12 files changed, 254 insertions, 110 deletions

diff --git a/application/bookmark/Bookmark.php b/application/bookmark/Bookmark.php
index ea565d1f..4238ef25 100644
--- a/application/bookmark/Bookmark.php
+++ b/application/bookmark/Bookmark.php
@@ -19,7 +19,7 @@ use Shaarli\Bookmark\Exception\InvalidBookmarkException;
 class Bookmark
 {
     /** @var string Date format used in string (former ID format) */
-    const LINK_DATE_FORMAT = 'Ymd_His';
+    public const LINK_DATE_FORMAT = 'Ymd_His';
 
     /** @var int Bookmark ID */
     protected $id;
@@ -60,11 +60,13 @@ class Bookmark
     /**
      * Initialize a link from array data. Especially useful to create a Bookmark from former link storage format.
      *
-     * @param array $data
+     * @param array  $data
+     * @param string $tagsSeparator Tags separator loaded from the config file.
+     *                              This is a context data, and it should *never* be stored in the Bookmark object.
      *
      * @return $this
      */
-    public function fromArray(array $data): Bookmark
+    public function fromArray(array $data, string $tagsSeparator = ' '): Bookmark
     {
         $this->id = $data['id'] ?? null;
         $this->shortUrl = $data['shorturl'] ?? null;
@@ -77,7 +79,7 @@ class Bookmark
         if (is_array($data['tags'])) {
             $this->tags = $data['tags'];
         } else {
-            $this->tags = preg_split('/\s+/', $data['tags'] ?? '', -1, PREG_SPLIT_NO_EMPTY);
+            $this->tags = tags_str2array($data['tags'] ?? '', $tagsSeparator);
         }
         if (! empty($data['updated'])) {
             $this->updated = $data['updated'];
@@ -104,7 +106,8 @@ class Bookmark
      */
     public function validate(): void
     {
-        if ($this->id === null
+        if (
+            $this->id === null
             || ! is_int($this->id)
             || empty($this->shortUrl)
             || empty($this->created)
@@ -112,7 +115,7 @@ class Bookmark
             throw new InvalidBookmarkException($this);
         }
         if (empty($this->url)) {
-            $this->url = '/shaare/'. $this->shortUrl;
+            $this->url = '/shaare/' . $this->shortUrl;
         }
         if (empty($this->title)) {
             $this->title = $this->url;
@@ -348,7 +351,12 @@ class Bookmark
      */
     public function setTags(?array $tags): Bookmark
     {
-        $this->setTagsString(implode(' ', $tags ?? []));
+        $this->tags = array_map(
+            function (string $tag): string {
+                return $tag[0] === '-' ? substr($tag, 1) : $tag;
+            },
+            tags_filter($tags, ' ')
+        );
 
         return $this;
     }
@@ -378,6 +386,24 @@ class Bookmark
     }
 
     /**
+     * Return true if:
+     *   - the bookmark's thumbnail is not already set to false (= not found)
+     *   - it's not a note
+     *   - it's an HTTP(S) link
+     *   - the thumbnail has not yet be retrieved (null) or its associated cache file doesn't exist anymore
+     *
+     * @return bool True if the bookmark's thumbnail needs to be retrieved.
+     */
+    public function shouldUpdateThumbnail(): bool
+    {
+        return $this->thumbnail !== false
+            && !$this->isNote()
+            && startsWith(strtolower($this->url), 'http')
+            && (null === $this->thumbnail || !is_file($this->thumbnail))
+        ;
+    }
+
+    /**
      * Get the Sticky.
      *
      * @return bool
@@ -402,11 +428,13 @@ class Bookmark
     }
 
     /**
-     * @return string Bookmark's tags as a string, separated by a space
+     * @param string $separator Tags separator loaded from the config file.
+     *
+     * @return string Bookmark's tags as a string, separated by a separator
      */
-    public function getTagsString(): string
+    public function getTagsString(string $separator = ' '): string
     {
-        return implode(' ', $this->getTags());
+        return tags_array2str($this->getTags(), $separator);
     }
 
