectionSource(final DataSource dataSource, final String className, final String methodName,
                                            final String returnType) {
          this.dataSource = dataSource;
          this.description = "factory{ public static " + returnType + ' ' + className + '.' + methodName + "() }";
      }
  
      @Override
      public Connection getConnection() throws SQLException {
          return this.dataSource.getConnection();
      }
  
      @Override
      public String toString() {
          return this.description;
      }
  
      /**
       * Factory method for creating a connection source within the plugin manager.
       *
       * @param className The name of a public class that contains a static method capable of returning either a
       *                  {@link DataSource} or a {@link Connection}.
       * @param methodName The name of the public static method on the aforementioned class that returns the data source
       *                   or connection. If this method returns a {@link Connection}, it should return a new connection
       *                   every call.
       * @return the created connection source.
       */
      @PluginFactory
      public static FactoryMethodConnectionSource createConnectionSource(
              @PluginAttribute("class") final String className,
              @PluginAttribute("method") final String methodName) {
          if (Strings.isEmpty(className) || Strings.isEmpty(methodName)) {
              LOGGER.error("No class name or method name specified for the connection factory method.");
              return null;
          }
  
          final Method method;
          try {
              final Class<?> factoryClass = Loader.loadClass(className);
              method = factoryClass.getMethod(methodName);
          } catch (final Exception e) {
              LOGGER.error(e.toString(), e);
              return null;
          }
  
          final Class<?> returnType = method.getReturnType();
          String returnTypeString = returnType.getName();
          DataSource dataSource;
          if (returnType == DataSource.class) {
              try {
                  dataSource = (DataSource) method.invoke(null);
                  returnTypeString += "[" + dataSource + ']';
              } catch (final Exception e) {
                  LOGGER.error(e.toString(), e);
                  return null;
              }
         } else if (returnType == Connection.class) {
             dataSource = new DataSource() {
                 @Override
                 public Connection getConnection() throws SQLException {
                     try {
                         return (Connection) method.invoke(null);
                     } catch (final Exception e) {
                         throw new SQLException("Failed to obtain connection from factory method.", e);
                     }
                 }
 
                 @Override
                 public Connection getConnection(final String username, final String password) throws SQLException {
                     throw new UnsupportedOperationException();
                 }
 
                 @Override
                 public int getLoginTimeout() throws SQLException {
                     throw new UnsupportedOperationException();
                 }
 
                 @Override
                 public PrintWriter getLogWriter() throws SQLException {
                     throw new UnsupportedOperationException();
                 }
 
                 // method must be present to compile on Java 7!
                 // @Override must be absent to compile on Java 6!
                 @SuppressWarnings("unused")
                 public java.util.logging.Logger getParentLogger() {
                     throw new UnsupportedOperationException();
                 }
 
                 @Override
                 public boolean isWrapperFor(final Class<?> iface) throws SQLException {
                     return false;
                 }
 
                 @Override
                 public void setLoginTimeout(final int seconds) throws SQLException {
                     throw new UnsupportedOperationException();
                 }
 
                 @Override
                 public void setLogWriter(final PrintWriter out) throws SQLException {
                     throw new UnsupportedOperationException();
                 }
 
                 @Override
                 public <T> T unwrap(final Class<T> iface) throws SQLException {
                     return null;
                 }
             };
         } else {
             LOGGER.error("Method [{}.{}()] returns unsupported type [{}].", className, methodName,
                     returnType.getName());
             return null;
         }
 
         return new FactoryMethodConnectionSource(dataSource, className, methodName, returnTypeString);
     }
 }