init

internal/http/app.go

@@ -0,0 +1,703 @@
+package http
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net/http"
+	"net/url"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/go-chi/chi/v5"
+	"github.com/go-chi/chi/v5/middleware"
+	"github.com/jackc/pgx/v5/pgxpool"
+
+	"superbanka/internal/auth"
+	"superbanka/internal/config"
+	"superbanka/internal/db"
+	"superbanka/internal/platform"
+)
+
+const (
+	userSessionCookie  = "superbanka_user_session"
+	adminSessionCookie = "superbanka_admin_session"
+	csrfCookie         = "superbanka_csrf"
+)
+
+type contextKey string
+
+const (
+	ctxUserKey  contextKey = "current-user"
+	ctxAdminKey contextKey = "current-admin"
+	ctxCSRFKey  contextKey = "csrf-token"
+	flashCookie            = "superbanka_flash"
+)
+
+type App struct {
+	cfg      config.Config
+	dbPool   *pgxpool.Pool
+	store    *db.Store
+	renderer *Renderer
+	router   http.Handler
+}
+
+type HomeData struct {
+	UserCount        int
+	TransactionCount int
+}
+
+type DashboardData struct {
+	User         *db.User
+	Transactions []db.TransactionView
+}
+
+type AdminDashboardData struct {
+	Admin     *db.AdminUser
+	Dashboard *db.AdminDashboard
+}
+
+type UsersPageData struct {
+	Admin  *db.AdminUser
+	Search string
+	Users  []db.UserListItem
+}
+
+type UserDetailData struct {
+	Admin        *db.AdminUser
+	User         *db.User
+	Transactions []db.TransactionView
+}
+
+type LeaderboardData struct {
+	Entries []db.LeaderboardEntry
+}
+
+func NewApp(cfg config.Config) (*App, error) {
+	ctx := context.Background()
+	dbPool, err := pgxpool.New(ctx, cfg.DatabaseURL)
+	if err != nil {
+		return nil, fmt.Errorf("open db pool: %w", err)
+	}
+
+	if err := dbPool.Ping(ctx); err != nil {
+		dbPool.Close()
+		return nil, fmt.Errorf("ping db: %w", err)
+	}
+
+	if err := db.RunMigrations(ctx, dbPool, filepath.Join("migrations")); err != nil {
+		dbPool.Close()
+		return nil, fmt.Errorf("run migrations: %w", err)
+	}
+
+	store := db.NewStore(dbPool)
+	renderer, err := NewRenderer()
+	if err != nil {
+		dbPool.Close()
+		return nil, err
+	}
+
+	adminHash, err := auth.HashPassword(cfg.AdminPass)
+	if err != nil {
+		dbPool.Close()
+		return nil, fmt.Errorf("hash bootstrap admin password: %w", err)
+	}
+	if err := store.BootstrapAdmin(ctx, cfg.AdminEmail, adminHash); err != nil {
+		dbPool.Close()
+		return nil, err
+	}
+
+	app := &App{
+		cfg:      cfg,
+		dbPool:   dbPool,
+		store:    store,
+		renderer: renderer,
+	}
+	app.router = app.routes()
+
+	return app, nil
+}
+
+func (a *App) Router() http.Handler {
+	return a.router
+}
+
+func (a *App) Close() {
+	a.dbPool.Close()
+}
+
+func (a *App) routes() http.Handler {
+	r := chi.NewRouter()
+	r.Use(middleware.RealIP)
+	r.Use(middleware.RequestID)
+	r.Use(middleware.Logger)
+	r.Use(middleware.Recoverer)
+	r.Use(middleware.RedirectSlashes)
+	r.Use(middleware.Timeout(30 * time.Second))
+	r.Use(a.withCSRF)
+	r.Use(a.withCurrentSessions)
+
+	r.Get("/healthz", a.healthz)
+	r.Handle("/static/*", http.StripPrefix("/static/", http.FileServer(http.Dir(filepath.Join("web", "static")))))
+
+	r.Get("/", a.home)
+	r.Get("/leaderboard", a.leaderboard)
+	r.Get("/register", a.showRegister)
+	r.Post("/register", a.register)
+	r.Get("/login", a.showLogin)
+	r.Post("/login", a.login)
+	r.Post("/logout", a.logout)
+
+	r.Get("/admin/login", a.showAdminLogin)
+	r.Post("/admin/login", a.adminLogin)
+	r.Post("/admin/logout", a.adminLogout)
+
+	r.Group(func(protected chi.Router) {
