Desenvolver lógica para persistência e reenvio de e-mail para e-mails que falharam ao enviar

src/main/java/br/com/springnoobs/reminderapi/mail/engine/MailEngine.java

@@ -1,5 +1,6 @@
 package br.com.springnoobs.reminderapi.mail.engine;
 
+import br.com.springnoobs.reminderapi.mail.exception.EmailSendException;
 import jakarta.mail.MessagingException;
 import jakarta.mail.internet.MimeMessage;
 import java.io.IOException;
@@ -22,7 +23,7 @@ public MailEngine(JavaMailSender mailSender) {
         this.mailSender = mailSender;
     }
 
-    public void sendEmail(Map<String, String> variables) {
+    public MimeMessage createEmailMessage(Map<String, String> variables) {
         try {
             MimeMessage message = mailSender.createMimeMessage();
 
@@ -36,9 +37,19 @@ public void sendEmail(Map<String, String> variables) {
 
             helper.setText(mailTemplate, true);
 
-            mailSender.send(message);
+            return message;
         } catch (IOException | MessagingException e) {
-            logger.error("Error at send email: {}", e.getMessage());
+            logger.error("Error at create email: {}", e.getMessage());
+        }
+
+        return null;
+    }
+
+    public void sendEmail(MimeMessage message) throws EmailSendException {
+        try {
+            mailSender.send(message);
+        } catch (Exception e) {
+            throw new EmailSendException(e.getMessage());
         }
     }
 

src/main/java/br/com/springnoobs/reminderapi/mail/entity/EmailSendFailure.java

@@ -0,0 +1,152 @@
+package br.com.springnoobs.reminderapi.mail.entity;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.GenerationType;
+import jakarta.persistence.Id;
+import jakarta.persistence.Table;
+import java.time.Instant;
+
+@Entity
+@Table(name = "email_send_failures")
+public class EmailSendFailure {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    private String email;
+
+    private String subject;
+
+    private String name;
+
+    private String title;
+
+    private String remindAt;
+
+    private String dueDate;
+
+    private String disableNotificationUrl;
+
+    private Instant failedAt;
+
+    private int retryCount;
+
+    private String errorMessage;
+
+    public EmailSendFailure() {}
+
+    public EmailSendFailure(
+            Long id,
+            String email,
+            String subject,
+            String name,
+            String title,
+            String remindAt,
+            String dueDate,
+            String disableNotificationUrl,
+            Instant failedAt,
+            int retryCount,
+            String errorMessage) {
+        this.id = id;
+        this.email = email;
+        this.subject = subject;
+        this.name = name;
+        this.title = title;
+        this.remindAt = remindAt;
+        this.dueDate = dueDate;
+        this.disableNotificationUrl = disableNotificationUrl;
+        this.failedAt = failedAt;
+        this.retryCount = retryCount;
+        this.errorMessage = errorMessage;
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }
+
+    public String getSubject() {
+        return subject;
+    }
+
+    public void setSubject(String subject) {
+        this.subject = subject;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getTitle() {
+        return title;
+    }
+
+    public void setTitle(String title) {
+        this.title = title;
+    }
+
+    public String getRemindAt() {
+        return remindAt;
+    }
+
+    public void setRemindAt(String remindAt) {
+        this.remindAt = remindAt;
+    }
+
+    public String getDueDate() {
+        return dueDate;
+    }
+
+    public void setDueDate(String dueDate) {
+        this.dueDate = dueDate;
+    }
+
+    public String getDisableNotificationUrl() {
+        return disableNotificationUrl;
+    }
+
+    public void setDisableNotificationUrl(String disableNotificationUrl) {
+        this.disableNotificationUrl = disableNotificationUrl;
+    }
+
+    public Instant getFailedAt() {
+        return failedAt;
+    }
+
+    public void setFailedAt(Instant failedAt) {
+        this.failedAt = failedAt;
+    }
+
+    public int getRetryCount() {
+        return retryCount;
+    }
+
+    public void setRetryCount(int retryCount) {
+        this.retryCount = retryCount;
+    }
+
+    public String getErrorMessage() {
+        return errorMessage;
+    }
+
+    public void setErrorMessage(String errorMessage) {
+        this.errorMessage = errorMessage;
+    }
+}

src/main/java/br/com/springnoobs/reminderapi/mail/exception/EmailSendException.java

