mirror of
https://code.mensbeam.com/MensBeam/Arsse.git
synced 2024-12-22 13:12:41 +00:00
358 lines
No EOL
17 KiB
PHP
358 lines
No EOL
17 KiB
PHP
<?php
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declare(strict_types=1);
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namespace JKingWeb\Arsse;
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use PicoFeed\Reader\Reader;
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use PicoFeed\PicoFeedException;
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use PicoFeed\Reader\Favicon;
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use PicoFeed\Config\Config;
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class Feed {
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public $data = null;
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public $favicon;
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public $parser;
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public $reader;
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public $resource;
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public $modified = false;
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public $lastModified;
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public $nextFetch;
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public $newItems = [];
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public $changedItems = [];
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public function __construct(int $feedID = null, string $url, string $lastModified = '', string $etag = '', string $username = '', string $password = '') {
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// fetch the feed
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$this->download($url, $lastModified, $etag, $username, $password);
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// format the HTTP Last-Modified date returned
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$lastMod = $this->resource->getLastModified();
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if(strlen($lastMod)) {
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$this->lastModified = \DateTime::createFromFormat("!D, d M Y H:i:s e", $lastMod);
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}
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$this->modified = $this->resource->isModified();
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//parse the feed, if it has been modified
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if($this->modified) {
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$this->parse();
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// ascertain whether there are any articles not in the database
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$this->matchToDatabase($feedID);
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// if caching header fields are not sent by the server, try to ascertain a last-modified date from the feed contents
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if(!$this->lastModified) $this->lastModified = $this->computeLastModified();
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// we only really care if articles have been modified; if there are no new articles, act as if the feed is unchanged
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if(!sizeof($this->newItems) && !sizeof($this->changedItems)) $this->modified = false;
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}
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// compute the time at which the feed should next be fetched
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$this->nextFetch = $this->computeNextFetch();
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}
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public function download(string $url, string $lastModified = '', string $etag = '', string $username = '', string $password = ''): bool {
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try {
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$config = new Config;
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$config->setClientUserAgent(Data::$conf->userAgentString);
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$config->setGrabberUserAgent(Data::$conf->userAgentString);
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$this->reader = new Reader($config);
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$this->resource = $this->reader->download($url, $lastModified, $etag, $username, $password);
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} catch (PicoFeedException $e) {
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throw new Feed\Exception($url, $e);
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}
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return true;
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}
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public function parse(): bool {
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try {
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$this->parser = $this->reader->getParser(
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$this->resource->getUrl(),
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$this->resource->getContent(),
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$this->resource->getEncoding()
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);
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$feed = $this->parser->execute();
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// Grab the favicon for the feed; returns an empty string if it cannot find one.
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// Some feeds might use a different domain (eg: feedburner), so the site url is
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// used instead of the feed's url.
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$this->favicon = (new Favicon)->find($feed->siteUrl);
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} catch (PicoFeedException $e) {
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throw new Feed\Exception($this->resource->getUrl(), $e);
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}
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// PicoFeed does not provide valid ids when there is no id element. Its solution
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// of hashing the url, title, and content together for the id if there is no id
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// element is stupid. Many feeds are frankenstein mixtures of Atom and RSS, but
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// some are pure RSS with guid elements while others use the Dublin Core spec for
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// identification. These feeds shouldn't be duplicated when updated. That should
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// only be reserved for severely broken feeds.
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foreach ($feed->items as $f) {
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// Hashes used for comparison to check for updates and also to identify when an
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// id doesn't exist.
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$content = $f->content.$f->enclosureUrl.$f->enclosureType;
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// if the item link URL and item title are both equal to the feed link URL, then the item has neither a link URL nor a title
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if($f->url==$feed->siteUrl && $f->title==$feed->siteUrl) {
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$f->urlTitleHash = "";
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} else {
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$f->urlTitleHash = hash('sha256', $f->url.$f->title);
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}
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// if the item link URL is equal to the feed link URL, it has no link URL; if there is additionally no content, these should not be hashed
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if(!strlen($content) && $f->url==$feed->siteUrl) {
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$f->urlContentHash = "";
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} else {
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$f->urlContentHash = hash('sha256', $f->url.$content);
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}
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// if the item's title is the same as its link URL, it has no title; if there is additionally no content, these should not be hashed
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if(!strlen($content) && $f->title==$f->url) {
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$f->titleContentHash = "";
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} else {
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$f->titleContentHash = hash('sha256', $f->title.$content);
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}
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// If there is an id element then continue. The id is used already.
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$id = (string)$f->xml->id;
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if ($id !== '') {
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continue;
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}
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// If there is a guid element use it as the id.