+		protected.Use(a.requireUser)
+		protected.Get("/app", a.userDashboard)
+		protected.Get("/app/transfer", a.showTransfer)
+		protected.Post("/app/transfer", a.createTransfer)
+		protected.Get("/app/transactions", a.transactionsPage)
+	})
+
+	r.Route("/admin", func(admin chi.Router) {
+		admin.Use(a.requireAdmin)
+		admin.Get("/", a.adminDashboard)
+		admin.Get("/users", a.adminUsers)
+		admin.Get("/users/{userID}", a.adminUserDetail)
+		admin.Post("/users/{userID}/freeze", a.freezeUser)
+		admin.Post("/users/{userID}/unfreeze", a.unfreezeUser)
+		admin.Post("/accounts/{accountID}/adjust", a.adjustBalance)
+		admin.Get("/audit-logs", a.auditLogs)
+	})
+
+	return r
+}
+
+func (a *App) healthz(w http.ResponseWriter, r *http.Request) {
+	w.WriteHeader(http.StatusOK)
+	_, _ = w.Write([]byte("ok"))
+}
+
+func (a *App) home(w http.ResponseWriter, r *http.Request) {
+	user, _ := a.currentUser(r)
+	admin, _ := a.currentAdmin(r)
+
+	dashboard, err := a.store.AdminDashboard(r.Context())
+	if err != nil {
+		a.serverError(w, err)
+		return
+	}
+
+	a.render(w, http.StatusOK, ViewData{
+		Title:     "Superbanka",
+		Page:      "home",
+		User:      user,
+		Admin:     admin,
+		CSRFToken: a.csrfToken(r),
+		Flash:     a.readFlash(w, r),
+		Data: HomeData{
+			UserCount:        dashboard.UserCount,
+			TransactionCount: dashboard.TransactionCount,
+		},
+	})
+}
+
+func (a *App) leaderboard(w http.ResponseWriter, r *http.Request) {
+	user, _ := a.currentUser(r)
+	admin, _ := a.currentAdmin(r)
+
+	entries, err := a.store.Leaderboard(r.Context(), 100)
+	if err != nil {
+		a.serverError(w, err)
+		return
+	}
+
+	a.render(w, http.StatusOK, ViewData{
+		Title:     "Leaderboard",
+		Page:      "leaderboard",
+		User:      user,
+		Admin:     admin,
+		CSRFToken: a.csrfToken(r),
+		Flash:     a.readFlash(w, r),
+		Data:      LeaderboardData{Entries: entries},
+	})
+}
+
+func (a *App) showRegister(w http.ResponseWriter, r *http.Request) {
+	a.render(w, http.StatusOK, ViewData{Title: "Register", Page: "register", CSRFToken: a.csrfToken(r), Flash: a.readFlash(w, r)})
+}
+
+func (a *App) register(w http.ResponseWriter, r *http.Request) {
+	if !a.verifyCSRF(r) {
+		a.render(w, http.StatusBadRequest, ViewData{Title: "Register", Page: "register", CSRFToken: a.csrfToken(r), Error: "Invalid form token."})
+		return
+	}
+	if err := r.ParseForm(); err != nil {
+		a.serverError(w, err)
+		return
+	}
+
+	email := strings.TrimSpace(r.FormValue("email"))
+	username := strings.TrimSpace(r.FormValue("username"))
+	password := r.FormValue("password")
+
+	if email == "" || username == "" || len(password) < 8 {
+		a.render(w, http.StatusBadRequest, ViewData{Title: "Register", Page: "register", CSRFToken: a.csrfToken(r), Error: "Email, username, and a password with at least 8 characters are required."})
+		return
+	}
+
+	passwordHash, err := auth.HashPassword(password)
+	if err != nil {
+		a.serverError(w, err)
+		return
+	}
+
+	user, err := a.store.CreateUser(r.Context(), email, username, passwordHash)
+	if err != nil {
+		if errors.Is(err, db.ErrConflict) {
+			a.render(w, http.StatusConflict, ViewData{Title: "Register", Page: "register", CSRFToken: a.csrfToken(r), Error: "Email or username is already taken."})
+			return
+		}
+		a.serverError(w, err)
+		return
+	}
+
+	if err := a.startUserSession(w, r, user.ID); err != nil {
+		a.serverError(w, err)
+		return
+	}
+
+	a.setFlash(w, "Account created. Your signup bonus of 10 000,00 CZK is ready.")
