Add Parcel2Go account consent with PKCE

app/Http/Controllers/Parcel2GoConnectionController.php

@@ -0,0 +1,47 @@
+<?php
+
+namespace App\Http\Controllers;
+
+use App\Services\Parcel2Go;
+use Illuminate\Http\RedirectResponse;
+use Illuminate\Http\Request;
+use Throwable;
+
+class Parcel2GoConnectionController extends Controller
+{
+    public function connect(Request $request, Parcel2Go $parcel2Go): RedirectResponse
+    {
+        abort_unless($request->user()->role === 'admin', 403);
+        if (! $parcel2Go->profileClientConfigured()) {
+            return redirect()->route('settings.index')->withErrors(['parcel2go' => 'Save the Parcel2Go Authorization Code Client ID first.']);
+        }
+
+        $state = bin2hex(random_bytes(24));
+        $verifier = rtrim(strtr(base64_encode(random_bytes(48)), '+/', '-_'), '=');
+        $request->session()->put('parcel2go_oauth', ['state' => $state, 'verifier' => $verifier, 'started' => time()]);
+
+        return redirect()->away($parcel2Go->authorizationUrl($state, $verifier));
+    }
+
+    public function callback(Request $request, Parcel2Go $parcel2Go): RedirectResponse
+    {
+        abort_unless($request->user()->role === 'admin', 403);
+        $pending = $request->session()->pull('parcel2go_oauth');
+        if (! is_array($pending) || time() - ($pending['started'] ?? 0) > 600
+            || ! is_string($request->query('state'))
+            || ! hash_equals($pending['state'] ?? '', $request->query('state'))
+            || ! is_string($request->query('code'))) {
+            return redirect()->route('settings.index')->withErrors(['parcel2go' => 'Parcel2Go consent expired or was not verified. Please try again.']);
+        }
+
+        try {
+            $parcel2Go->connectProfile($request->query('code'), $pending['verifier']);
+
+            return redirect()->route('settings.index')->with('status', 'Parcel2Go account connected. Shipment history is available in Shipping.');
+        } catch (Throwable $exception) {
+            report($exception);
+
+            return redirect()->route('settings.index')->withErrors(['parcel2go' => 'Parcel2Go rejected the account connection. Check the Client ID, scopes and callback URL.']);
+        }
+    }
+}