     /**
@@ -426,19 +454,13 @@ class Bookmark
      *   - trailing dash in tags will be removed
      *
      * @param string|null $tags
+     * @param string      $separator Tags separator loaded from the config file.
      *
      * @return $this
      */
-    public function setTagsString(?string $tags): Bookmark
+    public function setTagsString(?string $tags, string $separator = ' '): Bookmark
     {
-        // Remove first '-' char in tags.
-        $tags = preg_replace('/(^| )\-/', '$1', $tags ?? '');
-        // Explode all tags separted by spaces or commas
-        $tags = preg_split('/[\s,]+/', $tags);
-        // Remove eventual empty values
-        $tags = array_values(array_filter($tags));
-
-        $this->tags = $tags;
+        $this->setTags(tags_str2array($tags, $separator));
 
         return $this;
     }
@@ -489,7 +511,7 @@ class Bookmark
      */
     public function renameTag(string $fromTag, string $toTag): void
     {
-        if (($pos = array_search($fromTag, $this->tags)) !== false) {
+        if (($pos = array_search($fromTag, $this->tags ?? [])) !== false) {
             $this->tags[$pos] = trim($toTag);
         }
     }
@@ -501,7 +523,7 @@ class Bookmark
      */
     public function deleteTag(string $tag): void
     {
-        if (($pos = array_search($tag, $this->tags)) !== false) {
+        if (($pos = array_search($tag, $this->tags ?? [])) !== false) {
             unset($this->tags[$pos]);
             $this->tags = array_values($this->tags);
         }
diff --git a/application/bookmark/BookmarkArray.php b/application/bookmark/BookmarkArray.php
index 67bb3b73..b9328116 100644
--- a/application/bookmark/BookmarkArray.php
+++ b/application/bookmark/BookmarkArray.php
@@ -72,7 +72,8 @@ class BookmarkArray implements \Iterator, \Countable, \ArrayAccess
      */
     public function offsetSet($offset, $value)
     {
-        if (! $value instanceof Bookmark
+        if (
+            ! $value instanceof Bookmark
             || $value->getId() === null || empty($value->getUrl())
             || ($offset !== null && ! is_int($offset)) || ! is_int($value->getId())
             || $offset !== null && $offset !== $value->getId()
@@ -222,7 +223,8 @@ class BookmarkArray implements \Iterator, \Countable, \ArrayAccess
      */
     public function getByUrl(string $url): ?Bookmark
     {
-        if (! empty($url)
+        if (
+            ! empty($url)
             && isset($this->urls[$url])
             && isset($this->bookmarks[$this->urls[$url]])
         ) {
diff --git a/application/bookmark/BookmarkFileService.php b/application/bookmark/BookmarkFileService.php
index eb7899bf..6666a251 100644
--- a/application/bookmark/BookmarkFileService.php
+++ b/application/bookmark/BookmarkFileService.php
@@ -69,7 +69,7 @@ class BookmarkFileService implements BookmarkServiceInterface
         } else {
             try {
                 $this->bookmarks = $this->bookmarksIO->read();
-            } catch (EmptyDataStoreException|DatastoreNotInitializedException $e) {
+            } catch (EmptyDataStoreException | DatastoreNotInitializedException $e) {
                 $this->bookmarks = new BookmarkArray();
 
                 if ($this->isLoggedIn) {
@@ -85,25 +85,29 @@ class BookmarkFileService implements BookmarkServiceInterface
             if (! $this->bookmarks instanceof BookmarkArray) {
                 $this->migrate();
                 exit(
-                    'Your data store has been migrated, please reload the page.'. PHP_EOL .
+                    'Your data store has been migrated, please reload the page.' . PHP_EOL .
                     'If this message keeps showing up, please delete data/updates.txt file.'
                 );
             }
         }
 
-        $this->bookmarkFilter = new BookmarkFilter($this->bookmarks);
+        $this->bookmarkFilter = new BookmarkFilter($this->bookmarks, $this->conf);
     }
 
     /**
      * @inheritDoc
      */
-    public function findByHash(string $hash): Bookmark
+    public function findByHash(string $hash, string $privateKey = null): Bookmark
     {
         $bookmark = $this->bookmarkFilter->filter(BookmarkFilter::$FILTER_HASH, $hash);
         // PHP 7.3 introduced array_key_first() to avoid this hack
         $first = reset($bookmark);
-        if (! $this->isLoggedIn && $first->isPrivate()) {
-            throw new Exception('Not authorized');
+        if (
+            !$this->isLoggedIn
+            && $first->isPrivate()
+            && (empty($privateKey) || $privateKey !== $first->getAdditionalContentEntry('private_key'))
+        ) {
+            throw new BookmarkNotFoundException();
         }
 
         return $first;
@@ -162,7 +166,8 @@ class BookmarkFileService implements BookmarkServiceInterface
         }
 
         $bookmark = $this->bookmarks[$id];
-        if (($bookmark->isPrivate() && $visibility != 'all' && $visibility != 'private')
+        if (
+            ($bookmark->isPrivate() && $visibility != 'all' && $visibility != 'private')
             || (! $bookmark->isPrivate() && $visibility != 'all' && $visibility != 'public')
         ) {
             throw new Exception('Unauthorized');
@@ -262,7 +267,8 @@ class BookmarkFileService implements BookmarkServiceInterface
         }
 
