mirror of
https://github.com/RSS-Bridge/rss-bridge.git
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257 lines
9 KiB
PHP
257 lines
9 KiB
PHP
<?php
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/**
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* This file is part of RSS-Bridge, a PHP project capable of generating RSS and
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* Atom feeds for websites that don't have one.
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*
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* For the full license information, please view the UNLICENSE file distributed
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* with this source code.
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*
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* @package Core
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* @license http://unlicense.org/ UNLICENSE
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* @link https://github.com/rss-bridge/rss-bridge
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*/
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/**
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* Removes unwanted tags from a given HTML text.
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*
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* @param string $textToSanitize The HTML text to sanitize.
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* @param array $removedTags A list of tags to remove from the DOM.
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* @param array $keptAttributes A list of attributes to keep on tags (other
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* attributes are removed).
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* @param array $keptText A list of tags where the innertext replaces the tag
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* (i.e. `<p>Hello World!</p>` becomes `Hello World!`).
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* @return object A simplehtmldom object of the remaining contents.
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*
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* @todo Check if this implementation is still necessary, because simplehtmldom
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* already removes some of the tags (search for `remove_noise` in simple_html_dom.php).
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* @todo Rename parameters to make more sense. `$textToSanitize` must be HTML,
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* `$removedTags`, `$keptAttributes` and `$keptText` are past tense.
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* @todo Clarify the meaning of `*[!b38fd2b1fe7f4747d6b1c1254ccd055e]`, which
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* looks like a SHA1 hash (does simplehtmldom not support `find('*')`?).
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*/
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function sanitize($textToSanitize,
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$removedTags = array('script', 'iframe', 'input', 'form'),
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$keptAttributes = array('title', 'href', 'src'),
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$keptText = array()){
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$htmlContent = str_get_html($textToSanitize);
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foreach($htmlContent->find('*[!b38fd2b1fe7f4747d6b1c1254ccd055e]') as $element) {
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if(in_array($element->tag, $keptText)) {
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$element->outertext = $element->plaintext;
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} elseif(in_array($element->tag, $removedTags)) {
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$element->outertext = '';
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} else {
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foreach($element->getAllAttributes() as $attributeName => $attribute) {
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if(!in_array($attributeName, $keptAttributes))
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$element->removeAttribute($attributeName);
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}
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}
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}
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return $htmlContent;
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}
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/**
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* Replace background by image
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*
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* Replaces tags with styles of `backgroud-image` by `<img />` tags.
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*
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* For example:
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*
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* ```HTML
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* <html>
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* <body style="background-image: url('bgimage.jpg');">
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* <h1>Hello world!</h1>
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* </body>
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* </html>
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* ```
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*
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* results in this output:
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*
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* ```HTML
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* <html>
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* <img style="display:block;" src="bgimage.jpg" />
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* </html>
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* ```
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*
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* @param string $htmlContent The HTML content
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* @return string The HTML content with all ocurrences replaced
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*
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* @todo Clarify the meaning of `*[!b38fd2b1fe7f4747d6b1c1254ccd055e]`, which
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* looks like a SHA1 hash (does simplehtmldom not support `find('*')`?).
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*/
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function backgroundToImg($htmlContent) {
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$regex = '/background-image[ ]{0,}:[ ]{0,}url\([\'"]{0,}(.*?)[\'"]{0,}\)/';
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$htmlContent = str_get_html($htmlContent);
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foreach($htmlContent->find('*[!b38fd2b1fe7f4747d6b1c1254ccd055e]') as $element) {
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if(preg_match($regex, $element->style, $matches) > 0) {
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$element->outertext = '<img style="display:block;" src="' . $matches[1] . '" />';
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}
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}
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return $htmlContent;
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}
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/**
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* Convert relative links in HTML into absolute links
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*
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* This function is based on `php-urljoin`.
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*
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* @link https://github.com/plaidfluff/php-urljoin php-urljoin
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*
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* @param string|object $content The HTML content. Supports HTML objects or string objects
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* @param string $server Fully qualified URL to the page containing relative links
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* @return object Content with fixed URLs.
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*
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* @todo If the input type was a string, this function should return a string as
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* well. This is currently done implicitly by how the simplehtmldom object works.
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*/
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function defaultLinkTo($content, $server){
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$string_convert = false;
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if (is_string($content)) {
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$string_convert = true;
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$content = str_get_html($content);
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}
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foreach($content->find('img') as $image) {
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$image->src = urljoin($server, $image->src);
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}
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foreach($content->find('a') as $anchor) {
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$anchor->href = urljoin($server, $anchor->href);
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}
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if ($string_convert) {
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$content = $content->outertext;
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}
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return $content;
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}
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/**
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* Extract the first part of a string matching the specified start and end delimiters
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*
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* @param string $string Input string, e.g. `<div>Post author: John Doe</div>`
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* @param string $start Start delimiter, e.g. `author: `
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* @param string $end End delimiter, e.g. `<`
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* @return string|bool Extracted string, e.g. `John Doe`, or false if the
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* delimiters were not found.
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*
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* @todo This function can possibly be simplified to use a single `substr` command.
