degesch: watch away statuses with away-notify/WHO

We're not going to implement polling.  Polling is complex.
Freenode supports away-notify.

degesch.c

@@ -1310,10 +1310,9 @@ struct user
 	REF_COUNTABLE_HEADER
 
 	char *nickname;                     ///< Literal nickname
-	// TODO: write code to poll for the away status
 	bool away;                          ///< User is away
 
-	struct user_channel *channels;      ///< Channels the user is on
+	struct user_channel *channels;      ///< Channels the user is on (with us)
 };
 
 static struct ispect_field g_user_ispect[] =
@@ -1379,6 +1378,8 @@ struct channel
 {
 	REF_COUNTABLE_HEADER
 
+	struct server *s;                   ///< Server
+
 	char *name;                         ///< Channel name
 	char *topic;                        ///< Channel topic
 
@@ -1391,6 +1392,7 @@ struct channel
 	size_t users_len;                   ///< User count
 
 	bool left_manually;                 ///< Don't rejoin on reconnect
+	bool show_names_after_who;          ///< RPL_ENDOFWHO delays RPL_ENDOFNAMES
 };
 
 static struct ispect_field g_channel_ispect[] =
@@ -1405,12 +1407,12 @@ static struct ispect_field g_channel_ispect[] =
 };
 
 static struct channel *
-channel_new (char *name, char *topic)
+channel_new (struct server *s, char *name)
 {
 	struct channel *self = xcalloc (1, sizeof *self);
 	self->ref_count = 1;
+	self->s = s;
 	self->name = name;
-	self->topic = topic;
 	self->no_param_modes = str_make ();
 	self->param_modes = str_map_make (free);
 	self->names_buf = strv_make ();
@@ -1714,7 +1716,8 @@ struct server
 	char *irc_user_host;                ///< Our current user@host
 	bool autoaway_active;               ///< Autoaway is currently active
 
-	bool cap_echo_message;              ///< Whether the server echos messages
+	bool cap_echo_message;              ///< Whether the server echoes messages
+	bool cap_away_notify;               ///< Whether we get AWAY notifications
 
 	// Server-specific information (from RPL_ISUPPORT):
 
@@ -2329,7 +2332,8 @@ static struct config_schema g_config_server[] =
 	  .comment   = "Capabilities to use if supported by server",
 	  .type      = CONFIG_ITEM_STRING_ARRAY,
 	  .validate  = config_validate_nonjunk_string,
-	  .default_  = "\"multi-prefix,invite-notify,server-time,echo-message\"" },
+	  .default_  = "\"multi-prefix,invite-notify,server-time,echo-message,"
+		"message-tags,away-notify\"" },
 
 	{ .name      = "tls",
 	  .comment   = "Whether to use TLS",
@@ -4523,6 +4527,11 @@ irc_channel_unlink_user
 			user_channel_destroy (iter);
 		}
 
+	// TODO: poll the away status for users we don't share a channel with.
+	//   It might or might not be worth to auto-set this on with RPL_AWAY.
+	if (!user->channels && user != channel->s->irc_user)
+		user->away = false;
+
 	// Then just unlink the user from the channel
 	LIST_UNLINK (channel->users, channel_user);
 	channel_user_destroy (channel_user);
@@ -4545,7 +4554,7 @@ irc_make_channel (struct server *s, char *name)
 {
 	hard_assert (!str_map_find (&s->irc_channels, name));
 
-	struct channel *channel = channel_new (name, NULL);
+	struct channel *channel = channel_new (s, name);
 	(void) channel_weak_ref (channel, irc_channel_on_destroy, s);
 	str_map_set (&s->irc_channels, channel->name, channel);
 	return channel;
@@ -4571,6 +4580,9 @@ irc_remove_user_from_channel (struct user *user, struct channel *channel)
 static void
 irc_left_channel (struct channel *channel)
 {
+	strv_reset (&channel->names_buf);
+	channel->show_names_after_who = false;
+
 	LIST_FOR_EACH (struct channel_user, iter, channel->users)
 		irc_channel_unlink_user (channel, iter);
 }
@@ -6456,6 +6468,21 @@ irc_process_sent_message (const struct irc_message *msg, struct server *s)
 
 // --- Input handling ----------------------------------------------------------
 
+static void
+irc_handle_away (struct server *s, const struct irc_message *msg)
+{
+	if (!msg->prefix)
+		return;
+
+	char *nickname = irc_cut_nickname (msg->prefix);
+	struct user *user = str_map_find (&s->irc_users, nickname);
+	free (nickname);
+
+	// Let's allow the server to make us away
+	if (user)
+		user->away = !!msg->params.len;
+}
+
 static void
 irc_handle_cap (struct server *s, const struct irc_message *msg)
 {
@@ -6483,6 +6510,8 @@ irc_handle_cap (struct server *s, const struct irc_message *msg)
 			}
 			if (!strcasecmp_ascii (cap, "echo-message"))
 				s->cap_echo_message = active;
+			if (!strcasecmp_ascii (cap, "away-notify"))
+				s->cap_away_notify = active;
 		}
 		irc_send (s, "CAP END");
 	}
@@ -6596,6 +6625,9 @@ irc_handle_join (struct server *s, const struct irc_message *msg)
 		str_reset (&channel->no_param_modes);
 		str_map_clear (&channel->param_modes);
 		irc_send (s, "MODE %s", channel_name);
+
+		if ((channel->show_names_after_who = s->cap_away_notify))
+			irc_send (s, "WHO %s", channel_name);
 	}
 
