facebook: Use FetchContactsDeltaQuery for contact sync

This has a number of benefits:

- Most of the time the contact sync reply will be empty
- We can do contact sync more frequently (It's 5 mins now, was 30)
- Figuring out what contacts were added or removed is much simpler and
  less likely to get things wrong.
- Non-friends are no longer accidentally removed because there's no need
  to compare contact lists
- On accounts with lots of friends this gets rid of one source of CPU
  usage spikes
- Less load for facebook's servers (lol)

2 files changed, 201 insertions, 30 deletions

diff --git a/libpurple/protocols/facebook/api.c b/libpurple/protocols/facebook/api.c
index 55462dc509..517a14aa4d 100644
--- a/libpurple/protocols/facebook/api.c
+++ b/libpurple/protocols/facebook/api.c
@@ -67,6 +67,7 @@ struct _FbApiPrivate
 	gboolean invisible;
 	guint unread;
 	FbId lastmid;
+	gchar *contacts_delta;
 };
 
 struct _FbApiData
@@ -87,6 +88,9 @@ fb_api_message_send(FbApi *api, FbApiMessage *msg);
 static void
 fb_api_sticker(FbApi *api, FbId sid, FbApiMessage *msg);
 
+void
+fb_api_contacts_delta(FbApi *api, const gchar *delta_cursor);
+
 G_DEFINE_TYPE(FbApi, fb_api, G_TYPE_OBJECT);
 
 static void
@@ -184,6 +188,7 @@ fb_api_dispose(GObject *obj)
 	g_free(priv->did);
 	g_free(priv->stoken);
 	g_free(priv->token);
+	g_free(priv->contacts_delta);
 }
 
 static void
@@ -342,6 +347,22 @@ fb_api_class_init(FbApiClass *klass)
 	             2, G_TYPE_POINTER, G_TYPE_BOOLEAN);
 
 	/**
+	 * FbApi::contacts-delta:
+	 * @api: The #FbApi.
+	 * @added: The #GSList of added #FbApiUser's.
+	 * @removed: The #GSList of strings with removed user ids.
+	 *
+	 * Like 'contacts', but only the deltas.
+	 */
+	g_signal_new("contacts-delta",
+	             G_TYPE_FROM_CLASS(klass),
+	             G_SIGNAL_ACTION,
+	             0,
+	             NULL, NULL, NULL,
+	             G_TYPE_NONE,
+	             2, G_TYPE_POINTER, G_TYPE_POINTER);
+
+	/**
 	 * FbApi::error:
 	 * @api: The #FbApi.
 	 * @error: The #GError.
@@ -2067,6 +2088,7 @@ fb_api_cb_contacts_nodes(FbApi *api, JsonNode *root, GSList *users)
 	FbApiUser *user;
 	FbId uid;
 	FbJsonValues *values;
+	gboolean is_array;
 	GError *err = NULL;
 
 	values = fb_json_values_new(root);
@@ -2078,8 +2100,12 @@ fb_api_cb_contacts_nodes(FbApi *api, JsonNode *root, GSList *users)
 	                   "$.structured_name.text");
 	fb_json_values_add(values, FB_JSON_TYPE_STR, FALSE,
 	                   "$.hugePictureUrl.uri");
-	fb_json_values_set_array(values, FALSE, "$.viewer.messenger_contacts"
-	                                         ".nodes");
+
+	is_array = (JSON_NODE_TYPE(root) == JSON_NODE_ARRAY);
+
+	if (is_array) {
+		fb_json_values_set_array(values, FALSE, "$");
+	}
 
 	while (fb_json_values_update(values, &err)) {
 		str = fb_json_values_next_str(values, "0");
@@ -2089,6 +2115,9 @@ fb_api_cb_contacts_nodes(FbApi *api, JsonNode *root, GSList *users)
 		if ((!purple_strequal(str, "ARE_FRIENDS") &&
 		    (uid != priv->uid)) || (uid == 0))
 		{
+			if (!is_array) {
+				break;
+			}
 			continue;
 		}
 
