[tracker] rss: Add support for enclosures

[Carlos Garnacho <carlosg src gnome org>]

commit deb5f6cf46e2cdbd8493e3bf12c19b13ed492fca
Author: Lucas Satabin <lucas satabin gnieh org>
Date:   Tue Jul 25 19:18:26 2017 +0200

    rss: Add support for enclosures
    
    Some feed (e.g. podcasts) use the `enclosure` element of the RSS feed
    format. The ontology supports these element throught the
    `mfo:enclosureList` relationship and `mfo:Enclosure` class.
    
    Support for enclosures is simply added by looping over such elements if
    any, and adding the relationships upon feed message insertion or update.
    Enclosures are deleted when the `mfo:FeedMessage` that links to it is
    deleted.
    
    Also fixes a problem of double free when contributor list is not empty.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=785454

 src/miners/rss/tracker-miner-rss.c |   82 +++++++++++++++++++++++++++++++++---
 1 files changed, 76 insertions(+), 6 deletions(-)
---
diff --git a/src/miners/rss/tracker-miner-rss.c b/src/miners/rss/tracker-miner-rss.c
index daa09cb..3d87052 100644
--- a/src/miners/rss/tracker-miner-rss.c
+++ b/src/miners/rss/tracker-miner-rss.c
@@ -303,8 +303,10 @@ static void
 delete_unbound_messages (TrackerMinerRSS *miner)
 {
        tracker_sparql_connection_update_async (tracker_miner_get_connection (TRACKER_MINER (miner)),
-                                               "DELETE { ?msg a rdfs:Resource }"
-                                               "WHERE  { ?msg a mfo:FeedMessage ."
+                                               "DELETE { ?msg a rdfs:Resource."
+                                               "         ?encl a rdfs:Resource. }"
+                                               "WHERE  { ?msg a mfo:FeedMessage ;"
+                                               "                mfo:enclosureList ?encl ."
                                                "              FILTER(!BOUND(nmo:communicationChannel(?msg)))"
                                                "}",
                                                G_PRIORITY_DEFAULT,
@@ -720,6 +722,37 @@ sparql_add_contact (TrackerSparqlBuilder *sparql,
        }
 }
 
+static void
+sparql_add_enclosure (TrackerSparqlBuilder *sparql,
+                      const gchar          *subject,
+                      GrssFeedEnclosure    *enclosure)
+{
+       gchar *url;
+       gint length;
+       gchar * format;
+
+       url = grss_feed_enclosure_get_url (enclosure);
+       length = grss_feed_enclosure_get_length (enclosure);
+       format = grss_feed_enclosure_get_format (enclosure);
+
+       tracker_sparql_builder_subject (sparql, subject);
+       tracker_sparql_builder_predicate (sparql, "a");
+       tracker_sparql_builder_object (sparql, "mfo:Enclosure");
+       tracker_sparql_builder_object (sparql, "nfo:RemoteDataObject");
+
+       tracker_sparql_builder_predicate (sparql, "mfo:remoteLink");
+       tracker_sparql_builder_object_unvalidated (sparql, url);
+
+       tracker_sparql_builder_predicate (sparql, "nfo:fileSize");
+       tracker_sparql_builder_object_int64 (sparql, length);
+
+       if (format != NULL) {
+               tracker_sparql_builder_predicate (sparql, "nie:mimeType");
+               tracker_sparql_builder_object_unvalidated (sparql, format);
+       }
+
+}
+
 static gchar *
 feed_message_create_update_channel_query (const gchar  *item_urn,
                                           GrssFeedItem *item)
@@ -761,10 +794,14 @@ feed_message_create_insert_builder (TrackerMinerRSS    *miner,
        GrssFeedChannel *channel;
        gboolean has_geolocation;
        const GList *contributors;
+       const GList *enclosures;
        const GList *list, *l;
        GList *contrib_aliases = NULL;
+       GList *enclosure_aliases = NULL;
        GHashTable *websites;
+       GHashTable *enclosure_urls;
        gboolean is_iri = FALSE;
+       gint i = 0;
 
        if (!item_urn) {
                item_urn = "_:message";
@@ -784,6 +821,7 @@ feed_message_create_insert_builder (TrackerMinerRSS    *miner,
        author = grss_feed_item_get_author (item);
        contributors = grss_feed_item_get_contributors (item);
        channel = grss_feed_item_get_parent (item);
+       enclosures = grss_feed_item_get_enclosures (item);
 
        for (l = contributors; l; l = l->next) {
                const gchar *person_url;
@@ -840,9 +878,9 @@ feed_message_create_insert_builder (TrackerMinerRSS    *miner,
                                    (tmp_string && tmp_string[0] != '_'));
        }
 
+       i = 0;
        for (l = contributors; l; l = l->next) {
                gchar *subject;
-               gint i = 0;
 
                g_debug ("  Contributor:'%s'", grss_person_get_name (l->data));
 
@@ -856,7 +894,33 @@ feed_message_create_insert_builder (TrackerMinerRSS    *miner,
 
                sparql_add_contact (sparql, subject, l->data, tmp_string,
                                    (tmp_string && tmp_string[0] != '_'));
-               g_free (subject);
+
+               /* subject is not freed right now as it will be freed at the end of the
+                * method in a foreach loop over the contrib_aliases list */
+       }
+
+       enclosure_urls = g_hash_table_new_full (g_str_hash, g_str_equal,
+                                               (GDestroyNotify) g_free,
+                                               (GDestroyNotify) g_free);
+       i = 0;
+       for (l = enclosures; l; l = l->next) {
+               gchar *subject;
+               gchar *url;
+
+               url = grss_feed_enclosure_get_url (l->data);
+
+               if (!g_hash_table_contains (enclosure_urls, url)) {
+                       g_debug ("  Enclosure:'%s'", url);
+                       subject = g_strdup_printf ("_:enclosure%d", i++);
+                       enclosure_aliases = g_list_prepend (enclosure_aliases, subject);
+                       g_hash_table_insert (enclosure_urls, g_strdup (url), NULL);
+
+                       sparql_add_enclosure (sparql, subject, l->data);
+
+               }
+
+               /* subject is not freed right now as it will be freed at the end of the
+                * method in a foreach loop over the enclosure_aliases list */
        }
 
        if (is_iri) {
@@ -892,6 +956,11 @@ feed_message_create_insert_builder (TrackerMinerRSS    *miner,
                tracker_sparql_builder_object (sparql, l->data);
        }
 
+       for (l = enclosure_aliases; l; l = l->next) {
+               tracker_sparql_builder_predicate (sparql, "mfo:enclosureList");
+               tracker_sparql_builder_object (sparql, l->data);
+       }
+
        tmp_string = grss_feed_item_get_description (item);
        if (tmp_string != NULL) {
                gchar *plain_text;
@@ -946,9 +1015,10 @@ feed_message_create_insert_builder (TrackerMinerRSS    *miner,
 
        tracker_sparql_builder_insert_close (sparql);
 
-       g_list_foreach (contrib_aliases, (GFunc) g_free, NULL);
-       g_list_free (contrib_aliases);
+       g_list_free_full (contrib_aliases, g_free);
+       g_list_free_full (enclosure_aliases, g_free);
        g_hash_table_destroy (websites);
+       g_hash_table_destroy (enclosure_urls);
 
        return sparql;
 }