From bb915f8f0a5433e37cbe19e6c6effb49e082a415 Mon Sep 17 00:00:00 2001
From: Donovan <donovan.a.kelly@pm.me>
Date: Sun, 6 Oct 2024 09:57:29 -0500
Subject: [PATCH] implement email queue

---
 core/aws_ses.go                 |   6 +-
 core/config.go                  |   3 +-
 core/email_queue.go             | 152 ++++++++++++++++++++++++++++++++
 core/email_queue_test.go        |  29 ++++++
 core/in_memory_db.go            |   4 +-
 core/jwt_claims.go              |   2 +-
 core/jwt_claims_test.go         |   2 +-
 core/nkode_api.go               |  34 +++++--
 core/nkode_api_test.go          |  10 ++-
 core/sqlite-init/sqlite_init.go |   9 +-
 core/sqlite_db.go               |   2 +-
 core/sqlite_db_test.go          |   2 +-
 core/type.go                    |   8 +-
 core/user.go                    |   4 +-
 core/user_signup_session.go     |   4 +-
 go.mod                          |   1 +
 go.sum                          |   2 +
 main.go                         |   9 +-
 {core => test}/customer_test.go |  33 +++----
 19 files changed, 270 insertions(+), 46 deletions(-)
 create mode 100644 core/email_queue.go
 create mode 100644 core/email_queue_test.go
 rename {core => test}/customer_test.go (51%)

diff --git a/core/aws_ses.go b/core/aws_ses.go
index 2029e2a..fd12999 100644
--- a/core/aws_ses.go
+++ b/core/aws_ses.go
@@ -10,7 +10,7 @@ import (
 	"github.com/aws/aws-sdk-go-v2/service/ses/types"
 )
 
-func ResetUserEmail(userEmail Email, customerId CustomerId) error {
+func ResetUserEmail(userEmail UserEmail, customerId CustomerId) error {
 	// Load AWS configuration
 	cfg, err := config.LoadDefaultConfig(context.TODO(), config.WithRegion("us-east-1"))
 	if err != nil {
@@ -29,7 +29,7 @@ func ResetUserEmail(userEmail Email, customerId CustomerId) error {
 
 	// Define email subject and body
 	subject := "nKode Reset"
-	htmlBody := fmt.Sprintf("<h1>Hello!</h1><p>Click the link to reset your nKode.</p><a href=\"http://%s?token=%s\">Reset nKode</a>", FrontendHost, nkodeResetJwt)
+	htmlBody := fmt.Sprintf("<h1>Hello!</h1><p>Click the link to reset your nKode.</p><a href=\"%s?token=%s\">Reset nKode</a>", FrontendHost, nkodeResetJwt)
 
 	// Construct the email message
 	input := &ses.SendEmailInput{
@@ -56,6 +56,6 @@ func ResetUserEmail(userEmail Email, customerId CustomerId) error {
 	}
 
 	// Output the message ID of the sent email
-	fmt.Printf("Email sent successfully, Message ID: %s\n", *resp.MessageId)
+	fmt.Printf("UserEmail sent successfully, Message ID: %s\n", *resp.MessageId)
 	return nil
 }
diff --git a/core/config.go b/core/config.go
index 113bba0..0728bd1 100644
--- a/core/config.go
+++ b/core/config.go
@@ -1,6 +1,5 @@
 package core
 