@@ -2100,6 +2129,10 @@ fb_api_cb_contacts_nodes(FbApi *api, JsonNode *root, GSList *users)
 		user->csum = fb_api_user_icon_checksum(user->icon);
 
 		users = g_slist_prepend(users, user);
+
+		if (!is_array) {
+			break;
+		}
 	}
 
 	g_object_unref(values);
@@ -2107,35 +2140,112 @@ fb_api_cb_contacts_nodes(FbApi *api, JsonNode *root, GSList *users)
 	return users;
 }
 
+/* base64(contact:<our id>:<their id>:<whatever>) */
+static GSList *
+fb_api_cb_contacts_parse_removed(FbApi *api, JsonNode *node, GSList *users)
+{
+	gsize len;
+	char **split;
+	char *decoded = (char *) g_base64_decode(json_node_get_string(node), &len);
+
+	g_return_val_if_fail(decoded[len] == '\0', users);
+	g_return_val_if_fail(len == strlen(decoded), users);
+	g_return_val_if_fail(g_str_has_prefix(decoded, "contact:"), users);
+
+	split = g_strsplit_set(decoded, ":", 4);
+
+	g_return_val_if_fail(g_strv_length(split) == 4, users);
+
+	users = g_slist_prepend(users, g_strdup(split[2]));
+
+	g_strfreev(split);
+	g_free(decoded);
+
+	return users;
+}
+
 static void
 fb_api_cb_contacts(PurpleHttpConnection *con, PurpleHttpResponse *res,
                    gpointer data)
 {
-	//XXX
 	const gchar *cursor;
+	const gchar *delta_cursor;
 	FbApi *api = data;
+	FbApiPrivate *priv = api->priv;
 	FbJsonValues *values;
 	gboolean complete;
+	gboolean is_delta;
 	GError *err = NULL;
+	GList *l;
 	GSList *users = NULL;
 	JsonNode *root;
+	JsonNode *croot;
+	JsonNode *node;
 
 	if (!fb_api_http_chk(api, con, res, &root)) {
 		return;
 	}
 
-	users = fb_api_cb_contacts_nodes(api, root, users);
+	croot = fb_json_node_get(root, "$.viewer.messenger_contacts.deltas", NULL);
+	is_delta = (croot != NULL);
 
-	values = fb_json_values_new(root);
+	if (!is_delta) {
+		croot = fb_json_node_get(root, "$.viewer.messenger_contacts", NULL);
+		node = fb_json_node_get(croot, "$.nodes", NULL);
+		users = fb_api_cb_contacts_nodes(api, node, users);
+		json_node_free(node);
+
+	} else {
+		GSList *added = NULL;
+		GSList *removed = NULL;
+		JsonArray *arr = fb_json_node_get_arr(croot, "$.nodes", NULL);
+		GList *elms = json_array_get_elements(arr);
+
+		for (l = elms; l != NULL; l = l->next) {
+			if ((node = fb_json_node_get(l->data, "$.added", NULL))) {
+				added = fb_api_cb_contacts_nodes(api, node, added);
+				json_node_free(node);
+			}
+
+			if ((node = fb_json_node_get(l->data, "$.removed", NULL))) {
+				removed = fb_api_cb_contacts_parse_removed(api, node, removed);
+				json_node_free(node);
+			}
+		}
+
+		g_signal_emit_by_name(api, "contacts-delta", added, removed);
+
+		g_slist_free_full(added, (GDestroyNotify) fb_api_user_free);
+		g_slist_free_full(removed, (GDestroyNotify) g_free);
+
+		g_list_free(elms);
+		json_array_unref(arr);
+	}
+
+	values = fb_json_values_new(croot);
+	fb_json_values_add(values, FB_JSON_TYPE_BOOL, FALSE,
+	                   "$.page_info.has_next_page");
 	fb_json_values_add(values, FB_JSON_TYPE_STR, FALSE,
-                       "$.viewer.messenger_contacts.page_info.end_cursor");
+	                   "$.page_info.delta_cursor");
+	fb_json_values_add(values, FB_JSON_TYPE_STR, FALSE,
+	                   "$.page_info.end_cursor");
 	fb_json_values_update(values, NULL);
 
