New HTML to Plaintext handling

app/Activity/Models/Comment.php

@@ -9,6 +9,7 @@
 use BookStack\Users\Models\OwnableInterface;
 use BookStack\Util\HtmlContentFilter;
 use BookStack\Util\HtmlContentFilterConfig;
+use BookStack\Util\HtmlToPlainText;
 use Illuminate\Database\Eloquent\Builder;
 use Illuminate\Database\Eloquent\Factories\HasFactory;
 use Illuminate\Database\Eloquent\Relations\BelongsTo;
@@ -87,6 +88,12 @@ public function safeHtml(): string
         return $filter->filterString($this->html ?? '');
     }
 
+    public function getPlainText(): string
+    {
+        $converter = new HtmlToPlainText();
+        return $converter->convert($this->html ?? '');
+    }
+
     public function jointPermissions(): HasMany
     {
         return $this->hasMany(JointPermission::class, 'entity_id', 'commentable_id')

app/Activity/Notifications/Messages/CommentCreationNotification.php

@@ -24,7 +24,7 @@ public function toMail(User $notifiable): MailMessage
             $locale->trans('notifications.detail_page_name') => new EntityLinkMessageLine($page),
             $locale->trans('notifications.detail_page_path') => $this->buildPagePathLine($page, $notifiable),
             $locale->trans('notifications.detail_commenter') => $this->user->name,
-            $locale->trans('notifications.detail_comment') => strip_tags($comment->html),
+            $locale->trans('notifications.detail_comment') => $comment->getPlainText(),
         ]);
 
         return $this->newMailMessage($locale)

app/Activity/Notifications/Messages/CommentMentionNotification.php

@@ -24,7 +24,7 @@ public function toMail(User $notifiable): MailMessage
             $locale->trans('notifications.detail_page_name') => new EntityLinkMessageLine($page),
             $locale->trans('notifications.detail_page_path') => $this->buildPagePathLine($page, $notifiable),
             $locale->trans('notifications.detail_commenter') => $this->user->name,
-            $locale->trans('notifications.detail_comment') => strip_tags($comment->html),
+            $locale->trans('notifications.detail_comment') => $comment->getPlainText(),
         ]);
 
         return $this->newMailMessage($locale)

app/Entities/Repos/BaseRepo.php

@@ -16,6 +16,7 @@
 use BookStack\Sorting\BookSorter;
 use BookStack\Uploads\ImageRepo;
 use BookStack\Util\HtmlDescriptionFilter;
+use BookStack\Util\HtmlToPlainText;
 use Illuminate\Http\UploadedFile;
 
 class BaseRepo
@@ -151,9 +152,10 @@ protected function updateDescription(Entity $entity, array $input): void
         }
 
         if (isset($input['description_html'])) {
+            $plainTextConverter = new HtmlToPlainText();
             $entity->descriptionInfo()->set(
                 HtmlDescriptionFilter::filterFromString($input['description_html']),
-                html_entity_decode(strip_tags($input['description_html']))
+                $plainTextConverter->convert($input['description_html']),
             );
         } else if (isset($input['description'])) {
             $entity->descriptionInfo()->set('', $input['description']);

app/Entities/Tools/PageContent.php

@@ -16,6 +16,7 @@
 use BookStack\Util\HtmlContentFilter;
 use BookStack\Util\HtmlContentFilterConfig;
 use BookStack\Util\HtmlDocument;
+use BookStack\Util\HtmlToPlainText;
 use BookStack\Util\WebSafeMimeSniffer;
 use Closure;
 use DOMElement;
@@ -303,8 +304,8 @@ protected function setUniqueId(DOMNode $element, array &$idMap): array
     public function toPlainText(): string
     {
         $html = $this->render(true);
-
-        return html_entity_decode(strip_tags($html));
+        $converter = new HtmlToPlainText();
+        return $converter->convert($html);
     }
 
     /**

app/Exports/ExportFormatter.php

@@ -11,6 +11,7 @@
 use BookStack\Uploads\ImageService;
 use BookStack\Util\CspService;
 use BookStack\Util\HtmlDocument;
+use BookStack\Util\HtmlToPlainText;
 use DOMElement;
 use Exception;
 use Throwable;
@@ -242,32 +243,21 @@ protected function containHtml(string $htmlContent): string
 
     /**
      * Converts the page contents into simple plain text.
-     * This method filters any bad looking content to provide a nice final output.
+     * We re-generate the plain text from HTML at this point, post-page-content rendering.
      */
     public function pageToPlainText(Page $page, bool $pageRendered = false, bool $fromParent = false): string
     {
         $html = $pageRendered ? $page->html : (new PageContent($page))->render();
-        // Add proceeding spaces before tags so spaces remain between
-        // text within elements after stripping tags.
-        $html = str_replace('<', " <", $html);
-        $text = trim(strip_tags($html));
-        // Replace multiple spaces with single spaces
-        $text = preg_replace('/ {2,}/', ' ', $text);
-        // Reduce multiple horrid whitespace characters.
-        $text = preg_replace('/(\x0A|\xA0|\x0A|\r|\n){2,}/su', "\n\n", $text);
-        $text = html_entity_decode($text);
-        // Add title
-        $text = $page->name . ($fromParent ? "\n" : "\n\n") . $text;
-
-        return $text;
+        $contentText = (new HtmlToPlainText())->convert($html);
+        return $page->name . ($fromParent ? "\n" : "\n\n") . $contentText;
     }
 
