Finish the big cleanup

8 files changed, 313 insertions, 247 deletions

diff --git a/database.go b/database.go
index f7cdf9b..583974f 100644
--- a/database.go
+++ b/database.go
@@ -7,6 +7,7 @@ import (
 	"golang.org/x/crypto/bcrypt"
 
 	"stevenlr.com/timer/model"
+	"stevenlr.com/timer/utils"
 )
 
 func initializeDatabaseV1(db *sql.DB) error {
@@ -49,7 +50,7 @@ func initializeDatabaseV1(db *sql.DB) error {
 
 	userName := "admin"
 	userPassword := "admin"
-	salt, err := GenerateRandomString(33)
+	salt, err := utils.GenerateRandomString(33)
 	if err != nil {
 		return err
 	}
diff --git a/model/timer.go b/model/timer.go
index 27e46da..3f13d0d 100644
--- a/model/timer.go
+++ b/model/timer.go
@@ -1,5 +1,17 @@
 package model
 
+import (
+	"database/sql"
+	"log"
+	"time"
+
+	"stevenlr.com/timer/utils"
+)
+
+func GenerateTimerToken() (string, error) {
+	return utils.GenerateRandomString(66)
+}
+
 type Timer struct {
 	Id        UUID
 	Name      string
@@ -12,3 +24,87 @@ type Timer struct {
 func (self Timer) IsFinished() bool {
 	return MakeTimeNow().Compare(self.EndTime) >= 0
 }
+
+func InsertTimer(tx *sql.Tx, name string, seconds int, ownerId UUID) error {
+	now := MakeTimeNow()
+	end := Time(time.Time(now).Add(time.Duration(seconds) * time.Second))
+	id := MakeUUID()
+	token, _ := GenerateTimerToken()
+	_, err := tx.Exec(`
+		INSERT INTO Timer VALUES ($1, $2, $3, $4, $5, $6)`, id, name, now, end, ownerId, token)
+	return err
+}
+
+func GetTimersForUser(db *sql.DB, owner UUID) []Timer {
+	rows, err := db.Query("SELECT Id, Name FROM Timer WHERE Owner=$1", owner)
+	if err != nil {
+		log.Fatalln(err)
+	}
+
+	timers := []Timer{}
+	for rows.Next() {
+		var t Timer
+		if err := rows.Scan(&t.Id, &t.Name); err == nil {
+			timers = append(timers, t)
+		}
+	}
+
+	return timers
+}
+
+func GetTimerForUser(db *sql.DB, id UUID, userId UUID) *Timer {
+	row := db.QueryRow("SELECT Id, Name, StartTime, EndTime, Owner, Token FROM Timer WHERE Id=$1 AND Owner=$2", id, userId)
+
+	var t Timer
+	if err := row.Scan(&t.Id, &t.Name, &t.StartTime, &t.EndTime, &t.Owner, &t.Token); err == nil {
+		return &t
+	}
+
+	return nil
+}
+
+func GetTimerWithToken(db *sql.DB, id UUID, token string) *Timer {
+	row := db.QueryRow("SELECT Id, Name, StartTime, EndTime, Owner, Token FROM Timer WHERE Id=$1 AND Token=$2", id, token)
+
+	var t Timer
+	if err := row.Scan(&t.Id, &t.Name, &t.StartTime, &t.EndTime, &t.Owner, &t.Token); err == nil {
+		return &t
+	}
+
+	return nil
+}
+
+func DeleteTimer(db *sql.DB, id UUID, userId UUID) bool {
+	res, err := db.Exec("DELETE FROM Timer WHERE Id=$1 AND Owner=$2", id, userId)
+	if err != nil {
+		return false
+	}
+
+	affected, err := res.RowsAffected()
+	return err == nil && affected == 1
+}
+
+func UpdateTimerEndTime(db *sql.DB, id UUID, endTime Time, userId UUID) bool {
+	res, err := db.Exec("UPDATE Timer SET EndTime=$1 WHERE Id=$2 AND Owner=$3", endTime, id, userId)