         $bookmark = $this->bookmarks[$id];
-        if (($bookmark->isPrivate() && $visibility != 'all' && $visibility != 'private')
+        if (
+            ($bookmark->isPrivate() && $visibility != 'all' && $visibility != 'private')
             || (! $bookmark->isPrivate() && $visibility != 'all' && $visibility != 'public')
         ) {
             return false;
@@ -304,7 +310,8 @@ class BookmarkFileService implements BookmarkServiceInterface
         $caseMapping = [];
         foreach ($bookmarks as $bookmark) {
             foreach ($bookmark->getTags() as $tag) {
-                if (empty($tag)
+                if (
+                    empty($tag)
                     || (! $this->isLoggedIn && startsWith($tag, '.'))
                     || $tag === BookmarkMarkdownFormatter::NO_MD_TAG
                     || in_array($tag, $filteringTags, true)
@@ -340,26 +347,42 @@ class BookmarkFileService implements BookmarkServiceInterface
     /**
      * @inheritDoc
      */
-    public function days(): array
-    {
-        $bookmarkDays = [];
-        foreach ($this->search() as $bookmark) {
-            $bookmarkDays[$bookmark->getCreated()->format('Ymd')] = 0;
+    public function findByDate(
+        \DateTimeInterface $from,
+        \DateTimeInterface $to,
+        ?\DateTimeInterface &$previous,
+        ?\DateTimeInterface &$next
+    ): array {
+        $out = [];
+        $previous = null;
+        $next = null;
+
+        foreach ($this->search([], null, false, false, true) as $bookmark) {
+            if ($to < $bookmark->getCreated()) {
+                $next = $bookmark->getCreated();
+            } elseif ($from < $bookmark->getCreated() && $to > $bookmark->getCreated()) {
+                $out[] = $bookmark;
+            } else {
+                if ($previous !== null) {
+                    break;
+                }
+                $previous = $bookmark->getCreated();
+            }
         }
-        $bookmarkDays = array_keys($bookmarkDays);
-        sort($bookmarkDays);
 
-        return array_map('strval', $bookmarkDays);
+        return $out;
     }
 
     /**
      * @inheritDoc
      */
-    public function filterDay(string $request)
+    public function getLatest(): ?Bookmark
     {
-        $visibility = $this->isLoggedIn ? BookmarkFilter::$ALL : BookmarkFilter::$PUBLIC;
+        foreach ($this->search([], null, false, false, true) as $bookmark) {
+            return $bookmark;
+        }
 
-        return $this->bookmarkFilter->filter(BookmarkFilter::$FILTER_DAY, $request, false, $visibility);
+        return null;
     }
 
     /**
@@ -386,14 +409,14 @@ class BookmarkFileService implements BookmarkServiceInterface
             false
         );
         $updater = new LegacyUpdater(
-            UpdaterUtils::read_updates_file($this->conf->get('resource.updates')),
+            UpdaterUtils::readUpdatesFile($this->conf->get('resource.updates')),
             $bookmarkDb,
             $this->conf,
             true
         );
         $newUpdates = $updater->update();
         if (! empty($newUpdates)) {
-            UpdaterUtils::write_updates_file(
+            UpdaterUtils::writeUpdatesFile(
                 $this->conf->get('resource.updates'),
                 $updater->getDoneUpdates()
             );
diff --git a/application/bookmark/BookmarkFilter.php b/application/bookmark/BookmarkFilter.php
index c79386ea..db83c51c 100644
--- a/application/bookmark/BookmarkFilter.php
+++ b/application/bookmark/BookmarkFilter.php
@@ -6,6 +6,7 @@ namespace Shaarli\Bookmark;
 
 use Exception;
 use Shaarli\Bookmark\Exception\BookmarkNotFoundException;
+use Shaarli\Config\ConfigManager;
 
 /**
  * Class LinkFilter.
@@ -58,12 +59,16 @@ class BookmarkFilter
      */
     private $bookmarks;
 
+    /** @var ConfigManager */
+    protected $conf;
+
     /**
      * @param Bookmark[] $bookmarks initialization.
      */
-    public function __construct($bookmarks)
+    public function __construct($bookmarks, ConfigManager $conf)
     {
         $this->bookmarks = $bookmarks;
+        $this->conf = $conf;
     }
 
