From 82ac33ec665d055351e5d9ec4fa6e3e8d1335908 Mon Sep 17 00:00:00 2001
From: juancwu <46619361+juancwu@users.noreply.github.com>
Date: Sun, 14 Dec 2025 18:24:30 -0500
Subject: [PATCH] setup resend client for email service

---
 go.mod                    |  1 +
 go.sum                    |  2 ++
 internal/app/app.go       | 21 +++++++++++++--------
 internal/config/config.go |  6 ++++++
 internal/service/email.go | 35 ++++++++++++++++++++++++++++++++++-
 5 files changed, 56 insertions(+), 9 deletions(-)

diff --git a/go.mod b/go.mod
index f7b4dcb..3956fbd 100644
--- a/go.mod
+++ b/go.mod
@@ -52,6 +52,7 @@ require (
 	github.com/pierrec/lz4/v4 v4.1.22 // indirect
 	github.com/prometheus/procfs v0.15.1 // indirect
 	github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec // indirect
+	github.com/resend/resend-go/v2 v2.28.0 // indirect
 	github.com/segmentio/asm v1.2.0 // indirect
 	github.com/sethvargo/go-retry v0.3.0 // indirect
 	github.com/shopspring/decimal v1.4.0 // indirect
diff --git a/go.sum b/go.sum
index d865300..deb32e0 100644
--- a/go.sum
+++ b/go.sum
@@ -191,6 +191,8 @@ github.com/rekby/fixenv v0.6.1 h1:jUFiSPpajT4WY2cYuc++7Y1zWrnCxnovGCIX72PZniM=
 github.com/rekby/fixenv v0.6.1/go.mod h1:/b5LRc06BYJtslRtHKxsPWFT/ySpHV+rWvzTg+XWk4c=
 github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec h1:W09IVJc94icq4NjY3clb7Lk8O1qJ8BdBEF8z0ibU0rE=
 github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec/go.mod h1:qqbHyh8v60DhA7CoWK5oRCqLrMHRGoxYCSS9EjAz6Eo=
+github.com/resend/resend-go/v2 v2.28.0 h1:ttM1/VZR4fApBv3xI1TneSKi1pbfFsVrq7fXFlHKtj4=
+github.com/resend/resend-go/v2 v2.28.0/go.mod h1:3YCb8c8+pLiqhtRFXTyFwlLvfjQtluxOr9HEh2BwCkQ=
 github.com/rogpeppe/fastuuid v1.2.0/go.mod h1:jVj6XXZzXRy/MSR5jhDC/2q6DgLz+nrA6LYCDYWNEvQ=
 github.com/rogpeppe/go-internal v1.14.1 h1:UQB4HGPB6osV0SQTLymcB4TgvyWu6ZyliaW0tI/otEQ=
 github.com/rogpeppe/go-internal v1.14.1/go.mod h1:MaRKkUm5W0goXpeCfT7UZI6fk/L7L7so1lCWt35ZSgc=
diff --git a/internal/app/app.go b/internal/app/app.go
index a3cc268..736d1ca 100644
--- a/internal/app/app.go
+++ b/internal/app/app.go
@@ -11,10 +11,11 @@ import (
 )
 
 type App struct {
-	Cfg         *config.Config
-	DB          *sqlx.DB
-	UserService *service.UserService
-	AuthService *service.AuthService
+	Cfg          *config.Config
+	DB           *sqlx.DB
+	UserService  *service.UserService
+	AuthService  *service.AuthService
+	EmailService *service.EmailService
 }
 
 func New(cfg *config.Config) (*App, error) {
@@ -28,16 +29,20 @@ func New(cfg *config.Config) (*App, error) {
 		return nil, fmt.Errorf("failed to run migrations: %w", err)
 	}
 
+	emailClient := service.NewResendClient(cfg.ResendKey)
+
 	userRepository := repository.NewUserRepository(database)
 
 	userService := service.NewUserService(userRepository)
 	authService := service.NewAuthService(userRepository)
+	emailService := service.NewEmailService(emailClient, cfg.EmailFrom, cfg.AppURL, cfg.AppName, cfg.AppEnv == "development")
 
 	return &App{
-		Cfg:         cfg,
-		DB:          database,
-		UserService: userService,
-		AuthService: authService,
+		Cfg:          cfg,
+		DB:           database,
+		UserService:  userService,
+		AuthService:  authService,
+		EmailService: emailService,
 	}, nil
 }
 
diff --git a/internal/config/config.go b/internal/config/config.go
index 82d7e56..484af08 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -20,6 +20,9 @@ type Config struct {
 
 	JWTSecret string
 	JWTExpiry time.Duration
+
+	EmailFrom string
+	ResendKey string
 }
 
 func Load() *Config {
@@ -40,6 +43,9 @@ func Load() *Config {
 
 		JWTSecret: envRequired("JWT_SECRET"),
 		JWTExpiry: envDuration("JWT_EXPIRY", 168*time.Hour), // 7 days default
+
+		EmailFrom: envString("EMAIL_FROM", ""),
+		ResendKey: envString("RESEND_KEY", ""),
 	}
 
 	return cfg
diff --git a/internal/service/email.go b/internal/service/email.go
index 83e44c0..4eef9b6 100644
--- a/internal/service/email.go
+++ b/internal/service/email.go
@@ -1,6 +1,11 @@
 package service
 
-import "context"
+import (
+	"context"
+	"log/slog"
+
+	"github.com/resend/resend-go/v2"
+)
 
 type EmailParams struct {
 	From    string
@@ -13,6 +18,34 @@ type EmailClient interface {
 	SendWithContext(ctx context.Context, params EmailParams) (string, error)
 }
 
+type ResendClient struct {
+	client *resend.Client
+}
+
+func NewResendClient(apiKey string) *ResendClient {
+	var client *resend.Client
+	if apiKey != "" {
+		client = resend.NewClient(apiKey)
+	} else {
+		slog.Warn("cannot initialize Resend client with empty api key")
+		return nil
+	}
+	return &ResendClient{client: client}
+}
+
+func (c *ResendClient) SendWithContext(ctx context.Context, params EmailParams) (string, error) {
+	res, err := c.client.Emails.SendWithContext(ctx, &resend.SendEmailRequest{
+		From:    params.From,
+		To:      params.To,
+		Subject: params.Subject,
+		Text:    params.Text,
+	})
+	if err != nil {
+		return "", err
+	}
+	return res.Id, nil
+}
+
 type EmailService struct {
 	client    EmailClient
 	fromEmail string