+	complete = !fb_json_values_next_bool(values, FALSE);
+
+	delta_cursor = fb_json_values_next_str(values, NULL);
+
 	cursor = fb_json_values_next_str(values, NULL);
 
 	if (G_UNLIKELY(err == NULL)) {
-		complete = (cursor == NULL);
-		g_signal_emit_by_name(api, "contacts", users, complete);
+		if (is_delta || complete) {
+			g_free(priv->contacts_delta);
+			priv->contacts_delta = g_strdup(is_delta ? cursor : delta_cursor);
+		}
+
+		if (users) {
+			g_signal_emit_by_name(api, "contacts", users, complete);
+		}
 
 		if (!complete) {
 			fb_api_contacts_after(api, cursor);
@@ -2146,14 +2256,25 @@ fb_api_cb_contacts(PurpleHttpConnection *con, PurpleHttpResponse *res,
 
 	g_slist_free_full(users, (GDestroyNotify) fb_api_user_free);
 	g_object_unref(values);
+
+	json_node_free(croot);
 	json_node_free(root);
 }
 
 void
 fb_api_contacts(FbApi *api)
 {
+	FbApiPrivate *priv;
 	JsonBuilder *bldr;
 
+	g_return_if_fail(FB_IS_API(api));
+	priv = api->priv;
+
+	if (priv->contacts_delta) {
+		fb_api_contacts_delta(api, priv->contacts_delta);
+		return;
+	}
+
 	bldr = fb_json_bldr_new(JSON_NODE_OBJECT);
 	fb_json_bldr_arr_begin(bldr, "0");
 	fb_json_bldr_add_str(bldr, NULL, "user");
@@ -2181,6 +2302,24 @@ fb_api_contacts_after(FbApi *api, const gchar *cursor)
 }
 
 void
+fb_api_contacts_delta(FbApi *api, const gchar *delta_cursor)
+{
+	JsonBuilder *bldr;
+
+	bldr = fb_json_bldr_new(JSON_NODE_OBJECT);
+
+	fb_json_bldr_add_str(bldr, "0", delta_cursor);
+
+	fb_json_bldr_arr_begin(bldr, "1");
+	fb_json_bldr_add_str(bldr, NULL, "user");
+	fb_json_bldr_arr_end(bldr);
+
+	fb_json_bldr_add_str(bldr, "2", G_STRINGIFY(FB_API_CONTACTS_COUNT));
+	fb_api_http_query(api, FB_API_QUERY_CONTACTS_DELTA, bldr,
+	                  fb_api_cb_contacts);
+}
+
+void
 fb_api_connect(FbApi *api, gboolean invisible)
 {
 	FbApiPrivate *priv;
diff --git a/libpurple/protocols/facebook/facebook.c b/libpurple/protocols/facebook/facebook.c
index 8e7f8b2bcb..c1d28ccc2f 100644
--- a/libpurple/protocols/facebook/facebook.c
+++ b/libpurple/protocols/facebook/facebook.c
@@ -221,11 +221,11 @@ fb_sync_contacts_add_timeout(FbData *fata)
 	gc = fb_data_get_connection(fata);
 	acct = purple_connection_get_account(gc);
 
-	sync = purple_account_get_int(acct, "sync-interval", 30);
+	sync = purple_account_get_int(acct, "sync-interval", 5);
 
-	if (sync < 5) {
-		purple_account_set_int(acct, "sync-interval", 5);
-		sync = 5;
+	if (sync < 1) {
+		purple_account_set_int(acct, "sync-interval", 1);
+		sync = 1;
 	}
 
 	sync *= 60 * 1000;
@@ -242,8 +242,6 @@ fb_cb_api_contacts(FbApi *api, GSList *users, gboolean complete, gpointer data)
 	FbData *fata = data;
 	FbId muid;
 	gchar uid[FB_ID_STRMAX];
-	gpointer bata;
-	GSList *buddies;
 	GSList *l;
 	GValue val = G_VALUE_INIT;
 	PurpleAccount *acct;
@@ -293,7 +291,6 @@ fb_cb_api_contacts(FbApi *api, GSList *users, gboolean complete, gpointer data)
 			purple_blist_add_buddy(bdy, NULL, grp, NULL);
 		}
 