+	if err != nil {
+		return false
+	}
+
+	affected, err := res.RowsAffected()
+	return err == nil && affected == 1
+}
+
+func RegenerateTimerToken(db *sql.DB, id UUID, userId UUID) bool {
+	newToken, err := GenerateTimerToken()
+	if err != nil {
+		return false
+	}
+
+	res, err := db.Exec("UPDATE Timer SET Token=$1 WHERE Id=$2 AND Owner=$3", newToken, id, userId)
+	if err != nil {
+		return false
+	}
+
+	affected, err := res.RowsAffected()
+	return err == nil && affected == 1
+}
diff --git a/session.go b/session.go
new file mode 100644
index 0000000..e32041f
--- /dev/null
+++ b/session.go
@@ -0,0 +1,84 @@
+package main
+
+import (
+	"database/sql"
+	"errors"
+	"net/http"
+
+	"stevenlr.com/timer/model"
+	"stevenlr.com/timer/utils"
+)
+
+func generateSessionId() (string, error) {
+	return utils.GenerateRandomString(66)
+}
+
+type Sessions struct {
+	sessions map[string]Session
+}
+
+type Session struct {
+	UserId model.UUID
+}
+
+const sessionCookieName = "timerSession"
+
+func removeCookie(cookieName string, w http.ResponseWriter) {
+	cookie := http.Cookie{
+		Name:   cookieName,
+		Value:  "",
+		MaxAge: -1,
+	}
+	http.SetCookie(w, &cookie)
+}
+
+func MakeSessions() Sessions {
+	return Sessions{
+		sessions: make(map[string]Session),
+	}
+}
+
+func (sessions *Sessions) FindCurrentUser(db *sql.DB, w http.ResponseWriter, r *http.Request) *model.User {
+	cookie, err := r.Cookie(sessionCookieName)
+	if err != nil {
+		return nil
+	}
+
+	userId, ok := sessions.sessions[cookie.Value]
+	if !ok {
+		removeCookie(sessionCookieName, w)
+		return nil
+	}
+
+	user := model.GetUserById(db, userId.UserId)
+	if user == nil {
+		removeCookie(sessionCookieName, w)
+	}
+
+	return user
+}
+
+func (sessions *Sessions) StartSession(user model.UUID, w http.ResponseWriter) error {
+	sessionId, err := generateSessionId()
+	if err != nil {
+		return errors.New("Couldn't generate session ID")
+	}
+
+	cookie := http.Cookie{
+		Name:     sessionCookieName,
+		Value:    sessionId,
+		HttpOnly: true,
+		Secure:   true,
+	}
+
+	sessions.sessions[sessionId] = Session{UserId: user}
+	http.SetCookie(w, &cookie)
+	return nil
+}
+
+func (sessions *Sessions) EndSession(w http.ResponseWriter, r *http.Request) {
+	if cookie, err := r.Cookie(sessionCookieName); err == nil {
+		delete(sessions.sessions, cookie.Value)
+		removeCookie(sessionCookieName, w)
+	}
+}
diff --git a/timer.db b/timer.db
index 29f7614..e71c0f4 100644
--- a/timer.db
+++ b/timer.db
diff --git a/timer.go b/timer.go
index cf2b7fb..7d5f320 100644
--- a/timer.go
+++ b/timer.go
@@ -3,175 +3,40 @@ package main
 import (
 	"context"
 	"database/sql"
-	"errors"
 	"fmt"
 	"log"
 	"net/http"
-	"strconv"
 	"strings"
-	"time"
 
 	"golang.org/x/crypto/bcrypt"
 
 	_ "github.com/mattn/go-sqlite3"
 
 	"stevenlr.com/timer/model"
+	"stevenlr.com/timer/utils"
 	"stevenlr.com/timer/view"
 )
 