     /**
@@ -107,10 +112,14 @@ class BookmarkFilter
                     $filtered = $this->bookmarks;
                 }
                 if (!empty($request[0])) {
-                    $filtered = (new BookmarkFilter($filtered))->filterTags($request[0], $casesensitive, $visibility);
+                    $filtered = (new BookmarkFilter($filtered, $this->conf))
+                        ->filterTags($request[0], $casesensitive, $visibility)
+                    ;
                 }
                 if (!empty($request[1])) {
-                    $filtered = (new BookmarkFilter($filtered))->filterFulltext($request[1], $visibility);
+                    $filtered = (new BookmarkFilter($filtered, $this->conf))
+                        ->filterFulltext($request[1], $visibility)
+                    ;
                 }
                 return $filtered;
             case self::$FILTER_TEXT:
@@ -141,7 +150,7 @@ class BookmarkFilter
             return $this->bookmarks;
         }
 
-        $out = array();
+        $out = [];
         foreach ($this->bookmarks as $key => $value) {
             if ($value->isPrivate() && $visibility === 'private') {
                 $out[$key] = $value;
@@ -280,8 +289,9 @@ class BookmarkFilter
      *
      * @return string generated regex fragment
      */
-    private static function tag2regex(string $tag): string
+    protected function tag2regex(string $tag): string
     {
+        $tagsSeparator = $this->conf->get('general.tags_separator', ' ');
         $len = strlen($tag);
         if (!$len || $tag === "-" || $tag === "*") {
             // nothing to search, return empty regex
@@ -295,12 +305,13 @@ class BookmarkFilter
             $i = 0; // start at first character
             $regex = '(?='; // use positive lookahead
         }
-        $regex .= '.*(?:^| )'; // before tag may only be a space or the beginning
+        // before tag may only be the separator or the beginning
+        $regex .= '.*(?:^|' . $tagsSeparator . ')';
         // iterate over string, separating it into placeholder and content
         for (; $i < $len; $i++) {
             if ($tag[$i] === '*') {
                 // placeholder found
-                $regex .= '[^ ]*?';
+                $regex .= '[^' . $tagsSeparator . ']*?';
             } else {
                 // regular characters
                 $offset = strpos($tag, '*', $i);
@@ -316,7 +327,8 @@ class BookmarkFilter
                 $i = $offset;
             }
         }
-        $regex .= '(?:$| ))'; // after the tag may only be a space or the end
+        // after the tag may only be the separator or the end
+        $regex .= '(?:$|' . $tagsSeparator . '))';
         return $regex;
     }
 
@@ -334,14 +346,15 @@ class BookmarkFilter
      */
     public function filterTags($tags, bool $casesensitive = false, string $visibility = 'all')
     {
+        $tagsSeparator = $this->conf->get('general.tags_separator', ' ');
         // get single tags (we may get passed an array, even though the docs say different)
         $inputTags = $tags;
         if (!is_array($tags)) {
             // we got an input string, split tags
-            $inputTags = preg_split('/(?:\s+)|,/', $inputTags, -1, PREG_SPLIT_NO_EMPTY);
+            $inputTags = tags_str2array($inputTags, $tagsSeparator);
         }
 
-        if (!count($inputTags)) {
+        if (count($inputTags) === 0) {
             // no input tags
             return $this->noFilter($visibility);
         }
@@ -358,7 +371,7 @@ class BookmarkFilter
         }
 
         // build regex from all tags
-        $re = '/^' . implode(array_map("self::tag2regex", $inputTags)) . '.*$/';
+        $re = '/^' . implode(array_map([$this, 'tag2regex'], $inputTags)) . '.*$/';
         if (!$casesensitive) {
             // make regex case insensitive
             $re .= 'i';
@@ -378,10 +391,11 @@ class BookmarkFilter
                     continue;
                 }
             }
-            $search = $link->getTagsString(); // build search string, start with tags of current link
+            // build search string, start with tags of current link
+            $search = $link->getTagsString($tagsSeparator);
             if (strlen(trim($link->getDescription())) && strpos($link->getDescription(), '#') !== false) {
                 // description given and at least one possible tag found
-                $descTags = array();
+                $descTags = [];
                 // find all tags in the form of #tag in the description
                 preg_match_all(
                     '/(?<![' . self::$HASHTAG_CHARS . '])#([' . self::$HASHTAG_CHARS . ']+?)\b/sm',
@@ -390,9 +404,9 @@ class BookmarkFilter
                 );
                 if (count($descTags[1])) {
                     // there were some tags in the description, add them to the search string
-                    $search .= ' ' . implode(' ', $descTags[1]);
+                    $search .= $tagsSeparator . tags_array2str($descTags[1], $tagsSeparator);
                 }
-            };
+            }
             // match regular expression with search string
             if (!preg_match($re, $search)) {
                 // this entry does _not_ match our regex
@@ -422,7 +436,7 @@ class BookmarkFilter
                 }
             }
 
