--- /dev/null
+<?php
+
+declare(strict_types=1);
+
+namespace Shaarli\Front\Controller\Visitor;
+
+use Slim\Http\Request;
+use Slim\Http\Response;
+
+/**
+ * Class TagCloud
+ *
+ * Slim controller used to render the tag cloud and tag list pages.
+ */
+class TagCloudController extends ShaarliVisitorController
+{
+ protected const TYPE_CLOUD = 'cloud';
+ protected const TYPE_LIST = 'list';
+
+ /**
+ * Display the tag cloud through the template engine.
+ * This controller a few filters:
+ * - Visibility stored in the session for logged in users
+ * - `searchtags` query parameter: will return tags associated with filter in at least one bookmark
+ */
+ public function cloud(Request $request, Response $response): Response
+ {
+ return $this->processRequest(static::TYPE_CLOUD, $request, $response);
+ }
+
+ /**
+ * Display the tag list through the template engine.
+ * This controller a few filters:
+ * - Visibility stored in the session for logged in users
+ * - `searchtags` query parameter: will return tags associated with filter in at least one bookmark
+ * - `sort` query parameters:
+ * + `usage` (default): most used tags first
+ * + `alpha`: alphabetical order
+ */
+ public function list(Request $request, Response $response): Response
+ {
+ return $this->processRequest(static::TYPE_LIST, $request, $response);
+ }
+
+ /**
+ * Process the request for both tag cloud and tag list endpoints.
+ */
+ protected function processRequest(string $type, Request $request, Response $response): Response
+ {
+ if ($this->container->loginManager->isLoggedIn() === true) {
+ $visibility = $this->container->sessionManager->getSessionParameter('visibility');
+ }
+
+ $sort = $request->getQueryParam('sort');
+ $searchTags = $request->getQueryParam('searchtags');
+ $filteringTags = $searchTags !== null ? explode(' ', $searchTags) : [];
+
+ $tags = $this->container->bookmarkService->bookmarksCountPerTag($filteringTags, $visibility ?? null);
+
+ if (static::TYPE_CLOUD === $type || 'alpha' === $sort) {
+ // TODO: the sorting should be handled by bookmarkService instead of the controller
+ alphabetical_sort($tags, false, true);
+ }
+
+ if (static::TYPE_CLOUD === $type) {
+ $tags = $this->formatTagsForCloud($tags);
+ }
+
+ $searchTags = implode(' ', escape($filteringTags));
+ $data = [
+ 'search_tags' => $searchTags,
+ 'tags' => $tags,
+ ];
+ $data = $this->executeHooks('tag' . $type, $data);
+ foreach ($data as $key => $value) {
+ $this->assignView($key, $value);
+ }
+
+ $searchTags = !empty($searchTags) ? $searchTags .' - ' : '';
+ $this->assignView(
+ 'pagetitle',
+ $searchTags . t('Tag '. $type) .' - '. $this->container->conf->get('general.title', 'Shaarli')
+ );
+
+ return $response->write($this->render('tag.'. $type));
+ }
+
+ /**
+ * Format the tags array for the tag cloud template.
+ *
+ * @param array<string, int> $tags List of tags as key with count as value
+ *
+ * @return mixed[] List of tags as key, with count and expected font size in a subarray
+ */
+ protected function formatTagsForCloud(array $tags): array
+ {
+ // We sort tags alphabetically, then choose a font size according to count.
+ // First, find max value.
+ $maxCount = count($tags) > 0 ? max($tags) : 0;
+ $logMaxCount = $maxCount > 1 ? log($maxCount, 30) : 1;
+ $tagList = [];
+ foreach ($tags as $key => $value) {
+ // Tag font size scaling:
+ // default 15 and 30 logarithm bases affect scaling,
+ // 2.2 and 0.8 are arbitrary font sizes in em.
+ $size = log($value, 15) / $logMaxCount * 2.2 + 0.8;
+ $tagList[$key] = [
+ 'count' => $value,
+ 'size' => number_format($size, 2, '.', ''),
+ ];
+ }
+
+ return $tagList;
+ }
+
+ /**
+ * @param mixed[] $data Template data
+ *
+ * @return mixed[] Template data after active plugins hook execution.
+ */
+ protected function executeHooks(string $template, array $data): array
+ {
+ $this->container->pluginManager->executeHooks(
+ 'render_'. $template,
+ $data,
+ ['loggedin' => $this->container->loginManager->isLoggedIn()]
+ );
+
+ return $data;
+ }
+}