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$id = (string)$f->xml->guid;
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if ($id !== '') {
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$f->id = hash('sha256', $id);
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continue;
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}
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// If there is a Dublin Core identifier use it.
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$id = (string)$f->xml->children('http://purl.org/dc/elements/1.1/')->identifier;
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if ($id !== '') {
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$f->id = hash('sha256', $id);
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continue;
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}
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// If there aren't any of those there is no id.
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$f->id = '';
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}
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$this->data = $feed;
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return true;
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}
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protected function deduplicateItems(array $items): array {
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/* Rationale:
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Some newsfeeds (notably Planet) include multiple versions of an
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item if it is updated. As we only care about the latest, we
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try to remove any "old" versions of an item that might also be
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present within the feed.
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*/
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$out = [];
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foreach($items as $item) {
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foreach($out as $index => $check) {
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// if the two items both have IDs and they differ, they do not match, regardless of hashes
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if($item->id && $check->id && $item->id != $check->id) continue;
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// if the two items have the same ID or any one hash matches, they are two versions of the same item
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if(
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($item->id && $check->id && $item->id == $check->id) ||
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($item->urlTitleHash && $item->urlTitleHash == $check->urlTitleHash) ||
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($item->urlContentHash && $item->urlContentHash == $check->urlContentHash) ||
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($item->titleContentHash && $item->titleContentHash == $check->titleContentHash)
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) {
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if(// because newsfeeds are usually order newest-first, the later item should only be used if...
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// the later item has an update date and the existing item does not
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($item->updatedDate && !$check->updatedDate) ||
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// the later item has an update date newer than the existing item's
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($item->updatedDate && $check->updatedDate && $item->updatedDate->getTimestamp() > $check->updatedDate->getTimestamp()) ||
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// neither item has update dates, both have publish dates, and the later item has a newer publish date
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(!$item->updatedDate && !$check->updatedDate && $item->publishedDate && $check->publishedDate && $item->publishedDate->getTimestamp() > $check->publishedDate->getTimestamp())
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) {
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// if the later item should be used, replace the existing one
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$out[$index] = $item;
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continue 2;
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} else {
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// otherwise skip the item
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continue 2;
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}
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}
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}
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// if there was no match, add the item
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$out[] = $item;
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}
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return $out;
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}
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public function matchToDatabase(int $feedID = null): bool {
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// first perform deduplication on items
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$items = $this->deduplicateItems($this->data->items);
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// if we haven't been given a database feed ID to check against, all items are new
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if(is_null($feedID)) {
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$this->newItems = $items;
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return true;
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}
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// get as many of the latest articles in the database as there are in the feed
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$articles = Data::$db->articleMatchLatest($feedID, sizeof($items));
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// arrays holding new, edited, and tentatively new items; items may be tentatively new because we perform two passes
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$new = $tentative = $edited = [];
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// iterate through the articles and for each determine whether it is existing, edited, or entirely new
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foreach($items as $index => $i) {
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$found = false;
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foreach($articles as $a) {
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// if the item has an ID and it doesn't match the article ID, the two don't match, regardless of hashes
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if($i->id && $i->id !== $a['guid']) continue;
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if(
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// the item matches if the GUID matches...
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($i->id && $i->id === $a['guid']) ||
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// ... or if any one of the hashes match
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($i->urlTitleHash && $i->urlTitleHash === $a['url_title_hash']) ||
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($i->urlContentHash && $i->urlContentHash === $a['url_content_hash']) ||
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($i->titleContentHash && $i->titleContentHash === $a['title_content_hash'])
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) {
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if($i->updatedDate && $i->updatedDate->getTimestamp() !== $match['edited_date']) {
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// if the item has an edit timestamp and it doesn't match that of the article in the database, the the article has been edited
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// we store the item index and database record ID as a key/value pair
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$found = true;
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$edited[$index] = $a['id'];
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break;
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} else if($i->urlTitleHash !== $a['url_title_hash'] || $i->urlContentHash !== $a['url_content_hash'] || $i->titleContentHash !== $a['title_content_hash']) {
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// if any of the hashes do not match, then the article has been edited
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$found = true;
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$edited[$index] = $a['id'];
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break;
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} else {
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// otherwise the item is unchanged and we can ignore it
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$found = true;
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break;
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}
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}
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}
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if(!$found) $tentative[] = $index;
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}
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if(sizeof($tentative) && sizeof($items)==sizeof($articles)) {
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// if we need to, perform a second pass on the database looking specifically for IDs and hashes of the new items
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$ids = $hashesUT = $hashesUC = $hashesTC = [];
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foreach($tentative as $index) {
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$i = $items[$index];
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if($i->id) $ids[] = $i->id;
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if($i->urlTitleHash) $hashesUT[] = $i->urlTitleHash;
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if($i->urlContentHash) $hashesUC[] = $i->urlContentHash;
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if($i->titleContentHash) $hashesTC[] = $i->titleContentHash;
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}
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$articles = Data::$db->articleMatchIds($feedID, $ids, $hashesUT, $hashesUC, $hashesTC);
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foreach($tentative as $index) {
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$i = $items[$index];
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$found = false;
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foreach($articles as $a) {
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// if the item has an ID and it doesn't match the article ID, the two don't match, regardless of hashes
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if($i->id && $i->id !== $a['guid']) continue;
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if(
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// the item matches if the GUID matches...