-            if (empty(trim($link->getTagsString()))) {
+            if (empty($link->getTags())) {
                 $filtered[$key] = $link;
             }
         }
@@ -537,10 +551,11 @@ class BookmarkFilter
      */
     protected function buildFullTextSearchableLink(Bookmark $link, array &$lengths): string
     {
-        $content  = mb_convert_case($link->getTitle(), MB_CASE_LOWER, 'UTF-8') .'\\';
-        $content .= mb_convert_case($link->getDescription(), MB_CASE_LOWER, 'UTF-8') .'\\';
-        $content .= mb_convert_case($link->getUrl(), MB_CASE_LOWER, 'UTF-8') .'\\';
-        $content .= mb_convert_case($link->getTagsString(), MB_CASE_LOWER, 'UTF-8') .'\\';
+        $tagString = $link->getTagsString($this->conf->get('general.tags_separator', ' '));
+        $content  = mb_convert_case($link->getTitle(), MB_CASE_LOWER, 'UTF-8') . '\\';
+        $content .= mb_convert_case($link->getDescription(), MB_CASE_LOWER, 'UTF-8') . '\\';
+        $content .= mb_convert_case($link->getUrl(), MB_CASE_LOWER, 'UTF-8') . '\\';
+        $content .= mb_convert_case($tagString, MB_CASE_LOWER, 'UTF-8') . '\\';
 
         $lengths['title'] = ['start' => 0, 'end' => mb_strlen($link->getTitle())];
         $nextField = $lengths['title']['end'] + 1;
@@ -548,7 +563,7 @@ class BookmarkFilter
         $nextField = $lengths['description']['end'] + 1;
         $lengths['url'] = ['start' => $nextField, 'end' => $nextField + mb_strlen($link->getUrl())];
         $nextField = $lengths['url']['end'] + 1;
-        $lengths['tags'] = ['start' => $nextField, 'end' => $nextField + mb_strlen($link->getTagsString())];
+        $lengths['tags'] = ['start' => $nextField, 'end' => $nextField + mb_strlen($tagString)];
 
         return $content;
     }
diff --git a/application/bookmark/BookmarkIO.php b/application/bookmark/BookmarkIO.php
index f40fa476..8439d470 100644
--- a/application/bookmark/BookmarkIO.php
+++ b/application/bookmark/BookmarkIO.php
@@ -4,6 +4,7 @@ declare(strict_types=1);
 
 namespace Shaarli\Bookmark;
 
+use malkusch\lock\exception\LockAcquireException;
 use malkusch\lock\mutex\Mutex;
 use malkusch\lock\mutex\NoMutex;
 use Shaarli\Bookmark\Exception\DatastoreNotInitializedException;
@@ -80,7 +81,7 @@ class BookmarkIO
         }
 
         $content = null;
-        $this->mutex->synchronized(function () use (&$content) {
+        $this->synchronized(function () use (&$content) {
             $content = file_get_contents($this->datastore);
         });
 
@@ -112,18 +113,35 @@ class BookmarkIO
         if (is_file($this->datastore) && !is_writeable($this->datastore)) {
             // The datastore exists but is not writeable
             throw new NotWritableDataStoreException($this->datastore);
-        } else if (!is_file($this->datastore) && !is_writeable(dirname($this->datastore))) {
+        } elseif (!is_file($this->datastore) && !is_writeable(dirname($this->datastore))) {
             // The datastore does not exist and its parent directory is not writeable
             throw new NotWritableDataStoreException(dirname($this->datastore));
         }
 
-        $data = self::$phpPrefix.base64_encode(gzdeflate(serialize($links))).self::$phpSuffix;
+        $data = self::$phpPrefix . base64_encode(gzdeflate(serialize($links))) . self::$phpSuffix;
 