-func generateSessionId() (string, error) {
-	return GenerateRandomString(66)
-}
-
-func generateTimerToken() (string, error) {
-	return GenerateRandomString(66)
-}
-
-func insertTimer(tx *sql.Tx, name string, seconds int, ownerId model.UUID) error {
-	now := model.MakeTimeNow()
-	end := model.Time(time.Time(now).Add(time.Duration(seconds) * time.Second))
-	id := model.MakeUUID()
-	token, _ := generateTimerToken()
-	_, err := tx.Exec(`
-		INSERT INTO Timer VALUES ($1, $2, $3, $4, $5, $6)`, id, name, now, end, ownerId, token)
-	return err
-}
-
-func queryAllTimers(db *sql.DB, owner model.UUID) []model.Timer {
-	rows, err := db.Query("SELECT Id, Name FROM Timer WHERE Owner=$1", owner)
-	if err != nil {
-		log.Fatalln(err)
-	}
-
-	timers := []model.Timer{}
-	for rows.Next() {
-		var t model.Timer
-		if err := rows.Scan(&t.Id, &t.Name); err == nil {
-			timers = append(timers, t)
-		}
-	}
-
-	return timers
-}
-
-func queryTimerFromUser(db *sql.DB, idStr string, userId model.UUID) *model.Timer {
-	var id model.UUID
-	if err := id.Scan(idStr); err != nil {
-		return nil
-	}
-
-	row := db.QueryRow("SELECT Id, Name, StartTime, EndTime, Owner, Token FROM Timer WHERE Id=$1 AND Owner=$2", id, userId)
-
-	var t model.Timer
-	if err := row.Scan(&t.Id, &t.Name, &t.StartTime, &t.EndTime, &t.Owner, &t.Token); err == nil {
-		return &t
-	}
-
-	return nil
-}
-
-func queryTimerFromToken(db *sql.DB, idStr string, token string) *model.Timer {
-	var id model.UUID
-	if err := id.Scan(idStr); err != nil {
-		return nil
-	}
-
-	row := db.QueryRow("SELECT Id, Name, StartTime, EndTime, Owner, Token FROM Timer WHERE Id=$1 AND Token=$2", id, token)
-
-	var t model.Timer
-	if err := row.Scan(&t.Id, &t.Name, &t.StartTime, &t.EndTime, &t.Owner, &t.Token); err == nil {
-		return &t
-	}
-
-	return nil
-}
-
-func deleteTimer(db *sql.DB, idStr string, userId model.UUID) bool {
-	var id model.UUID
-	if err := id.Scan(idStr); err != nil {
-		return false
-	}
-
-	res, err := db.Exec("DELETE FROM Timer WHERE Id=$1 AND Owner=$2", id, userId)
-	if err != nil {
-		return false
-	}
-
-	affected, err := res.RowsAffected()
-	return err == nil && affected == 1
-}
-
-func updateTimerEndTime(db *sql.DB, id model.UUID, endTime model.Time, userId model.UUID) bool {
-	res, err := db.Exec("UPDATE Timer SET EndTime=$1 WHERE Id=$2 AND Owner=$3", endTime, id, userId)
-	if err != nil {
-		return false
-	}
-
-	affected, err := res.RowsAffected()
-	return err == nil && affected == 1
-}
-
-func updateTimerToken(db *sql.DB, id model.UUID, token string, userId model.UUID) bool {
-	res, err := db.Exec("UPDATE Timer SET Token=$1 WHERE Id=$2 AND Owner=$3", token, id, userId)
-	if err != nil {
-		return false
-	}
-
-	affected, err := res.RowsAffected()
-	return err == nil && affected == 1
-}
-
-type Session struct {
-	UserId model.UUID
-}
-
-type MyServer struct {
+type TimerServer struct {
 	db       *sql.DB
-	sessions map[string]Session
-}
-
-const SessionCookieName = "timerSession"
-
-func removeCookie(cookieName string, w http.ResponseWriter) {
-	cookie := http.Cookie{
-		Name:   cookieName,
-		Value:  "",
-		MaxAge: -1,
-	}
-	http.SetCookie(w, &cookie)
+	sessions Sessions
 }
 
-func (server *MyServer) findCurrentUser(w http.ResponseWriter, r *http.Request) *model.User {
-	cookie, err := r.Cookie(SessionCookieName)
-	if err != nil {
-		return nil
-	}
-
-	userId, ok := server.sessions[cookie.Value]
-	if !ok {
-		removeCookie(SessionCookieName, w)
-		return nil
-	}
-
-	user := model.GetUserById(server.db, userId.UserId)
-	if user == nil {
-		removeCookie(SessionCookieName, w)
-	}
-
-	return user
+func (server *TimerServer) findCurrentUser(w http.ResponseWriter, r *http.Request) *model.User {
+	return server.sessions.FindCurrentUser(server.db, w, r)
 }
 
