/*
 * Copyright 2014-2018 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 de.codecentric.boot.admin.server.notify;

import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;

import javax.annotation.Nullable;
import javax.mail.MessagingException;
import javax.mail.internet.MimeMessage;

import org.springframework.mail.javamail.JavaMailSender;
import org.springframework.mail.javamail.MimeMessageHelper;
import org.thymeleaf.TemplateEngine;
import org.thymeleaf.context.Context;
import reactor.core.publisher.Mono;

import de.codecentric.boot.admin.server.domain.entities.Instance;
import de.codecentric.boot.admin.server.domain.entities.InstanceRepository;
import de.codecentric.boot.admin.server.domain.events.InstanceEvent;

import static java.util.Collections.singleton;

/**
 * Notifier sending emails using thymleaf templates.
 *
 * @author Johannes Edmeier
 */
public class MailNotifier extends AbstractStatusChangeNotifier {

	private final JavaMailSender mailSender;

	private final TemplateEngine templateEngine;

	/**
	 * recipients of the mail
	 */
	private String[] to = { "root@localhost" };

	/**
	 * cc-recipients of the mail
	 */
	private String[] cc = {};

	/**
	 * sender of the change
	 */
	private String from = "Spring Boot Admin <noreply@localhost>";

	/**
	 * Additional properties to be set for the template
	 */
	private Map<String, Object> additionalProperties = new HashMap<>();

	/**
	 * Base-URL used for hyperlinks in mail
	 */
	@Nullable
	private String baseUrl;

	/**
	 * Thymleaf template for mail
	 */
	private String template = "classpath:/META-INF/spring-boot-admin-server/mail/status-changed.html";

	public MailNotifier(JavaMailSender mailSender, InstanceRepository repository, TemplateEngine templateEngine) {
		super(repository);
		this.mailSender = mailSender;
		this.templateEngine = templateEngine;
	}

	@Override
	protected Mono<Void> doNotify(InstanceEvent event, Instance instance) {
		return Mono.fromRunnable(() -> {
			Context ctx = new Context();
			ctx.setVariables(additionalProperties);
			ctx.setVariable("baseUrl", this.baseUrl);
			ctx.setVariable("event", event);
			ctx.setVariable("instance", instance);
			ctx.setVariable("lastStatus", getLastStatus(event.getInstance()));

			try {
				MimeMessage mimeMessage = mailSender.createMimeMessage();
				MimeMessageHelper message = new MimeMessageHelper(mimeMessage, StandardCharsets.UTF_8.name());
				message.setText(getBody(ctx).replaceAll("\\s+\\n", "\n"), true);
				message.setSubject(getSubject(ctx));
				message.setTo(this.to);
				message.setCc(this.cc);
				message.setFrom(this.from);
				mailSender.send(mimeMessage);
			}
			catch (MessagingException ex) {
				throw new RuntimeException("Error sending mail notification", ex);
			}
		});
	}

	protected String getBody(Context ctx) {
		return templateEngine.process(this.template, ctx);
	}

	protected String getSubject(Context ctx) {
		return templateEngine.process(this.template, singleton("subject"), ctx).trim();
	}

	public void setTo(String[] to) {
		this.to = Arrays.copyOf(to, to.length);
	}

	public String[] getTo() {
		return Arrays.copyOf(to, to.length);
	}

	public void setCc(String[] cc) {
		this.cc = Arrays.copyOf(cc, cc.length);
	}

	public String[] getCc() {
		return Arrays.copyOf(cc, cc.length);
	}

	public void setFrom(String from) {
		this.from = from;
	}

	public String getFrom() {
		return from;
	}

	public String getTemplate() {
		return template;
	}

	public void setTemplate(String template) {
		this.template = template;
	}

	@Nullable
	public String getBaseUrl() {
		return baseUrl;
	}

	public void setBaseUrl(@Nullable String baseUrl) {
		this.baseUrl = baseUrl;
	}

	public Map<String, Object> getAdditionalProperties() {
		return additionalProperties;
	}

	public void setAdditionalProperties(Map<String, Object> additionalProperties) {
		this.additionalProperties = additionalProperties;
	}

}
