Add subjects OPDS feeds, and switch to a more object-oriented approach to generating the OPDS feeds

templates/OpdsAcquisitionFeed.php

@@ -0,0 +1,36 @@
+<?
+
+/* Notes:
+
+- *All* OPDS feeds must contain a rel="http://opds-spec.org/crawlable" link pointing to the /opds/all feed
+
+- The <fh:complete/> element is required to note this as a "Complete Acquisition Feeds"; see https://specs.opds.io/opds-1.2#25-complete-acquisition-feeds
+
+*/
+
+if(!isset($isCrawlable)){
+	$isCrawlable = false;
+}
+
+print("<?xml version=\"1.0\" encoding=\"utf-8\"?>\n");
+?>
+<feed xmlns="http://www.w3.org/2005/Atom" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:schema="http://schema.org/"<? if($isCrawlable){ ?> xmlns:fh="http://purl.org/syndication/history/1.0"<? } ?>>
+	<id><?= $id ?></id>
+	<link href="<?= $url ?>" rel="self" type="application/atom+xml;profile=opds-catalog;kind=acquisition"/>
+	<link href="/opds" rel="start" type="application/atom+xml;profile=opds-catalog;kind=navigation"/>
+	<link href="<?= $parentUrl ?>" rel="up" type="application/atom+xml;profile=opds-catalog;kind=navigation"/>
+	<link href="/opds/all" rel="http://opds-spec.org/crawlable" type="application/atom+xml;profile=opds-catalog;kind=acquisition"/>
+	<link href="/ebooks/opensearch" rel="search" type="application/opensearchdescription+xml" />
+	<title><?= htmlspecialchars($title, ENT_QUOTES|ENT_XML1, 'utf-8') ?></title>
+	<subtitle>Free and liberated ebooks, carefully produced for the true book lover.</subtitle>
+	<icon>/images/logo.png</icon>
+	<updated><?= $updatedTimestamp ?></updated>
+	<? if($isCrawlable){ ?><fh:complete/><? } ?>
+	<author>
+		<name>Standard Ebooks</name>
+		<uri><?= SITE_URL ?></uri>
+	</author>
+	<? foreach($entries as $ebook){ ?>
+		<?= Template::OpdsAcquisitionEntry(['ebook' => $ebook]) ?>
+	<? } ?>
+</feed>