content: package com.konsol.beatstream.service;
  
  import com.konsol.beatstream.domain.User;
  import jakarta.mail.MessagingException;
  import jakarta.mail.internet.MimeMessage;
  import java.nio.charset.StandardCharsets;
  import java.util.Locale;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import org.springframework.context.MessageSource;
  import org.springframework.mail.MailException;
  import org.springframework.mail.javamail.JavaMailSender;
  import org.springframework.mail.javamail.MimeMessageHelper;
  import org.springframework.scheduling.annotation.Async;
  import org.springframework.stereotype.Service;
  import org.thymeleaf.context.Context;
  import org.thymeleaf.spring6.SpringTemplateEngine;
  import tech.jhipster.config.JHipsterProperties;
  
  /**
   * Service for sending emails asynchronously.
   * <p>
   * We use the {@link Async} annotation to send emails asynchronously.
   */
  @Service
  public class MailService {
  
      private static final Logger LOG = LoggerFactory.getLogger(MailService.class);
  
      private static final String USER = "user";
  
      private static final String BASE_URL = "baseUrl";
  
      private final JHipsterProperties jHipsterProperties;
  
      private final JavaMailSender javaMailSender;
  
      private final MessageSource messageSource;
  
      private final SpringTemplateEngine templateEngine;
  
      public MailService(
          JHipsterProperties jHipsterProperties,
          JavaMailSender javaMailSender,
          MessageSource messageSource,
          SpringTemplateEngine templateEngine
      ) {
          this.jHipsterProperties = jHipsterProperties;
          this.javaMailSender = javaMailSender;
          this.messageSource = messageSource;
          this.templateEngine = templateEngine;
      }
  
      @Async
      public void sendEmail(String to, String subject, String content, boolean isMultipart, boolean isHtml) {
          this.sendEmailSync(to, subject, content, isMultipart, isHtml);
      }
  
      private void sendEmailSync(String to, String subject, String content, boolean isMultipart, boolean isHtml) {
          LOG.debug(
              "Send email[multipart '{}' and html '{}'] to '{}' with subject '{}' and content={}",
              isMultipart,
              isHtml,
              to,
              subject,
              content
          );
  
          // Prepare message using a Spring helper
          MimeMessage mimeMessage = javaMailSender.createMimeMessage();
          try {
              MimeMessageHelper message = new MimeMessageHelper(mimeMessage, isMultipart, StandardCharsets.UTF_8.name());
              message.setTo(to);
              message.setFrom(jHipsterProperties.getMail().getFrom());
              message.setSubject(subject);
              message.setText(content, isHtml);
              javaMailSender.send(mimeMessage);
              LOG.debug("Sent email to User '{}'", to);
          } catch (MailException | MessagingException e) {
              LOG.warn("Email could not be sent to user '{}'", to, e);
          }
      }
  
      @Async
      public void sendEmailFromTemplate(User user, String templateName, String titleKey) {
          this.sendEmailFromTemplateSync(user, templateName, titleKey);
      }
  
      private void sendEmailFromTemplateSync(User user, String templateName, String titleKey) {
          if (user.getEmail() == null) {
              LOG.debug("Email doesn't exist for user '{}'", user.getLogin());
              return;
          }
          Locale locale = Locale.forLanguageTag(user.getLangKey());
          Context context = new Context(locale);
          context.setVariable(USER, user);
          context.setVariable(BASE_URL, jHipsterProperties.getMail().getBaseUrl());
          String content = templateEngine.process(templateName, context);
          String subject = messageSource.getMessage(titleKey, null, locale);
          this.sendEmailSync(user.getEmail(), subject, content, false, true);
      }
  
      @Async
      public void sendActivationEmail(User user) {
          LOG.debug("Sending activation email to '{}'", user.getEmail());
          this.sendEmailFromTemplateSync(user, "mail/activationEmail", "email.activation.title");
      }
  
      @Async
      public void sendCreationEmail(User user) {
          LOG.debug("Sending creation email to '{}'", user.getEmail());
          this.sendEmailFromTemplateSync(user, "mail/creationEmail", "email.activation.title");
      }
  
      @Async
      public void sendPasswordResetMail(User user) {
          LOG.debug("Sending password reset email to '{}'", user.getEmail());
          this.sendEmailFromTemplateSync(user, "mail/passwordResetEmail", "email.reset.title");
      }
  }
  