-func (server *MyServer) handleNotFound(w http.ResponseWriter, _ *http.Request) {
+func (server *TimerServer) handleNotFound(w http.ResponseWriter, _ *http.Request) {
 	w.WriteHeader(http.StatusNotFound)
 	view.Error404().Render(context.Background(), w)
 }
 
-func (server *MyServer) handleMain(w http.ResponseWriter, r *http.Request) {
+func (server *TimerServer) handleMain(w http.ResponseWriter, r *http.Request) {
 	currentUser := server.findCurrentUser(w, r)
 	if r.URL.Path == "/" {
 		timers := make([]model.Timer, 0)
 		if currentUser != nil {
-			timers = queryAllTimers(server.db, currentUser.Id)
+			timers = model.GetTimersForUser(server.db, currentUser.Id)
 		}
 		view.Main(view.TimersList(timers, currentUser != nil), currentUser).Render(context.Background(), w)
 	} else {
@@ -179,14 +44,20 @@ func (server *MyServer) handleMain(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
-func (server *MyServer) handleTimer(w http.ResponseWriter, r *http.Request) {
+func (server *TimerServer) handleTimer(w http.ResponseWriter, r *http.Request) {
 	currentUser := server.findCurrentUser(w, r)
 	if currentUser == nil {
 		server.handleNotFound(w, r)
 		return
 	}
 
-	timer := queryTimerFromUser(server.db, r.PathValue("timerId"), currentUser.Id)
+	var id model.UUID
+	if err := id.Scan(r.PathValue("timerId")); err != nil {
+		server.handleNotFound(w, r)
+		return
+	}
+
+	timer := model.GetTimerForUser(server.db, id, currentUser.Id)
 	if timer != nil && timer.Owner == currentUser.Id {
 		view.Main(view.TimerView(*timer), currentUser).Render(context.Background(), w)
 	} else {
@@ -194,44 +65,14 @@ func (server *MyServer) handleTimer(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
-func parseDuration(value string) (time.Duration, error) {
-	const nullDuration = time.Duration(0)
-	if len(value) == 0 {
-		return nullDuration, errors.New("Empty duration string")
-	}
-
-	var unit time.Duration
-	switch value[len(value)-1] {
-	case 's':
-		unit = time.Second
-	case 'm':
-		unit = time.Minute
-	case 'h':
-		unit = time.Hour
-	case 'd':
-		unit = time.Duration(24) * time.Hour
-	case 'w':
-		unit = time.Duration(24*7) * time.Hour
-	default:
-		return nullDuration, errors.New("Invalid duration format")
-	}
-
-	amount, err := strconv.ParseInt(value[0:len(value)-1], 10, 64)
-	if err != nil || amount < 0 {
-		return nullDuration, errors.New("Invalid duration value")
-	}
-
-	return time.Duration(amount) * unit, nil
-}
-
-func (server *MyServer) handleTimerAddTimeCommon(w http.ResponseWriter, r *http.Request, timer *model.Timer) bool {
+func (server *TimerServer) handleTimerAddTimeCommon(w http.ResponseWriter, r *http.Request, timer *model.Timer) bool {
 	if timer.IsFinished() {
 		w.WriteHeader(http.StatusBadRequest)
 		w.Write([]byte("Timer already finished"))
 		return false
 	}
 
-	duration, err := parseDuration(r.FormValue("timeToAdd"))
+	duration, err := utils.ParseDuration(r.FormValue("timeToAdd"))
 	if err != nil {
 		w.WriteHeader(http.StatusBadRequest)
 		w.Write([]byte(err.Error()))
@@ -239,7 +80,7 @@ func (server *MyServer) handleTimerAddTimeCommon(w http.ResponseWriter, r *http.
 	}
 
 	timer.EndTime.Add(duration)
-	res := updateTimerEndTime(server.db, timer.Id, timer.EndTime, timer.Owner)
+	res := model.UpdateTimerEndTime(server.db, timer.Id, timer.EndTime, timer.Owner)
 	if !res {
 		w.WriteHeader(http.StatusInternalServerError)
 		return false
@@ -248,14 +89,20 @@ func (server *MyServer) handleTimerAddTimeCommon(w http.ResponseWriter, r *http.
 	return true
 }
 