-        $this->mutex->synchronized(function () use ($data) {
+        $this->synchronized(function () use ($data) {
             file_put_contents(
                 $this->datastore,
                 $data
             );
         });
     }
+
+    /**
+     * Wrapper applying mutex to provided function.
+     * If the lock can't be acquired (e.g. some shared hosting provider), we execute the function without mutex.
+     *
+     * @see https://github.com/shaarli/Shaarli/issues/1650
+     *
+     * @param callable $function
+     */
+    protected function synchronized(callable $function): void
+    {
+        try {
+            $this->mutex->synchronized($function);
+        } catch (LockAcquireException $exception) {
+            $function();
+        }
+    }
 }
diff --git a/application/bookmark/BookmarkInitializer.php b/application/bookmark/BookmarkInitializer.php
index 04b996f3..8ab5c441 100644
--- a/application/bookmark/BookmarkInitializer.php
+++ b/application/bookmark/BookmarkInitializer.php
@@ -13,6 +13,9 @@ namespace Shaarli\Bookmark;
  * To prevent data corruption, it does not overwrite existing bookmarks,
  * even though there should not be any.
  *
+ * We disable this because otherwise it creates indentation issues, and heredoc is not supported by PHP gettext.
+ * @phpcs:disable Generic.Files.LineLength.TooLong
+ *
  * @package Shaarli\Bookmark
  */
 class BookmarkInitializer
@@ -36,10 +39,10 @@ class BookmarkInitializer
     public function initialize(): void
     {
         $bookmark = new Bookmark();
-        $bookmark->setTitle('quicksilver (loop) on Vimeo ' . t('(private bookmark with thumbnail demo)'));
-        $bookmark->setUrl('https://vimeo.com/153493904');
+        $bookmark->setTitle('Calm Jazz Music - YouTube ' . t('(private bookmark with thumbnail demo)'));
+        $bookmark->setUrl('https://www.youtube.com/watch?v=DVEUcbPkb-c');
         $bookmark->setDescription(t(
-'Shaarli will automatically pick up the thumbnail for links to a variety of websites.
+            'Shaarli will automatically pick up the thumbnail for links to a variety of websites.
 
 Explore your new Shaarli instance by trying out controls and menus.
 Visit the project on [Github](https://github.com/shaarli/Shaarli) or [the documentation](https://shaarli.readthedocs.io/en/master/) to learn more about Shaarli.
@@ -54,7 +57,7 @@ Now you can edit or delete the default shaares.
         $bookmark = new Bookmark();
         $bookmark->setTitle(t('Note: Shaare descriptions'));
         $bookmark->setDescription(t(
-'Adding a shaare without entering a URL creates a text-only "note" post such as this one.
+            'Adding a shaare without entering a URL creates a text-only "note" post such as this one.
 This note is private, so you are the only one able to see it while logged in.
 
 You can use this to keep notes, post articles, code snippets, and much more.
@@ -91,7 +94,7 @@ Markdown also supports tables:
             'Shaarli - ' . t('The personal, minimalist, super-fast, database free, bookmarking service')
         );
         $bookmark->setDescription(t(
-'Welcome to Shaarli!
+            'Welcome to Shaarli!
 
 Shaarli allows you to bookmark your favorite pages, and share them with others or store them privately.
 You can add a description to your bookmarks, such as this one, and tag them.
diff --git a/application/bookmark/BookmarkServiceInterface.php b/application/bookmark/BookmarkServiceInterface.php
index 37a54d03..08cdbb4e 100644
--- a/application/bookmark/BookmarkServiceInterface.php
+++ b/application/bookmark/BookmarkServiceInterface.php
@@ -20,13 +20,14 @@ interface BookmarkServiceInterface
     /**
      * Find a bookmark by hash
      *
-     * @param string $hash
+     * @param string      $hash       Bookmark's hash
+     * @param string|null $privateKey Optional key used to access private links while logged out
      *
      * @return Bookmark
      *
      * @throws \Exception
      */
-    public function findByHash(string $hash): Bookmark;
+    public function findByHash(string $hash, string $privateKey = null);
 
     /**
      * @param $url
@@ -155,22 +156,29 @@ interface BookmarkServiceInterface
     public function bookmarksCountPerTag(array $filteringTags = [], ?string $visibility = null): array;
 
     /**
-     * Returns the list of days containing articles (oldest first)
+     * Return a list of bookmark matching provided period of time.
+     * It also update directly previous and next date outside of given period found in the datastore.
      *
-     * @return array containing days (in format YYYYMMDD).
+     * @param \DateTimeInterface      $from     Starting date.
+     * @param \DateTimeInterface      $to       Ending date.
+     * @param \DateTimeInterface|null $previous (by reference) updated with first created date found before $from.
+     * @param \DateTimeInterface|null $next     (by reference) updated with first created date found after $to.
+     *
+     * @return array List of bookmarks matching provided period of time.
      */
-    public function days(): array;
+    public function findByDate(
+        \DateTimeInterface $from,
+        \DateTimeInterface $to,
+        ?\DateTimeInterface &$previous,
+        ?\DateTimeInterface &$next
+    ): array;
 
