Derive feed from HTML (#10)
- Prevent duplicate feed subscriptions - Move FeedItem to its own file
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@ -1,7 +1,7 @@
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<?php
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/** The current Feed Reader Central version */
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const FRC_VERSION = '1.0.0-alpha4';
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const FRC_VERSION = '1.0.0-alpha5';
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spl_autoload_register(function ($class) {
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$file = implode(DIRECTORY_SEPARATOR, [__DIR__, 'lib', "$class.php"]);
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203
src/lib/Feed.php
203
src/lib/Feed.php
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@ -1,84 +1,5 @@
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<?php
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/**
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* Information for a feed item
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*/
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class FeedItem {
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/** @var string The title of the feed item */
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public string $title = '';
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/** @var string The unique ID for the feed item */
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public string $guid = '';
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/** @var string The link to the original content */
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public string $link = '';
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/** @var string When this item was published */
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public string $publishedOn = '';
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/** @var ?string When this item was last updated */
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public ?string $updatedOn = null;
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/** @var string The content for the item */
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public string $content = '';
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/**
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* Construct a feed item from an Atom feed's `<entry>` tag
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*
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* @param DOMNode $node The XML node from which a feed item should be constructed
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* @return FeedItem A feed item constructed from the given node
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*/
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public static function fromAtom(DOMNode $node): FeedItem {
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$guid = Feed::atomValue($node, 'id');
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$link = '';
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foreach ($node->getElementsByTagName('link') as $linkElt) {
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if ($linkElt->hasAttributes()) {
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$relAttr = $linkElt->attributes->getNamedItem('rel');
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if ($relAttr && $relAttr->value == 'alternate') {
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$link = $linkElt->attributes->getNamedItem('href')->value;
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break;
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}
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}
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}
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if ($link == '' && str_starts_with($guid, 'http')) $link = $guid;
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$item = new FeedItem();
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$item->guid = $guid;
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$item->title = Feed::atomValue($node, 'title');
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$item->link = $link;
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$item->publishedOn = Data::formatDate(Feed::atomValue($node, 'published'));
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$item->updatedOn = Data::formatDate(Feed::atomValue($node, 'updated'));
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$item->content = Feed::atomValue($node, 'content');
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return $item;
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}
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/**
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* Construct a feed item from an RSS feed's `<item>` tag
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*
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* @param DOMNode $node The XML node from which a feed item should be constructed
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* @return FeedItem A feed item constructed from the given node
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*/
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public static function fromRSS(DOMNode $node): FeedItem {
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$itemGuid = Feed::rssValue($node, 'guid');
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$updNodes = $node->getElementsByTagNameNS(Feed::ATOM_NS, 'updated');
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$encNodes = $node->getElementsByTagNameNS(Feed::CONTENT_NS, 'encoded');
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$item = new FeedItem();
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$item->guid = $itemGuid == 'guid not found' ? Feed::rssValue($node, 'link') : $itemGuid;
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$item->title = Feed::rssValue($node, 'title');
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$item->link = Feed::rssValue($node, 'link');
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$item->publishedOn = Data::formatDate(Feed::rssValue($node, 'pubDate'));
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$item->updatedOn = Data::formatDate($updNodes->length > 0 ? $updNodes->item(0)->textContent : null);
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$item->content = $encNodes->length > 0
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? $encNodes->item(0)->textContent
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: Feed::rssValue($node, 'description');
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return $item;
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}
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}
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/**
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* Feed retrieval, parsing, and manipulation
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*/
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@ -114,7 +35,7 @@ class Feed {
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* @throws DOMException If the error is a warning
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*/
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private static function xmlParseError(int $errno, string $errstr): bool {
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if ($errno == E_WARNING && substr_count($errstr, 'DOMDocument::loadXml()') > 0) {
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if ($errno == E_WARNING && substr_count($errstr, 'DOMDocument::loadXML()') > 0) {
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throw new DOMException($errstr, $errno);
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}
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return false;
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@ -181,6 +102,17 @@ class Feed {
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return ['ok' => $feed];
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}
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/**
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* Get an attribute value from a DOM node
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*
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* @param DOMNode $node The node with an attribute value to obtain
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* @param string $name The name of the attribute whose value should be obtained
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* @return string The attribute value if it exists, an empty string if not
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*/
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private static function attrValue(DOMNode $node, string $name): string {
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return ($node->hasAttributes() ? $node->attributes->getNamedItem($name)?->value : null) ?? '';
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}
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/**