-func (server *MyServer) handleTimerAddTime(w http.ResponseWriter, r *http.Request) {
+func (server *TimerServer) handleTimerAddTime(w http.ResponseWriter, r *http.Request) {
 	currentUser := server.findCurrentUser(w, r)
 	if currentUser == nil {
 		w.WriteHeader(http.StatusUnauthorized)
 		return
 	}
 
-	timer := queryTimerFromUser(server.db, r.PathValue("timerId"), currentUser.Id)
+	var id model.UUID
+	if err := id.Scan(r.PathValue("timerId")); err != nil {
+		w.WriteHeader(http.StatusNotFound)
+		return
+	}
+
+	timer := model.GetTimerForUser(server.db, id, currentUser.Id)
 	if timer == nil {
 		w.WriteHeader(http.StatusNotFound)
 		return
@@ -268,8 +115,14 @@ func (server *MyServer) handleTimerAddTime(w http.ResponseWriter, r *http.Reques
 	view.TimerInfo(*timer).Render(context.Background(), w)
 }
 
-func (server *MyServer) handleApiTimerAddTime(w http.ResponseWriter, r *http.Request) {
-	timer := queryTimerFromToken(server.db, r.PathValue("timerId"), r.FormValue("token"))
+func (server *TimerServer) handleApiTimerAddTime(w http.ResponseWriter, r *http.Request) {
+	var id model.UUID
+	if err := id.Scan(r.PathValue("timerId")); err != nil {
+		w.WriteHeader(http.StatusNotFound)
+		return
+	}
+
+	timer := model.GetTimerWithToken(server.db, id, r.FormValue("token"))
 	if timer == nil {
 		w.WriteHeader(http.StatusNotFound)
 		return
@@ -280,14 +133,20 @@ func (server *MyServer) handleApiTimerAddTime(w http.ResponseWriter, r *http.Req
 	}
 }
 
-func (server *MyServer) handleGetTimerToken(w http.ResponseWriter, r *http.Request) {
+func (server *TimerServer) handleGetTimerToken(w http.ResponseWriter, r *http.Request) {
 	currentUser := server.findCurrentUser(w, r)
 	if currentUser == nil {
 		w.WriteHeader(http.StatusUnauthorized)
 		return
 	}
 
-	timer := queryTimerFromUser(server.db, r.PathValue("timerId"), currentUser.Id)
+	var id model.UUID
+	if err := id.Scan(r.PathValue("timerId")); err != nil {
+		w.WriteHeader(http.StatusNotFound)
+		return
+	}
+
+	timer := model.GetTimerForUser(server.db, id, currentUser.Id)
 	if timer == nil {
 		server.handleNotFound(w, r)
 		return
@@ -296,27 +155,26 @@ func (server *MyServer) handleGetTimerToken(w http.ResponseWriter, r *http.Reque
 	w.Write([]byte(fmt.Sprint("<code>", timer.Token, "</code>")))
 }
 
-func (server *MyServer) handleResetTimerToken(w http.ResponseWriter, r *http.Request) {
+func (server *TimerServer) handleResetTimerToken(w http.ResponseWriter, r *http.Request) {
 	currentUser := server.findCurrentUser(w, r)
 	if currentUser == nil {
 		w.WriteHeader(http.StatusUnauthorized)
 		return
 	}
 
-	timer := queryTimerFromUser(server.db, r.PathValue("timerId"), currentUser.Id)
-	if timer == nil {
-		server.handleNotFound(w, r)
+	var id model.UUID
+	if err := id.Scan(r.PathValue("timerId")); err != nil {
+		w.WriteHeader(http.StatusNotFound)
 		return
 	}
 
-	newToken, err := generateTimerToken()
-	if err != nil {
-		w.WriteHeader(http.StatusInternalServerError)
+	timer := model.GetTimerForUser(server.db, id, currentUser.Id)
+	if timer == nil {
+		w.WriteHeader(http.StatusNotFound)
 		return
 	}
 