+	http.Redirect(w, r, "/app", http.StatusSeeOther)
+}
+
+func (a *App) showLogin(w http.ResponseWriter, r *http.Request) {
+	a.render(w, http.StatusOK, ViewData{Title: "Login", Page: "login", CSRFToken: a.csrfToken(r), Flash: a.readFlash(w, r)})
+}
+
+func (a *App) login(w http.ResponseWriter, r *http.Request) {
+	if !a.verifyCSRF(r) {
+		a.render(w, http.StatusBadRequest, ViewData{Title: "Login", Page: "login", CSRFToken: a.csrfToken(r), Error: "Invalid form token."})
+		return
+	}
+	if err := r.ParseForm(); err != nil {
+		a.serverError(w, err)
+		return
+	}
+
+	user, hash, err := a.store.GetUserByEmail(r.Context(), r.FormValue("email"))
+	if err != nil || !auth.CheckPassword(hash, r.FormValue("password")) {
+		a.render(w, http.StatusUnauthorized, ViewData{Title: "Login", Page: "login", CSRFToken: a.csrfToken(r), Error: "Invalid email or password."})
+		return
+	}
+	if user.Status != "active" {
+		a.render(w, http.StatusForbidden, ViewData{Title: "Login", Page: "login", CSRFToken: a.csrfToken(r), Error: "This user is frozen."})
+		return
+	}
+
+	if err := a.startUserSession(w, r, user.ID); err != nil {
+		a.serverError(w, err)
+		return
+	}
+
+	http.Redirect(w, r, "/app", http.StatusSeeOther)
+}
+
+func (a *App) logout(w http.ResponseWriter, r *http.Request) {
+	if !a.verifyCSRF(r) {
+		http.Redirect(w, r, "/login", http.StatusSeeOther)
+		return
+	}
+	if cookie, err := r.Cookie(userSessionCookie); err == nil {
+		_ = a.store.DeleteUserSession(r.Context(), auth.HashToken(cookie.Value))
+	}
+	a.clearCookie(w, userSessionCookie)
+	a.setFlash(w, "Signed out.")
