[core] Added APIs to modify metadata

2 files changed, 126 insertions, 0 deletions

diff --git a/src/grl-metadata-source.c b/src/grl-metadata-source.c
index 94bd04c..f0ffc65 100644
--- a/src/grl-metadata-source.c
+++ b/src/grl-metadata-source.c
@@ -283,6 +283,16 @@ resolve_idle (gpointer user_data)
   return FALSE;
 }
 
+static gboolean
+set_metadata_idle (gpointer user_data)
+{
+  g_debug ("set_metadata_idle");
+  GrlMetadataSourceSetMetadataSpec *sms =
+    (GrlMetadataSourceSetMetadataSpec *) user_data;
+  GRL_METADATA_SOURCE_GET_CLASS (sms->source)->set_metadata (sms->source, sms);
+  return FALSE;
+}
+
 /* ================ API ================ */
 
 /**
@@ -340,6 +350,27 @@ grl_metadata_source_key_depends (GrlMetadataSource *source, GrlKeyID key_id)
 }
 
 /**
+ * grl_metadata_source_writable_keys:
+ * @source: a metadata source
+ *
+ * Similar to grl_metadata_source_supported_keys(), but these keys
+ * are marked as writable, meaning the source allows the client 
+ * to provide new values for these keys that will be stored permanently.
+ *
+ * Returns: (transfer none) (allow-none): a #GList with the keys
+ */
+const GList *
+grl_metadata_source_writable_keys (GrlMetadataSource *source)
+{
+  g_return_val_if_fail (GRL_IS_METADATA_SOURCE (source), NULL);
+  if (GRL_METADATA_SOURCE_GET_CLASS (source)->writable_keys) {
+    return GRL_METADATA_SOURCE_GET_CLASS (source)->writable_keys (source);
+  } else {
+    return NULL;
+  }
+}
+
+/**
  * grl_metadata_source_resolve:
  * @source: a metadata source
  * @keys: the #GList of #GrlKeyID to retrieve
@@ -716,6 +747,48 @@ grl_metadata_source_get_description (GrlMetadataSource *source)
 }
 
 /**
+ * grl_metadata_source_set_metadata:
+ * @source: a metadata source
+ * @media: the #GrlMedia object that we want to operate on.
+ * @key: a #GrlKeyID which value we want to change.
+ * @callback: the callback to execute when the operation is finished.
+ * @user_data: user data set for the @callback
+ *
+ * This is the main method of the #GrlMetadataSource class. It will
+ * get the value for @key from @media and store it permanently. After
+ * calling this method, future queries that return this media object 
+ * shall return this new value for the selected key.
+ *
+ * This function is asynchronic and uses the Glib's main loop.
+ */
+void
+grl_metadata_source_set_metadata (GrlMetadataSource *source,
+				  GrlMedia *media,
+				  GrlKeyID key_id,
+				  GrlMetadataSourceSetMetadataCb callback,
+				  gpointer user_data)
+{
+  GrlMetadataSourceSetMetadataSpec *sms;
+
+  g_debug ("grl_metadata_source_set_metadata");
+
+  g_return_if_fail (GRL_IS_METADATA_SOURCE (source));
+  g_return_if_fail (callback != NULL);
+  g_return_if_fail (media != NULL);
+  g_return_if_fail (grl_metadata_source_supported_operations (source) &
+		    GRL_OP_SET_METADATA);
+
+  sms = g_new0 (GrlMetadataSourceSetMetadataSpec, 1);
+  sms->source = g_object_ref (source);
+  sms->media = g_object_ref (media);
+  sms->key_id = key_id;
+  sms->callback = callback;
+  sms->user_data = user_data;
+
+  g_idle_add (set_metadata_idle, sms);  
+}
+
+/**
  * grl_metadata_source_supported_operations:
  * @source: a metadata source
  *
@@ -738,5 +811,8 @@ grl_metadata_source_supported_operations_impl (GrlMetadataSource *source)
   metadata_source_class = GRL_METADATA_SOURCE_GET_CLASS (source);
   if (metadata_source_class->resolve)
     caps |= GRL_OP_RESOLVE;
+  if (metadata_source_class->set_metadata)
+    caps |= GRL_OP_SET_METADATA;
   return caps;
 }
+
diff --git a/src/grl-metadata-source.h b/src/grl-metadata-source.h
index e95ab27..e5033da 100644
--- a/src/grl-metadata-source.h
+++ b/src/grl-metadata-source.h
@@ -103,6 +103,21 @@ typedef void (*GrlMetadataSourceResolveCb) (GrlMetadataSource *source,
                                             GrlMedia *media,
                                             gpointer user_data,
                                             const GError *error);
+
+/**
+ * GrlMetadataSourceSetMetadataCb:
+ * @source: a metadata source
+ * @media: a #GrlMedia transfer object
+ * @user_data: user data passed to grl_metadata_source_set_metadata()
+ * @error: (not-error): possible #GError generated when updating the metadata
+ *
+ * Prototype for the callback passed to grl_metadata_source_set_metadata()
+ */
+typedef void (*GrlMetadataSourceSetMetadataCb) (GrlMetadataSource *source,
+						GrlMedia *media,
+						gpointer user_data,
+						const GError *error);
+
 /* Types for GrlMetadataSource */
 