 const (
-	BackendHost  = "localhost:8080"
-	FrontendHost = "localhost:8090"
+	FrontendHost = "https://nkode.tech"
 )
diff --git a/core/email_queue.go b/core/email_queue.go
new file mode 100644
index 0000000..2e24a68
--- /dev/null
+++ b/core/email_queue.go
@@ -0,0 +1,152 @@
+package core
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"github.com/aws/aws-sdk-go-v2/aws"
+	"github.com/aws/aws-sdk-go-v2/config"
+	"github.com/aws/aws-sdk-go-v2/service/ses"
+	"github.com/aws/aws-sdk-go-v2/service/ses/types"
+	"github.com/patrickmn/go-cache"
+	"log"
+	"sync"
+	"time"
+)
+
+type EmailClient interface {
+	SendEmail(Email) error
+}
+
+// Email represents a dummy email structure
+type Email struct {
+	Sender    string
+	Recipient string
+	Subject   string
+	Content   string
+}
+
+type TestEmailClient struct{}
+
+// SendEmail simulates sending an email via AWS SES
+func (c *TestEmailClient) SendEmail(email Email) error {
+	// Simulate sending email (replace with actual AWS SES API call)
+	fmt.Printf("Sending email to %s\n", email.Recipient)
+	return nil
+}
+
+type SESClient struct {
+	ResetCache *cache.Cache
+}
+
+const (
+	defaultExpiration = 5 * time.Minute
+	cleanupInterval   = 10 * time.Minute
+)
+
+func NewSESClient() SESClient {
+	return SESClient{
+		ResetCache: cache.New(defaultExpiration, cleanupInterval),
+	}
+}
+
+func (s *SESClient) SendEmail(email Email) error {
+	if _, exists := s.ResetCache.Get(email.Recipient); exists {
+		return fmt.Errorf("email already sent to %s with subject %s", email.Recipient, email.Subject)
+	}
+
+	// Load AWS configuration
+	cfg, err := config.LoadDefaultConfig(context.TODO(), config.WithRegion("us-east-1"))
+	if err != nil {
+		errMsg := fmt.Sprintf("unable to load SDK config, %v", err)
+		log.Print(errMsg)
+		return errors.New(errMsg)
+	}
+
+	// Create an SES client
+	sesClient := ses.NewFromConfig(cfg)
+
+	// Construct the email message
+	input := &ses.SendEmailInput{
+		Destination: &types.Destination{
+			ToAddresses: []string{email.Recipient},
+		},
+		Message: &types.Message{
+			Body: &types.Body{
+				Html: &types.Content{
+					Data: aws.String(email.Content),
+				},
+			},
+			Subject: &types.Content{
+				Data: aws.String(email.Subject),
+			},
+		},
+		Source: aws.String(email.Sender),
+	}
+
+	// Send the email
+	resp, err := sesClient.SendEmail(context.TODO(), input)
+	if err != nil {
+		return fmt.Errorf("failed to send email, %v", err)
+	}
+
+	// Output the message ID of the sent email
+	fmt.Printf("UserEmail sent successfully, Message ID: %s\n", *resp.MessageId)
+	return nil
+}
+
+// EmailQueue represents the email queue with rate limiting
+type EmailQueue struct {
+	emailQueue      chan Email       // Email queue
+	rateLimit       <-chan time.Time // Rate limiter
+	client          EmailClient      // SES client to send emails
+	wg              sync.WaitGroup   // To wait for all emails to be processed
+	FailedSendCount int
+}
+
+// NewEmailQueue creates a new rate-limited email queue
+func NewEmailQueue(bufferSize int, emailsPerSecond int, client EmailClient) *EmailQueue {
+	// Create a ticker that ticks every second to limit the rate of sending emails
+	rateLimit := time.Tick(time.Second / time.Duration(emailsPerSecond))
+
+	return &EmailQueue{
+		emailQueue:      make(chan Email, bufferSize),
+		rateLimit:       rateLimit,
+		client:          client,
+		FailedSendCount: 0,
+	}
+}
+
+// AddEmail queues a new email to be sent
+func (q *EmailQueue) AddEmail(email Email) {
+	q.wg.Add(1)
+	q.emailQueue <- email
+}
+
+// Start begins processing the email queue with rate limiting
+func (q *EmailQueue) Start() {
+	// Worker goroutine that processes emails from the queue
+	go func() {
+		for email := range q.emailQueue {
+			<-q.rateLimit // Wait for the rate limiter to allow the next email
+			q.sendEmail(email)
+			q.wg.Done() // Mark the email as processed
+		}
+	}()
+}
+
+// sendEmail sends an email using the SES client
+func (q *EmailQueue) sendEmail(email Email) {
+	if err := q.client.SendEmail(email); err != nil {
+		q.FailedSendCount += 1
+		log.Printf("Failed to send email to %s: %v\n", email.Recipient, err)
+	}
+}
+
+// Stop stops the queue after all emails have been processed
+func (q *EmailQueue) Stop() {
+	// Wait for all emails to be processed
+	q.wg.Wait()
+	// Close the email queue
+	close(q.emailQueue)
+}
diff --git a/core/email_queue_test.go b/core/email_queue_test.go
new file mode 100644
index 0000000..43aa4a1
--- /dev/null
+++ b/core/email_queue_test.go
@@ -0,0 +1,29 @@
+package core
+
+import (
+	"fmt"
+	"github.com/stretchr/testify/assert"
+	"testing"
+)
+
+func TestEmailQueue(t *testing.T) {
+	queue := NewEmailQueue(100, 14, &TestEmailClient{})
+
+	// Start the queue processing
+	queue.Start()
+
+	// Enqueue some emails
+	for i := 1; i <= 28; i++ {
+		email := Email{
+			Sender:    "test@example.com",
+			Recipient: fmt.Sprintf("user%d@example.com", i),
+			Subject:   "test subject",
+			Content:   "This is a test email",
+		}
+		queue.AddEmail(email)
+	}
+	// Stop the queue after all emails are processed
+	queue.Stop()
+
+	assert.Equal(t, queue.FailedSendCount, 0)
+}
diff --git a/core/in_memory_db.go b/core/in_memory_db.go
index 31d7bb9..1f71989 100644
--- a/core/in_memory_db.go
+++ b/core/in_memory_db.go
@@ -27,7 +27,7 @@ func (db *InMemoryDb) GetCustomer(id CustomerId) (*Customer, error) {
 	return &customer, nil
 }
 
