package net.ramapuram.thomas.service;
   
   import org.apache.commons.logging.Log;
   import org.apache.commons.logging.LogFactory;
   import org.apache.velocity.app.VelocityEngine;
   import org.apache.velocity.exception.VelocityException;
   import org.springframework.core.io.ClassPathResource;
   import org.springframework.mail.MailException;
   import org.springframework.mail.MailSender;
  import org.springframework.mail.SimpleMailMessage;
  import org.springframework.mail.javamail.JavaMailSenderImpl;
  import org.springframework.mail.javamail.MimeMessageHelper;
  import org.springframework.ui.velocity.VelocityEngineUtils;
  
  import javax.mail.MessagingException;
  import javax.mail.internet.MimeMessage;
  import java.util.Map;
  
  /**
   * Class for sending e-mail messages based on Velocity templates
   * or with attachments.
   * 
   * @author Matt Raible
   */
  public class MailEngine {
      private final Log log = LogFactory.getLog(MailEngine.class);
      private MailSender mailSender;
      private VelocityEngine velocityEngine;
      private String defaultFrom;
  
      public void setMailSender(MailSender mailSender) {
          this.mailSender = mailSender;
      }
  
      public MailSender getMailSender() {
          return mailSender;
      }
  
      public void setVelocityEngine(VelocityEngine velocityEngine) {
          this.velocityEngine = velocityEngine;
      }
  
      public void setFrom(String from) {
          this.defaultFrom = from;
      }
  
      /**
       * Send a simple message based on a Velocity template.
       * @param msg the message to populate
       * @param templateName the Velocity template to use (relative to classpath)
       * @param model a map containing key/value pairs
       */
      public void sendMessage(SimpleMailMessage msg, String templateName, Map model) {
          String result = null;
  
          try {
              result =
                  VelocityEngineUtils.mergeTemplateIntoString(velocityEngine,
                                                              templateName, model);
          } catch (VelocityException e) {
              e.printStackTrace();
              log.error(e.getMessage());
          }
  
          msg.setText(result);
          send(msg);
      }
  
      /**
       * Send a simple message with pre-populated values.
       * @param msg the message to send
       * @throws org.springframework.mail.MailException when SMTP server is down
       */
      public void send(SimpleMailMessage msg) throws MailException {
          try {
              mailSender.send(msg);
          } catch (MailException ex) {
              log.error(ex.getMessage());
              throw ex;
          }
      }
  
      /**
       * Convenience method for sending messages with attachments.
       * 
       * @param recipients array of e-mail addresses
       * @param sender e-mail address of sender
       * @param resource attachment from classpath
       * @param bodyText text in e-mail
       * @param subject subject of e-mail
       * @param attachmentName name for attachment
       * @throws MessagingException thrown when can't communicate with SMTP server
       */
      public void sendMessage(String[] recipients, String sender, 
                              ClassPathResource resource, String bodyText,
                              String subject, String attachmentName)
      throws MessagingException {
          MimeMessage message = ((JavaMailSenderImpl) mailSender).createMimeMessage();
  
         // use the true flag to indicate you need a multipart message
         MimeMessageHelper helper = new MimeMessageHelper(message, true);
 
         helper.setTo(recipients);
 
         // use the default sending if no sender specified
         if (sender == null) {
             helper.setFrom(defaultFrom);
         } else {
            helper.setFrom(sender);
         }
 
         helper.setText(bodyText);
         helper.setSubject(subject);
 
         helper.addAttachment(attachmentName, resource);
 
         ((JavaMailSenderImpl) mailSender).send(message);
     }
 }