+	http.Redirect(w, r, "/login", http.StatusSeeOther)
+}
+
+func (a *App) userDashboard(w http.ResponseWriter, r *http.Request) {
+	user, _ := a.currentUser(r)
+	transactions, err := a.store.RecentTransactionsForAccount(r.Context(), user.AccountID, 10)
+	if err != nil {
+		a.serverError(w, err)
+		return
+	}
+
+	a.render(w, http.StatusOK, ViewData{
+		Title:     "Dashboard",
+		Page:      "dashboard",
+		User:      user,
+		CSRFToken: a.csrfToken(r),
+		Flash:     a.readFlash(w, r),
+		Data:      DashboardData{User: user, Transactions: transactions},
+	})
+}
+
+func (a *App) showTransfer(w http.ResponseWriter, r *http.Request) {
+	user, _ := a.currentUser(r)
+	a.render(w, http.StatusOK, ViewData{Title: "Send money", Page: "transfer", User: user, CSRFToken: a.csrfToken(r), Flash: a.readFlash(w, r)})
+}
+
+func (a *App) createTransfer(w http.ResponseWriter, r *http.Request) {
+	user, _ := a.currentUser(r)
+	if !a.verifyCSRF(r) {
+		a.render(w, http.StatusBadRequest, ViewData{Title: "Send money", Page: "transfer", User: user, CSRFToken: a.csrfToken(r), Error: "Invalid form token."})
+		return
+	}
+	if err := r.ParseForm(); err != nil {
+		a.serverError(w, err)
+		return
+	}
+
+	amountMinor, err := platform.ParseCZK(r.FormValue("amount"))
+	if err != nil || amountMinor <= 0 {
+		a.render(w, http.StatusBadRequest, ViewData{Title: "Send money", Page: "transfer", User: user, CSRFToken: a.csrfToken(r), Error: "Enter a valid positive CZK amount."})
+		return
+	}
+
+	err = a.store.CreateTransfer(r.Context(), user.ID, r.FormValue("account_number"), r.FormValue("description"), amountMinor)
+	if err != nil {
+		switch {
+		case errors.Is(err, db.ErrInsufficientFunds):
+			a.render(w, http.StatusBadRequest, ViewData{Title: "Send money", Page: "transfer", User: user, CSRFToken: a.csrfToken(r), Error: "Insufficient funds."})
+		case errors.Is(err, db.ErrFrozen):
+			a.render(w, http.StatusForbidden, ViewData{Title: "Send money", Page: "transfer", User: user, CSRFToken: a.csrfToken(r), Error: "This transfer is not allowed because one of the accounts is frozen."})
+		case errors.Is(err, db.ErrNotFound):
+			a.render(w, http.StatusBadRequest, ViewData{Title: "Send money", Page: "transfer", User: user, CSRFToken: a.csrfToken(r), Error: "Destination account number was not found."})
+		default:
+			a.render(w, http.StatusBadRequest, ViewData{Title: "Send money", Page: "transfer", User: user, CSRFToken: a.csrfToken(r), Error: err.Error()})
+		}
+		return
+	}
+
+	a.setFlash(w, "Transfer completed.")
+	http.Redirect(w, r, "/app", http.StatusSeeOther)
+}
+
+func (a *App) transactionsPage(w http.ResponseWriter, r *http.Request) {
+	user, _ := a.currentUser(r)
+	transactions, err := a.store.RecentTransactionsForAccount(r.Context(), user.AccountID, 100)
+	if err != nil {
+		a.serverError(w, err)
+		return
+	}
+	a.render(w, http.StatusOK, ViewData{Title: "Transactions", Page: "transactions", User: user, CSRFToken: a.csrfToken(r), Flash: a.readFlash(w, r), Data: DashboardData{User: user, Transactions: transactions}})
+}
+
+func (a *App) showAdminLogin(w http.ResponseWriter, r *http.Request) {
+	a.render(w, http.StatusOK, ViewData{Title: "Admin login", Page: "admin_login", CSRFToken: a.csrfToken(r), Flash: a.readFlash(w, r)})
+}
+
+func (a *App) adminLogin(w http.ResponseWriter, r *http.Request) {
+	if !a.verifyCSRF(r) {
+		a.render(w, http.StatusBadRequest, ViewData{Title: "Admin login", Page: "admin_login", CSRFToken: a.csrfToken(r), Error: "Invalid form token."})
+		return
+	}
+	if err := r.ParseForm(); err != nil {
+		a.serverError(w, err)
+		return
+	}
+
+	admin, hash, err := a.store.GetAdminByEmail(r.Context(), r.FormValue("email"))
+	if err != nil || !auth.CheckPassword(hash, r.FormValue("password")) {
+		a.render(w, http.StatusUnauthorized, ViewData{Title: "Admin login", Page: "admin_login", CSRFToken: a.csrfToken(r), Error: "Invalid email or password."})
+		return
+	}
+	if admin.Status != "active" {
+		a.render(w, http.StatusForbidden, ViewData{Title: "Admin login", Page: "admin_login", CSRFToken: a.csrfToken(r), Error: "This admin account is inactive."})
+		return
+	}
+
+	if err := a.startAdminSession(w, r, admin.ID); err != nil {
+		a.serverError(w, err)
+		return
+	}
+
+	http.Redirect(w, r, "/admin", http.StatusSeeOther)
+}
+
+func (a *App) adminLogout(w http.ResponseWriter, r *http.Request) {
+	if !a.verifyCSRF(r) {
+		http.Redirect(w, r, "/admin/login", http.StatusSeeOther)
+		return
+	}
+	if cookie, err := r.Cookie(adminSessionCookie); err == nil {
+		_ = a.store.DeleteAdminSession(r.Context(), auth.HashToken(cookie.Value))
+	}
+	a.clearCookie(w, adminSessionCookie)
+	a.setFlash(w, "Admin signed out.")