-func (db *InMemoryDb) GetUser(username Email, customerId CustomerId) (*User, error) {
+func (db *InMemoryDb) GetUser(username UserEmail, customerId CustomerId) (*User, error) {
 	key := userIdKey(customerId, username)
 	userId, exists := db.userIdMap[key]
 	if !exists {
@@ -129,7 +129,7 @@ func (db *InMemoryDb) GetSvgStringInterface(idxs SvgIdInterface) ([]string, erro
 	return make([]string, len(idxs)), nil
 }
 
-func userIdKey(customerId CustomerId, username Email) string {
+func userIdKey(customerId CustomerId, username UserEmail) string {
 	key := fmt.Sprintf("%s:%s", customerId, username)
 	return key
 }
diff --git a/core/jwt_claims.go b/core/jwt_claims.go
index 2dba3d2..3e38be9 100644
--- a/core/jwt_claims.go
+++ b/core/jwt_claims.go
@@ -116,7 +116,7 @@ func ClaimExpired(claims jwt.RegisteredClaims) error {
 	return errors.New("claim expired")
 }
 
-func ResetNKodeToken(userEmail Email, customerId CustomerId) (string, error) {
+func ResetNKodeToken(userEmail UserEmail, customerId CustomerId) (string, error) {
 	resetClaims := ResetNKodeClaims{
 		true,
 		jwt.RegisteredClaims{
diff --git a/core/jwt_claims_test.go b/core/jwt_claims_test.go
index 4637ca1..76ed0ba 100644
--- a/core/jwt_claims_test.go
+++ b/core/jwt_claims_test.go
@@ -19,7 +19,7 @@ func TestJwtClaims(t *testing.T) {
 	assert.NoError(t, err)
 	assert.Equal(t, refreshToken.Subject, email)
 	assert.NoError(t, ClaimExpired(*refreshToken))
-	resetNKode, err := ResetNKodeToken(Email(email), customerId)
+	resetNKode, err := ResetNKodeToken(UserEmail(email), customerId)
 	assert.NoError(t, err)
 	resetToken, err := ParseRestNKodeToken(resetNKode)
 	assert.NoError(t, err)
diff --git a/core/nkode_api.go b/core/nkode_api.go
index 290cdef..e7df9bb 100644
--- a/core/nkode_api.go
+++ b/core/nkode_api.go
@@ -4,17 +4,20 @@ import (
 	"errors"
 	"fmt"
 	"github.com/google/uuid"
+	"os"
 )
 
