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https://github.com/BookStackApp/BookStack.git
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460 lines
15 KiB
PHP
460 lines
15 KiB
PHP
<?php
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namespace BookStack\Entities\Tools;
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use BookStack\Entities\Models\Page;
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use BookStack\Entities\Tools\Markdown\MarkdownToHtml;
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use BookStack\Exceptions\ImageUploadException;
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use BookStack\Facades\Theme;
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use BookStack\Theming\ThemeEvents;
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use BookStack\Uploads\ImageRepo;
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use BookStack\Uploads\ImageService;
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use BookStack\Util\HtmlContentFilter;
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use DOMDocument;
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use DOMElement;
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use DOMNode;
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use DOMNodeList;
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use DOMXPath;
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use Illuminate\Support\Str;
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class PageContent
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{
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public function __construct(
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protected Page $page
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) {
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}
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/**
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* Update the content of the page with new provided HTML.
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*/
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public function setNewHTML(string $html): void
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{
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$html = $this->extractBase64ImagesFromHtml($html);
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$this->page->html = $this->formatHtml($html);
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$this->page->text = $this->toPlainText();
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$this->page->markdown = '';
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}
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/**
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* Update the content of the page with new provided Markdown content.
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*/
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public function setNewMarkdown(string $markdown): void
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{
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$markdown = $this->extractBase64ImagesFromMarkdown($markdown);
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$this->page->markdown = $markdown;
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$html = (new MarkdownToHtml($markdown))->convert();
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$this->page->html = $this->formatHtml($html);
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$this->page->text = $this->toPlainText();
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}
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/**
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* Convert all base64 image data to saved images.
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*/
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protected function extractBase64ImagesFromHtml(string $htmlText): string
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{
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if (empty($htmlText) || !str_contains($htmlText, 'data:image')) {
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return $htmlText;
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}
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$doc = $this->loadDocumentFromHtml($htmlText);
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$container = $doc->documentElement;
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$body = $container->childNodes->item(0);
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$childNodes = $body->childNodes;
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$xPath = new DOMXPath($doc);
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// Get all img elements with image data blobs
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$imageNodes = $xPath->query('//img[contains(@src, \'data:image\')]');
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foreach ($imageNodes as $imageNode) {
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$imageSrc = $imageNode->getAttribute('src');
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$newUrl = $this->base64ImageUriToUploadedImageUrl($imageSrc);
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$imageNode->setAttribute('src', $newUrl);
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}
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// Generate inner html as a string
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$html = '';
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foreach ($childNodes as $childNode) {
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$html .= $doc->saveHTML($childNode);
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}
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return $html;
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}
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/**
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* Convert all inline base64 content to uploaded image files.
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* Regex is used to locate the start of data-uri definitions then
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* manual looping over content is done to parse the whole data uri.
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* Attempting to capture the whole data uri using regex can cause PHP
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* PCRE limits to be hit with larger, multi-MB, files.
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*/
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protected function extractBase64ImagesFromMarkdown(string $markdown): string
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{
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$matches = [];
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$contentLength = strlen($markdown);
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$replacements = [];
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preg_match_all('/!\[.*?]\(.*?(data:image\/.{1,6};base64,)/', $markdown, $matches, PREG_OFFSET_CAPTURE);
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foreach ($matches[1] as $base64MatchPair) {
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[$dataUri, $index] = $base64MatchPair;
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for ($i = strlen($dataUri) + $index; $i < $contentLength; $i++) {
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$char = $markdown[$i];
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if ($char === ')' || $char === ' ' || $char === "\n" || $char === '"') {
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break;
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}
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$dataUri .= $char;
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}
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$newUrl = $this->base64ImageUriToUploadedImageUrl($dataUri);
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$replacements[] = [$dataUri, $newUrl];
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}
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foreach ($replacements as [$dataUri, $newUrl]) {
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$markdown = str_replace($dataUri, $newUrl, $markdown);
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}
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return $markdown;
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}
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/**
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* Parse the given base64 image URI and return the URL to the created image instance.
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* Returns an empty string if the parsed URI is invalid or causes an error upon upload.
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*/
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protected function base64ImageUriToUploadedImageUrl(string $uri): string
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{
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$imageRepo = app()->make(ImageRepo::class);
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$imageInfo = $this->parseBase64ImageUri($uri);
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// Validate extension and content
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if (empty($imageInfo['data']) || !ImageService::isExtensionSupported($imageInfo['extension'])) {
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return '';
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}
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// Validate that the content is not over our upload limit
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$uploadLimitBytes = (config('app.upload_limit') * 1000000);
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if (strlen($imageInfo['data']) > $uploadLimitBytes) {
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return '';
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}
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// Save image from data with a random name
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$imageName = 'embedded-image-' . Str::random(8) . '.' . $imageInfo['extension'];
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try {
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$image = $imageRepo->saveNewFromData($imageName, $imageInfo['data'], 'gallery', $this->page->id);
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} catch (ImageUploadException $exception) {
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return '';
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}
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return $image->url;
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}
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/**
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* Parse a base64 image URI into the data and extension.
