8 files changed, 807 insertions, 0 deletions

diff --git a/application/front/controller/visitor/DailyController.php b/application/front/controller/visitor/DailyController.php
new file mode 100644
index 00000000..47e2503a
--- /dev/null
+++ b/application/front/controller/visitor/DailyController.php
@@ -0,0 +1,208 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Shaarli\Front\Controller\Visitor;
+
+use DateTime;
+use DateTimeImmutable;
+use Shaarli\Bookmark\Bookmark;
+use Slim\Http\Request;
+use Slim\Http\Response;
+
+/**
+ * Class DailyController
+ *
+ * Slim controller used to render the daily page.
+ */
+class DailyController extends ShaarliVisitorController
+{
+    public static $DAILY_RSS_NB_DAYS = 8;
+
+    /**
+     * Controller displaying all bookmarks published in a single day.
+     * It take a `day` date query parameter (format YYYYMMDD).
+     */
+    public function index(Request $request, Response $response): Response
+    {
+        $day = $request->getQueryParam('day') ?? date('Ymd');
+
+        $availableDates = $this->container->bookmarkService->days();
+        $nbAvailableDates = count($availableDates);
+        $index = array_search($day, $availableDates);
+
+        if ($index === false) {
+            // no bookmarks for day, but at least one day with bookmarks
+            $day = $availableDates[$nbAvailableDates - 1] ?? $day;
+            $previousDay = $availableDates[$nbAvailableDates - 2] ?? '';
+        } else {
+            $previousDay = $availableDates[$index - 1] ?? '';
+            $nextDay = $availableDates[$index + 1] ?? '';
+        }
+
+        if ($day === date('Ymd')) {
+            $this->assignView('dayDesc', t('Today'));
+        } elseif ($day === date('Ymd', strtotime('-1 days'))) {
+            $this->assignView('dayDesc', t('Yesterday'));
+        }
+
+        try {
+            $linksToDisplay = $this->container->bookmarkService->filterDay($day);
+        } catch (\Exception $exc) {
+            $linksToDisplay = [];
+        }
+
+        $formatter = $this->container->formatterFactory->getFormatter();
+        // We pre-format some fields for proper output.
+        foreach ($linksToDisplay as $key => $bookmark) {
+            $linksToDisplay[$key] = $formatter->format($bookmark);
+            // This page is a bit specific, we need raw description to calculate the length
+            $linksToDisplay[$key]['formatedDescription'] = $linksToDisplay[$key]['description'];
+            $linksToDisplay[$key]['description'] = $bookmark->getDescription();
+        }
+
+        $dayDate = DateTime::createFromFormat(Bookmark::LINK_DATE_FORMAT, $day.'_000000');
+        $data = [
+            'linksToDisplay' => $linksToDisplay,
+            'day' => $dayDate->getTimestamp(),
+            'dayDate' => $dayDate,
+            'previousday' => $previousDay ?? '',
+            'nextday' => $nextDay ?? '',
+        ];
+
+        // Hooks are called before column construction so that plugins don't have to deal with columns.
+        $this->executeHooks($data);
+
+        $data['cols'] = $this->calculateColumns($data['linksToDisplay']);
+
+        foreach ($data as $key => $value) {
+            $this->assignView($key, $value);
+        }
+
+        $mainTitle = $this->container->conf->get('general.title', 'Shaarli');
+        $this->assignView(
+            'pagetitle',
+            t('Daily') .' - '. format_date($dayDate, false) . ' - ' . $mainTitle
+        );
+
+        return $response->write($this->render('daily'));
+    }
+
+    /**
+     * Daily RSS feed: 1 RSS entry per day giving all the bookmarks on that day.
+     * Gives the last 7 days (which have bookmarks).
+     * This RSS feed cannot be filtered and does not trigger plugins yet.
