/*
    * 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;
  
  import java.io.Serializable;
  
  import org.apache.logging.log4j.core.Appender;
  import org.apache.logging.log4j.core.Core;
  import org.apache.logging.log4j.core.Filter;
  import org.apache.logging.log4j.core.Layout;
  import org.apache.logging.log4j.core.LogEvent;
  import org.apache.logging.log4j.core.config.Configuration;
  import org.apache.logging.log4j.core.config.DefaultConfiguration;
  import org.apache.logging.log4j.core.config.Property;
  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.PluginConfiguration;
  import org.apache.logging.log4j.core.config.plugins.PluginElement;
  import org.apache.logging.log4j.core.config.plugins.PluginFactory;
  import org.apache.logging.log4j.core.config.plugins.validation.constraints.Required;
  import org.apache.logging.log4j.core.config.plugins.validation.constraints.ValidPort;
  import org.apache.logging.log4j.core.filter.ThresholdFilter;
  import org.apache.logging.log4j.core.layout.HtmlLayout;
  import org.apache.logging.log4j.core.net.SmtpManager;
  import org.apache.logging.log4j.core.util.Booleans;
  
  /**
   * Send an e-mail when a specific logging event occurs, typically on errors or
   * fatal errors.
   *
   * <p>
   * The number of logging events delivered in this e-mail depend on the value of
   * <b>BufferSize</b> option. The <code>SmtpAppender</code> keeps only the last
   * <code>BufferSize</code> logging events in its cyclic buffer. This keeps
   * memory requirements at a reasonable level while still delivering useful
   * application context.
   *
   * By default, an email message will formatted as HTML. This can be modified by
   * setting a layout for the appender.
   *
   * By default, an email message will be sent when an ERROR or higher severity
   * message is appended. This can be modified by setting a filter for the
   * appender.
   */
  @Plugin(name = "SMTP", category = Core.CATEGORY_NAME, elementType = Appender.ELEMENT_TYPE, printObject = true)
  public final class SmtpAppender extends AbstractAppender {
  
      private static final int DEFAULT_BUFFER_SIZE = 512;
  
      /** The SMTP Manager */
      private final SmtpManager manager;
  
      private SmtpAppender(final String name, final Filter filter, final Layout<? extends Serializable> layout,
              final SmtpManager manager, final boolean ignoreExceptions, final Property[] properties) {
          super(name, filter, layout, ignoreExceptions, properties);
          this.manager = manager;
      }
  
      /**
       * Create a SmtpAppender.
       *
       * @param name
       *            The name of the Appender.
       * @param to
       *            The comma-separated list of recipient email addresses.
       * @param cc
       *            The comma-separated list of CC email addresses.
       * @param bcc
       *            The comma-separated list of BCC email addresses.
       * @param from
       *            The email address of the sender.
       * @param replyTo
       *            The comma-separated list of reply-to email addresses.
       * @param subject The subject of the email message.
       * @param smtpProtocol The SMTP transport protocol (such as "smtps", defaults to "smtp").
       * @param smtpHost
       *            The SMTP hostname to send to.
       * @param smtpPortStr
       *            The SMTP port to send to.
       * @param smtpUsername
       *            The username required to authenticate against the SMTP server.
       * @param smtpPassword
       *            The password required to authenticate against the SMTP server.
       * @param smtpDebug
      *            Enable mail session debuging on STDOUT.
      * @param bufferSizeStr
      *            How many log events should be buffered for inclusion in the
      *            message?
      * @param layout
      *            The layout to use (defaults to HtmlLayout).
      * @param filter
      *            The Filter or null (defaults to ThresholdFilter, level of
      *            ERROR).
      * @param ignore If {@code "true"} (default) exceptions encountered when appending events are logged; otherwise
      *               they are propagated to the caller.
      * @return The SmtpAppender.
      */
     @PluginFactory
     public static SmtpAppender createAppender(
             @PluginConfiguration final Configuration config,
             @PluginAttribute("name") @Required final String name,
             @PluginAttribute("to") final String to,
             @PluginAttribute("cc") final String cc,
             @PluginAttribute("bcc") final String bcc,
             @PluginAttribute("from") final String from,
             @PluginAttribute("replyTo") final String replyTo,
             @PluginAttribute("subject") final String subject,
             @PluginAttribute("smtpProtocol") final String smtpProtocol,
             @PluginAttribute("smtpHost") final String smtpHost,
             @PluginAttribute(value = "smtpPort", defaultString = "0") @ValidPort final String smtpPortStr,
             @PluginAttribute("smtpUsername") final String smtpUsername,
             @PluginAttribute(value = "smtpPassword", sensitive = true) final String smtpPassword,
             @PluginAttribute("smtpDebug") final String smtpDebug,
             @PluginAttribute("bufferSize") final String bufferSizeStr,
             @PluginElement("Layout") Layout<? extends Serializable> layout,
             @PluginElement("Filter") Filter filter,
             @PluginAttribute("ignoreExceptions") final String ignore) {
         if (name == null) {
             LOGGER.error("No name provided for SmtpAppender");
             return null;
         }
 
         final boolean ignoreExceptions = Booleans.parseBoolean(ignore, true);
         final int smtpPort = AbstractAppender.parseInt(smtpPortStr, 0);
         final boolean isSmtpDebug = Boolean.parseBoolean(smtpDebug);
         final int bufferSize = bufferSizeStr == null ? DEFAULT_BUFFER_SIZE : Integer.parseInt(bufferSizeStr);
 
         if (layout == null) {
             layout = HtmlLayout.createDefaultLayout();
         }
         if (filter == null) {
             filter = ThresholdFilter.createFilter(null, null, null);
         }
         final Configuration configuration = config != null ? config : new DefaultConfiguration();
 
         final SmtpManager manager = SmtpManager.getSmtpManager(configuration, to, cc, bcc, from, replyTo, subject, smtpProtocol,
             smtpHost, smtpPort, smtpUsername, smtpPassword, isSmtpDebug, filter.toString(),  bufferSize);
         if (manager == null) {
             return null;
         }
 
         return new SmtpAppender(name, filter, layout, manager, ignoreExceptions, null);
     }
 
     /**
      * Capture all events in CyclicBuffer.
      * @param event The Log event.
      * @return true if the event should be filtered.
      */
     @Override
     public boolean isFiltered(final LogEvent event) {
         final boolean filtered = super.isFiltered(event);
         if (filtered) {
             manager.add(event);
         }
         return filtered;
     }
 
     /**
      * Perform SmtpAppender specific appending actions, mainly adding the event
      * to a cyclic buffer and checking if the event triggers an e-mail to be
      * sent.
      * @param event The Log event.
      */
     @Override
     public void append(final LogEvent event) {
         manager.sendEvents(getLayout(), event);
     }
 }