dnet-applications/libs/dnet-is-services/src/main/java/eu/dnetlib/notifications/mail/EmailDispatcher.java

package eu.dnetlib.notifications.mail;

import java.util.Date;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Properties;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;

import javax.annotation.PostConstruct;
import javax.mail.Authenticator;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Service;

import com.google.common.base.Splitter;

import eu.dnetlib.manager.wf.repository.EmailTemplateRepository;

@Service
public class EmailDispatcher {

	private static final Log log = LogFactory.getLog(EmailDispatcher.class);
	private final BlockingQueue<Message> queue = new LinkedBlockingQueue<>();

	@Value("${'dnet.configuration.mail.sender.email'}")
	private String from;
	@Value("${'dnet.configuration.mail.sender.name'}")
	private String fromName;
	@Value("${'dnet.configuration.mail.cc'}")
	private String cc;
	@Value("${'dnet.configuration.mail.smtp.host'}")
	private String smtpHost;
	@Value("${'dnet.configuration.mail.smtp.port'}")
	private final int smtpPort = 587;
	@Value("${'dnet.configuration.mail.smtp.user'}")
	private String smtpUser;
	@Value("${'dnet.configuration.mail.smtp.password'}")
	private String smtpPassword;
	@Value("${'dnet.configuration.baseUrl'}")
	private String baseUrl;
	@Value("${'dnet.configuration.infrastructure'}")
	private String infrastructure;

	@Autowired
	private EmailTemplateRepository emailTemplateRepository;

	@PostConstruct
	private void init() {
		new Thread(() -> {
			while (true) {
				try {
					final Message message = this.queue.take();
					if (message != null) {
						try {
							log.info("Sending mail...");
							Transport.send(message);
							log.info("...sent");
						} catch (final MessagingException e) {
							log.error("Error sending email", e);
							this.queue.add(message);
						}
					}
				} catch (final InterruptedException e1) {
					throw new RuntimeException(e1);
				}
			}
		}).run();
	}

	public void sendMail(final String to, final String subject, final String message) {
		try {
			final Session session = Session.getInstance(obtainProperties(), obtainAuthenticator());

			final MimeMessage mimeMessage = new MimeMessage(session);
			mimeMessage.setFrom(new InternetAddress(this.from, this.fromName));
			mimeMessage.setSubject(subject);
			mimeMessage.setContent(message, "text/html; charset=utf-8");
			mimeMessage.setSentDate(new Date());

			mimeMessage.addRecipient(Message.RecipientType.TO, new InternetAddress(to));

			if (this.cc != null && !this.cc.isEmpty()) {
				for (final String aCC : Splitter.on(",").omitEmptyStrings().trimResults().split(cc)) {
					mimeMessage.addRecipient(Message.RecipientType.CC, new InternetAddress(aCC));
				}
			}

			this.queue.add(mimeMessage);

			log.info("Mail to " + to + " in queue");
		} catch (final Exception e) {
			log.error("Error sending mail", e);
		}
	}

	public void sendStoredMail(final String to, final String emailId, final Map<String, Object> params) {

		// TODO use a real template library
		emailTemplateRepository.findById(emailId).ifPresent(tmpl -> {
			String msg = tmpl.getMessage();
			String subject = tmpl.getSubject();

			for (final Entry<String, Object> e : params.entrySet()) {
				msg = msg.replaceAll("{" + e.getKey() + "}", e.getValue().toString());
				subject = subject.replaceAll("{" + e.getKey() + "}", e.getValue().toString());
			}
			sendMail(to, subject, msg);
		});

	}

	private Properties obtainProperties() {
		final Properties props = new Properties();
		props.put("mail.transport.protocol", "smtp");
		props.put("mail.smtp.host", this.smtpHost);
		props.put("mail.smtp.port", this.smtpPort);
		props.put("mail.smtp.auth", Boolean.toString(this.smtpUser != null && !this.smtpUser.isEmpty()));
		return props;
	}

	private Authenticator obtainAuthenticator() {
		if (this.smtpUser == null || this.smtpUser.isEmpty()) { return null; }

		return new Authenticator() {

			private final PasswordAuthentication authentication = new PasswordAuthentication(EmailDispatcher.this.smtpUser, EmailDispatcher.this.smtpPassword);

			@Override
			protected PasswordAuthentication getPasswordAuthentication() {
				return this.authentication;
			}

		};
	}

}