1 files changed, 119 insertions, 0 deletions

diff --git a/admin/include/functions.php b/admin/include/functions.php
index 9a827d1d6..030e7fa31 100644
--- a/admin/include/functions.php
+++ b/admin/include/functions.php
@@ -1519,6 +1519,8 @@ function add_tags($tags, $images)
     return;
   }
 
+  $taglist_before = get_image_tag_ids($images);
+
   // we can't insert twice the same {image_id,tag_id} so we must first
   // delete lines we'll insert later
   $query = '
@@ -1545,6 +1547,11 @@ DELETE
     array_keys($inserts[0]),
     $inserts
     );
+
+  $taglist_after = get_image_tag_ids($images);
+  $images_to_update = compare_image_tag_lists($taglist_before, $taglist_after);
+  update_images_lastmodified($images_to_update);
+
   invalidate_user_cache_nb_tags();
 }
 
@@ -1565,6 +1572,15 @@ function delete_tags($tag_ids)
     return false;
   }
 
+  // we need the list of impacted images, to update their lastmodified
+  $query = '
+SELECT
+    image_id
+  FROM '.IMAGE_TAG_TABLE.'
+  WHERE tag_id IN ('.implode(',', $tag_ids).')
+;';
+  $image_ids = query2array($query, null, 'image_id');
+
   $query = '
 DELETE
   FROM '.IMAGE_TAG_TABLE.'
@@ -1579,6 +1595,7 @@ DELETE
 ;';
   pwg_query($query);
 
+  update_images_lastmodified($image_ids);
   invalidate_user_cache_nb_tags();
 }
 
@@ -1662,6 +1679,9 @@ function set_tags_of($tags_of)
 {
   if (count($tags_of) > 0)
   {
+    $taglist_before = get_image_tag_ids(array_keys($tags_of));
+    global $logger; $logger->debug('taglist_before', $taglist_before);
+
     $query = '
 DELETE
   FROM '.IMAGE_TAG_TABLE.'
@@ -1691,11 +1711,83 @@ DELETE
         );
     }
 
+    $taglist_after = get_image_tag_ids(array_keys($tags_of));
+    global $logger; $logger->debug('taglist_after', $taglist_after);
+    $images_to_update = compare_image_tag_lists($taglist_before, $taglist_after);
+    global $logger; $logger->debug('$images_to_update', $images_to_update);
+
+    update_images_lastmodified($images_to_update);
     invalidate_user_cache_nb_tags();
   }
 }
 
 /**
+ * Get list of tag ids for each image. Returns an empty list if the image has
+ * no tags.
+ *
+ * @since 2.9
+ * @param array $image_ids
+ * @return associative array, image_id => list of tag ids
+ */
+function get_image_tag_ids($image_ids)
+{
+  if (!is_array($image_ids) and is_int($image_ids))
+  {
+    $images_ids = array($image_ids);
+  }
+  
+  if (count($image_ids) == 0)
+  {
+    return array();
+  }
+
+  $query = '
+SELECT
+    image_id,
+    tag_id
+  FROM '.IMAGE_TAG_TABLE.'
+  WHERE image_id IN ('.implode(',', $image_ids).')
+;';
+
+  $tags_of = array_fill_keys($image_ids, array());
+  $image_tags = query2array($query);
+  foreach ($image_tags as $image_tag)
+  {
+    $tags_of[ $image_tag['image_id'] ][] = $image_tag['tag_id'];
+  }
+  
+  return $tags_of;
+}
+
+/**
+ * Compare the list of tags, for each image. Returns image_ids where tag list has changed.
+ *
+ * @since 2.9
+ * @param array $taglist_before - for each image_id (key), list of tag ids
+ * @param array $taglist_after - for each image_id (key), list of tag ids
+ * @return array - image_ids where the list has changed
+ */
+function compare_image_tag_lists($taglist_before, $taglist_after)
+{
+  $images_to_update = array();
+
+  foreach ($taglist_after as $image_id => $list_after)
+  {
+    sort($list_after);
+
+    $list_before = isset($taglist_before[$image_id]) ? $taglist_before[$image_id] : array();
+    sort($list_before);
+    
+    if ($list_after != $list_before)
+    {
+      $images_to_update[] = $image_id;
+    }
+  }
+
+  return $images_to_update;
+}
+
+/**
  * Associate a list of images to a list of categories.
  * The function will not duplicate links and will preserve ranks.
  *
@@ -2887,3 +2979,30 @@ function save_images_order($category_id, $images)
     );
   mass_updates(IMAGE_CATEGORY_TABLE, $fields, $datas);
 }
+
+/**
+ * Force update on images.lastmodified column. Useful when modifying the tag
+ * list.
+ *
+ * @since 2.9
+ * @param array $image_ids
+ */
+function update_images_lastmodified($image_ids)
+{
+  if (!is_array($image_ids) and is_int($image_ids))
+  {
+    $images_ids = array($image_ids);
+  }
+  
+  if (count($image_ids) == 0)
+  {
+    return;
+  }
+
+  $query = '
+UPDATE '.IMAGES_TABLE.'
+  SET lastmodified = NOW()
+  WHERE id IN ('.implode(',', $image_ids).')
+;';
+  pwg_query($query);
+}