AsyncMailInviteService.java

/*
 * Copyright 2010 the original author or authors.
 *
 * Licensed 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 com.springsource.greenhouse.invite.mail;

import java.util.List;

import javax.inject.Inject;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.core.io.ClassPathResource;
import org.springframework.mail.MailSender;
import org.springframework.mail.SimpleMailMessage;
import org.springframework.scheduling.annotation.Async;
import org.springframework.security.crypto.keygen.KeyGenerators;
import org.springframework.security.crypto.keygen.StringKeyGenerator;
import org.springframework.stereotype.Service;
import org.springframework.templating.LocalStringTemplate;
import org.springframework.templating.ResourceStringTemplateFactory;
import org.springframework.templating.StringTemplate;
import org.springframework.templating.StringTemplateFactory;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.web.util.UriTemplate;

import com.springsource.greenhouse.account.Account;
import com.springsource.greenhouse.invite.InviteRepository;
import com.springsource.greenhouse.invite.Invitee;

/**
 * A MailInviteService implementation that sends email invites asynchronously in a separate thread.
 * Relies on Spring's @Async support enabled by AspectJ for the asynchronous behavior.
 * Uses a StringTemplate to generate the invitation mail text from a template.
 * The text will contain a link to the invite accept page and instruct the invitee to activate it.
 * @author Keith Donald
 */
@Service
public class AsyncMailInviteService implements MailInviteService {

	private final MailSender mailSender;

	private final InviteRepository inviteRepository;

	private final UriTemplate acceptUriTemplate;
	
	/**
	 * Creates the AsyncMailInviteService.
	 * @param mailSender the object that actually does the mail delivery using the JavaMail API.
	 * @param inviteRepository the interface for saving the invite for retrieval later
	 * @param acceptUriTemplate a template for generating the URL the invitee should visit to accept the invite; defaults to a secure application URL e.g. https://host/invite/accept?token={token}
	 */
	@Inject
	public AsyncMailInviteService(MailSender mailSender, InviteRepository inviteRepository, @Value("#{environment['application.secureUrl']}/invite/accept?token={token}") String acceptUriTemplate) {
		this.mailSender = mailSender;
		this.inviteRepository = inviteRepository;
		this.acceptUriTemplate = new UriTemplate(acceptUriTemplate);
	}

	public void sendInvite(Account from, List<Invitee> to, String invitationBody) {
		StringTemplate textTemplate = textTemplateFactory.getStringTemplate();
		textTemplate.put("account", from);
		StringTemplate bodyTemplate = new LocalStringTemplate(invitationBody);
		for (Invitee invitee : to) {
			bodyTemplate.put("invitee", invitee);
			textTemplate.put("body",  bodyTemplate.render());
			String token = tokenGenerator.generateKey();
			textTemplate.put("acceptUrl", acceptUriTemplate.expand(token));
			send(from, invitee, textTemplate.render(), token);
		}
	}

	// internal helpers
	
	@Async
	@Transactional
	private void send(Account from, Invitee to, String text, String token) {
		SimpleMailMessage mailMessage = createInviteMailMessage(to, text);
		if (!inviteRepository.alreadyInvited(to.getEmail())) {
			inviteRepository.saveInvite(token, to, text, from.getId());
			mailSender.send(mailMessage);
		}
	}
	
	private SimpleMailMessage createInviteMailMessage(Invitee to, String text) {
		SimpleMailMessage mailMessage = new SimpleMailMessage();
		mailMessage.setFrom("Greenhouse <noreply@springsource.com>");
		mailMessage.setTo(to.getEmail());
		mailMessage.setSubject("Your Greenhouse Invitation");
		mailMessage.setText(text);
		return mailMessage;
	}

	private final StringTemplateFactory textTemplateFactory = new ResourceStringTemplateFactory(new ClassPathResource("invite-text.st", getClass()));

	private final StringKeyGenerator tokenGenerator = KeyGenerators.string();
	
}