 type NKodeAPI struct {
 	Db             DbAccessor
 	SignupSessions map[SessionId]UserSignSession
+	EmailQueue     *EmailQueue
 }
 
-func NewNKodeAPI(db DbAccessor) NKodeAPI {
+func NewNKodeAPI(db DbAccessor, queue *EmailQueue) NKodeAPI {
 	return NKodeAPI{
 		Db:             db,
 		SignupSessions: make(map[SessionId]UserSignSession),
+		EmailQueue:     queue,
 	}
 }
 
@@ -34,7 +37,7 @@ func (n *NKodeAPI) CreateNewCustomer(nkodePolicy NKodePolicy, id *CustomerId) (*
 	return &newCustomer.Id, nil
 }
 
-func (n *NKodeAPI) GenerateSignupResetInterface(userEmail Email, customerId CustomerId, kp KeypadDimension, reset bool) (*GenerateSignupResetInterfaceResp, error) {
+func (n *NKodeAPI) GenerateSignupResetInterface(userEmail UserEmail, customerId CustomerId, kp KeypadDimension, reset bool) (*GenerateSignupResetInterfaceResp, error) {
 	svgIdxInterface, err := n.Db.RandomSvgIdxInterface(kp)
 	if err != nil {
 		return nil, err
@@ -104,7 +107,7 @@ func (n *NKodeAPI) ConfirmNKode(customerId CustomerId, sessionId SessionId, keyS
 	return err
 }
 
-func (n *NKodeAPI) GetLoginInterface(userEmail Email, customerId CustomerId) (*GetLoginInterfaceResp, error) {
+func (n *NKodeAPI) GetLoginInterface(userEmail UserEmail, customerId CustomerId) (*GetLoginInterfaceResp, error) {
 	user, err := n.Db.GetUser(userEmail, customerId)
 	if err != nil {
 		return nil, err
@@ -133,7 +136,7 @@ func (n *NKodeAPI) GetLoginInterface(userEmail Email, customerId CustomerId) (*G
 	return &resp, nil
 }
 
-func (n *NKodeAPI) Login(customerId CustomerId, userEmail Email, keySelection KeySelection) (*AuthenticationTokens, error) {
+func (n *NKodeAPI) Login(customerId CustomerId, userEmail UserEmail, keySelection KeySelection) (*AuthenticationTokens, error) {
 	customer, err := n.Db.GetCustomer(customerId)
 	if err != nil {
 		return nil, err
@@ -179,7 +182,7 @@ func (n *NKodeAPI) GetSvgStringInterface(svgId SvgIdInterface) ([]string, error)
 	return n.Db.GetSvgStringInterface(svgId)
 }
 
-func (n *NKodeAPI) RefreshToken(userEmail Email, customerId CustomerId, refreshToken string) (string, error) {
+func (n *NKodeAPI) RefreshToken(userEmail UserEmail, customerId CustomerId, refreshToken string) (string, error) {
 	user, err := n.Db.GetUser(userEmail, customerId)
 	if err != nil {
 		return "", err
@@ -201,7 +204,7 @@ func (n *NKodeAPI) RefreshToken(userEmail Email, customerId CustomerId, refreshT
 	return EncodeAndSignClaims(newAccessClaims)
 }
 
