[exam] finish assign and remove

app/Http/Middleware/Permission.php

@@ -0,0 +1,31 @@
+<?php
+
+namespace App\Http\Middleware;
+
+use App\Models\User;
+use Closure;
+use Illuminate\Http\Request;
+use Illuminate\Validation\UnauthorizedException;
+
+class Permission
+{
+    /**
+     * Handle an incoming request.
+     *
+     * @param  \Illuminate\Http\Request  $request
+     * @param  \Closure  $next
+     * @return mixed
+     */
+    public function handle(Request $request, Closure $next)
+    {
+        $user = $request->user();
+        $targetClass = User::CLASS_MODERATOR;
+        $log = sprintf('user: %s, class: %s, target class: %s', $user->id, $user->class, $targetClass);
+        if (!$user || $user->class < $targetClass) {
+            do_log("$log, denied!");
+            throw new UnauthorizedException('Unauthorized!');
+        }
+        do_log("$log, pass!");
+        return $next($request);
+    }
+}