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($i->id && $i->id === $a['guid']) ||
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// ... or if any one of the hashes match
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($i->urlTitleHash && $i->urlTitleHash === $a['url_title_hash']) ||
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($i->urlContentHash && $i->urlContentHash === $a['url_content_hash']) ||
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($i->titleContentHash && $i->titleContentHash === $a['title_content_hash'])
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) {
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if($i->updatedDate && $i->updatedDate->getTimestamp() !== $match['edited_date']) {
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// if the item has an edit timestamp and it doesn't match that of the article in the database, the the article has been edited
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// we store the item index and database record ID as a key/value pair
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$found = true;
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$edited[$index] = $a['id'];
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break;
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} else if($i->urlTitleHash !== $a['url_title_hash'] || $i->urlContentHash !== $a['url_content_hash'] || $i->titleContentHash !== $a['title_content_hash']) {
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// if any of the hashes do not match, then the article has been edited
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$found = true;
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$edited[$index] = $a['id'];
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break;
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} else {
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// otherwise the item is unchanged and we can ignore it
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$found = true;
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break;
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}
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}
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}
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if(!$found) $new[] = $index;
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}
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} else {
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// if there are no tentatively new articles and/or the number of stored articles is less than the size of the feed, don't do a second pass; assume any tentatively new items are in fact new
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$new = $tentative;
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}
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// TODO: fetch full content when appropriate
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foreach($new as $index) {
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$this->newItems[] = $items[$index];
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}
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foreach($edited as $index => $id) {
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$this->changedItems[$id] = $items[$index];
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}
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return true;
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}
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public function computeNextFetch(): \DateTime {
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$now = new \DateTime();
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if(!$this->modified) {
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$diff = $now->getTimestamp() - $this->lastModified->getTimestamp();
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$offset = $this->normalizeDateDiff($diff);
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$now->modify("+".$offset);
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} else {
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$offsets = [];
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$dates = $this->gatherDates();
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if(sizeof($dates) > 3) {
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for($a = 0; $a < 3; $a++) {
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$diff = $dates[$a+1] - $dates[$a];
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$offsets[] = $this->normalizeDateDiff($diff);
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}
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if($offsets[0]==$offsets[1] || $offsets[0]==$offsets[2]) {
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$now->modify("+".$offsets[0]);
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} else if($offsets[1]==$offsets[2]) {
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$now->modify("+".$offsets[1]);
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} else {
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$now->modify("+ 1 hour");
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}
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} else {
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$now->modify("+ 1 hour");
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}
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}
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return $now;
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}
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public static function nextFetchOnError($errCount): \DateTime {
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if($errCount < 3) {
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$offset = "5 minutes";
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} else if($errCount < 15) {
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$offset = "3 hours";
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} else {
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$offset = "1 day";
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}
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return new \DateTime("now + ".$offset);
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}
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protected function normalizeDateDiff(int $diff): string {
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if($diff < (30 * 60)) { // less than 30 minutes
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$offset = "15 minutes";
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} else if($diff < (60 * 60)) { // less than an hour
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$offset = "30 minutes";
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} else if($diff < (3 * 60 * 60)) { // less than three hours
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$offset = "1 hour";
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} else if($diff >= (36 * 60 * 60)) { // more than 36 hours
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$offset = "1 day";
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} else {
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$offset = "3 hours";
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}
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return $offset;
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}
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public function computeLastModified() {
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if(!$this->modified) {
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return $this->lastModified;
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} else {
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$dates = $this->gatherDates();
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}
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if(sizeof($dates)) {
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$now = new \DateTime();
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$now->setTimestamp($dates[0]);
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return $now;
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} else {
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return null;
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}
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}
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protected function gatherDates(): array {
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$dates = [];
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foreach($this->data->items as $item) {
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if($item->updatedDate) $dates[] = $item->updatedDate->getTimestamp();
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if($item->publishedDate) $dates[] = $item->publishedDate->getTimestamp();
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}
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$dates = array_unique($dates, \SORT_NUMERIC);
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rsort($dates);
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return $dates;
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}
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} |