-func (n *NKodeAPI) ResetNKode(userEmail Email, customerId CustomerId) error {
+func (n *NKodeAPI) ResetNKode(userEmail UserEmail, customerId CustomerId) error {
 	user, err := n.Db.GetUser(userEmail, customerId)
 	if err != nil {
 		return fmt.Errorf("error getting user in rest nkode %v", err)
@@ -209,5 +212,22 @@ func (n *NKodeAPI) ResetNKode(userEmail Email, customerId CustomerId) error {
 	if user == nil {
 		return nil
 	}
-	return ResetUserEmail(userEmail, customerId)
+
+	nkodeResetJwt, err := ResetNKodeToken(userEmail, customerId)
+	if err != nil {
+		return errors.New(fmt.Sprintf("unable to load SDK config, %v", err))
+	}
+	frontendHost := os.Getenv("FRONTEND_HOST")
+	if frontendHost == "" {
+		frontendHost = FrontendHost
+	}
+	htmlBody := fmt.Sprintf("<h1>Hello!</h1><p>Click the link to reset your nKode.</p><a href=\"%s?token=%s\">Reset nKode</a>", frontendHost, nkodeResetJwt)
+	email := Email{
+		Sender:    "no-reply@nkode.tech",
+		Recipient: string(userEmail),
+		Subject:   "nKode Reset",
+		Content:   htmlBody,
+	}
+	n.EmailQueue.AddEmail(email)
+	return nil
 }
diff --git a/core/nkode_api_test.go b/core/nkode_api_test.go
index 9ad0340..2d82750 100644
--- a/core/nkode_api_test.go
+++ b/core/nkode_api_test.go
@@ -25,14 +25,20 @@ func TestNKodeAPI(t *testing.T) {
 }
 
 func testNKodeAPI(t *testing.T, db DbAccessor) {
+	bufferSize := 100
+	emailsPerSec := 14
+	testClient := TestEmailClient{}
+	queue := NewEmailQueue(bufferSize, emailsPerSec, &testClient)
+	queue.Start()
+	defer queue.Stop()
 	attrsPerKey := 5
 	numbOfKeys := 4
 	for idx := 0; idx < 1; idx++ {
-		userEmail := Email("test_username" + util.GenerateRandomString(12) + "@example.com")
+		userEmail := UserEmail("test_username" + util.GenerateRandomString(12) + "@example.com")
 		passcodeLen := 4
 		nkodePolicy := NewDefaultNKodePolicy()
 		keypadSize := KeypadDimension{AttrsPerKey: attrsPerKey, NumbOfKeys: numbOfKeys}
-		nkodeApi := NewNKodeAPI(db)
+		nkodeApi := NewNKodeAPI(db, queue)
 		customerId, err := nkodeApi.CreateNewCustomer(nkodePolicy, nil)
 		assert.NoError(t, err)
 		signupResponse, err := nkodeApi.GenerateSignupResetInterface(userEmail, *customerId, keypadSize, false)
diff --git a/core/sqlite-init/sqlite_init.go b/core/sqlite-init/sqlite_init.go
index 5999a5c..6070714 100644
--- a/core/sqlite-init/sqlite_init.go
+++ b/core/sqlite-init/sqlite_init.go
@@ -57,7 +57,7 @@ VALUES (?)
 }
 
 func MakeSvgFiles() string {
-	jsonFiles, err := GetAllFiles("./sqlite-init/json")
+	jsonFiles, err := GetAllFiles("./core//sqlite-init/json")
 	if err != nil {
 		log.Fatalf("Error getting JSON files: %v", err)
 	}
@@ -158,11 +158,16 @@ CREATE TABLE IF NOT EXISTS customer (
     expiration INTEGER NOT NULL,
     attribute_values BLOB NOT NULL,
     set_values BLOB NOT NULL
+--	created_at TEXT NOT NULL,
+--	last_renew TEXT NOT NULL,
 );
 