     /**
      * Convert a chapter into a plain text string.
      */
     public function chapterToPlainText(Chapter $chapter): string
     {
-        $text = $chapter->name . "\n" . $chapter->description;
+        $text = $chapter->name . "\n" . $chapter->descriptionInfo()->getPlain();
         $text = trim($text) . "\n\n";
 
         $parts = [];

app/Util/HtmlToPlainText.php

@@ -0,0 +1,47 @@
+<?php
+
+namespace BookStack\Util;
+
+class HtmlToPlainText
+{
+    /**
+     * Inline tags types where the content should not be put on a new line.
+     */
+    protected array $inlineTags = [
+        'a', 'b', 'i', 'u', 'strong', 'em', 'small', 'sup', 'sub', 'span', 'div',
+    ];
+
+    /**
+     * Convert the provided HTML to relatively clean plain text.
+     */
+    public function convert(string $html): string
+    {
+        $doc = new HtmlDocument($html);
+        $text = $this->nodeToText($doc->getBody());
+
+        // Remove repeated newlines
+        $text = preg_replace('/\n+/', "\n", $text);
+        // Remove leading/trailing whitespace
+        $text = trim($text);
+
+        return $text;
+    }
+
+    protected function nodeToText(\DOMNode $node): string
+    {
+        if ($node->nodeType === XML_TEXT_NODE) {
+            return $node->textContent;
+        }
+
+        $text = '';
+        if (!in_array($node->nodeName, $this->inlineTags)) {
+            $text .= "\n";
+        }
+
+        foreach ($node->childNodes as $childNode) {
+            $text .= $this->nodeToText($childNode);
+        }
+
+        return $text;
+    }
+}

tests/Exports/TextExportTest.php

@@ -52,7 +52,7 @@ public function test_book_text_export_format()
         $resp = $this->asEditor()->get($entities['book']->getUrl('/export/plaintext'));
 
         $expected = "Export Book\nThis is a book with stuff to export\n\nExport chapter\nA test chapter to be exported\nIt has loads of info within\n\n";
-        $expected .= "My wonderful page!\nMy great page Full of great stuff";
+        $expected .= "My wonderful page!\nMy great page\nFull of great stuff";
         $resp->assertSee($expected);
     }
 
@@ -82,7 +82,7 @@ public function test_chapter_text_export_format()
         $resp = $this->asEditor()->get($entities['book']->getUrl('/export/plaintext'));
 
         $expected = "Export chapter\nA test chapter to be exported\nIt has loads of info within\n\n";
-        $expected .= "My wonderful page!\nMy great page Full of great stuff";
+        $expected .= "My wonderful page!\nMy great page\nFull of great stuff";
         $resp->assertSee($expected);
     }
 }

tests/Util/HtmlToPlainTextTest.php

@@ -0,0 +1,63 @@
+<?php
+
+namespace Tests\Util;
+
+use BookStack\Util\HtmlToPlainText;
+use Tests\TestCase;
+
+class HtmlToPlainTextTest extends TestCase
+{
+    public function test_it_converts_html_to_plain_text()
+    {
+        $html = <<<HTML
+<p>This is a test</p>
+<ul>
+<li>Item 1</li>
+<li>Item 2</li>
+</ul>
+<h2>A Header</h2>
+<p>more &lt;&copy;&gt; text <strong>with bold</strong></p>
+HTML;
+        $expected = <<<TEXT
+This is a test
+Item 1
+Item 2
+A Header
+more <©> text with bold
+TEXT;
+
+        $this->runTest($html, $expected);
+    }
+
+    public function test_adjacent_list_items_are_separated_by_newline()
+    {
+        $html = <<<HTML
+<ul><li>Item A</li><li>Item B</li></ul>
+HTML;
+        $expected = <<<TEXT
+Item A
+Item B
+TEXT;
+
+        $this->runTest($html, $expected);
+    }
+
+    public function test_inline_formats_dont_cause_newlines()
+    {
+        $html = <<<HTML
+<p><strong>H</strong><a>e</a><sup>l</sup><span>l</span><em>o</em></p>
+HTML;
+        $expected = <<<TEXT
+Hello
+TEXT;
+
+        $this->runTest($html, $expected);
+    }
+
+    protected function runTest(string $html, string $expected): void
+    {
+        $converter = new HtmlToPlainText();
+        $result = $converter->convert(trim($html));
+        $this->assertEquals(trim($expected), $result);
+    }
+}