@Service
public class EmailService {
    private final JavaMailSender javaMailSender;
    private final ISpringTemplateEngine htmlTemplateEngine;

    public EmailService(JavaMailSender javaMailSender, ISpringTemplateEngine htmlTemplateEngine) {
        this.javaMailSender = javaMailSender;
        this.htmlTemplateEngine = htmlTemplateEngine;
    }

    /**
     * Thymeleaf 템플릿을 통해 이메일을 발송합니다.
     *
     * @param emailSenderDTO 이메일 전송 객체
     * @param template       사용할 템플릿 이름
     * @param variables      템플릿에 넣을 변수
     * @throws MessagingException
     */
    public void sendTemplateByThymeleaf(EmailSenderDto emailSenderDTO, String template, Map<String, Object> variables) throws MessagingException {
        MimeMessage message = javaMailSender.createMimeMessage();
        MimeMessageHelper helper = new MimeMessageHelper(message, true, "UTF-8");

        helper.setSubject(emailSenderDTO.getSubject());
        helper.setTo(emailSenderDTO.getTo());
        helper.setFrom(emailSenderDTO.getFrom());

        Context context = createContext(variables);
        String html = htmlTemplateEngine.process(template, context);
        helper.setText(html, true);

        helper.addInline("logo", new ClassPathResource("static/images/codesoom_logo.png"));

        javaMailSender.send(message);
    }

    /**
     * Template에 매핑시킬 파라미터를 Context로 변환한다
     *
     * @param variables
     * @return
     */
    private Context createContext(Map<String, Object> variables) {
        Context context = new Context();
        context.setVariables(variables);

        return context;
    }
}