-	timer.Token = newToken
-	res := updateTimerToken(server.db, timer.Id, newToken, currentUser.Id)
+	res := model.RegenerateTimerToken(server.db, timer.Id, currentUser.Id)
 	if !res {
 		w.WriteHeader(http.StatusInternalServerError)
 		return
@@ -325,29 +183,26 @@ func (server *MyServer) handleResetTimerToken(w http.ResponseWriter, r *http.Req
 	view.TimerTokenForm(*timer).Render(context.Background(), w)
 }
 
-func (server *MyServer) handleDeleteTimer(w http.ResponseWriter, r *http.Request) {
+func (server *TimerServer) handleDeleteTimer(w http.ResponseWriter, r *http.Request) {
 	user := server.findCurrentUser(w, r)
 	if user == nil {
 		w.WriteHeader(http.StatusUnauthorized)
 		return
 	}
 
-	success := deleteTimer(server.db, r.PathValue("timerId"), user.Id)
-	if !success {
+	var id model.UUID
+	if err := id.Scan(r.PathValue("timerId")); err != nil {
 		w.WriteHeader(http.StatusNotFound)
+		return
 	}
-}
 
-func parseNumber(s string) (int64, error) {
-	s = strings.TrimSpace(s)
-	if len(s) == 0 {
-		s = "0"
+	success := model.DeleteTimer(server.db, id, user.Id)
+	if !success {
+		w.WriteHeader(http.StatusNotFound)
 	}
-
-	return strconv.ParseInt(s, 10, 64)
 }
 
-func (server *MyServer) handleCreateTimer(w http.ResponseWriter, r *http.Request) {
+func (server *TimerServer) handleCreateTimer(w http.ResponseWriter, r *http.Request) {
 	timerName := strings.TrimSpace(r.FormValue("timerName"))
 
 	user := server.findCurrentUser(w, r)
@@ -357,14 +212,14 @@ func (server *MyServer) handleCreateTimer(w http.ResponseWriter, r *http.Request
 		return
 	}
 
-	days, err := parseNumber(r.FormValue("days"))
+	days, err := utils.ParseNumber(r.FormValue("days"))
 	if err != nil {
 		w.WriteHeader(http.StatusBadRequest)
 		view.TimerCreateForm(timerName, "Error parsing days").Render(context.Background(), w)
 		return
 	}
 
-	hours, err := parseNumber(r.FormValue("hours"))
+	hours, err := utils.ParseNumber(r.FormValue("hours"))
 	if err != nil {
 		w.WriteHeader(http.StatusBadRequest)
 		view.TimerCreateForm(timerName, "Error parsing hours").Render(context.Background(), w)
@@ -385,7 +240,7 @@ func (server *MyServer) handleCreateTimer(w http.ResponseWriter, r *http.Request
 		return
 	}
 
-	err = insertTimer(tx, timerName, int(((max(days, 0)*24)+max(hours, 0))*3600), user.Id)
+	err = model.InsertTimer(tx, timerName, int(((max(days, 0)*24)+max(hours, 0))*3600), user.Id)
 	if err != nil {
 		w.WriteHeader(http.StatusInternalServerError)
 		view.TimerCreateForm(timerName, "Internal server error").Render(context.Background(), w)
@@ -394,13 +249,13 @@ func (server *MyServer) handleCreateTimer(w http.ResponseWriter, r *http.Request
 
 	tx.Commit()
 
-	timers := queryAllTimers(server.db, user.Id)
+	timers := model.GetTimersForUser(server.db, user.Id)
 	view.TimersList(timers, user != nil).Render(context.Background(), w)
 }
 
-func (server *MyServer) handlePostLogin(w http.ResponseWriter, r *http.Request) {
+func (server *TimerServer) handlePostLogin(w http.ResponseWriter, r *http.Request) {
 	if server.findCurrentUser(w, r) != nil {
-		HtmxRedirect(w, "/")
+		utils.HtmxRedirect(w, "/")
 		return
 	}
 
@@ -421,30 +276,17 @@ func (server *MyServer) handlePostLogin(w http.ResponseWriter, r *http.Request)
 		return
 	}
 
