Pick a new album cover when the photo that's the current cover is

deleted.  Fixes ticket #1083.

modules/gallery/helpers/gallery_event.php

@@ -97,6 +97,17 @@ static function item_created($item) {
 
   static function item_deleted($item) {
     access::delete_item($item);
+
+    $parent = $item->parent();
+    if (!$parent->album_cover_item_id) {
+      // Assume we deleted the album cover and pick a new one.  Choosing the first photo in the
+      // album is logical, but it's not the most efficient in the case where we're deleting all
+      // the photos in the album one at a time since we'll probably delete them in order which
+      // means that we'll be resetting the album cover each time.
+      if ($child = $parent->children(1)->current()) {
+        item::make_album_cover($child);
+      }
+    }
   }
 
   static function item_moved($item, $old_parent) {

modules/gallery/tests/Item_Helper_Test.php

@@ -54,7 +54,6 @@ public function move_test() {
     $this->assert_same($dst_album->id, $photo->parent_id);
   }
 
-
   public function move_updates_album_covers_test() {
     // 2 photos in the source album
     $src_album = test::random_album();
@@ -106,4 +105,16 @@ public function move_conflicts_result_in_a_rename_test() {
     $this->assert_not_same("{$rand}.jpg", $photo2->name);
     $this->assert_not_same($rand, $photo2->slug);
   }
+
+  public function delete_cover_photo_picks_new_album_cover() {
+    $album = test::random_album();
+    $photo1 = test::random_photo($album);
+    // At this point, $photo1 is the album cover.  We verify this in
+    // Item_Model_Test::first_photo_becomes_album_cover
+    $photo2 = test::random_photo($album);
+    $photo1->delete();
+    $album->reload();
+
+    $this->assert_same($photo2->id, $album->album_cover_item_id);
+  }
 }

modules/gallery/tests/Item_Model_Test.php

@@ -363,4 +363,12 @@ public function as_restful_array_test() {
     $this->assert_true(!array_key_exists("parent_id", $result));
     $this->assert_true(!array_key_exists("album_cover_item_id", $result));
   }
+
+  public function first_photo_becomes_album_cover() {
+    $album = test::random_album();
+    $photo = test::random_photo($album);
+    $album->reload();
+
+    $this->assert_same($photo->id, $album->album_cover_item_id);
+  }
 }