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*
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* @return array{extension: string, data: string}
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*/
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protected function parseBase64ImageUri(string $uri): array
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{
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[$dataDefinition, $base64ImageData] = explode(',', $uri, 2);
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$extension = strtolower(preg_split('/[\/;]/', $dataDefinition)[1] ?? '');
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return [
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'extension' => $extension,
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'data' => base64_decode($base64ImageData) ?: '',
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];
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}
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/**
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* Formats a page's html to be tagged correctly within the system.
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*/
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protected function formatHtml(string $htmlText): string
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{
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if (empty($htmlText)) {
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return $htmlText;
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}
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$doc = $this->loadDocumentFromHtml($htmlText);
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$container = $doc->documentElement;
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$body = $container->childNodes->item(0);
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$childNodes = $body->childNodes;
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$xPath = new DOMXPath($doc);
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// Map to hold used ID references
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$idMap = [];
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// Map to hold changing ID references
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$changeMap = [];
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$this->updateIdsRecursively($body, 0, $idMap, $changeMap);
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$this->updateLinks($xPath, $changeMap);
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// Generate inner html as a string
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$html = '';
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foreach ($childNodes as $childNode) {
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$html .= $doc->saveHTML($childNode);
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}
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// Perform required string-level tweaks
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$html = str_replace(' ', ' ', $html);
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return $html;
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}
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/**
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* For the given DOMNode, traverse its children recursively and update IDs
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* where required (Top-level, headers & elements with IDs).
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* Will update the provided $changeMap array with changes made, where keys are the old
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* ids and the corresponding values are the new ids.
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*/
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protected function updateIdsRecursively(DOMNode $element, int $depth, array &$idMap, array &$changeMap): void
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{
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/* @var DOMNode $child */
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foreach ($element->childNodes as $child) {
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if ($child instanceof DOMElement && ($depth === 0 || in_array($child->nodeName, ['h1', 'h2', 'h3', 'h4', 'h5', 'h6']) || $child->getAttribute('id'))) {
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[$oldId, $newId] = $this->setUniqueId($child, $idMap);
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if ($newId && $newId !== $oldId && !isset($idMap[$oldId])) {
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$changeMap[$oldId] = $newId;
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}
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}
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if ($child->hasChildNodes()) {
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$this->updateIdsRecursively($child, $depth + 1, $idMap, $changeMap);
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}
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}
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}
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/**
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* Update the all links in the given xpath to apply requires changes within the
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* given $changeMap array.
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*/
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protected function updateLinks(DOMXPath $xpath, array $changeMap): void
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{
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if (empty($changeMap)) {
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return;
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}
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$links = $xpath->query('//body//*//*[@href]');
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/** @var DOMElement $domElem */
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foreach ($links as $domElem) {
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$href = ltrim($domElem->getAttribute('href'), '#');
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$newHref = $changeMap[$href] ?? null;
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if ($newHref) {
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$domElem->setAttribute('href', '#' . $newHref);
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}
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}
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}
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/**
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* Set a unique id on the given DOMElement.
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* A map for existing ID's should be passed in to check for current existence,
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* and this will be updated with any new IDs set upon elements.
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* Returns a pair of strings in the format [old_id, new_id].
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*/
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protected function setUniqueId(DOMNode $element, array &$idMap): array
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{
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if (!$element instanceof DOMElement) {
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return ['', ''];
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}
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// Stop if there's an existing valid id that has not already been used.
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$existingId = $element->getAttribute('id');
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if (str_starts_with($existingId, 'bkmrk') && !isset($idMap[$existingId])) {
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$idMap[$existingId] = true;
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return [$existingId, $existingId];
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}
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// Create a unique id for the element
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// Uses the content as a basis to ensure output is the same every time
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// the same content is passed through.
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$contentId = 'bkmrk-' . mb_substr(strtolower(preg_replace('/\s+/', '-', trim($element->nodeValue))), 0, 20);
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$newId = urlencode($contentId);
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$loopIndex = 1;
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while (isset($idMap[$newId])) {
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$newId = urlencode($contentId . '-' . $loopIndex);
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$loopIndex++;
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}
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$element->setAttribute('id', $newId);
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$idMap[$newId] = true;
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return [$existingId, $newId];
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}
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/**
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* Get a plain-text visualisation of this page.
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*/
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protected function toPlainText(): string
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{
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$html = $this->render(true);
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return html_entity_decode(strip_tags($html));
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}
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/**
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* Render the page for viewing.