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* Get the value of a child element by its tag name for an Atom feed
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*
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@ -196,7 +128,7 @@ class Feed {
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if ($tags->length == 0) return "$tagName not found";
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$tag = $tags->item(0);
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if (!($tag instanceof DOMElement)) return $tag->textContent;
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if ($tag->hasAttributes() && $tag->attributes->getNamedItem('type') == 'xhtml') {
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if (self::attrValue($tag, 'type') == 'xhtml') {
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$div = $tag->getElementsByTagNameNS(Feed::XHTML_NS, 'div');
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if ($div->length == 0) return "-- invalid XHTML content --";
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return $div->item(0)->textContent;
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@ -225,6 +157,54 @@ class Feed {
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return ['ok' => $feed];
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}
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/**
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* Retrieve a document (http/https)
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*
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* @param string $url The URL of the document to retrieve
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* @return array ['content' => document content, 'error' => error message, 'code' => HTTP response code,
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* 'url' => effective URL]
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*/
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private static function retrieveDocument(string $url): array {
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$docReq = curl_init($url);
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curl_setopt($docReq, CURLOPT_FOLLOWLOCATION, true);
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curl_setopt($docReq, CURLOPT_RETURNTRANSFER, true);
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curl_setopt($docReq, CURLOPT_CONNECTTIMEOUT, 5);
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curl_setopt($docReq, CURLOPT_TIMEOUT, 15);
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$result = [
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'content' => curl_exec($docReq),
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'error' => curl_error($docReq),
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'code' => curl_getinfo($docReq, CURLINFO_RESPONSE_CODE),
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'url' => curl_getinfo($docReq, CURLINFO_EFFECTIVE_URL)
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];
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curl_close($docReq);
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return $result;
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}
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/**
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* Derive a feed URL from an HTML document
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*
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* @param string $content The HTML document content from which to derive a feed URL
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* @return array|string[] ['ok' => feed URL] if successful, ['error' => message] if not
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*/
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private static function deriveFeedFromHTML(string $content): array {
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$html = new DOMDocument();
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$html->loadHTML(substr($content, 0, strpos($content, '</head>') + 7));
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$headTags = $html->getElementsByTagName('head');
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if ($headTags->length < 1) return ['error' => 'Cannot find feed at this URL'];
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$head = $headTags->item(0);
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foreach ($head->getElementsByTagName('link') as $link) {
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if (self::attrValue($link, 'rel') == 'alternate') {
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$type = self::attrValue($link, 'type');
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if ($type == 'application/rss+xml' || $type == 'application/atom+xml') {
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return ['ok' => self::attrValue($link, 'href')];
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}
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}
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}
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return ['error' => 'Cannot find feed at this URL'];
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}
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/**
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* Retrieve the feed
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*
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@ -232,34 +212,33 @@ class Feed {
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* @return array|Feed[]|string[] ['ok' => feed] if successful, ['error' => message] if not
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*/
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public static function retrieveFeed(string $url): array {
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$feedReq = curl_init($url);
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curl_setopt($feedReq, CURLOPT_FOLLOWLOCATION, true);
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curl_setopt($feedReq, CURLOPT_RETURNTRANSFER, true);
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curl_setopt($feedReq, CURLOPT_CONNECTTIMEOUT, 5);
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curl_setopt($feedReq, CURLOPT_TIMEOUT, 15);
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$doc = self::retrieveDocument($url);
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$feedContent = curl_exec($feedReq);
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$result = array();
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$error = curl_error($feedReq);
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$code = curl_getinfo($feedReq, CURLINFO_RESPONSE_CODE);
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if ($error) {
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$result['error'] = $error;
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} elseif ($code == 200) {
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$parsed = self::parseFeed($feedContent);
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if (array_key_exists('error', $parsed)) {
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$result['error'] = $parsed['error'];
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} else {
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$extract = $parsed['ok']->getElementsByTagNameNS(self::ATOM_NS, 'feed')->length > 0
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? self::fromAtom(...) : self::fromRSS(...);
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$result = $extract($parsed['ok'], curl_getinfo($feedReq, CURLINFO_EFFECTIVE_URL));
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}
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} else {
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$result['error'] = "Prospective feed URL $url returned HTTP Code $code: $feedContent";
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if ($doc['error'] != '') return ['error' => $doc['error']];
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if ($doc['code'] != 200) {
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return ['error' => "Prospective feed URL $url returned HTTP Code {$doc['code']}: {$doc['content']}"];
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}
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curl_close($feedReq);
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return $result;
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$start = strtolower(strlen($doc['content']) >= 9 ? substr($doc['content'], 0, 9) : $doc['content']);
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if ($start == '<!doctype' || str_starts_with($start, '<html')) {
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$derivedURL = self::deriveFeedFromHTML($doc['content']);
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if (array_key_exists('error', $derivedURL)) return ['error' => $derivedURL['error']];
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$feedURL = $derivedURL['ok'];
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if (!str_starts_with($feedURL, 'http')) {
