Add ability to disable avatar publishing

Add "/avatar disable" to comply with point "3.5 Publisher Disables
Avatar Publishing" in XEP-0084.

src/command/cmd_defs.c:2416
Add "disable" argument. Reword the "/avatar" command description
so it flows better.

src/command/cmd_ac.c:1101
Add "disable" to the "/avatar" autocomplete dictionary.

src/command/cmd_funcs.c:9277
Split "/avatar" commands into two groups with an if statement; those
with a parameter and those without. "cons_bad_cmd_usage()" is in both
groups, which is messy. "disable" has similar logic to "set", but it
includes a failure message.

src/xmpp/avatar.c:152
"avatar_publishing_disable()" uses the same logic to publish metadata
as in "avatar_set()".

src/xmpp/avatar.c:238
Add a message to inform users when they do not receive an avatar after
using "/avatar get" and "/avatar open". In case of a failure, the user
will be subscribed to future avatar updates as long as they continue
to use their current instance of profanity. Adding
"caps_remove_feature()" after "cons_show()" will unsubscribe the user
from avatar updates and prevent the user from downloading an avatar
unexpectedly hours later without issuing an "/avatar" command.

src/xmpp/stanza.c:2698
The new "disable" function follows the same logic as
"stanza_create_avatar_metadata_publish_iq()".

src/command/cmd_ac.c

@@ -1102,6 +1102,7 @@ cmd_ac_init(void)
 
     avatar_ac = autocomplete_new();
     autocomplete_add(avatar_ac, "set");
+    autocomplete_add(avatar_ac, "disable");
     autocomplete_add(avatar_ac, "get");
     autocomplete_add(avatar_ac, "open");
 

src/command/cmd_defs.c

@@ -2418,25 +2418,29 @@ static const struct cmd_t command_defs[] = {
     },
 
     { CMD_PREAMBLE("/avatar",
-                   parse_args, 2, 2, NULL)
+                   parse_args, 1, 2, NULL)
       CMD_MAINFUNC(cmd_avatar)
       CMD_TAGS(
               CMD_TAG_CHAT)
       CMD_SYN(
               "/avatar set <path>",
+              "/avatar disable",
               "/avatar get <barejid>",
               "/avatar open <barejid>")
       CMD_DESC(
-              "Upload avatar for oneself (XEP-0084). "
-              "Download avatar (XEP-0084) for a certain contact. "
-              "If nothing happens after using this command the user either doesn't have an avatar set at all "
+              "Upload an avatar for yourself, "
+              "disable your avatar, "
+              "or download a contact's avatar (XEP-0084). "
+              "If nothing happens after using this command, the user either doesn't have an avatar set "
               "or doesn't use XEP-0084 to publish it.")
       CMD_ARGS(
               { "set <path>", "Set avatar to the image at <path>." },
+              { "disable", "Disable avatar publishing; your avatar will not display to others." },
               { "get <barejid>", "Download the avatar. barejid is the JID to download avatar from." },
               { "open <barejid>", "Download avatar and open it with command." })
       CMD_EXAMPLES(
               "/avatar set ~/images/avatar.png",
+              "/avatar disable",
               "/avatar get thor@valhalla.edda",
               "/avatar open freyja@vanaheimr.edda") },
 

src/command/cmd_funcs.c

@@ -9287,25 +9287,34 @@ gboolean
 cmd_avatar(ProfWin* window, const char* const command, gchar** args)
 {
     if (args[1] == NULL) {
-        cons_bad_cmd_usage(command);
-        return TRUE;
-    }
-
-    if (g_strcmp0(args[0], "set") == 0) {
-#ifdef HAVE_PIXBUF
-        if (avatar_set(args[1])) {
-            cons_show("Avatar updated successfully");
+        if (g_strcmp0(args[0], "disable") == 0) {
+            if (avatar_publishing_disable()) {
+                cons_show("Avatar publishing disabled. To enable avatar publishing, use '/avatar set <path>'.");
+            } else {
+                cons_show("Failed to disable avatar publishing.");
+            }
+        } else {
+            cons_bad_cmd_usage(command);
         }
+    } else {
+        if (g_strcmp0(args[0], "set") == 0) {
+#ifdef HAVE_PIXBUF
+            if (avatar_set(args[1])) {
+                cons_show("Avatar updated successfully");
+            }
 #else
-        cons_show("Profanity has not been built with GDK Pixbuf support enabled which is needed to scale the avatar when uploading.");
+            cons_show("Profanity has not been built with GDK Pixbuf support enabled which is needed to scale the avatar when uploading.");
 #endif
-    } else if (g_strcmp0(args[0], "get") == 0) {
-        avatar_get_by_nick(args[1], false);
-    } else if (g_strcmp0(args[0], "open") == 0) {
-        avatar_get_by_nick(args[1], true);
-    } else if (g_strcmp0(args[0], "cmd") == 0) {
-        prefs_set_string(PREF_AVATAR_CMD, args[1]);
-        cons_show("Avatar cmd set to: %s", args[1]);
+        } else if (g_strcmp0(args[0], "get") == 0) {
+            avatar_get_by_nick(args[1], false);
+        } else if (g_strcmp0(args[0], "open") == 0) {
+            avatar_get_by_nick(args[1], true);
+        } else if (g_strcmp0(args[0], "cmd") == 0) {
+            prefs_set_string(PREF_AVATAR_CMD, args[1]);
+            cons_show("Avatar cmd set to: %s", args[1]);
+        } else {
+            cons_bad_cmd_usage(command);
+        }
     }
 
     return TRUE;