 /**
@@ -128,6 +143,24 @@ typedef struct {
 } GrlMetadataSourceResolveSpec;
 
 /**
+ * GrlMetadataSourceSetMetadataSpec:
+ * @source: a metadata source
+ * @media: a #GrlMedia transfer object
+ * @key_id: Key which value is to be stored
+ * @callback: the callback passed to grl_metadata_source_set_metadata()
+ * @user_data: user data passed to grl_metadata_source_set_metadata()
+ *
+ * Represents the closure used by the derived objects to operate.
+ */
+typedef struct {
+  GrlMetadataSource *source;
+  GrlMedia *media;
+  GrlKeyID key_id;
+  GrlMetadataSourceSetMetadataCb callback;
+  gpointer user_data;
+} GrlMetadataSourceSetMetadataSpec;
+
+/**
  * GrlSupportedOps:
  * @GRL_OP_NONE: no one operation is supported
  * @GRL_OP_METADATA: TBD
@@ -152,6 +185,7 @@ typedef enum {
   GRL_OP_STORE        = 1 << 5,
   GRL_OP_STORE_PARENT = 1 << 6,
   GRL_OP_REMOVE       = 1 << 7,
+  GRL_OP_SET_METADATA = 1 << 8,
 } GrlSupportedOps;
 
 /* GrlMetadataSource class */
@@ -165,7 +199,10 @@ typedef struct _GrlMetadataSourceClass GrlMetadataSourceClass;
  * @supported_keys: the list of keys that can be handled
  * @slow_keys: the list of slow keys that can be fetched
  * @key_depends: the list of keys which @key_id depends on
+ * @writable_keys: the list of keys which value can be written
  * @resolve: resolve the metadata of a given transfer object
+ * @set_metadata: update metadata values for a given object in a
+ * permanent fashion
  *
  * Grilo MetadataSource class. Override the vmethods to implement the
  * element functionality.
@@ -182,8 +219,13 @@ struct _GrlMetadataSourceClass {
 
   const GList * (*key_depends) (GrlMetadataSource *source, GrlKeyID key_id);
 
+  const GList * (*writable_keys) (GrlMetadataSource *source);
+
   void (*resolve) (GrlMetadataSource *source,
 		   GrlMetadataSourceResolveSpec *rs);
+
+  void (*set_metadata) (GrlMetadataSource *source,
+			GrlMetadataSourceSetMetadataSpec *sms);
 };
 
 G_BEGIN_DECLS
@@ -207,6 +249,8 @@ GList *grl_metadata_source_filter_slow (GrlMetadataSource *source,
 const GList *grl_metadata_source_key_depends (GrlMetadataSource *source,
                                               GrlKeyID key_id);
 
+const GList *grl_metadata_source_writable_keys (GrlMetadataSource *source);
+
 void grl_metadata_source_resolve (GrlMetadataSource *source,
                                   const GList *keys,
                                   GrlMedia *media,
@@ -214,6 +258,12 @@ void grl_metadata_source_resolve (GrlMetadataSource *source,
                                   GrlMetadataSourceResolveCb callback,
                                   gpointer user_data);
 
+void grl_metadata_source_set_metadata (GrlMetadataSource *source,
+				       GrlMedia *media,
+				       GrlKeyID key_id,
+				       GrlMetadataSourceSetMetadataCb callback,
+				       gpointer user_data);
+
 const gchar *grl_metadata_source_get_id (GrlMetadataSource *source);
 
 const gchar *grl_metadata_source_get_name (GrlMetadataSource *source);