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*/
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function extractFromDelimiters($string, $start, $end) {
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if (strpos($string, $start) !== false) {
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$section_retrieved = substr($string, strpos($string, $start) + strlen($start));
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$section_retrieved = substr($section_retrieved, 0, strpos($section_retrieved, $end));
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return $section_retrieved;
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} return false;
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}
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/**
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* Remove one or more part(s) of a string using a start and end delmiters
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*
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* @param string $string Input string, e.g. `foo<script>superscript()</script>bar`
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* @param string $start Start delimiter, e.g. `<script`
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* @param string $end End delimiter, e.g. `</script>`
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* @return string Cleaned string, e.g. `foobar`
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*
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* @todo This function can possibly be simplified to use a single `substr` command.
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*/
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function stripWithDelimiters($string, $start, $end) {
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while(strpos($string, $start) !== false) {
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$section_to_remove = substr($string, strpos($string, $start));
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$section_to_remove = substr($section_to_remove, 0, strpos($section_to_remove, $end) + strlen($end));
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$string = str_replace($section_to_remove, '', $string);
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}
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return $string;
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}
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/**
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* Remove HTML sections containing one or more sections using the same HTML tag
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*
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* @param string $string Input string, e.g. `foo<div class="ads"><div>ads</div>ads</div>bar`
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* @param string $tag_name Name of the HTML tag, e.g. `div`
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* @param string $tag_start Start of the HTML tag to remove, e.g. `<div class="ads">`
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* @return string Cleaned String, e.g. `foobar`
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*
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* @todo This function needs more documentation to make it maintainable.
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*/
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function stripRecursiveHTMLSection($string, $tag_name, $tag_start){
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$open_tag = '<' . $tag_name;
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$close_tag = '</' . $tag_name . '>';
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$close_tag_length = strlen($close_tag);
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if(strpos($tag_start, $open_tag) === 0) {
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while(strpos($string, $tag_start) !== false) {
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$max_recursion = 100;
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$section_to_remove = null;
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$section_start = strpos($string, $tag_start);
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$search_offset = $section_start;
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do {
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$max_recursion--;
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$section_end = strpos($string, $close_tag, $search_offset);
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$search_offset = $section_end + $close_tag_length;
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$section_to_remove = substr($string, $section_start, $section_end - $section_start + $close_tag_length);
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$open_tag_count = substr_count($section_to_remove, $open_tag);
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$close_tag_count = substr_count($section_to_remove, $close_tag);
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} while ($open_tag_count > $close_tag_count && $max_recursion > 0);
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$string = str_replace($section_to_remove, '', $string);
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}
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}
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return $string;
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}
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/**
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* Convert Markdown into HTML. Only a subset of the Markdown syntax is implemented.
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*
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* @link https://daringfireball.net/projects/markdown/ Markdown
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* @link https://github.github.com/gfm/ GitHub Flavored Markdown Spec
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*
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* @param string $string Input string in Markdown format
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* @return string output string in HTML format
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*/
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function markdownToHtml($string) {
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//For more details about how these regex work:
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// https://github.com/RSS-Bridge/rss-bridge/pull/802#discussion_r216138702
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// Images: https://regex101.com/r/JW9Evr/1
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// Links: https://regex101.com/r/eRGVe7/1
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// Bold: https://regex101.com/r/2p40Y0/1
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// Italic: https://regex101.com/r/xJkET9/1
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// Separator: https://regex101.com/r/ZBEqFP/1
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// Plain URL: https://regex101.com/r/2JHYwb/1
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// Site name: https://regex101.com/r/qIuKYE/1
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$string = preg_replace('/\!\[([^\]]+)\]\(([^\) ]+)(?: [^\)]+)?\)/', '<img src="$2" alt="$1" />', $string);
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$string = preg_replace('/\[([^\]]+)\]\(([^\)]+)\)/', '<a href="$2">$1</a>', $string);
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$string = preg_replace('/\*\*(.*)\*\*/U', '<b>$1</b>', $string);
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$string = preg_replace('/\*(.*)\*/U', '<i>$1</i>', $string);
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$string = preg_replace('/__(.*)__/U', '<b>$1</b>', $string);
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$string = preg_replace('/_(.*)_/U', '<i>$1</i>', $string);
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$string = preg_replace('/[-]{6,99}/', '<hr />', $string);
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$string = str_replace(' ', '<br />', $string);
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$string = preg_replace('/([^"])(https?:\/\/[^ "<]+)([^"])/', '$1<a href="$2">$2</a>$3', $string . ' ');
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$string = preg_replace('/([^"\/])(www\.[^ "<]+)([^"])/', '$1<a href="http://$2">$2</a>$3', $string . ' ');
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//As the regex are not perfect, we need to fix <i> and </i> that are introduced in URLs
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// Fixup regex <i>: https://regex101.com/r/NTRPf6/1
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// Fixup regex </i>: https://regex101.com/r/aNklRp/1
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$count = 1;
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while($count > 0) {
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$string = preg_replace('/ (src|href)="([^"]+)<i>([^"]+)"/U', ' $1="$2_$3"', $string, -1, $count);
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}
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$count = 1;
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while($count > 0) {
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$string = preg_replace('/ (src|href)="([^"]+)<\/i>([^"]+)"/U', ' $1="$2_$3"', $string, -1, $count);
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}
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return '<div>' . trim($string) . '</div>';
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}
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