Theme System: Added new page-content focused events

Closes #6049

app/Entities/Tools/PageContent.php

@@ -39,7 +39,14 @@ class PageContent
     public function setNewHTML(string $html, User $updater): void
     {
         $html = $this->extractBase64ImagesFromHtml($html, $updater);
-        $this->page->html = $this->formatHtml($html);
+        $html = $this->formatHtml($html);
+
+        $themeResult = Theme::dispatch(ThemeEvents::PAGE_CONTENT_PRE_STORE, $html, $this->page);
+        if (is_string($themeResult)) {
+            $html = $themeResult;
+        }
+
+        $this->page->html = $html;
         $this->page->text = $this->toPlainText();
         $this->page->markdown = '';
     }
@@ -52,7 +59,14 @@ class PageContent
         $markdown = $this->extractBase64ImagesFromMarkdown($markdown, $updater);
         $this->page->markdown = $markdown;
         $html = (new MarkdownToHtml($markdown))->convert();
-        $this->page->html = $this->formatHtml($html);
+        $html = $this->formatHtml($html);
+
+        $themeResult = Theme::dispatch(ThemeEvents::PAGE_CONTENT_PRE_STORE, $html, $this->page);
+        if (is_string($themeResult)) {
+            $html = $themeResult;
+        }
+
+        $this->page->html = $html;
         $this->page->text = $this->toPlainText();
     }
 
@@ -81,7 +95,7 @@ class PageContent
 
     /**
      * Convert all inline base64 content to uploaded image files.
-     * Regex is used to locate the start of data-uri definitions then
+     * Regex is used to locate the start of data-uri definitions, then
      * manual looping over content is done to parse the whole data uri.
      * Attempting to capture the whole data uri using regex can cause PHP
      * PCRE limits to be hit with larger, multi-MB, files.
@@ -301,7 +315,7 @@ class PageContent
         $html = $this->page->html ?? '';
 
         if (empty($html)) {
-            return $html;
+            return $this->handlePostRender('');
         }
 
         $doc = new HtmlDocument($html);
@@ -322,7 +336,7 @@ class PageContent
         $cacheKey = $this->getContentCacheKey($doc->getBodyInnerHtml());
         $cached = cache()->get($cacheKey, null);
         if ($cached !== null) {
-            return $cached;
+            return $this->handlePostRender($cached);
         }
 
         $filterConfig = HtmlContentFilterConfig::fromConfigString(config('app.content_filtering'));
@@ -332,7 +346,13 @@ class PageContent
         $cacheTime = 86400 * 7; // 1 week
         cache()->put($cacheKey, $filtered, $cacheTime);
 
-        return $filtered;
+        return $this->handlePostRender($filtered);
+    }
+
+    protected function handlePostRender(string $html): string
+    {
+        $themeResult = Theme::dispatch(ThemeEvents::PAGE_CONTENT_POST_RENDER, $html, $this->page);
+        return is_string($themeResult) ? $themeResult : $html;
     }
 
     protected function getContentCacheKey(string $html): string

app/Theming/ThemeEvents.php

@@ -111,6 +111,31 @@ class ThemeEvents
      */
     const OIDC_ID_TOKEN_PRE_VALIDATE = 'oidc_id_token_pre_validate';
 
+    /**
+     * Page content post-render event.
+     * Runs after any display rendering of page content, typically when page content is being processed for viewing.
+     * Rendering typically includes parsing of page includes, and content filtering.
+     * Provides the HTML content about to be shown, along with the related page instance.
+     * If the listener returns a string value, that will be used as the HTML content instead.
+     *
+     * @param string $html
+     * @param \BookStack\Entities\Models\Page $page
+     * @return string|null
+     */
+    const PAGE_CONTENT_POST_RENDER = 'page_content_post_render';
+
+    /**
+     * Page content pre-store event.
+     * Runs just before page HTML is stored in the database, after BookStack's own processing.
+     * Provides the HTML content about to be stored, along with the related page instance.
+     * If the listener returns a string value, that will be used as the HTML content instead.
+     *
+     * @param string $html
+     * @param \BookStack\Entities\Models\Page $page
+     * @return string|null
+     */
+    const PAGE_CONTENT_PRE_STORE = 'page_content_pre_store';
+
     /**
      * Page include parse event.
      * Runs when a page include tag is being parsed, typically when page content is being processed for viewing.

tests/Theme/LogicalThemeEventsTest.php

@@ -215,6 +215,82 @@ class LogicalThemeEventsTest extends TestCase
         $this->assertEquals($book->id, $args[1]->id);
     }
 
+    public function test_page_content_pre_store_fires_on_page_save()
+    {
+        $page = $this->entities->page();
+
+        $args = [];
+        $callback = function (...$eventArgs) use (&$args) {
+            $args = $eventArgs;
+            return '<p>New Content!</p>';
+        };
+
+        Theme::listen(ThemeEvents::PAGE_CONTENT_PRE_STORE, $callback);
+
+        $this->asEditor();
+        $this->entities->updatePage($page, ['name' => 'My cool update page!', 'html' => '<p>Old content!</p>']);
+
+        $this->assertCount(2, $args);
+        $this->assertEquals($page->id, $args[1]->id);
+        $this->assertEquals('<p id="bkmrk-old-content%21">Old content!</p>', $args[0]);
+
+        $newPageHtml = $page->refresh()->html;
+        $this->assertEquals('<p>New Content!</p>', $newPageHtml);
+    }
+
+    public function test_page_content_pre_store_does_not_change_content_if_nothing_returned()
+    {
+        $page = $this->entities->page();
+        Theme::listen(ThemeEvents::PAGE_CONTENT_PRE_STORE, fn() => null);
+
+        $this->asEditor();
+        $this->entities->updatePage($page, ['name' => 'My cool update page!', 'html' => '<p>Old content!</p>']);
+
+        $newPageHtml = $page->refresh()->html;
+        $this->assertEquals('<p id="bkmrk-old-content%21">Old content!</p>', $newPageHtml);
+    }
+
+    public function test_page_content_post_render_fires_on_page_view()
+    {
+        $page = $this->entities->page();
+        $page->html = '<p>Old content!</p>';
+        $page->save();
+
+        $args = [];
+        $callback = function (...$eventArgs) use (&$args) {
+            $args = $eventArgs;
+            return '<p>New postrendercontentforyou!</p>';
+        };
+
+        Theme::listen(ThemeEvents::PAGE_CONTENT_POST_RENDER, $callback);
+
+        $resp = $this->asEditor()->get($page->getUrl());
+        $resp->assertSee('<p>New postrendercontentforyou!</p>', false);
+
+        $this->assertCount(2, $args);
+        $this->assertEquals($page->id, $args[1]->id);
+        $this->assertEquals('<p>Old content!</p>', $args[0]);
+    }
+
+    public function test_page_content_post_render_returns_original_content_if_no_return()
+    {
+        $page = $this->entities->page();
+        $page->html = '<p>Old content!</p>';
+        $page->save();
+
+        $args = [];
+        $callback = function (...$eventArgs) use (&$args) {
+            $args = $eventArgs;
+        };
+
+        Theme::listen(ThemeEvents::PAGE_CONTENT_POST_RENDER, $callback);
+
+        $resp = $this->asEditor()->get($page->getUrl());
+        $resp->assertSee('<p>Old content!</p>', false);
+
+        $this->assertCount(2, $args);
+    }
+
     public function test_page_include_parse()
     {
         /** @var Page $page */