Add support for tag browsing and collection browsing

lib/Collection.php

@@ -0,0 +1,11 @@
+<?
+class Collection{
+	public $Name;
+	public $Url;
+
+	public function __construct(string $name){
+		$this->Name = $name;
+		$this->Url = '/collections/' . strtolower(str_replace(' ', '-', Formatter::ToPlainText($this->Name))) . '/';
+	}
+}
+?>

lib/Ebook.php

@@ -12,6 +12,7 @@ class Ebook{
 	public $GitCommits = [];
 	public $Tags = [];
 	public $LocTags = [];
+	public $Collections = [];
 	public $Identifier;
 	public $UrlSafeIdentifier;
 	public $HeroImageUrl;
@@ -149,7 +150,12 @@ class Ebook{
 
 		// Get SE tags
 		foreach($xml->xpath('/package/metadata/meta[@property="se:subject"]') ?: [] as $tag){
-			$this->Tags[] = (string)$tag;
+			$this->Tags[] = new Tag($tag);
+		}
+
+		// Get SE collections
+		foreach($xml->xpath('/package/metadata/meta[@property="se:collection"]') ?: [] as $collection){
+			$this->Collections[] = new Collection($collection);
 		}
 
 		// Get LoC tags
@@ -337,7 +343,7 @@ class Ebook{
 		}
 
 		foreach($this->Tags as $tag){
-			$searchString .= ' ' . $tag;
+			$searchString .= ' ' . $tag->Name;
 		}
 
 		foreach($this->LocTags as $tag){
@@ -502,5 +508,25 @@ class Ebook{
 
 		return null;
 	}
+
+	public function HasTag(string $tag): bool{
+		foreach($this->Tags as $t){
+			if(strtolower($t->Name) == strtolower($tag)){
+				return true;
+			}
+		}
+
+		return false;
+	}
+
+	public function IsInCollection(string $collection): bool{
+		foreach($this->Collections as $c){
+			if(strtolower($c->Name) == strtolower($collection)){
+				return true;
+			}
+		}
+
+		return false;
+	}
 }
 ?>

lib/Library.php

@@ -100,6 +100,70 @@ class Library{
 		return $ebooks;
 	}
 
+	public static function GetEbooksByTag(string $tag): array{
+		// Do we have the tag's ebooks cached?
+		$ebooks = apcu_fetch('tag-' . $tag, $success);
+
+		if(!$success){
+			$ebooks = [];
+
+			foreach(explode("\n", trim(shell_exec('find ' . SITE_ROOT . '/www/ebooks/ -name "content.opf"') ?? '')) as $filename){
+				try{
+					$ebookWwwFilesystemPath = preg_replace('|/src/.+|ius', '', $filename) ?? '';
+					$ebook = apcu_fetch('ebook-' . $ebookWwwFilesystemPath, $success);
+
+					if(!$success){
+						$ebook = new Ebook($ebookWwwFilesystemPath);
+						apcu_store('ebook-' . $ebookWwwFilesystemPath, $ebook);
+					}
+
+					if($ebook->HasTag($tag)){
+						$ebooks[] = $ebook;
+					}
+				}
+				catch(\Exception $ex){
+					// An error in a book isn't fatal; just carry on.
+				}
+			}
+
+			apcu_store('tag-' . $tag, $ebooks);
+		}
+
+		return $ebooks;
+	}
+
+	public static function GetEbooksByCollection(string $collection): array{
+		// Do we have the tag's ebooks cached?
+		$ebooks = apcu_fetch('collection-' . $collection, $success);
+
+		if(!$success){
+			$ebooks = [];
+
+			foreach(explode("\n", trim(shell_exec('find ' . SITE_ROOT . '/www/ebooks/ -name "content.opf"') ?? '')) as $filename){
+				try{
+					$ebookWwwFilesystemPath = preg_replace('|/src/.+|ius', '', $filename) ?? '';
+					$ebook = apcu_fetch('ebook-' . $ebookWwwFilesystemPath, $success);
+
+					if(!$success){
+						$ebook = new Ebook($ebookWwwFilesystemPath);
+						apcu_store('ebook-' . $ebookWwwFilesystemPath, $ebook);
+					}
+
+					if($ebook->IsInCollection($collection)){
+						$ebooks[] = $ebook;
+					}
+				}
+				catch(\Exception $ex){
+					// An error in a book isn't fatal; just carry on.
+				}
+			}
+
+			apcu_store('collection-' . $collection, $ebooks);
+		}
+
+		return $ebooks;
+	}
+
 	public static function Search(string $query): array{
 		$ebooks = Library::GetEbooks();
 		$matches = [];

lib/Tag.php

@@ -0,0 +1,11 @@
+<?
+class Tag{
+	public $Name;
+	public $Url;
+
+	public function __construct(string $name){
+		$this->Name = $name;
+		$this->Url = '/tags/' . strtolower(str_replace(' ', '-', Formatter::ToPlainText($this->Name))) . '/';
+	}
+}
+?>

templates/SearchForm.php

@@ -1,5 +1,5 @@
 <form action="/ebooks/" method="get">
 	<label class="search">
-		Search ebooks: <input type="search" name="query" placeholder="Search ebooks..." value="<?= Formatter::ToPlainText($query ?? '') ?>" />
+		Search ebooks: <input type="search" name="query" placeholder="Search all ebooks..." value="<?= Formatter::ToPlainText($query ?? '') ?>" />
 	</label>
 </form>

