Add exclusion in tag search

  * Searching '-mytag' will now exlude all shaares with 'mytag' tag.
  * All tags starting with a '-' are renamed without it (through the Updater).
  * Unit tests.

Minor code changes:

 * LinkDB->filter() can now take no parameters (get all link depending on logged status).
 * tagsStrToArray() is now static and filters blank tags.

3 files changed, 38 insertions, 9 deletions

diff --git a/application/LinkDB.php b/application/LinkDB.php
index a95b3f36..416aa0d3 100644
--- a/application/LinkDB.php
+++ b/application/LinkDB.php
@@ -340,7 +340,7 @@ You use the community supported version of the original Shaarli project, by Seba
      *
      * @return array filtered links
      */
-    public function filter($type, $request, $casesensitive = false, $privateonly = false)
+    public function filter($type = '', $request = '', $casesensitive = false, $privateonly = false)
     {
         $linkFilter = new LinkFilter($this->_links);
         $requestFilter = is_array($request) ? implode(' ', $request) : $request;
diff --git a/application/LinkFilter.php b/application/LinkFilter.php
index 096d3b04..ceb47d16 100644
--- a/application/LinkFilter.php
+++ b/application/LinkFilter.php
@@ -209,19 +209,33 @@ class LinkFilter
      */
     public function filterTags($tags, $casesensitive = false, $privateonly = false)
     {
-        $searchtags = $this->tagsStrToArray($tags, $casesensitive);
+        $searchtags = self::tagsStrToArray($tags, $casesensitive);
         $filtered = array();
+        if (empty($searchtags)) {
+            return $filtered;
+        }
 
-        foreach ($this->links as $l) {
+        foreach ($this->links as $link) {
             // ignore non private links when 'privatonly' is on.
-            if (! $l['private'] && $privateonly === true) {
+            if (! $link['private'] && $privateonly === true) {
                 continue;
             }
 
-            $linktags = $this->tagsStrToArray($l['tags'], $casesensitive);
+            $linktags = self::tagsStrToArray($link['tags'], $casesensitive);
 
-            if (count(array_intersect($linktags, $searchtags)) == count($searchtags)) {
-                $filtered[$l['linkdate']] = $l;
+            $found = true;
+            for ($i = 0 ; $i < count($searchtags) && $found; $i++) {
+                // Exclusive search, quit if tag found.
+                // Or, tag not found in the link, quit.
+                if (($searchtags[$i][0] == '-' && in_array(substr($searchtags[$i], 1), $linktags))
+                    || ($searchtags[$i][0] != '-') && ! in_array($searchtags[$i], $linktags)
+                ) {
+                    $found = false;
+                }
+            }
+
+            if ($found) {
+                $filtered[$link['linkdate']] = $link;
             }
         }
         krsort($filtered);
@@ -266,12 +280,12 @@ class LinkFilter
      *
      * @return array filtered tags string.
     */
-    public function tagsStrToArray($tags, $casesensitive)
+    public static function tagsStrToArray($tags, $casesensitive)
     {
         // We use UTF-8 conversion to handle various graphemes (i.e. cyrillic, or greek)
         $tagsOut = $casesensitive ? $tags : mb_convert_case($tags, MB_CASE_LOWER, 'UTF-8');
         $tagsOut = str_replace(',', ' ', $tagsOut);
 
-        return explode(' ', trim($tagsOut));
+        return array_filter(explode(' ', trim($tagsOut)), 'strlen');
     }
 }
diff --git a/application/Updater.php b/application/Updater.php
index 20ae0c4d..773a1ffa 100644
--- a/application/Updater.php
+++ b/application/Updater.php
@@ -131,6 +131,21 @@ class Updater
 
         return true;
     }
+
+    /**
+     * Rename tags starting with a '-' to work with tag exclusion search.
+     */
+    public function updateMethodRenameDashTags()
+    {
+        $linklist = $this->linkDB->filter();
+        foreach ($linklist as $link) {
+            $link['tags'] = preg_replace('/(^| )\-/', '$1', $link['tags']);
+            $link['tags'] = implode(' ', array_unique(LinkFilter::tagsStrToArray($link['tags'], true)));
+            $this->linkDB[$link['linkdate']] = $link;
+        }
+        $this->linkDB->savedb($this->config['config']['PAGECACHE']);
+        return true;
+    }
 }
 
 /**