+	http.Redirect(w, r, "/admin/login", http.StatusSeeOther)
+}
+
+func (a *App) adminDashboard(w http.ResponseWriter, r *http.Request) {
+	admin, _ := a.currentAdmin(r)
+	dashboard, err := a.store.AdminDashboard(r.Context())
+	if err != nil {
+		a.serverError(w, err)
+		return
+	}
+	a.render(w, http.StatusOK, ViewData{Title: "Admin dashboard", Page: "admin_dashboard", Admin: admin, CSRFToken: a.csrfToken(r), Flash: a.readFlash(w, r), Data: AdminDashboardData{Admin: admin, Dashboard: dashboard}})
+}
+
+func (a *App) adminUsers(w http.ResponseWriter, r *http.Request) {
+	admin, _ := a.currentAdmin(r)
+	search := r.URL.Query().Get("q")
+	users, err := a.store.SearchUsers(r.Context(), search)
+	if err != nil {
+		a.serverError(w, err)
+		return
+	}
+	a.render(w, http.StatusOK, ViewData{Title: "Users", Page: "admin_users", Admin: admin, CSRFToken: a.csrfToken(r), Flash: a.readFlash(w, r), Data: UsersPageData{Admin: admin, Search: search, Users: users}})
+}
+
+func (a *App) adminUserDetail(w http.ResponseWriter, r *http.Request) {
+	admin, _ := a.currentAdmin(r)
+	user, transactions, err := a.store.GetUserDetail(r.Context(), chi.URLParam(r, "userID"))
+	if err != nil {
+		if errors.Is(err, db.ErrNotFound) {
+			http.NotFound(w, r)
+			return
+		}
+		a.serverError(w, err)
+		return
+	}
+	a.render(w, http.StatusOK, ViewData{Title: "User detail", Page: "admin_user_detail", Admin: admin, CSRFToken: a.csrfToken(r), Flash: a.readFlash(w, r), Data: UserDetailData{Admin: admin, User: user, Transactions: transactions}})
+}
+
+func (a *App) freezeUser(w http.ResponseWriter, r *http.Request) {
+	a.changeUserStatus(w, r, "frozen")
+}
+
+func (a *App) unfreezeUser(w http.ResponseWriter, r *http.Request) {
+	a.changeUserStatus(w, r, "active")
+}
+
+func (a *App) changeUserStatus(w http.ResponseWriter, r *http.Request, status string) {
+	admin, _ := a.currentAdmin(r)
+	if !a.verifyCSRF(r) {
+		a.setFlash(w, "Invalid form token.")
+		http.Redirect(w, r, "/admin/users/"+chi.URLParam(r, "userID"), http.StatusSeeOther)
+		return
+	}
+	if err := a.store.SetUserStatus(r.Context(), chi.URLParam(r, "userID"), status, admin.ID); err != nil {
+		a.setFlash(w, err.Error())
+	} else {
+		a.setFlash(w, "User status updated.")