+     */
+    public function rss(Request $request, Response $response): Response
+    {
+        $response = $response->withHeader('Content-Type', 'application/rss+xml; charset=utf-8');
+
+        $pageUrl = page_url($this->container->environment);
+        $cache = $this->container->pageCacheManager->getCachePage($pageUrl);
+
+        $cached = $cache->cachedVersion();
+        if (!empty($cached)) {
+            return $response->write($cached);
+        }
+
+        $days = [];
+        foreach ($this->container->bookmarkService->search() as $bookmark) {
+            $day = $bookmark->getCreated()->format('Ymd');
+
+            // Stop iterating after DAILY_RSS_NB_DAYS entries
+            if (count($days) === static::$DAILY_RSS_NB_DAYS && !isset($days[$day])) {
+                break;
+            }
+
+            $days[$day][] = $bookmark;
+        }
+
+        // Build the RSS feed.
+        $indexUrl = escape(index_url($this->container->environment));
+
+        $formatter = $this->container->formatterFactory->getFormatter();
+        $formatter->addContextData('index_url', $indexUrl);
+
+        $dataPerDay = [];
+
+        /** @var Bookmark[] $bookmarks */
+        foreach ($days as $day => $bookmarks) {
+            $dayDatetime = DateTimeImmutable::createFromFormat(Bookmark::LINK_DATE_FORMAT, $day.'_000000');
+            $dataPerDay[$day] = [
+                'date' => $dayDatetime,
+                'date_rss' => $dayDatetime->format(DateTime::RSS),
+                'date_human' => format_date($dayDatetime, false, true),
+                'absolute_url' => $indexUrl . '/daily?day=' . $day,
+                'links' => [],
+            ];
+
+            foreach ($bookmarks as $key => $bookmark) {
+                $dataPerDay[$day]['links'][$key] = $formatter->format($bookmark);
+
+                // Make permalink URL absolute
+                if ($bookmark->isNote()) {
+                    $dataPerDay[$day]['links'][$key]['url'] = $indexUrl . $bookmark->getUrl();
+                }
+            }
+        }
+
+        $this->assignView('title', $this->container->conf->get('general.title', 'Shaarli'));
+        $this->assignView('index_url', $indexUrl);
+        $this->assignView('page_url', $pageUrl);
+        $this->assignView('hide_timestamps', $this->container->conf->get('privacy.hide_timestamps', false));
+        $this->assignView('days', $dataPerDay);
+
+        $rssContent = $this->render('dailyrss');
+
+        $cache->cache($rssContent);
+
+        return $response->write($rssContent);
+    }
+
+    /**
+     * We need to spread the articles on 3 columns.
+     * did not want to use a JavaScript lib like http://masonry.desandro.com/
+     * so I manually spread entries with a simple method: I roughly evaluate the
+     * height of a div according to title and description length.
+     */
+    protected function calculateColumns(array $links): array
+    {
+        // Entries to display, for each column.
+        $columns = [[], [], []];
+        // Rough estimate of columns fill.
+        $fill = [0, 0, 0];
+        foreach ($links as $link) {
+            // Roughly estimate length of entry (by counting characters)
+            // Title: 30 chars = 1 line. 1 line is 30 pixels height.
+            // Description: 836 characters gives roughly 342 pixel height.
+            // This is not perfect, but it's usually OK.
+            $length = strlen($link['title'] ?? '') + (342 * strlen($link['description'] ?? '')) / 836;
+            if (! empty($link['thumbnail'])) {
+                $length += 100; // 1 thumbnails roughly takes 100 pixels height.
+            }
+            // Then put in column which is the less filled:
+            $smallest = min($fill); // find smallest value in array.
+            $index = array_search($smallest, $fill); // find index of this smallest value.
+            array_push($columns[$index], $link); // Put entry in this column.
+            $fill[$index] += $length;
+        }
+
+        return $columns;
+    }
+
+    /**
+     * @param mixed[] $data Variables passed to the template engine
+     *
+     * @return mixed[] Template data after active plugins render_picwall hook execution.
