Add email sending functionality with Google SMTP

src/main/java/org/justjava/gymcore/config/smtp/AbstractSmtpConfig.java

@@ -0,0 +1,58 @@
+package org.justjava.gymcore.config.smtp;
+
+public abstract class AbstractSmtpConfig {
+    private String host;
+    private String port;
+    private String username; //use with encryption
+    private String password; //use with encryption
+    private String auth;
+    private String starttls;
+
+    public String getHost() {
+        return host;
+    }
+
+    public void setHost(String host) {
+        this.host = host;
+    }
+
+    public String getPort() {
+        return port;
+    }
+
+    public void setPort(String port) {
+        this.port = port;
+    }
+
+    public String getUsername() {
+        return username;
+    }
+
+    public void setUsername(String username) {
+        this.username = username;
+    }
+
+    public String getPassword() {
+        return password;
+    }
+
+    public void setPassword(String password) {
+        this.password = password;
+    }
+
+    public String getAuth() {
+        return auth;
+    }
+
+    public void setAuth(String auth) {
+        this.auth = auth;
+    }
+
+    public String getStarttls() {
+        return starttls;
+    }
+
+    public void setStarttls(String starttls) {
+        this.starttls = starttls;
+    }
+}

src/main/java/org/justjava/gymcore/config/smtp/GoogleSmtpConfig.java

@@ -0,0 +1,9 @@
+package org.justjava.gymcore.config.smtp;
+
+import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+@ConfigurationProperties(prefix = "smtp.google")
+public class GoogleSmtpConfig extends AbstractSmtpConfig {
+}

src/main/java/org/justjava/gymcore/controller/MailController.java

@@ -0,0 +1,35 @@
+package org.justjava.gymcore.controller;
+
+import jakarta.mail.MessagingException;
+import jakarta.validation.Valid;
+import jakarta.validation.constraints.Email;
+import lombok.RequiredArgsConstructor;
+import org.justjava.gymcore.model.MailModel;
+import org.justjava.gymcore.service.MailService;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.*;
+
+@RestController
+@RequestMapping(value = "/mail")
+@RequiredArgsConstructor
+public class MailController {
+
+    private final MailService mailService;
+
+    @PostMapping("/sendMail/{to}")
+    public ResponseEntity<String> sendMail( @PathVariable("to")
+            @Email(message = "Invalid email address format")
+            String to,
+            @Valid @RequestBody MailModel mailModel) {
+        try {
+            mailService.sendMail(to, mailModel.subject(), mailModel.body());
+            return ResponseEntity.ok()
+                    .body("Email sent successfully to: " + to);
+        } catch (MessagingException e) {
+            return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR)
+                    .body("Failed to send email: " + e.getMessage());
+        }
+    }
+
+}

src/main/java/org/justjava/gymcore/model/MailModel.java

@@ -0,0 +1,15 @@
+package org.justjava.gymcore.model;
+
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.Size;
+
+public record MailModel(
+        @NotBlank(message = "Email subject cannot be blank")
+        @Size(max = 998, message = "Email subject cannot exceed 998 characters")
+        String subject,
+
+        @NotBlank(message = "Email body cannot be blank")
+        @Size(max = 50000, message = "Email body cannot exceed 50KB")
+        String body
+) {
+}

src/main/java/org/justjava/gymcore/service/MailService.java

@@ -0,0 +1,47 @@
+package org.justjava.gymcore.service;
+
+import jakarta.mail.*;
+import jakarta.mail.internet.InternetAddress;
+import jakarta.mail.internet.MimeMessage;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.justjava.gymcore.config.smtp.GoogleSmtpConfig;
+import org.springframework.stereotype.Service;
+
+import java.util.Properties;
+
+@Slf4j
+@Service
+@RequiredArgsConstructor
+public class MailService {
+
+    private final GoogleSmtpConfig googleSmtpConfig;
+
+    // Host, Host e-mail, password and port will be provided under yaml file. If you want to get configurations from yaml file use smtpConfigurationService.
+    public void sendMail(String to, String subject, String body) throws MessagingException {
+
+        Properties props = new Properties();
+        props.put("mail.transport.protocol", "smtp");
+        props.put("mail.smtp.host", googleSmtpConfig.getHost());
+        props.put("mail.smtp.auth", googleSmtpConfig.getAuth());
+        props.put("mail.smtp.port", googleSmtpConfig.getPort());
+        props.put("mail.smtp.starttls.enable", googleSmtpConfig.getStarttls());
+
+
+        Authenticator authenticator = new Authenticator() {
+            protected PasswordAuthentication getPasswordAuthentication() {
+                return new PasswordAuthentication(googleSmtpConfig.getUsername(), googleSmtpConfig.getPassword());
+            }
+        };
+
+        Session session = Session.getInstance(props, authenticator);
+            Message message = new MimeMessage(session);
+            message.setFrom(new InternetAddress(googleSmtpConfig.getUsername()));
+            message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(to, false));
+            message.setSubject(subject);
+            message.setText(body);
+
+            Transport.send(message);
+            log.info("Email sent successfully to: {}", to);
+    }
+}

src/main/resources/application.properties

@@ -24,3 +24,16 @@ logging.file.name=gymcore.log
 logging.appender.type=FILE
 logging.level.root=INFO
 logging.level.org.justjava.gymcore=INFO
+
+#Google SMTP configurations
+smtp.google.host: smtp.gmail.com
+smtp.google.port: 587
+# smtp.google.username: ${SMTP_USERNAME:your-email@gmail.com}
+# smtp.google.password: ${SMTP_PASSWORD:your-app-password}
+smtp.google.auth: true
+smtp.google.starttls: true
+
+# Security Note:
+# 1. Use environment variables for credentials in production
+# 2. For Gmail, use App Passwords instead of regular passwords
+# 3. Enable 2FA on your Google account before generating App Passwords