refactor: simplify email service

- simplify email service by using smtp values from env vars
- add more context to errors for better debugging

internal/services/auth_service.go

@@ -1,6 +1,7 @@
 package services
 
 import (
+	"fmt"
 	"keizer-auth-api/internal/models"
 	"keizer-auth-api/internal/repositories"
 	"keizer-auth-api/internal/utils"
@@ -18,23 +19,29 @@ func NewAuthService(userRepo *repositories.UserRepository) *AuthService {
 func (as *AuthService) RegisterUser(userRegister *validators.UserRegister) error {
 	passwordHash, err := utils.HashPassword(userRegister.Password)
 	if err != nil {
-		return err
+		return fmt.Errorf("failed to hash password: %w", err)
 	}
 	otp, err := utils.GenerateOTP()
 	if err != nil {
-		return err
+		return fmt.Errorf("failed to generate OTP: %w", err)
 	}
 
 	err = SendOTPEmail(userRegister.Email, otp)
 	if err != nil {
-		return err
+		return fmt.Errorf("failed to send OTP email: %w", err)
 	}
 
-	return as.userRepo.CreateUser(&models.User{
+	err = as.userRepo.CreateUser(&models.User{
 		Email:        userRegister.Email,
 		FirstName:    userRegister.FirstName,
 		LastName:     userRegister.LastName,
 		PasswordHash: passwordHash,
 		Otp:          otp,
 	})
+
+	if err != nil {
+		return fmt.Errorf("failed to create user: %w", err)
+	}
+
+	return nil
 }

internal/services/email_service.go

@@ -1,51 +1,52 @@
 package services
 
 import (
-	"errors"
-	"keizer-auth-api/internal/utils"
+	"fmt"
 	"net/smtp"
 	"os"
 )
 
 var (
-	from = os.Getenv("EMAIL_FROM")
+	smtpHost     = os.Getenv("SMTP_HOST")
+	smtpPort     = os.Getenv("SMTP_PORT")
+	smtpUser     = os.Getenv("SMTP_USER")
+	smtpPassword = os.Getenv("SMTP_PASSWORD")
+	from         = os.Getenv("EMAIL_FROM")
 )
 
 type EmailService struct {
+	host string
+	port string
+	user string
+	pass string
+	from string
 }
 
 func NewEmailService() *EmailService {
-	return &EmailService{}
+	return &EmailService{host: smtpHost, port: smtpPort, user: smtpUser, pass: smtpPassword, from: from}
 }
 
-func (es *EmailService) SendEmail(to string, message string) error {
-	appEnv := os.Getenv("APP_ENV")
+func (es *EmailService) SendEmail(to string, subject string, body string) error {
+	message := []byte("To: " + to + "\r\n" +
+		"Subject: " + subject + "\r\n" +
+		"\r\n" +
+		body + "\r\n")
 
-	if appEnv == "local" {
-		// Send email using mailhog
-		sendEmailUsingMailHog(to, message)
-	} else if appEnv == "production" {
-		// Send email using SendGrid
-	} else {
-		return errors.New("invalid APP_ENV")
+	var auth smtp.Auth
+	if es.pass != "" {
+		auth = smtp.PlainAuth("", es.user, es.pass, es.host)
 	}
-	return nil
-}
+	err := smtp.SendMail(es.host+":"+es.port, auth, es.from, []string{to}, message)
 
-func sendEmailUsingMailHog(to string, message string) error {
-	smtpHost := "localhost"
-	smtpPort := "1025"
-	err := smtp.SendMail(smtpHost+":"+smtpPort, nil, from, []string{to}, []byte(message))
 	if err != nil {
-		return err
+		return fmt.Errorf("failed to send email: %w", err)
 	}
 	return nil
 }
 
 func SendOTPEmail(to string, otp string) error {
 	emailService := NewEmailService()
-	message := utils.ConstructOTPMail("OTP Verification", "Your OTP is "+otp)
-	err := emailService.SendEmail(to, message)
+	err := emailService.SendEmail(to, "OTP Verification", "Your OTP is "+otp)
 	if err != nil {
 		return err
 	}

internal/utils/email_helpers.go

@@ -20,7 +20,3 @@ func GenerateOTP() (string, error) {
 	}
 	return otp, nil
 }
-
-func ConstructOTPMail(subject string, body string) string {
-	return "Subject: " + subject + "\r\n\r\n" + body
-}