create an api controller for sessions endpoint

src/controllers/api/Sessions.php

@@ -0,0 +1,54 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Steamy\Controller\API;
+
+use Steamy\Model\Administrator;
+
+/**
+ * Handles /sessions route of API
+ */
+class Sessions
+{
+    private function handleLogin(): void
+    {
+        $email = trim($_POST['email'] ?? "");
+        $password = trim($_POST['password'] ?? "");
+
+        if (empty($email) || empty($password)) {
+            http_response_code(400);
+            die();
+        }
+
+        // fetch administrator account
+        $admin = Administrator::getByEmail($email);
+
+        // validate email
+        if (!$admin) {
+            http_response_code(401);
+            die();
+        }
+
+        // validate password
+        if (!$admin->verifyPassword($password)) {
+            http_response_code(401);
+            die();
+        }
+
+        $_SESSION['admin_email'] = $email;
+        session_regenerate_id();
+    }
+
+    public function index(): void
+    {
+        switch ($_SERVER['REQUEST_METHOD']) {
+            case 'POST':
+                $this->handleLogin();
+                break;
+            default:
+                http_response_code(400);
+                die();
+        }
+    }
+}