 	// Add the user to the channel
@@ -7153,6 +7185,7 @@ irc_handle_topic (struct server *s, const struct irc_message *msg)
 static struct irc_handler g_irc_handlers[] =
 {
 	// This list needs to stay sorted
+	{ "AWAY",    irc_handle_away    },
 	{ "CAP",     irc_handle_cap     },
 	{ "ERROR",   irc_handle_error   },
 	{ "INVITE",  irc_handle_invite  },
@@ -7359,11 +7392,16 @@ make_channel_users_list (struct server *s, struct channel *channel)
 
 	qsort (entries, n_users, sizeof *entries, channel_user_sort_entry_cmp);
 
+	// Make names of users that are away italicised, constructing a formatter
+	// and adding a new attribute seems like unnecessary work
 	struct str list = str_make ();
 	for (i = 0; i < n_users; i++)
 	{
-		irc_get_channel_user_prefix (s, entries[i].channel_user, &list);
+		struct channel_user *channel_user = entries[i].channel_user;
-		str_append (&list, entries[i].channel_user->user->nickname);
+		if (channel_user->user->away) str_append_c (&list, '\x1d');
+		irc_get_channel_user_prefix (s, channel_user, &list);
+		str_append (&list, channel_user->user->nickname);
+		if (channel_user->user->away) str_append_c (&list, '\x1d');
 		str_append_c (&list, ' ');
 	}
 	if (list.len)
@@ -7392,6 +7430,17 @@ irc_sync_channel_user (struct server *s, struct channel *channel,
 		cstr_set (&channel_user->prefixes, xstrdup (prefixes));
 }
 
+static void
+irc_process_names_finish (struct server *s, struct channel *channel)
+{
+	struct buffer *buffer = str_map_find (&s->irc_buffer_map, channel->name);
+	if (buffer)
+	{
+		log_server_status (s, buffer, "Users on #S: #&m",
+			channel->name, make_channel_users_list (s, channel));
+	}
+}
+
 static void
 irc_process_names (struct server *s, struct channel *channel)
 {
@@ -7421,15 +7470,8 @@ irc_process_names (struct server *s, struct channel *channel)
 	str_map_free (&present);
 	strv_reset (&channel->names_buf);
 
-	char *all_users = make_channel_users_list (s, channel);
+	if (!channel->show_names_after_who)
-	struct buffer *buffer = str_map_find (&s->irc_buffer_map, channel->name);
+		irc_process_names_finish (s, channel);
-	if (buffer)
-	{
-		log_server_status (s, buffer, "Users on #S: #S",
-			channel->name, all_users);
-	}
-
-	free (all_users);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@@ -7453,6 +7495,47 @@ irc_handle_rpl_endofnames (struct server *s, const struct irc_message *msg)
 		irc_process_names (s, channel);
 }
 
+static bool
+irc_handle_rpl_whoreply (struct server *s, const struct irc_message *msg)
+{
+	if (msg->params.len < 7)
+		return false;
+
+	// Sequence: channel, user, host, server, nick, chars
+	const char *channel_name = msg->params.vector[1];
+	const char *nickname     = msg->params.vector[5];
+	const char *chars        = msg->params.vector[6];
+
+	struct channel *channel = str_map_find (&s->irc_channels, channel_name);
+	struct user *user = str_map_find (&s->irc_users, nickname);
+
+	// This makes sense to set only with the away-notify capability so far.
+	// We track ourselves by other means and we can't track PM-only users yet.
+	if (!channel || !channel->show_names_after_who
+	 || !user || user == s->irc_user || !user->channels)
+		return false;
+
+	user->away = *chars == 'G';
+	return true;
+}
+
+static bool
+irc_handle_rpl_endofwho (struct server *s, const struct irc_message *msg)
+{
+	if (msg->params.len < 2)
+		return false;
+
+	const char *target = msg->params.vector[1];
+
+	struct channel *channel = str_map_find (&s->irc_channels, target);
+	if (!channel || !channel->show_names_after_who)
+		return false;
+
+	irc_process_names_finish (s, channel);
+	channel->show_names_after_who = false;
+	return true;
+}
+
 static void
 irc_handle_rpl_topic (struct server *s, const struct irc_message *msg)
 {
@@ -7790,9 +7873,12 @@ irc_process_numeric (struct server *s,
 		if (s->irc_user) s->irc_user->away = false;
 		break;
 
-	case IRC_RPL_LIST:
 	case IRC_RPL_WHOREPLY:
+		if (irc_handle_rpl_whoreply (s, msg))  buffer = NULL; break;
 	case IRC_RPL_ENDOFWHO:
+		if (irc_handle_rpl_endofwho (s, msg))  buffer = NULL; break;
+
+	case IRC_RPL_LIST:
 
 	case IRC_ERR_UNKNOWNCOMMAND:
 	case IRC_ERR_NEEDMOREPARAMS:
@@ -8255,6 +8341,7 @@ server_remove (struct app_context *ctx, struct server *s)
 static void
 server_rename (struct app_context *ctx, struct server *s, const char *new_name)
 {
+	hard_assert (!str_map_find (&ctx->servers, new_name));
 	str_map_set (&ctx->servers, new_name,
 		str_map_steal (&ctx->servers, s->name));