 CREATE TABLE IF NOT EXISTS user (
 	id TEXT NOT NULL PRIMARY KEY,
 	username TEXT NOT NULL,
+--	email TEXT NOT NULL,
+--	first_name TEXT NOT NULL,
+--	last_name TEXT NOT NULL,
 	renew INT NOT NULL,
 	refresh_token TEXT,
 	customer_id TEXT NOT NULL,
@@ -187,6 +192,8 @@ CREATE TABLE IF NOT EXISTS user (
 	idx_interface BLOB NOT NULL,
 	svg_id_interface BLOB NOT NULL,
 	
+--	created_at TEXT NOT NULL,
+--	last_login TEXT NOT NULL,
 	
 	FOREIGN KEY (customer_id) REFERENCES customers(id),
 	UNIQUE(customer_id, username)
diff --git a/core/sqlite_db.go b/core/sqlite_db.go
index 0588881..496ad4f 100644
--- a/core/sqlite_db.go
+++ b/core/sqlite_db.go
@@ -186,7 +186,7 @@ func (d *SqliteDB) GetCustomer(id CustomerId) (*Customer, error) {
 	return &customer, nil
 }
 
-func (d *SqliteDB) GetUser(username Email, customerId CustomerId) (*User, error) {
+func (d *SqliteDB) GetUser(username UserEmail, customerId CustomerId) (*User, error) {
 	tx, err := d.db.Begin()
 	if err != nil {
 		return nil, err
diff --git a/core/sqlite_db_test.go b/core/sqlite_db_test.go
index ecc93c8..a9fac67 100644
--- a/core/sqlite_db_test.go
+++ b/core/sqlite_db_test.go
@@ -40,7 +40,7 @@ func testSignupLoginRenew(t *testing.T, db DbAccessor) {
 	assert.NoError(t, err)
 	err = db.WriteNewUser(*userOrig)
 	assert.NoError(t, err)
-	user, err := db.GetUser(Email(username), customer.Id)
+	user, err := db.GetUser(UserEmail(username), customer.Id)
 	assert.NoError(t, err)
 	assert.Equal(t, userOrig, user)
 
diff --git a/core/type.go b/core/type.go
index b805e15..f7debdc 100644
--- a/core/type.go
+++ b/core/type.go
@@ -94,14 +94,14 @@ func CustomerIdToString(customerId CustomerId) string {
 type SessionId uuid.UUID
 type UserId uuid.UUID
 
-type Email string
+type UserEmail string
 
-func ParseEmail(email string) (Email, error) {
+func ParseEmail(email string) (UserEmail, error) {
 	_, err := mail.ParseAddress(email)
 	if err != nil {
 		return "", err
 	}
-	return Email(email), err
+	return UserEmail(email), err
 
 }
 
@@ -124,7 +124,7 @@ type EncipheredNKode struct {
 
 type DbAccessor interface {
 	GetCustomer(CustomerId) (*Customer, error)
-	GetUser(Email, CustomerId) (*User, error)
+	GetUser(UserEmail, CustomerId) (*User, error)
 	WriteNewCustomer(Customer) error
 	WriteNewUser(User) error
 	UpdateUserNKode(User) error
diff --git a/core/user.go b/core/user.go
index 37dc813..5b91244 100644
--- a/core/user.go
+++ b/core/user.go
@@ -10,7 +10,7 @@ import (
 type User struct {
 	Id                 UserId
 	CustomerId         CustomerId
-	Email              Email
+	Email              UserEmail
 	EncipheredPasscode EncipheredNKode
 	Kp                 KeypadDimension
 	CipherKeys         UserCipherKeys
@@ -136,7 +136,7 @@ func NewUser(customer Customer, userEmail string, passcodeIdx []int, ui UserInte
 	}
 	newUser := User{
 		Id:                 UserId(uuid.New()),
-		Email:              Email(userEmail),
+		Email:              UserEmail(userEmail),
 		EncipheredPasscode: *encipheredNKode,
 		CipherKeys:         *newKeys,
 		Interface:          ui,
diff --git a/core/user_signup_session.go b/core/user_signup_session.go
index 0e42911..b9f6666 100644
--- a/core/user_signup_session.go
+++ b/core/user_signup_session.go
@@ -17,12 +17,12 @@ type UserSignSession struct {
 	SetIdxInterface     IdxInterface
 	ConfirmIdxInterface IdxInterface
 	SetKeySelection     KeySelection
-	UserEmail           Email
+	UserEmail           UserEmail
 	Reset               bool
 	Expire              int
 }
 