+     */
+    protected function executeHooks(array $data): array
+    {
+        $this->container->pluginManager->executeHooks(
+            'render_daily',
+            $data,
+            ['loggedin' => $this->container->loginManager->isLoggedIn()]
+        );
+
+        return $data;
+    }
+}
diff --git a/application/front/controller/visitor/FeedController.php b/application/front/controller/visitor/FeedController.php
new file mode 100644
index 00000000..70664635
--- /dev/null
+++ b/application/front/controller/visitor/FeedController.php
@@ -0,0 +1,77 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Shaarli\Front\Controller\Visitor;
+
+use Shaarli\Feed\FeedBuilder;
+use Slim\Http\Request;
+use Slim\Http\Response;
+
+/**
+ * Class FeedController
+ *
+ * Slim controller handling ATOM and RSS feed.
+ */
+class FeedController extends ShaarliVisitorController
+{
+    public function atom(Request $request, Response $response): Response
+    {
+        return $this->processRequest(FeedBuilder::$FEED_ATOM, $request, $response);
+    }
+
+    public function rss(Request $request, Response $response): Response
+    {
+        return $this->processRequest(FeedBuilder::$FEED_RSS, $request, $response);
+    }
+
+    protected function processRequest(string $feedType, Request $request, Response $response): Response
+    {
+        $response = $response->withHeader('Content-Type', 'application/'. $feedType .'+xml; charset=utf-8');
+
+        $pageUrl = page_url($this->container->environment);
+        $cache = $this->container->pageCacheManager->getCachePage($pageUrl);
+
+        $cached = $cache->cachedVersion();
+        if (!empty($cached)) {
+            return $response->write($cached);
+        }
+
+        // Generate data.
+        $this->container->feedBuilder->setLocale(strtolower(setlocale(LC_COLLATE, 0)));
+        $this->container->feedBuilder->setHideDates($this->container->conf->get('privacy.hide_timestamps', false));
+        $this->container->feedBuilder->setUsePermalinks(
+            null !== $request->getParam('permalinks') || !$this->container->conf->get('feed.rss_permalinks')
+        );
+
+        $data = $this->container->feedBuilder->buildData($feedType, $request->getParams());
+
+        $this->executeHooks($data, $feedType);
+        $this->assignAllView($data);
+
+        $content = $this->render('feed.'. $feedType);
+
+        $cache->cache($content);
+
+        return $response->write($content);
+    }
+
+    /**
+     * @param mixed[] $data Template data
+     *
+     * @return mixed[] Template data after active plugins hook execution.
+     */
+    protected function executeHooks(array $data, string $feedType): array
+    {
+        $this->container->pluginManager->executeHooks(
+            'render_feed',
+            $data,
+            [
+                'loggedin' => $this->container->loginManager->isLoggedIn(),
+                'target' => $feedType,
+            ]
+        );
+
+        return $data;
+    }
+}
diff --git a/application/front/controller/visitor/LoginController.php b/application/front/controller/visitor/LoginController.php
new file mode 100644
index 00000000..4de2f55d
--- /dev/null
+++ b/application/front/controller/visitor/LoginController.php
@@ -0,0 +1,46 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Shaarli\Front\Controller\Visitor;
+
+use Shaarli\Front\Exception\LoginBannedException;
+use Slim\Http\Request;
+use Slim\Http\Response;
+
+/**
+ * Class LoginController
+ *
+ * Slim controller used to render the login page.
+ *
+ * The login page is not available if the user is banned
+ * or if open shaarli setting is enabled.
+ */
+class LoginController extends ShaarliVisitorController
+{
+    public function index(Request $request, Response $response): Response
+    {
+        if ($this->container->loginManager->isLoggedIn()
+            || $this->container->conf->get('security.open_shaarli', false)
+        ) {
+            return $response->withRedirect('./');
+        }
+
+        $userCanLogin = $this->container->loginManager->canLogin($request->getServerParams());
+        if ($userCanLogin !== true) {
+            throw new LoginBannedException();
+        }
+
+        if ($request->getParam('username') !== null) {
+            $this->assignView('username', escape($request->getParam('username')));
+        }
+
+        $this
+            ->assignView('returnurl', escape($request->getServerParam('HTTP_REFERER')))
+            ->assignView('remember_user_default', $this->container->conf->get('privacy.remember_user_default', true))
+            ->assignView('pagetitle', t('Login') .' - '. $this->container->conf->get('general.title', 'Shaarli'))
+        ;
+
+        return $response->write($this->render('loginform'));
+    }
+}
diff --git a/application/front/controller/visitor/OpenSearchController.php b/application/front/controller/visitor/OpenSearchController.php
new file mode 100644
index 00000000..0fd68db6
--- /dev/null
+++ b/application/front/controller/visitor/OpenSearchController.php
@@ -0,0 +1,26 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Shaarli\Front\Controller\Visitor;
+
+use Slim\Http\Request;
+use Slim\Http\Response;
+
+/**
+ * Class OpenSearchController
+ *
+ * Slim controller used to render open search template.
