admin: add admin panel for user management

internal/middleware/admin.go

@@ -0,0 +1,29 @@
+package middleware
+
+import (
+	"net/http"
+
+	"mal/internal/db"
+	"mal/web/shared/admin"
+)
+
+func IsAdmin(user *database.User) bool {
+	return admin.IsAdmin(user)
+}
+
+func RequireAdmin(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		user, ok := r.Context().Value(UserContextKey).(*database.User)
+		if !ok || user == nil {
+			http.Redirect(w, r, "/login", http.StatusFound)
+			return
+		}
+
+		if !admin.IsAdmin(user) {
+			http.Error(w, "Forbidden", http.StatusForbidden)
+			return
+		}
+
+		next.ServeHTTP(w, r)
+	})
+}