-func NewSignupResetSession(userEmail Email, kp KeypadDimension, customerId CustomerId, svgInterface SvgIdInterface, reset bool) (*UserSignSession, error) {
+func NewSignupResetSession(userEmail UserEmail, kp KeypadDimension, customerId CustomerId, svgInterface SvgIdInterface, reset bool) (*UserSignSession, error) {
 	loginInterface, err := NewUserInterface(&kp, svgInterface)
 	if err != nil {
 		return nil, err
diff --git a/go.mod b/go.mod
index 4552e92..1c77d0c 100644
--- a/go.mod
+++ b/go.mod
@@ -31,6 +31,7 @@ require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/golang-jwt/jwt/v5 v5.2.1 // indirect
 	github.com/jmespath/go-jmespath v0.4.0 // indirect
+	github.com/patrickmn/go-cache v2.1.0+incompatible // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
diff --git a/go.sum b/go.sum
index 5d6d19b..2d0c68a 100644
--- a/go.sum
+++ b/go.sum
@@ -40,6 +40,8 @@ github.com/jmespath/go-jmespath v0.4.0/go.mod h1:T8mJZnbsbmF+m6zOOFylbeCJqk5+pHW
 github.com/jmespath/go-jmespath/internal/testify v1.5.1/go.mod h1:L3OGu8Wl2/fWfCI6z80xFu9LTZmf1ZRjMHUOPmWr69U=
 github.com/mattn/go-sqlite3 v1.14.22 h1:2gZY6PC6kBnID23Tichd1K+Z0oS6nE/XwU+Vz/5o4kU=
 github.com/mattn/go-sqlite3 v1.14.22/go.mod h1:Uh1q+B4BYcTPb+yiD3kU8Ct7aC0hY9fxUwlHK0RXw+Y=
+github.com/patrickmn/go-cache v2.1.0+incompatible h1:HRMgzkcYKYpi3C8ajMPV8OFXaaRUnok+kx1WdO15EQc=
+github.com/patrickmn/go-cache v2.1.0+incompatible/go.mod h1:3Qf8kWWT7OJRJbdiICTKqZju1ZixQ/KpMGzzAfe6+WQ=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
diff --git a/main.go b/main.go
index 4cbb117..df7445e 100644
--- a/main.go
+++ b/main.go
@@ -8,10 +8,17 @@ import (
 	"net/http"
 )
 
+const (
+	emailQueueBufferSize = 100
+	maxEmailsPerSecond   = 13 // SES allows 14 but I don't want to push it
+)
+
 func main() {
 	db := core.NewSqliteDB("nkode.db")
 	defer db.CloseDb()
-	nkodeApi := core.NewNKodeAPI(db)
+	sesClient := core.NewSESClient()
+	emailQueue := core.NewEmailQueue(emailQueueBufferSize, maxEmailsPerSecond, &sesClient)
+	nkodeApi := core.NewNKodeAPI(db, emailQueue)
 	AddDefaultCustomer(nkodeApi)
 	handler := core.NKodeHandler{Api: nkodeApi}
 	mux := http.NewServeMux()
diff --git a/core/customer_test.go b/test/customer_test.go
similarity index 51%
rename from core/customer_test.go
rename to test/customer_test.go
index 610bb0d..16205fc 100644
--- a/core/customer_test.go
+++ b/test/customer_test.go
@@ -1,7 +1,8 @@
-package core
+package test
 
 import (
 	"github.com/stretchr/testify/assert"
+	"go-nkode/core"
 	"testing"
 )
 
