400 lines
		
	
	
		
			13 KiB
		
	
	
	
		
			PHP
		
	
	
	
			
		
		
	
	
			400 lines
		
	
	
		
			13 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\Users\Models\User;
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use BookStack\Util\HtmlContentFilter;
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use BookStack\Util\HtmlDocument;
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use BookStack\Util\WebSafeMimeSniffer;
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use Closure;
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use DOMElement;
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use DOMNode;
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use DOMNodeList;
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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, User $updater): void
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    {
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        $html = $this->extractBase64ImagesFromHtml($html, $updater);
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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, User $updater): void
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    {
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        $markdown = $this->extractBase64ImagesFromMarkdown($markdown, $updater);
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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, User $updater): string
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    {
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        if (empty($htmlText) || !str_contains($htmlText, 'data:image')) {
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            return $htmlText;
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        }
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        $doc = new HtmlDocument($htmlText);
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        // Get all img elements with image data blobs
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        $imageNodes = $doc->queryXPath('//img[contains(@src, \'data:image\')]');
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        foreach ($imageNodes as $imageNode) {
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            $imageSrc = $imageNode->getAttribute('src');
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            $newUrl = $this->base64ImageUriToUploadedImageUrl($imageSrc, $updater);
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            $imageNode->setAttribute('src', $newUrl);
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        }
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        return $doc->getBodyInnerHtml();
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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, User $updater): 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, $updater);
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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, User $updater): 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 user has permission to create images
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        if (!$updater->can('image-create-all')) {
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            return '';
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        }
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        // Validate extension and content
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        if (empty($imageInfo['data']) || !ImageService::isExtensionSupported($imageInfo['extension'])) {
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            return '';
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        }
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        // Validate content looks like an image via sniffing mime type
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        $mimeSniffer = new WebSafeMimeSniffer();
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        $mime = $mimeSniffer->sniff($imageInfo['data']);
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        if (!str_starts_with($mime, 'image/')) {
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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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        $doc = new HtmlDocument($htmlText);
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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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        $this->updateIdsRecursively($doc->getBody(), 0, $idMap, $changeMap);
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        $this->updateLinks($doc, $changeMap);
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        // Generate inner html as a string & perform required string-level tweaks
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        $html = $doc->getBodyInnerHtml();
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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(HtmlDocument $doc, 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 = $doc->queryXPath('//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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        $html = $this->page->html ?? '';
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        if (empty($html)) {
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            return $html;
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        }
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        $doc = new HtmlDocument($html);
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        $contentProvider = $this->getContentProviderClosure($blankIncludes);
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        $parser = new PageIncludeParser($doc, $contentProvider);
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        $nodesAdded = 1;
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        for ($includeDepth = 0; $includeDepth < 3 && $nodesAdded !== 0; $includeDepth++) {
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            $nodesAdded = $parser->parse();
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        }
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        if ($includeDepth > 1) {
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            $idMap = [];
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            $changeMap = [];
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            $this->updateIdsRecursively($doc->getBody(), 0, $idMap, $changeMap);
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        }
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        if (!config('app.allow_content_scripts')) {
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            HtmlContentFilter::removeScriptsFromDocument($doc);
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        }
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        return $doc->getBodyInnerHtml();
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    }
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    /**
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     * Get the closure used to fetch content for page includes.
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     */
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    protected function getContentProviderClosure(bool $blankIncludes): Closure
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    {
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        $contextPage = $this->page;
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        return function (PageIncludeTag $tag) use ($blankIncludes, $contextPage): PageIncludeContent {
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            if ($blankIncludes) {
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                return PageIncludeContent::fromHtmlAndTag('', $tag);
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            }
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            $matchedPage = Page::visible()->find($tag->getPageId());
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            $content = PageIncludeContent::fromHtmlAndTag($matchedPage->html ?? '', $tag);
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            if (Theme::hasListeners(ThemeEvents::PAGE_INCLUDE_PARSE)) {
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                $themeReplacement = Theme::dispatch(
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                    ThemeEvents::PAGE_INCLUDE_PARSE,
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                    $tag->tagContent,
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                    $content->toHtml(),
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                    clone $contextPage,
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                    $matchedPage ? (clone $matchedPage) : null,
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                );
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                if ($themeReplacement !== null) {
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                    $content = PageIncludeContent::fromInlineHtml(strval($themeReplacement));
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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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    /**
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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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        $doc = new HtmlDocument($htmlContent);
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        $headers = $doc->queryXPath('//h1|//h2|//h3|//h4|//h5|//h6');
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        return $headers->count() === 0 ? [] : $this->headerNodesToLevelList($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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