-		purple_buddy_set_protocol_data(bdy, GINT_TO_POINTER(TRUE));
 		purple_buddy_set_server_alias(bdy, user->name);
 		csum = purple_buddy_icons_get_checksum_for_user(bdy);
 
@@ -309,20 +306,6 @@ fb_cb_api_contacts(FbApi *api, GSList *users, gboolean complete, gpointer data)
 		return;
 	}
 
-	buddies = purple_blist_find_buddies(acct, NULL);
-
-	while (buddies != NULL) {
-		bdy = buddies->data;
-		bata = purple_buddy_get_protocol_data(bdy);
-		buddies = g_slist_delete_link(buddies, buddies);
-
-		if (GPOINTER_TO_INT(bata)) {
-			purple_buddy_set_protocol_data(bdy, NULL);
-		} else if (purple_buddy_get_group(bdy) != grpn) {
-			purple_blist_remove_buddy(bdy);
-		}
-	}
-
 	if (state != PURPLE_CONNECTION_CONNECTED) {
 		status = purple_account_get_active_status(acct);
 		type = purple_status_get_status_type(status);
@@ -336,6 +319,51 @@ fb_cb_api_contacts(FbApi *api, GSList *users, gboolean complete, gpointer data)
 }
 
 static void
+fb_cb_api_contacts_delta(FbApi *api, GSList *added, GSList *removed, gpointer data)
+{
+	FbApiUser *user;
+	FbData *fata = data;
+	gchar uid[FB_ID_STRMAX];
+	GSList *l;
+	PurpleAccount *acct;
+	PurpleBuddy *bdy;
+	PurpleConnection *gc;
+	PurpleGroup *grp;
+	PurpleGroup *grpn;
+
+	gc = fb_data_get_connection(fata);
+	acct = purple_connection_get_account(gc);
+	grp = fb_get_group(TRUE);
+	grpn = fb_get_group(FALSE);
+
+	for (l = added; l != NULL; l = l->next) {
+		user = l->data;
+		FB_ID_TO_STR(user->uid, uid);
+
+		bdy = purple_blist_find_buddy(acct, uid);
+
+		if ((bdy != NULL) && (purple_buddy_get_group(bdy) == grpn)) {
+			purple_blist_remove_buddy(bdy);
+		}
+
+		bdy = purple_buddy_new(acct, uid, NULL);
+		purple_blist_add_buddy(bdy, NULL, grp, NULL);
+
+		purple_buddy_set_server_alias(bdy, user->name);
+	}
+
+	for (l = removed; l != NULL; l = l->next) {
+		bdy = purple_blist_find_buddy(acct, l->data);
+
+		if (bdy != NULL) {
+			purple_blist_remove_buddy(bdy);
+		}
+	}
+
+	fb_sync_contacts_add_timeout(fata);
+}
+
+static void
 fb_cb_api_error(FbApi *api, GError *error, gpointer data)
 {
 	FbData *fata = data;
@@ -963,6 +991,10 @@ fb_login(PurpleAccount *acct)
 	                 G_CALLBACK(fb_cb_api_contacts),
 	                 fata);
 	g_signal_connect(api,
+	                 "contacts-delta",
+	                 G_CALLBACK(fb_cb_api_contacts_delta),
+	                 fata);
+	g_signal_connect(api,
 	                 "error",
 	                 G_CALLBACK(fb_cb_api_error),
 	                 fata);
@@ -1486,7 +1518,7 @@ facebook_protocol_init(PurpleProtocol *protocol)
 	protocol->options = OPT_PROTO_CHAT_TOPIC;
 
 	opt = purple_account_option_int_new(_("Buddy list sync interval"),
-	                                    "sync-interval", 30);
+	                                    "sync-interval", 5);
 	opts = g_list_prepend(opts, opt);
 
 	opt = purple_account_option_bool_new(_("Mark messages as read"),