     /**
-     * Returns the list of articles for a given day.
-     *
-     * @param string $request day to filter. Format: YYYYMMDD.
+     * Returns the latest bookmark by creation date.
      *
-     * @return Bookmark[] list of shaare found.
-     *
-     * @throws BookmarkNotFoundException
+     * @return Bookmark|null Found Bookmark or null if the datastore is empty.
      */
-    public function filterDay(string $request);
+    public function getLatest(): ?Bookmark;
 
     /**
      * Creates the default database after a fresh install.
diff --git a/application/bookmark/LinkUtils.php b/application/bookmark/LinkUtils.php
index faf5dbfd..0ab2d213 100644
--- a/application/bookmark/LinkUtils.php
+++ b/application/bookmark/LinkUtils.php
@@ -67,17 +67,20 @@ function html_extract_tag($tag, $html)
     $propertiesKey = ['property', 'name', 'itemprop'];
     $properties = implode('|', $propertiesKey);
     // We need a OR here to accept either 'property=og:noquote' or 'property="og:unrelated og:my-tag"'
-    $orCondition  = '["\']?(?:og:)?'. $tag .'["\']?|["\'][^\'"]*?(?:og:)?' . $tag . '[^\'"]*?[\'"]';
-    // Try to retrieve OpenGraph image.
-    $ogRegex = '#<meta[^>]+(?:'. $properties .')=(?:'. $orCondition .')[^>]*content=["\'](.*?)["\'].*?>#';
+    $orCondition  = '["\']?(?:og:)?' . $tag . '["\']?|["\'][^\'"]*?(?:og:)?' . $tag . '[^\'"]*?[\'"]';
+    // Support quotes in double quoted content, and the other way around
+    $content = 'content=(["\'])((?:(?!\1).)*)\1';
+    // Try to retrieve OpenGraph tag.
+    $ogRegex = '#<meta[^>]+(?:' . $properties . ')=(?:' . $orCondition . ')[^>]*' . $content . '.*?>#';
     // If the attributes are not in the order property => content (e.g. Github)
     // New regex to keep this readable... more or less.
-    $ogRegexReverse = '#<meta[^>]+content=["\'](.*?)["\'][^>]+(?:'. $properties .')=(?:'. $orCondition .').*?>#';
+    $ogRegexReverse = '#<meta[^>]+' . $content . '[^>]+(?:' . $properties . ')=(?:' . $orCondition . ').*?>#';
 
-    if (preg_match($ogRegex, $html, $matches) > 0
+    if (
+        preg_match($ogRegex, $html, $matches) > 0
         || preg_match($ogRegexReverse, $html, $matches) > 0
     ) {
-        return $matches[1];
+        return $matches[2];
     }
 
     return false;
@@ -116,7 +119,7 @@ function hashtag_autolink($description, $indexUrl = '')
      * \p{Mn} - any non marking space (accents, umlauts, etc)
      */
     $regex = '/(^|\s)#([\p{Pc}\p{N}\p{L}\p{Mn}]+)/mui';
-    $replacement = '$1<a href="'. $indexUrl .'./add-tag/$2" title="Hashtag $2">#$2</a>';
+    $replacement = '$1<a href="' . $indexUrl . './add-tag/$2" title="Hashtag $2">#$2</a>';
     return preg_replace($regex, $replacement, $description);
 }
 
@@ -138,12 +141,17 @@ function space2nbsp($text)
  *
  * @param string $description shaare's description.
  * @param string $indexUrl    URL to Shaarli's index.
-
+ * @param bool   $autolink    Turn on/off automatic linkifications of URLs and hashtags
+ *
  * @return string formatted description.
  */
-function format_description($description, $indexUrl = '')
+function format_description($description, $indexUrl = '', $autolink = true)
 {
-    return nl2br(space2nbsp(hashtag_autolink(text2clickable($description), $indexUrl)));
+    if ($autolink) {
+        $description = hashtag_autolink(text2clickable($description), $indexUrl);
+    }
+
+    return nl2br(space2nbsp($description));
 }
 