+ * This allows to add Shaarli as a search engine within the browser.
+ */
+class OpenSearchController extends ShaarliVisitorController
+{
+    public function index(Request $request, Response $response): Response
+    {
+        $response = $response->withHeader('Content-Type', 'application/opensearchdescription+xml; charset=utf-8');
+
+        $this->assignView('serverurl', index_url($this->container->environment));
+
+        return $response->write($this->render('opensearch'));
+    }
+}
diff --git a/application/front/controller/visitor/PictureWallController.php b/application/front/controller/visitor/PictureWallController.php
new file mode 100644
index 00000000..4e1dce8c
--- /dev/null
+++ b/application/front/controller/visitor/PictureWallController.php
@@ -0,0 +1,70 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Shaarli\Front\Controller\Visitor;
+
+use Shaarli\Front\Exception\ThumbnailsDisabledException;
+use Shaarli\Thumbnailer;
+use Slim\Http\Request;
+use Slim\Http\Response;
+
+/**
+ * Class PicturesWallController
+ *
+ * Slim controller used to render the pictures wall page.
+ * If thumbnails mode is set to NONE, we just render the template without any image.
+ */
+class PictureWallController extends ShaarliVisitorController
+{
+    public function index(Request $request, Response $response): Response
+    {
+        if ($this->container->conf->get('thumbnails.mode', Thumbnailer::MODE_NONE) === Thumbnailer::MODE_NONE) {
+            throw new ThumbnailsDisabledException();
+        }
+
+        $this->assignView(
+            'pagetitle',
+            t('Picture wall') .' - '. $this->container->conf->get('general.title', 'Shaarli')
+        );
+
+        // Optionally filter the results:
+        $links = $this->container->bookmarkService->search($request->getQueryParams());
+        $linksToDisplay = [];
+
+        // Get only bookmarks which have a thumbnail.
+        // Note: we do not retrieve thumbnails here, the request is too heavy.
+        $formatter = $this->container->formatterFactory->getFormatter('raw');
+        foreach ($links as $key => $link) {
+            if (!empty($link->getThumbnail())) {
+                $linksToDisplay[] = $formatter->format($link);
+            }
+        }
+
+        $data = $this->executeHooks($linksToDisplay);
+        foreach ($data as $key => $value) {
+            $this->assignView($key, $value);
+        }
+
+        return $response->write($this->render('picwall'));
+    }
+
+    /**
+     * @param mixed[] $linksToDisplay List of formatted bookmarks
+     *
+     * @return mixed[] Template data after active plugins render_picwall hook execution.
+     */
+    protected function executeHooks(array $linksToDisplay): array
+    {
+        $data = [
+            'linksToDisplay' => $linksToDisplay,
+        ];
+        $this->container->pluginManager->executeHooks(
+            'render_picwall',
+            $data,
+            ['loggedin' => $this->container->loginManager->isLoggedIn()]
+        );
+
+        return $data;
+    }
+}
diff --git a/application/front/controller/visitor/ShaarliVisitorController.php b/application/front/controller/visitor/ShaarliVisitorController.php
new file mode 100644
index 00000000..655b3baa
--- /dev/null
+++ b/application/front/controller/visitor/ShaarliVisitorController.php
@@ -0,0 +1,131 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Shaarli\Front\Controller\Visitor;
+
+use Shaarli\Bookmark\BookmarkFilter;
+use Shaarli\Container\ShaarliContainer;
+use Slim\Http\Request;
+use Slim\Http\Response;
+
+abstract class ShaarliVisitorController
+{
+    /** @var ShaarliContainer */
+    protected $container;
+
+    /** @param ShaarliContainer $container Slim container (extended for attribute completion). */
+    public function __construct(ShaarliContainer $container)
+    {
+        $this->container = $container;
+    }
+
+    /**
+     * Assign variables to RainTPL template through the PageBuilder.
