From c03455ac7db227f34320b06eb4c879d4b6bbc195 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rafa=C5=82=20Ca=C5=82ka?= <calka.rafal@gmail.com>
Date: Sun, 28 Jan 2024 21:22:37 +0100
Subject: [PATCH] feat: compatibility with `v17development/flarum-blog`

---
 composer.json                                 |  3 +-
 extend.php                                    |  9 +++
 .../FlarumBlog/FlarumBlogPurgeMiddleware.php  | 67 +++++++++++++++++++
 3 files changed, 78 insertions(+), 1 deletion(-)
 create mode 100644 src/Compatibility/v17development/FlarumBlog/FlarumBlogPurgeMiddleware.php

diff --git a/composer.json b/composer.json
index 5d9aec0..bd946b8 100644
--- a/composer.json
+++ b/composer.json
@@ -26,7 +26,8 @@
     },
     "require-dev": {
         "flarum/phpstan": "^1.8",
-        "flarum/tags": "*"
+        "flarum/tags": "*",
+        "v17development/flarum-blog": "^0.7.7"
     },
     "suggest": {
         "blomstra/flarum-redis": "This library allows using Redis as cache, session and for the queue. https://github.com/blomstra/flarum-redis#set-up"
diff --git a/extend.php b/extend.php
index 65df529..8519688 100644
--- a/extend.php
+++ b/extend.php
@@ -17,6 +17,7 @@
 use ACPL\FlarumCache\Compatibility\Flarum\Likes\FlarumLikesPurgeMiddleware;
 use ACPL\FlarumCache\Compatibility\Flarum\Tags\FlarumTagsPurgeMiddleware;
 use ACPL\FlarumCache\Compatibility\FriendsOfFlarum\Masquerade\FofMasqueradePurgeMiddleware;
+use ACPL\FlarumCache\Compatibility\v17development\FlarumBlog\FlarumBlogPurgeMiddleware;
 use ACPL\FlarumCache\Listener\ClearingCacheListener;
 use ACPL\FlarumCache\Middleware\LoginMiddleware;
 use ACPL\FlarumCache\Middleware\LogoutMiddleware;
@@ -83,4 +84,12 @@
         ->whenExtensionEnabled('fof-masquerade', [
             (new Extend\Middleware('api'))->add(FofMasqueradePurgeMiddleware::class),
         ])
+        ->whenExtensionEnabled('v17development-blog', [
+            // Using insertBefore enables reading headers set by LSCachePurgeMiddleware, while insertAfter does not.
+            // This suggests Flarum processes middleware in a reverse order 🤔.
+            (new Extend\Middleware('api'))->insertBefore(
+                LSCachePurgeMiddleware::class,
+                FlarumBlogPurgeMiddleware::class
+            ),
+        ])
 ];
diff --git a/src/Compatibility/v17development/FlarumBlog/FlarumBlogPurgeMiddleware.php b/src/Compatibility/v17development/FlarumBlog/FlarumBlogPurgeMiddleware.php
new file mode 100644
index 0000000..f330cb0
--- /dev/null
+++ b/src/Compatibility/v17development/FlarumBlog/FlarumBlogPurgeMiddleware.php
@@ -0,0 +1,67 @@
+<?php
+
+namespace ACPL\FlarumCache\Compatibility\v17development\FlarumBlog;
+
+use ACPL\FlarumCache\Abstract\PurgeMiddleware;
+use ACPL\FlarumCache\LSCacheHeadersEnum;
+use Illuminate\Support\Arr;
+use Illuminate\Support\Str;
+use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Message\ServerRequestInterface;
+use Psr\Http\Server\RequestHandlerInterface;
+use V17Development\FlarumBlog\BlogMeta\BlogMeta;
+
+class FlarumBlogPurgeMiddleware extends PurgeMiddleware
+{
+    protected function processPurge(
+        ServerRequestInterface $request,
+        RequestHandlerInterface $handler,
+        ResponseInterface $response
+    ): ResponseInterface {
+        $isDiscussion = $this->isDiscussion;
+        $isPost = $this->isPost;
+
+        if (! ($isDiscussion || $isPost)) {
+            return $response;
+        }
+
+        if ($this->currentRouteName === 'discussions.create') {
+            $body = $request->getParsedBody();
+            if (Arr::has($body, 'data.attributes.blogMeta')) {
+                return $this->addPurgeParamsToResponse($response, ['tag=blog.overview']);
+            }
+        }
+
+        $currentPurgeParams = $response->getHeaderLine(LSCacheHeadersEnum::PURGE);
+        if (empty($currentPurgeParams)) {
+            return $response;
+        }
+
+        $newPurgeParams = [];
+        $currentPurgeParams = explode(',', $currentPurgeParams);
+
+        // Blog extension is using default Flarum discussion api routes, so we can just reuse previous middleware to get the blog post id
+        $discussionParam = Arr::first(
+            $currentPurgeParams,
+            fn (string $param) => Str::startsWith($param, ['tag=discussion_', 'tag=discussions_'])
+        );
+        if (empty($discussionParam)) {
+            return $response;
+        }
+
+        if (preg_match('/(\d+)/', $discussionParam, $matches)) {
+            $discussionId = $matches[1];
+            $newPurgeParams[] = 'tag=blog_'.$discussionId;
+
+            // If the previous response wants to purge the index page and this is a blog post, we need to purge the blog overview page as well
+            if (
+                in_array('tag=index', $currentPurgeParams)
+                && BlogMeta::where('discussion_id', '=', $discussionId)->first()
+            ) {
+                $newPurgeParams[] = 'tag=blog.overview';
+            }
+        }
+
+        return $this->addPurgeParamsToResponse($response, $newPurgeParams);
+    }
+}