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// Relative URL; feed should be retrieved in the context of the original URL
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$original = parse_url($url);
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$port = array_key_exists('port', $original) ? ":{$original['port']}" : '';
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$feedURL = "{$original['scheme']}://{$original['host']}$port$feedURL";
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}
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$doc = self::retrieveDocument($feedURL);
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}
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$parsed = self::parseFeed($doc['content']);
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if (array_key_exists('error', $parsed)) return ['error' => $parsed['error']];
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$extract = $parsed['ok']->getElementsByTagNameNS(self::ATOM_NS, 'feed')->length > 0
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? self::fromAtom(...) : self::fromRSS(...);
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return $extract($parsed['ok'], $doc['url']);
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}
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/**
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@ -398,7 +377,17 @@ class Feed {
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$feedExtract = self::retrieveFeed($url);
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if (array_key_exists('error', $feedExtract)) return $feedExtract;
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$feed = $feedExtract['ok'];
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$feed = $feedExtract['ok'];
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$existsQuery = $db->prepare('SELECT COUNT(*) FROM feed WHERE user_id = :user AND url = :url');
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$existsQuery->bindValue(':user', $_SESSION[Key::USER_ID]);
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$existsQuery->bindValue(':url', $feed->url);
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$existsResult = $existsQuery->execute();
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if (!$existsResult) return ['error' => 'SQLite error: ' . $db->lastErrorMsg()];
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$exists = $existsResult->fetchArray(SQLITE3_NUM);
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if ($exists[0] != 0) return ['error' => "Already subscribed to feed $feed->url"];
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$query = $db->prepare(<<<'SQL'
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INSERT INTO feed (user_id, url, title, updated_on, checked_on)
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VALUES (:user, :url, :title, :updated, :checked)
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80
src/lib/FeedItem.php
Normal file
80
src/lib/FeedItem.php
Normal file
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@ -0,0 +1,80 @@
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<?php
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/**
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* Information for a feed item
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*/
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class FeedItem {
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/** @var string The title of the feed item */
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public string $title = '';
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/** @var string The unique ID for the feed item */
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public string $guid = '';
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/** @var string The link to the original content */
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public string $link = '';
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/** @var string When this item was published */
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public string $publishedOn = '';
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/** @var ?string When this item was last updated */
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public ?string $updatedOn = null;
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/** @var string The content for the item */
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public string $content = '';
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/**
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* Construct a feed item from an Atom feed's `<entry>` tag
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*
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* @param DOMNode $node The XML node from which a feed item should be constructed
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* @return FeedItem A feed item constructed from the given node
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*/
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public static function fromAtom(DOMNode $node): FeedItem {
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$guid = Feed::atomValue($node, 'id');
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$link = '';
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foreach ($node->getElementsByTagName('link') as $linkElt) {
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if ($linkElt->hasAttributes()) {
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$relAttr = $linkElt->attributes->getNamedItem('rel');
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if ($relAttr && $relAttr->value == 'alternate') {
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$link = $linkElt->attributes->getNamedItem('href')->value;
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break;
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}
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}
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}
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if ($link == '' && str_starts_with($guid, 'http')) $link = $guid;
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$item = new FeedItem();
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$item->guid = $guid;
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$item->title = Feed::atomValue($node, 'title');
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$item->link = $link;
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$item->publishedOn = Data::formatDate(Feed::atomValue($node, 'published'));
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$item->updatedOn = Data::formatDate(Feed::atomValue($node, 'updated'));
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$item->content = Feed::atomValue($node, 'content');
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return $item;
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}
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/**
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* Construct a feed item from an RSS feed's `<item>` tag
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*
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* @param DOMNode $node The XML node from which a feed item should be constructed
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* @return FeedItem A feed item constructed from the given node
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*/
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public static function fromRSS(DOMNode $node): FeedItem {
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$itemGuid = Feed::rssValue($node, 'guid');
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$updNodes = $node->getElementsByTagNameNS(Feed::ATOM_NS, 'updated');
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$encNodes = $node->getElementsByTagNameNS(Feed::CONTENT_NS, 'encoded');
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$item = new FeedItem();
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$item->guid = $itemGuid == 'guid not found' ? Feed::rssValue($node, 'link') : $itemGuid;
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$item->title = Feed::rssValue($node, 'title');
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$item->link = Feed::rssValue($node, 'link');
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$item->publishedOn = Data::formatDate(Feed::rssValue($node, 'pubDate'));
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$item->updatedOn = Data::formatDate($updNodes->length > 0 ? $updNodes->item(0)->textContent : null);
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$item->content = $encNodes->length > 0
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? $encNodes->item(0)->textContent
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: Feed::rssValue($node, 'description');
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return $item;
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}
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}
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