-	sessionId, err := generateSessionId()
-	if err != nil {
+	if err := server.sessions.StartSession(user.Id, w); err == nil {
+		utils.HtmxRedirect(w, "/")
+	} else {
 		w.WriteHeader(http.StatusInternalServerError)
 		view.LoginFormError(nil, "Internal server error").Render(context.Background(), w)
-		return
 	}
-
-	cookie := http.Cookie{
-		Name:     SessionCookieName,
-		Value:    sessionId,
-		HttpOnly: true,
-		Secure:   true,
-	}
-	server.sessions[sessionId] = Session{UserId: user.Id}
-	http.SetCookie(w, &cookie)
-	HtmxRedirect(w, "/")
 }
 
-func (server *MyServer) handlePostLogout(w http.ResponseWriter, r *http.Request) {
-	if cookie, err := r.Cookie(SessionCookieName); err == nil {
-		delete(server.sessions, cookie.Value)
-		removeCookie(SessionCookieName, w)
-	}
-	HtmxRedirect(w, "/")
+func (server *TimerServer) handlePostLogout(w http.ResponseWriter, r *http.Request) {
+	server.sessions.EndSession(w, r)
+	utils.HtmxRedirect(w, "/")
 }
 
 func main() {
@@ -460,7 +302,7 @@ func main() {
 		log.Fatalln(err)
 	}
 
-	myServer := MyServer{db: db, sessions: make(map[string]Session)}
+	myServer := TimerServer{db: db, sessions: MakeSessions()}
 
 	fs := http.FileServer(http.Dir("static/"))
 	http.Handle("GET /static/", http.StripPrefix("/static/", fs))
diff --git a/utils.go b/utils.go
deleted file mode 100644
index 5aa2894..0000000
--- a/utils.go
+++ /dev/null
@@ -1,15 +0,0 @@
-package main
-
-import (
-	"crypto/rand"
-	"encoding/base64"
-)
-
-func GenerateRandomString(len int) (string, error) {
-	bin := make([]byte, len)
-	_, err := rand.Read(bin)
-	if err != nil {
-		return "", err
-	}
-	return base64.StdEncoding.EncodeToString(bin), nil
-}
diff --git a/htmx.go b/utils/htmx.go
index 9605269..3cdd35e 100644
--- a/htmx.go
+++ b/utils/htmx.go
@@ -1,4 +1,4 @@
-package main
+package utils
 
 import (
 	"net/http"
diff --git a/utils/utils.go b/utils/utils.go
new file mode 100644
index 0000000..607236d
--- /dev/null
+++ b/utils/utils.go
@@ -0,0 +1,58 @@
+package utils
+
+import (
+	"crypto/rand"
+	"encoding/base64"
+	"errors"
+	"strconv"
+	"strings"
+	"time"
+)
+
+func GenerateRandomString(len int) (string, error) {
+	bin := make([]byte, len)
+	_, err := rand.Read(bin)
+	if err != nil {
+		return "", err
+	}
+	return base64.StdEncoding.EncodeToString(bin), nil
+}
+
+func ParseNumber(s string) (int64, error) {
+	s = strings.TrimSpace(s)
+	if len(s) == 0 {
+		s = "0"
+	}
+
+	return strconv.ParseInt(s, 10, 64)
+}
+
+func ParseDuration(value string) (time.Duration, error) {
+	const nullDuration = time.Duration(0)
+	if len(value) == 0 {
+		return nullDuration, errors.New("Empty duration string")
+	}
+
+	var unit time.Duration
+	switch value[len(value)-1] {
+	case 's':
+		unit = time.Second
+	case 'm':
+		unit = time.Minute
+	case 'h':
+		unit = time.Hour
+	case 'd':
+		unit = time.Duration(24) * time.Hour
+	case 'w':
+		unit = time.Duration(24*7) * time.Hour
+	default:
+		return nullDuration, errors.New("Invalid duration format")
+	}
+
+	amount, err := strconv.ParseInt(value[0:len(value)-1], 10, 64)
+	if err != nil || amount < 0 {
+		return nullDuration, errors.New("Invalid duration value")
+	}
+
+	return time.Duration(amount) * unit, nil
+}