+	}
+	http.Redirect(w, r, "/admin/users/"+chi.URLParam(r, "userID"), http.StatusSeeOther)
+}
+
+func (a *App) adjustBalance(w http.ResponseWriter, r *http.Request) {
+	admin, _ := a.currentAdmin(r)
+	if !a.verifyCSRF(r) {
+		a.setFlash(w, "Invalid form token.")
+		http.Redirect(w, r, r.Referer(), http.StatusSeeOther)
+		return
+	}
+	if err := r.ParseForm(); err != nil {
+		a.serverError(w, err)
+		return
+	}
+
+	amountMinor, err := platform.ParseCZK(r.FormValue("amount"))
+	if err != nil || amountMinor <= 0 {
+		a.setFlash(w, "Invalid adjustment amount.")
+		http.Redirect(w, r, r.Referer(), http.StatusSeeOther)
+		return
+	}
+
+	if err := a.store.CreateAdjustment(r.Context(), admin.ID, chi.URLParam(r, "accountID"), r.FormValue("direction"), amountMinor, r.FormValue("reason")); err != nil {
+		a.setFlash(w, err.Error())
+	} else {
+		a.setFlash(w, "Balance adjusted.")
+	}
+	http.Redirect(w, r, r.Referer(), http.StatusSeeOther)
+}
+
+func (a *App) auditLogs(w http.ResponseWriter, r *http.Request) {
+	admin, _ := a.currentAdmin(r)
+	logs, err := a.store.AuditLogs(r.Context())
+	if err != nil {
+		a.serverError(w, err)
+		return
+	}
+	a.render(w, http.StatusOK, ViewData{Title: "Audit logs", Page: "admin_audit_logs", Admin: admin, CSRFToken: a.csrfToken(r), Flash: a.readFlash(w, r), Data: logs})
+}
+
+func (a *App) withCurrentSessions(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		ctx := r.Context()
+		if cookie, err := r.Cookie(userSessionCookie); err == nil && cookie.Value != "" {
+			if user, err := a.store.UserFromSession(ctx, auth.HashToken(cookie.Value)); err == nil {
+				ctx = context.WithValue(ctx, ctxUserKey, user)
+			}
+		}
+		if cookie, err := r.Cookie(adminSessionCookie); err == nil && cookie.Value != "" {
+			if admin, err := a.store.AdminFromSession(ctx, auth.HashToken(cookie.Value)); err == nil {
+				ctx = context.WithValue(ctx, ctxAdminKey, admin)
+			}
+		}
+		next.ServeHTTP(w, r.WithContext(ctx))
+	})
+}
+
+func (a *App) requireUser(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		user, _ := a.currentUser(r)
+		if user == nil {
+			a.setFlash(w, "Please sign in first.")
+			http.Redirect(w, r, "/login", http.StatusSeeOther)
+			return
+		}
+		if user.Status != "active" {
+			a.clearCookie(w, userSessionCookie)
+			a.setFlash(w, "Your user is frozen.")
+			http.Redirect(w, r, "/login", http.StatusSeeOther)
+			return
+		}
+		next.ServeHTTP(w, r)
+	})
+}
+
+func (a *App) requireAdmin(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		admin, _ := a.currentAdmin(r)
+		if admin == nil {
+			a.setFlash(w, "Please sign in as admin.")