www/css/core.css

@@ -1035,6 +1035,40 @@ figure{
 	margin-top: 1rem;
 }
 
+ul.tags{
+	list-style: none;
+	display: flex;
+	justify-content: center;
+	flex-wrap: wrap;
+}
+
+ul.tags li{
+	margin: 0;
+}
+
+ul.tags li a{
+	border: 1px solid #222;
+	border-radius: 5px;
+	padding: .25rem .5rem;
+	font-style: normal;
+	background: rgba(0, 0, 0, .1);
+	text-decoration: none;
+	display: block;
+	line-height: 1;
+	white-space: nowrap;
+	text-transform: lowercase;
+	box-shadow: 1px 1px 0px rgba(255, 255, 255, .5) inset;
+}
+
+ul.tags li a:hover{
+	color: #fff;
+	background: #288da4;
+}
+
+ul.tags li + li{
+	margin-left: .5rem;
+}
+
 code.tag,
 code.path,
 code.program,

www/ebooks/ebook.php

@@ -71,6 +71,12 @@ catch(\Exception $ex){
 			<? if($ebook->ContributorsHtml !== null){ ?>
 			<p><?= $ebook->ContributorsHtml ?></p>
 			<? } ?>
+			<? if(sizeof($ebook->Collections) > 0){ ?>
+				<? foreach($ebook->Collections as $collection){ ?>
+				<p>Part of the <a href="<?= $collection->Url ?>"><?= Formatter::ToPlainText($collection->Name) ?> collection</a>.</p>
+				<? } ?>
+			<? } ?>
+			<ul class="tags"><? foreach($ebook->Tags as $tag){ ?><li><a href="<?= $tag->Url ?>"><?= Formatter::ToPlainText($tag->Name) ?></a></li><? } ?></ul>
 		</aside>
 
 		<section id="description">

www/ebooks/index.php

@@ -4,6 +4,8 @@ require_once('Core.php');
 try{
 	$page = HttpInput::GetInt('page') ?? 1;
 	$query = HttpInput::GetString('query', false);
+	$tag = HttpInput::GetString('tag', false);
+	$collection = HttpInput::GetString('collection', false);
 	$sort = HttpInput::GetString('sort', false) ?? SORT_NEWEST;
 	$pages = 0;
 	$totalEbooks = 0;
@@ -16,7 +18,29 @@ try{
 		$sort = SORT_NEWEST;
 	}
 
-	if($query === null){
+	if($query !== null){
+		$ebooks = Library::Search($query);
+		$pageTitle = 'Search Standard Ebooks';
+		$pageDescription = 'Search results';
+		$pageHeader = 'Search Ebooks';
+	}
+	elseif($tag !== null){
+		$tag = strtolower(str_replace('-', ' ', $tag));
+		$ebooks = Library::GetEbooksByTag($tag);
+		$pageTitle = 'Browse ebooks tagged “' . Formatter::ToPlainText($tag) . '”';
+		$pageDescription = 'A list of ebooks tagged “' . Formatter::ToPlainText($tag) . '”';
+		$pageHeader = 'Ebooks tagged “' . Formatter::ToPlainText($tag) . '”';
+	}
+	elseif($collection !== null){
+		$collection = strtolower(str_replace('-', ' ', $collection));
+		$ebooks = Library::GetEbooksByCollection($collection);
+		$pageTitle = 'Browse ebooks in the ' . Formatter::ToPlainText(ucwords($collection)) . ' collection';
+		$pageDescription = 'A list of ebooks in the ' . Formatter::ToPlainText(ucwords($collection)) . ' collection';
+		$pageHeader = 'Ebooks in the ' . Formatter::ToPlainText(ucwords($collection)) . ' collection';
+	}
+	else{
+		$pageTitle = 'Browse Standard Ebooks';
+		$pageHeader = 'Browse Ebooks';
 		$ebooks = Library::GetEbooks($sort);
 
 		$pages = ceil(sizeof($ebooks) / EBOOKS_PER_PAGE);
@@ -35,15 +59,6 @@ try{
 				break;
 		}
 	}
-	else{
-		$ebooks = Library::Search($query);
-		$pageDescription = 'Search results';
-	}
-
-	$pageTitle = 'Browse Standard Ebooks';
-	if($query !== null){
-		$pageTitle = 'Search Standard Ebooks';
-	}
 }
 catch(\Exception $ex){
 	http_response_code(404);
@@ -52,7 +67,7 @@ catch(\Exception $ex){
 }
 ?><?= Template::Header(['title' => $pageTitle, 'highlight' => 'ebooks', 'description' => $pageDescription]) ?>
 <main class="ebooks">
-		<h1><? if($query === null){ ?>Browse<? }else{ ?>Search<? } ?> Ebooks</h1>
+		<h1><?= $pageHeader ?></h1>
 		<?= Template::SearchForm(['query' => $query]) ?>
 		<? if(sizeof($ebooks) == 0){ ?>
 			<p class="no-results">No ebooks matched your search.  You can try different search terms, or <a href="/ebooks/">browse all of our ebooks</a>.</p>