/*
    * 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.nosql.appender.mongodb;
  
  import org.apache.logging.log4j.Level;
  import org.apache.logging.log4j.Logger;
  import org.apache.logging.log4j.core.appender.AppenderLoggingException;
  import org.apache.logging.log4j.nosql.appender.NoSqlConnection;
  import org.apache.logging.log4j.nosql.appender.NoSqlObject;
  import org.apache.logging.log4j.status.StatusLogger;
  import org.apache.logging.log4j.util.Strings;
  import org.bson.BSON;
  import org.bson.Transformer;
  
  import com.mongodb.BasicDBObject;
  import com.mongodb.DB;
  import com.mongodb.DBCollection;
  import com.mongodb.Mongo;
  import com.mongodb.MongoException;
  import com.mongodb.WriteConcern;
  import com.mongodb.WriteResult;
  
  /**
   * The MongoDB implementation of {@link NoSqlConnection}.
   */
  public final class MongoDbConnection implements NoSqlConnection<BasicDBObject, MongoDbObject> {
  
      private static final Logger LOGGER = StatusLogger.getLogger();
  
      static {
          BSON.addEncodingHook(Level.class, new Transformer() {
              @Override
              public Object transform(final Object o) {
                  if (o instanceof Level) {
                      return ((Level) o).name();
                  }
                  return o;
              }
          });
      }
  
      private final DBCollection collection;
      private final Mongo mongo;
      private final WriteConcern writeConcern;
  
      public MongoDbConnection(final DB database, final WriteConcern writeConcern, final String collectionName) {
          this.mongo = database.getMongo();
          this.collection = database.getCollection(collectionName);
          this.writeConcern = writeConcern;
      }
  
      @Override
      public MongoDbObject createObject() {
          return new MongoDbObject();
      }
  
      @Override
      public MongoDbObject[] createList(final int length) {
          return new MongoDbObject[length];
      }
  
      @Override
      public void insertObject(final NoSqlObject<BasicDBObject> object) {
          try {
              final WriteResult result = this.collection.insert(object.unwrap(), this.writeConcern);
              if (Strings.isNotEmpty(result.getError())) {
                  throw new AppenderLoggingException("Failed to write log event to MongoDB due to error: " +
                          result.getError() + '.');
              }
          } catch (final MongoException e) {
              throw new AppenderLoggingException("Failed to write log event to MongoDB due to error: " + e.getMessage(),
                      e);
          }
      }
  
      @Override
      public void close() {
          // there's no need to call this.mongo.close() since that literally closes the connection
          // MongoDBClient uses internal connection pooling
          // for more details, see LOG4J2-591
      }
  
      @Override
      public boolean isClosed() {
          return !this.mongo.getConnector().isOpen();
     }
 
     /**
      * To prevent class loading issues during plugin discovery, this code cannot live within MongoDbProvider. This
      * is because of how Java treats references to Exception classes different from references to other classes. When
      * Java loads a class, it normally won't load that class's dependent classes until and unless A) they are used, B)
      * the class being loaded extends or implements those classes, or C) those classes are the types of static members
      * in the class. However, exceptions that a class uses are always loaded when the class is loaded, even before
      * they are actually used.
      *
      * @param database The database to authenticate
      * @param username The username to authenticate with
      * @param password The password to authenticate with
      */
     static void authenticate(final DB database, final String username, final String password) {
         try {
             if (!database.authenticate(username, password.toCharArray())) {
                 LOGGER.error("Failed to authenticate against MongoDB server. Unknown error.");
             }
         } catch (final MongoException e) {
             LOGGER.error("Failed to authenticate against MongoDB: " + e.getMessage(), e);
         } catch (final IllegalStateException e) {
             LOGGER.error("Factory-supplied MongoDB database connection already authenticated with different" +
                     "credentials but lost connection.", e);
         }
     }
 }