@@ -0,0 +1,7 @@
+package br.com.springnoobs.reminderapi.mail.exception;
+
+public class EmailSendException extends RuntimeException {
+    public EmailSendException(String message) {
+        super(message);
+    }
+}

src/main/java/br/com/springnoobs/reminderapi/mail/repository/EmailSendFailureRepository.java

@@ -0,0 +1,9 @@
+package br.com.springnoobs.reminderapi.mail.repository;
+
+import br.com.springnoobs.reminderapi.mail.entity.EmailSendFailure;
+import java.util.List;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+public interface EmailSendFailureRepository extends JpaRepository<EmailSendFailure, Long> {
+    List<EmailSendFailure> findTop20ByOrderByFailedAtAsc();
+}

src/main/java/br/com/springnoobs/reminderapi/mail/service/EmailService.java

@@ -1,24 +1,35 @@
 package br.com.springnoobs.reminderapi.mail.service;
 
 import br.com.springnoobs.reminderapi.mail.engine.MailEngine;
+import br.com.springnoobs.reminderapi.mail.entity.EmailSendFailure;
+import br.com.springnoobs.reminderapi.mail.exception.EmailSendException;
+import br.com.springnoobs.reminderapi.mail.repository.EmailSendFailureRepository;
 import br.com.springnoobs.reminderapi.reminder.entity.Reminder;
 import br.com.springnoobs.reminderapi.user.entity.Contact;
+import jakarta.mail.internet.MimeMessage;
+import java.time.Instant;
 import java.time.ZoneId;
 import java.time.format.DateTimeFormatter;
 import java.util.HashMap;
 import java.util.Map;
+import org.slf4j.Logger;
 import org.springframework.stereotype.Service;
 
 @Service
 public class EmailService {
 
+    Logger logger = org.slf4j.LoggerFactory.getLogger(EmailService.class);
+
     private final MailEngine mailEngine;
 
+    private final EmailSendFailureRepository emailSendFailureRepository;
+
     private static final DateTimeFormatter DATE_FORMATTER =
             DateTimeFormatter.ofPattern("dd/MM/yyyy").withZone(ZoneId.of("America/Sao_Paulo"));
 
-    public EmailService(MailEngine mailEngine) {
+    public EmailService(MailEngine mailEngine, EmailSendFailureRepository emailSendFailureRepository) {
         this.mailEngine = mailEngine;
+        this.emailSendFailureRepository = emailSendFailureRepository;
     }
 
     public void send(Reminder reminder) {
@@ -30,7 +41,44 @@ public void send(Reminder reminder) {
 
         Map<String, String> variables = buildEmailVariables(contact, reminder, "#");
 
-        mailEngine.sendEmail(variables);
+        MimeMessage mimeMessage = mailEngine.createEmailMessage(variables);
+
+        if (mimeMessage == null) {
+            return;
+        }
+
+        sendEmailWithFailureHandling(reminder, mimeMessage, variables);
+    }
+
+    private void dispatchEmail(MimeMessage mimeMessage) throws EmailSendException {
+        mailEngine.sendEmail(mimeMessage);
+    }
+
+    private void sendEmailWithFailureHandling(
+            Reminder reminder, MimeMessage mimeMessage, Map<String, String> variables) {
+        try {
+            dispatchEmail(mimeMessage);
+        } catch (EmailSendException e) {
+            logger.error("Error at send email: {}, to reminder:  {}", e.getMessage(), reminder.getId());
+
+            registerEmailFailure(variables, e.getMessage());
+        }
+    }
+
+    private void registerEmailFailure(Map<String, String> variables, String errorMessage) {
+        EmailSendFailure emailSendFailure = new EmailSendFailure();
+
+        emailSendFailure.setName(variables.get("name"));
+        emailSendFailure.setEmail(variables.get("email"));
+        emailSendFailure.setTitle(variables.get("title"));
+        emailSendFailure.setRemindAt(variables.get("remind_at"));
+        emailSendFailure.setDueDate(variables.get("due_date"));
+        emailSendFailure.setDisableNotificationUrl(variables.get("disable_notification_url"));
+        emailSendFailure.setSubject(variables.get("subject"));
+        emailSendFailure.setErrorMessage(errorMessage);
+        emailSendFailure.setFailedAt(Instant.now());
+
+        emailSendFailureRepository.save(emailSendFailure);
     }
 