@@ -12,27 +13,27 @@ func TestCustomer(t *testing.T) {
 }
 
 func testNewCustomerAttributes(t *testing.T) {
-	_, nil := NewCustomerAttributes()
+	_, nil := core.NewCustomerAttributes()
 	assert.NoError(t, nil)
 }
 
 func testCustomerValidKeyEntry(t *testing.T) {
-	kp := KeypadDimension{AttrsPerKey: 10, NumbOfKeys: 9}
-	nkodePolicy := NewDefaultNKodePolicy()
-	customer, err := NewCustomer(nkodePolicy)
+	kp := core.KeypadDimension{AttrsPerKey: 10, NumbOfKeys: 9}
+	nkodePolicy := core.NewDefaultNKodePolicy()
+	customer, err := core.NewCustomer(nkodePolicy)
 	assert.NoError(t, err)
-	mockSvgInterface := make(SvgIdInterface, kp.TotalAttrs())
-	userInterface, err := NewUserInterface(&kp, mockSvgInterface)
+	mockSvgInterface := make(core.SvgIdInterface, kp.TotalAttrs())
+	userInterface, err := core.NewUserInterface(&kp, mockSvgInterface)
 	assert.NoError(t, err)
 	userEmail := "testing@example.com"
 	passcodeIdx := []int{0, 1, 2, 3}
-	user, err := NewUser(*customer, userEmail, passcodeIdx, *userInterface, kp)
+	user, err := core.NewUser(*customer, userEmail, passcodeIdx, *userInterface, kp)
 	assert.NoError(t, err)
 	userLoginInterface, err := user.GetLoginInterface()
 	assert.NoError(t, err)
-	selectedKeys, err := SelectKeyByAttrIdx(userLoginInterface, passcodeIdx, kp)
+	selectedKeys, err := core.SelectKeyByAttrIdx(userLoginInterface, passcodeIdx, kp)
 	assert.NoError(t, err)
-	validatedPasscode, err := ValidKeyEntry(*user, *customer, selectedKeys)
+	validatedPasscode, err := core.ValidKeyEntry(*user, *customer, selectedKeys)
 	assert.NoError(t, err)
 	assert.Equal(t, len(validatedPasscode), len(passcodeIdx))
 	for idx := range validatedPasscode {
@@ -41,16 +42,16 @@ func testCustomerValidKeyEntry(t *testing.T) {
 }
 
 func testCustomerIsValidNKode(t *testing.T) {
-	kp := KeypadDimension{AttrsPerKey: 10, NumbOfKeys: 7}
-	nkodePolicy := NewDefaultNKodePolicy()
-	customer, err := NewCustomer(nkodePolicy)
+	kp := core.KeypadDimension{AttrsPerKey: 10, NumbOfKeys: 7}
+	nkodePolicy := core.NewDefaultNKodePolicy()
+	customer, err := core.NewCustomer(nkodePolicy)
 	assert.NoError(t, err)
-	mockSvgInterface := make(SvgIdInterface, kp.TotalAttrs())
-	userInterface, err := NewUserInterface(&kp, mockSvgInterface)
+	mockSvgInterface := make(core.SvgIdInterface, kp.TotalAttrs())
+	userInterface, err := core.NewUserInterface(&kp, mockSvgInterface)
 	assert.NoError(t, err)
 	userEmail := "testing123@example.com"
 	passcodeIdx := []int{0, 1, 2, 3}
-	user, err := NewUser(*customer, userEmail, passcodeIdx, *userInterface, kp)
+	user, err := core.NewUser(*customer, userEmail, passcodeIdx, *userInterface, kp)
 	assert.NoError(t, err)
 	err = customer.IsValidNKode(user.Kp, passcodeIdx)
 	assert.NoError(t, err)