+     *
+     * @param mixed $value Value to assign to the template
+     */
+    protected function assignView(string $name, $value): self
+    {
+        $this->container->pageBuilder->assign($name, $value);
+
+        return $this;
+    }
+
+    /**
+     * Assign variables to RainTPL template through the PageBuilder.
+     *
+     * @param mixed $data Values to assign to the template and their keys
+     */
+    protected function assignAllView(array $data): self
+    {
+        foreach ($data as $key => $value) {
+            $this->assignView($key, $value);
+        }
+
+        return $this;
+    }
+
+    protected function render(string $template): string
+    {
+        $this->assignView('linkcount', $this->container->bookmarkService->count(BookmarkFilter::$ALL));
+        $this->assignView('privateLinkcount', $this->container->bookmarkService->count(BookmarkFilter::$PRIVATE));
+        $this->assignView('plugin_errors', $this->container->pluginManager->getErrors());
+
+        $this->executeDefaultHooks($template);
+
+        return $this->container->pageBuilder->render($template);
+    }
+
+    /**
+     * Call plugin hooks for header, footer and includes, specifying which page will be rendered.
+     * Then assign generated data to RainTPL.
+     */
+    protected function executeDefaultHooks(string $template): void
+    {
+        $common_hooks = [
+            'includes',
+            'header',
+            'footer',
+        ];
+
+        foreach ($common_hooks as $name) {
+            $plugin_data = [];
+            $this->container->pluginManager->executeHooks(
+                'render_' . $name,
+                $plugin_data,
+                [
+                    'target' => $template,
+                    'loggedin' => $this->container->loginManager->isLoggedIn()
+                ]
+            );
+            $this->assignView('plugins_' . $name, $plugin_data);
+        }
+    }
+
+    /**
+     * Generates a redirection to the previous page, based on the HTTP_REFERER.
+     * It fails back to the home page.
+     *
+     * @param array $loopTerms   Terms to remove from path and query string to prevent direction loop.
+     * @param array $clearParams List of parameter to remove from the query string of the referrer.
+     */
+    protected function redirectFromReferer(
+        Request $request,
+        Response $response,
+        array $loopTerms = [],
+        array $clearParams = []
+    ): Response {
+        $defaultPath = $request->getUri()->getBasePath();
+        $referer = $this->container->environment['HTTP_REFERER'] ?? null;
+
+        if (null !== $referer) {
+            $currentUrl = parse_url($referer);
+            parse_str($currentUrl['query'] ?? '', $params);
+            $path = $currentUrl['path'] ?? $defaultPath;
+        } else {
+            $params = [];
+            $path = $defaultPath;
+        }
+
+        // Prevent redirection loop
+        if (isset($currentUrl)) {
+            foreach ($clearParams as $value) {
+                unset($params[$value]);
+            }
+
+            $checkQuery = implode('', array_keys($params));
+            foreach ($loopTerms as $value) {
+                if (strpos($path . $checkQuery, $value) !== false) {
+                    $params = [];
+                    $path = $defaultPath;
+                    break;
+                }
+            }
+        }
+
+        $queryString = count($params) > 0 ? '?'. http_build_query($params) : '';
+
+        return $response->withRedirect($path . $queryString);
+    }
+}
diff --git a/application/front/controller/visitor/TagCloudController.php b/application/front/controller/visitor/TagCloudController.php
new file mode 100644
index 00000000..15b6d7b7
--- /dev/null
+++ b/application/front/controller/visitor/TagCloudController.php
@@ -0,0 +1,131 @@
+<?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;
+    }
+}
diff --git a/application/front/controller/visitor/TagController.php b/application/front/controller/visitor/TagController.php
new file mode 100644
index 00000000..a0bc1d1b
--- /dev/null
+++ b/application/front/controller/visitor/TagController.php
@@ -0,0 +1,118 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Shaarli\Front\Controller\Visitor;
+
+use Slim\Http\Request;
+use Slim\Http\Response;
+
+/**
+ * Class TagController
+ *
+ * Slim controller handle tags.