     private Map<String, String> buildEmailVariables(Contact contact, Reminder reminder, String disableUrl) {
@@ -50,4 +98,35 @@ private Map<String, String> buildEmailVariables(Contact contact, Reminder remind
 
         return map;
     }
+
+    public void retryEmailSendFailure(EmailSendFailure emailSendFailure) {
+
+        Map<String, String> variables = buildEmailParametersFromEmailFailure(emailSendFailure);
+
+        MimeMessage mimeMessage = mailEngine.createEmailMessage(variables);
+
+        if (mimeMessage == null) {
+            return;
+        }
+
+        dispatchEmail(mimeMessage);
+    }
+
+    private static Map<String, String> buildEmailParametersFromEmailFailure(EmailSendFailure emailSendFailure) {
+        Map<String, String> variables = new HashMap<>();
+
+        variables.put("name", emailSendFailure.getName());
+        variables.put("email", emailSendFailure.getEmail());
+        variables.put("title", emailSendFailure.getTitle());
+        variables.put(
+                "remind_at",
+                emailSendFailure.getRemindAt() != null
+                        ? emailSendFailure.getRemindAt()
+                        : emailSendFailure.getDueDate());
+        variables.put("due_date", emailSendFailure.getDueDate());
+        variables.put("disable_notification_url", emailSendFailure.getDisableNotificationUrl());
+        variables.put("subject", "Lembrete" + " - " + emailSendFailure.getTitle());
+
+        return variables;
+    }
 }

src/main/java/br/com/springnoobs/reminderapi/schedule/job/mail/RetryFailedEmailsJob.java

@@ -0,0 +1,58 @@
+package br.com.springnoobs.reminderapi.schedule.job.mail;
+
+import br.com.springnoobs.reminderapi.mail.entity.EmailSendFailure;
+import br.com.springnoobs.reminderapi.mail.exception.EmailSendException;
+import br.com.springnoobs.reminderapi.mail.repository.EmailSendFailureRepository;
+import br.com.springnoobs.reminderapi.mail.service.EmailService;
+import java.util.List;
+import org.quartz.Job;
+import org.quartz.JobExecutionContext;
+import org.quartz.JobExecutionException;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.stereotype.Component;
+
+@Component
+public class RetryFailedEmailsJob implements Job {
+
+    private static final Logger logger = LoggerFactory.getLogger(RetryFailedEmailsJob.class);
+
+    private final EmailSendFailureRepository repository;
+    private final EmailService emailService;
+
+    public RetryFailedEmailsJob(EmailSendFailureRepository repository, EmailService emailService) {
+        this.repository = repository;
+        this.emailService = emailService;
+    }
+
+    @Override
+    public void execute(JobExecutionContext jobExecutionContext) throws JobExecutionException {
+        List<EmailSendFailure> failureList = repository.findTop20ByOrderByFailedAtAsc();
+
+        if (failureList.isEmpty()) {
+            return;
+        }
+
+        for (EmailSendFailure failure : failureList) {
+            retryFailedEmailsSent(failure);
+        }
+    }
+
+    private void retryFailedEmailsSent(EmailSendFailure failure) {
+        try {
+            emailService.retryEmailSendFailure(failure);
+
+            repository.delete(failure);
+
+            logger.info("Email resend successful to {}", failure.getEmail());
+
+        } catch (EmailSendException e) {
+
+            logger.error("Failed to resend email ID {}: {}", failure.getId(), e.getMessage());
+
+            failure.setRetryCount(failure.getRetryCount() + 1);
+            failure.setErrorMessage(e.getMessage());
+            repository.save(failure);
+        }
+    }
+}

src/main/java/br/com/springnoobs/reminderapi/schedule/job/ReminderJob.java → src/main/java/br/com/springnoobs/reminderapi/schedule/job/reminder/ReminderJob.java

@@ -1,4 +1,4 @@
-package br.com.springnoobs.reminderapi.schedule.job;
+package br.com.springnoobs.reminderapi.schedule.job.reminder;
 
 import br.com.springnoobs.reminderapi.mail.service.EmailService;
 import br.com.springnoobs.reminderapi.reminder.repository.ReminderRepository;