 /**
@@ -171,3 +179,49 @@ function is_note($linkUrl)
 {
     return isset($linkUrl[0]) && $linkUrl[0] === '?';
 }
+
+/**
+ * Extract an array of tags from a given tag string, with provided separator.
+ *
+ * @param string|null $tags      String containing a list of tags separated by $separator.
+ * @param string      $separator Shaarli's default: ' ' (whitespace)
+ *
+ * @return array List of tags
+ */
+function tags_str2array(?string $tags, string $separator): array
+{
+    // For whitespaces, we use the special \s regex character
+    $separator = $separator === ' ' ? '\s' : $separator;
+
+    return preg_split('/\s*' . $separator . '+\s*/', trim($tags) ?? '', -1, PREG_SPLIT_NO_EMPTY);
+}
+
+/**
+ * Return a tag string with provided separator from a list of tags.
+ * Note that given array is clean up by tags_filter().
+ *
+ * @param array|null $tags      List of tags
+ * @param string     $separator
+ *
+ * @return string
+ */
+function tags_array2str(?array $tags, string $separator): string
+{
+    return implode($separator, tags_filter($tags, $separator));
+}
+
+/**
+ * Clean an array of tags: trim + remove empty entries
+ *
+ * @param array|null $tags List of tags
+ * @param string     $separator
+ *
+ * @return array
+ */
+function tags_filter(?array $tags, string $separator): array
+{
+    $trimDefault = " \t\n\r\0\x0B";
+    return array_values(array_filter(array_map(function (string $entry) use ($separator, $trimDefault): string {
+        return trim($entry, $trimDefault . $separator);
+    }, $tags ?? [])));
+}
diff --git a/application/bookmark/exception/BookmarkNotFoundException.php b/application/bookmark/exception/BookmarkNotFoundException.php
index 827a3d35..a91d1efa 100644
--- a/application/bookmark/exception/BookmarkNotFoundException.php
+++ b/application/bookmark/exception/BookmarkNotFoundException.php
@@ -1,4 +1,5 @@
 <?php
+
 namespace Shaarli\Bookmark\Exception;
 
 use Exception;
diff --git a/application/bookmark/exception/EmptyDataStoreException.php b/application/bookmark/exception/EmptyDataStoreException.php
index cd48c1e6..16a98470 100644
--- a/application/bookmark/exception/EmptyDataStoreException.php
+++ b/application/bookmark/exception/EmptyDataStoreException.php
@@ -1,7 +1,7 @@
 <?php
 
-
 namespace Shaarli\Bookmark\Exception;
 
-
-class EmptyDataStoreException extends \Exception {}
+class EmptyDataStoreException extends \Exception
+{
+}
diff --git a/application/bookmark/exception/InvalidBookmarkException.php b/application/bookmark/exception/InvalidBookmarkException.php
index 10c84a6d..fe184f8c 100644
--- a/application/bookmark/exception/InvalidBookmarkException.php
+++ b/application/bookmark/exception/InvalidBookmarkException.php
@@ -16,14 +16,14 @@ class InvalidBookmarkException extends \Exception
             } else {
                 $created = 'Not a DateTime object';
             }
-            $this->message = 'This bookmark is not valid'. PHP_EOL;
-            $this->message .= ' - ID: '. $bookmark->getId() . PHP_EOL;
-            $this->message .= ' - Title: '. $bookmark->getTitle() . PHP_EOL;
-            $this->message .= ' - Url: '. $bookmark->getUrl() . PHP_EOL;
-            $this->message .= ' - ShortUrl: '. $bookmark->getShortUrl() . PHP_EOL;
-            $this->message .= ' - Created: '. $created . PHP_EOL;
+            $this->message = 'This bookmark is not valid' . PHP_EOL;
+            $this->message .= ' - ID: ' . $bookmark->getId() . PHP_EOL;
+            $this->message .= ' - Title: ' . $bookmark->getTitle() . PHP_EOL;
+            $this->message .= ' - Url: ' . $bookmark->getUrl() . PHP_EOL;
+            $this->message .= ' - ShortUrl: ' . $bookmark->getShortUrl() . PHP_EOL;
+            $this->message .= ' - Created: ' . $created . PHP_EOL;
         } else {
-            $this->message = 'The provided data is not a bookmark'. PHP_EOL;
+            $this->message = 'The provided data is not a bookmark' . PHP_EOL;
             $this->message .= var_export($bookmark, true);
         }
     }
diff --git a/application/bookmark/exception/NotWritableDataStoreException.php b/application/bookmark/exception/NotWritableDataStoreException.php
index 95f34b50..df91f3bc 100644
--- a/application/bookmark/exception/NotWritableDataStoreException.php
+++ b/application/bookmark/exception/NotWritableDataStoreException.php
@@ -1,9 +1,7 @@
 <?php
 
-
 namespace Shaarli\Bookmark\Exception;
 
-
 class NotWritableDataStoreException extends \Exception
 {
     /**
@@ -13,7 +11,7 @@ class NotWritableDataStoreException extends \Exception
      */
     public function __construct($dataStore)
     {
-        $this->message = 'Couldn\'t load data from the data store file "'. $dataStore .'". '.
+        $this->message = 'Couldn\'t load data from the data store file "' . $dataStore . '". ' .
             'Your data might be corrupted, or your file isn\'t readable.';
     }
 }