+ */
+class TagController extends ShaarliVisitorController
+{
+    /**
+     * Add another tag in the current search through an HTTP redirection.
+     *
+     * @param array $args Should contain `newTag` key as tag to add to current search
+     */
+    public function addTag(Request $request, Response $response, array $args): Response
+    {
+        $newTag = $args['newTag'] ?? null;
+        $referer = $this->container->environment['HTTP_REFERER'] ?? null;
+
+        // In case browser does not send HTTP_REFERER, we search a single tag
+        if (null === $referer) {
+            if (null !== $newTag) {
+                return $response->withRedirect('./?searchtags='. urlencode($newTag));
+            }
+
+            return $response->withRedirect('./');
+        }
+
+        $currentUrl = parse_url($referer);
+        parse_str($currentUrl['query'] ?? '', $params);
+
+        if (null === $newTag) {
+            return $response->withRedirect(($currentUrl['path'] ?? './') .'?'. http_build_query($params));
+        }
+
+        // Prevent redirection loop
+        if (isset($params['addtag'])) {
+            unset($params['addtag']);
+        }
+
+        // Check if this tag is already in the search query and ignore it if it is.
+        // Each tag is always separated by a space
+        $currentTags = isset($params['searchtags']) ? explode(' ', $params['searchtags']) : [];
+
+        $addtag = true;
+        foreach ($currentTags as $value) {
+            if ($value === $newTag) {
+                $addtag = false;
+                break;
+            }
+        }
+
+        // Append the tag if necessary
+        if (true === $addtag) {
+            $currentTags[] = trim($newTag);
+        }
+
+        $params['searchtags'] = trim(implode(' ', $currentTags));
+
+        // We also remove page (keeping the same page has no sense, since the results are different)
+        unset($params['page']);
+
+        return $response->withRedirect(($currentUrl['path'] ?? './') .'?'. http_build_query($params));
+    }
+
+    /**
+     * Remove a tag from the current search through an HTTP redirection.
+     *
+     * @param array $args Should contain `tag` key as tag to remove from current search
+     */
+    public function removeTag(Request $request, Response $response, array $args): Response
+    {
+        $referer = $this->container->environment['HTTP_REFERER'] ?? null;
+
+        // If the referrer is not provided, we can update the search, so we failback on the bookmark list
+        if (empty($referer)) {
+            return $response->withRedirect('./');
+        }
+
+        $tagToRemove = $args['tag'] ?? null;
+        $currentUrl = parse_url($referer);
+        parse_str($currentUrl['query'] ?? '', $params);
+
+        if (null === $tagToRemove) {
+            return $response->withRedirect(($currentUrl['path'] ?? './') .'?'. http_build_query($params));
+        }
+
+        // Prevent redirection loop
+        if (isset($params['removetag'])) {
+            unset($params['removetag']);
+        }
+
+        if (isset($params['searchtags'])) {
+            $tags = explode(' ', $params['searchtags']);
+            // Remove value from array $tags.
+            $tags = array_diff($tags, [$tagToRemove]);
+            $params['searchtags'] = implode(' ', $tags);
+
+            if (empty($params['searchtags'])) {
+                unset($params['searchtags']);
+            }
+
+            // We also remove page (keeping the same page has no sense, since the results are different)
+            unset($params['page']);
+        }
+
+        $queryParams = count($params) > 0 ? '?' . http_build_query($params) : '';
+
+        return $response->withRedirect(($currentUrl['path'] ?? './') . $queryParams);
+    }
+}