+			http.Redirect(w, r, "/admin/login", http.StatusSeeOther)
+			return
+		}
+		next.ServeHTTP(w, r)
+	})
+}
+
+func (a *App) startUserSession(w http.ResponseWriter, r *http.Request, userID string) error {
+	token, err := platform.NewToken()
+	if err != nil {
+		return err
+	}
+	expires := time.Now().Add(24 * time.Hour)
+	if err := a.store.CreateUserSession(r.Context(), userID, auth.HashToken(token), expires); err != nil {
+		return err
+	}
+	a.setCookie(w, userSessionCookie, token, expires)
+	return nil
+}
+
+func (a *App) startAdminSession(w http.ResponseWriter, r *http.Request, adminID string) error {
+	token, err := platform.NewToken()
+	if err != nil {
+		return err
+	}
+	expires := time.Now().Add(24 * time.Hour)
+	if err := a.store.CreateAdminSession(r.Context(), adminID, auth.HashToken(token), expires); err != nil {
+		return err
+	}
+	a.setCookie(w, adminSessionCookie, token, expires)
+	return nil
+}
+
+func (a *App) withCSRF(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		token := ""
+		if cookie, err := r.Cookie(csrfCookie); err == nil && cookie.Value != "" {
+			token = cookie.Value
+		} else {
+			var err error
+			token, err = platform.NewToken()
+			if err != nil {
+				a.serverError(w, err)
+				return
+			}
+			a.setCookie(w, csrfCookie, token, time.Now().Add(7*24*time.Hour))
+		}
+
+		ctx := context.WithValue(r.Context(), ctxCSRFKey, token)
+		next.ServeHTTP(w, r.WithContext(ctx))
+	})
+}
+
+func (a *App) csrfToken(r *http.Request) string {
+	if token, ok := r.Context().Value(ctxCSRFKey).(string); ok && token != "" {
+		return token
+	}
+	cookie, err := r.Cookie(csrfCookie)
+	if err != nil {
+		return ""
+	}
+	return cookie.Value
+}
+
+func (a *App) verifyCSRF(r *http.Request) bool {
+	return a.csrfToken(r) != "" && a.csrfToken(r) == r.FormValue("csrf_token")
+}
+
+func (a *App) currentUser(r *http.Request) (*db.User, bool) {
+	user, ok := r.Context().Value(ctxUserKey).(*db.User)
+	return user, ok
+}
+
+func (a *App) currentAdmin(r *http.Request) (*db.AdminUser, bool) {
+	admin, ok := r.Context().Value(ctxAdminKey).(*db.AdminUser)
+	return admin, ok
+}
+
+func (a *App) setCookie(w http.ResponseWriter, name, value string, expires time.Time) {
+	http.SetCookie(w, &http.Cookie{
+		Name:     name,
+		Value:    value,
+		Path:     "/",
+		Expires:  expires,
+		HttpOnly: true,
+		SameSite: http.SameSiteLaxMode,
+		Secure:   a.cfg.AppEnv == "production",
+	})
+}
+
+func (a *App) clearCookie(w http.ResponseWriter, name string) {
+	http.SetCookie(w, &http.Cookie{
+		Name:     name,
+		Value:    "",
+		Path:     "/",
+		MaxAge:   -1,
+		HttpOnly: true,
+		SameSite: http.SameSiteLaxMode,
+		Secure:   a.cfg.AppEnv == "production",
+	})
+}
+
+func (a *App) setFlash(w http.ResponseWriter, message string) {
+	http.SetCookie(w, &http.Cookie{
+		Name:     flashCookie,
+		Value:    url.QueryEscape(message),
+		Path:     "/",
+		MaxAge:   60,
+		HttpOnly: true,
+		SameSite: http.SameSiteLaxMode,
+		Secure:   a.cfg.AppEnv == "production",
+	})
+}
+
+func (a *App) readFlash(w http.ResponseWriter, r *http.Request) string {
+	cookie, err := r.Cookie(flashCookie)
+	if err != nil || cookie.Value == "" {
+		return ""
+	}
+	a.clearCookie(w, flashCookie)
+	message, err := url.QueryUnescape(cookie.Value)
+	if err != nil {
+		return cookie.Value
+	}
+	return message
+}
+
+func (a *App) render(w http.ResponseWriter, status int, data ViewData) {
+	a.renderer.HTML(w, status, data)
+}
+
+func (a *App) serverError(w http.ResponseWriter, err error) {
+	http.Error(w, fmt.Sprintf("server error: %v", err), http.StatusInternalServerError)
+}