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*/
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public function render(bool $blankIncludes = false): string
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{
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$content = $this->page->html ?? '';
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if (!config('app.allow_content_scripts')) {
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$content = HtmlContentFilter::removeScripts($content);
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}
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if ($blankIncludes) {
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$content = $this->blankPageIncludes($content);
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} else {
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for ($includeDepth = 0; $includeDepth < 3; $includeDepth++) {
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$content = $this->parsePageIncludes($content);
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}
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}
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return $content;
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}
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/**
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* Parse the headers on the page to get a navigation menu.
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*/
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public function getNavigation(string $htmlContent): array
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{
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if (empty($htmlContent)) {
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return [];
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}
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$doc = $this->loadDocumentFromHtml($htmlContent);
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$xPath = new DOMXPath($doc);
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$headers = $xPath->query('//h1|//h2|//h3|//h4|//h5|//h6');
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return $headers ? $this->headerNodesToLevelList($headers) : [];
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}
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/**
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* Convert a DOMNodeList into an array of readable header attributes
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* with levels normalised to the lower header level.
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*/
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protected function headerNodesToLevelList(DOMNodeList $nodeList): array
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{
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$tree = collect($nodeList)->map(function (DOMElement $header) {
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$text = trim(str_replace("\xc2\xa0", '', $header->nodeValue));
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$text = mb_substr($text, 0, 100);
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return [
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'nodeName' => strtolower($header->nodeName),
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'level' => intval(str_replace('h', '', $header->nodeName)),
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'link' => '#' . $header->getAttribute('id'),
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'text' => $text,
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];
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})->filter(function ($header) {
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return mb_strlen($header['text']) > 0;
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});
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// Shift headers if only smaller headers have been used
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$levelChange = ($tree->pluck('level')->min() - 1);
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$tree = $tree->map(function ($header) use ($levelChange) {
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$header['level'] -= ($levelChange);
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return $header;
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});
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return $tree->toArray();
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}
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/**
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* Remove any page include tags within the given HTML.
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*/
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protected function blankPageIncludes(string $html): string
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{
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return preg_replace("/{{@\s?([0-9].*?)}}/", '', $html);
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}
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/**
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* Parse any include tags "{{@<page_id>#section}}" to be part of the page.
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*/
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protected function parsePageIncludes(string $html): string
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{
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$matches = [];
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preg_match_all("/{{@\s?([0-9].*?)}}/", $html, $matches);
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foreach ($matches[1] as $index => $includeId) {
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$fullMatch = $matches[0][$index];
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$splitInclude = explode('#', $includeId, 2);
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// Get page id from reference
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$pageId = intval($splitInclude[0]);
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if (is_nan($pageId)) {
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continue;
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}
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// Find page to use, and default replacement to empty string for non-matches.
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/** @var ?Page $matchedPage */
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$matchedPage = Page::visible()->find($pageId);
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$replacement = '';
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if ($matchedPage && count($splitInclude) === 1) {
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// If we only have page id, just insert all page html and continue.
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$replacement = $matchedPage->html;
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} elseif ($matchedPage && count($splitInclude) > 1) {
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// Otherwise, if our include tag defines a section, load that specific content
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$innerContent = $this->fetchSectionOfPage($matchedPage, $splitInclude[1]);
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$replacement = trim($innerContent);
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}
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$themeReplacement = Theme::dispatch(
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ThemeEvents::PAGE_INCLUDE_PARSE,
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$includeId,
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$replacement,
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clone $this->page,
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$matchedPage ? (clone $matchedPage) : null,
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);
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// Perform the content replacement
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$html = str_replace($fullMatch, $themeReplacement ?? $replacement, $html);
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}
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return $html;
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}
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/**
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* Fetch the content from a specific section of the given page.
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*/
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protected function fetchSectionOfPage(Page $page, string $sectionId): string
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{
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$topLevelTags = ['table', 'ul', 'ol', 'pre'];
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$doc = $this->loadDocumentFromHtml($page->html);
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// Search included content for the id given and blank out if not exists.
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$matchingElem = $doc->getElementById($sectionId);
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if ($matchingElem === null) {
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return '';
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}
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// Otherwise replace the content with the found content
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// Checks if the top-level wrapper should be included by matching on tag types
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$innerContent = '';
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$isTopLevel = in_array(strtolower($matchingElem->nodeName), $topLevelTags);
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if ($isTopLevel) {
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$innerContent .= $doc->saveHTML($matchingElem);
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} else {
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foreach ($matchingElem->childNodes as $childNode) {
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$innerContent .= $doc->saveHTML($childNode);
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}
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}
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libxml_clear_errors();
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return $innerContent;
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}
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/**
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* Create and load a DOMDocument from the given html content.
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*/
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protected function loadDocumentFromHtml(string $html): DOMDocument
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{
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libxml_use_internal_errors(true);
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$doc = new DOMDocument();
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$html = '<?xml encoding="utf-8" ?><body>' . $html . '</body>';
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$doc->loadHTML($html);
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return $doc;
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}
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}
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