[sound-juicer] Use MCN to resolve multiple album matches

[Phillip Wood <pwood src gnome org>]

commit 8a17c083aefd42f1c307a0a9a5df69b73a41bf2e
Author: Andreas Hehn <andreasgnmhehn noiseload de>
Date:   Tue Nov 3 22:54:48 2015 +0100

    Use MCN to resolve multiple album matches
    
    Added read-out of the MCN (Media catalog number) from the CD using
    libdiscid. If the MCN matches the barcode from MusicBrainz then return
    only the matching release which avoids showing the multiple album
    dialog.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=757247

 libjuicer/sj-metadata-musicbrainz5.c |   35 ++++++++++++++++++++++++++++++++-
 1 files changed, 33 insertions(+), 2 deletions(-)
---
diff --git a/libjuicer/sj-metadata-musicbrainz5.c b/libjuicer/sj-metadata-musicbrainz5.c
index b3cdebf..edb1cda 100644
--- a/libjuicer/sj-metadata-musicbrainz5.c
+++ b/libjuicer/sj-metadata-musicbrainz5.c
@@ -917,6 +917,30 @@ make_album_from_release (SjMetadataMusicbrainz5  *self,
   return album;
 }
 
+static gboolean
+album_barcode_matches_discid_mcn (const char *barcode,
+                                  DiscId     *disc)
+{
+  const char *mcn;
+
+  if (barcode == NULL || !discid_has_feature(DISCID_FEATURE_MCN))
+    return FALSE;
+
+  mcn = discid_get_mcn (disc);
+  if (mcn == NULL)
+    return FALSE;
+  /* The MCN should match an EAN barcode (13 digits)
+   * or an UPC barcode (12 digits) with a leading '0'.
+   */
+  gsize len = strlen (barcode);
+  if (len == 12) /* UPC barcode - skip leading '0' */
+    return *mcn == '0' && strcmp (mcn + 1, barcode) == 0;
+  else if (len == 13) /* EAN barcode */
+    return strcmp (mcn, barcode) == 0;
+  else /* Unknown/invalid barcode */
+    return FALSE;
+}
+
 /*
  * Virtual methods
  */
@@ -936,6 +960,7 @@ mb5_list_albums (SjMetadata    *metadata,
   char buffer[1024];
   int i;
   DiscId disc = NULL;
+  gboolean mcn_matches = FALSE;
 
   g_return_val_if_fail (SJ_IS_METADATA_MUSICBRAINZ5 (metadata), NULL);
 
@@ -949,7 +974,7 @@ mb5_list_albums (SjMetadata    *metadata,
   disc = discid_new ();
   if (disc == NULL)
     return NULL;
-  if (discid_read_sparse (disc, priv->cdrom, 0) == 0)
+  if (discid_read_sparse (disc, priv->cdrom, DISCID_FEATURE_MCN) == 0)
     goto free_discid;
 
   if (url != NULL)
@@ -975,7 +1000,7 @@ mb5_list_albums (SjMetadata    *metadata,
   if (mb5_release_list_size (releases) == 0)
     return NULL;
 
-  for (i = 0; i < mb5_release_list_size (releases); i++) {
+  for (i = 0; i < mb5_release_list_size (releases) && !mcn_matches; i++) {
     AlbumDetails *album;
 
     release = mb5_release_list_item (releases, i);
@@ -1040,6 +1065,12 @@ artist-rels";
             }
 
             album->metadata_source = SOURCE_MUSICBRAINZ;
+            mcn_matches = album_barcode_matches_discid_mcn (album->barcode, disc);
+            if (mcn_matches) {
+              g_list_free_full (albums, (GDestroyNotify) album_details_free);
+              albums = g_list_append (NULL, album);
+              break;
+            }
             albums = g_list_append (albums, album);
           }
         }