introduced i3 command for changing the hidden state and the mode of i3bar

The hidden_state and mode of each i3bar instance can now be controlled from within i3.
Therefore, two new i3 command were introduced:
    _
    bar hidden_state show|hide|toggle [<bar_id>]

    show: always show the bar
    hide: normal hide mode
    toggle: toggle between show and hide (individually for each bar)
    _
    bar mode dock|hide|invisible|toggle [<bar_id>]

    hide,dock: like before
    invisible: always keep the bar hidden
    toggle: toggle between dock and hide (individually for each bar)

This patch introduces a hidden_state ("hidden_state hide|show") in the
barconfig, which indicates the current hidden_state of each i3bar
instance. It only affects the bar when in hide mode. Additionally, a new
invisible mode was introduced. In order to change the hidden_state or
mode of the bar from i3, a barconfig-update event was introduced, for
which a bar can subscribe and the bar then gets notified about the
currently set hidden_state and mode in its barconfig.

For convenience, an id field ("id <bar_id>") was added to the barconfig, where one can
set the desired id for the corresponding bar. If the id is not specified, i3 will
deterministically choose an id; otherwise, with the previous random approach for finding
a new id, which is actually not shared with i3bar, as it would determine its id on
startup, the event-subscription would be destroyed on reload. Still, this issue remains
when manually changing the bar_id in the config and then reloading.

fixes #833, #651

src/commands.c

@@ -1632,6 +1632,8 @@ void cmd_reload(I3_CMD) {
     x_set_i3_atoms();
     /* Send an IPC event just in case the ws names have changed */
     ipc_send_event("workspace", I3_IPC_EVENT_WORKSPACE, "{\"change\":\"reload\"}");
+    /* Send an update event for the barconfig just in case it has changed */
+    update_barconfig();
 
     // XXX: default reply for now, make this a better reply
     ysuccess(true);
@@ -1915,3 +1917,113 @@ void cmd_rename_workspace(I3_CMD, char *old_name, char *new_name) {
 
     ipc_send_event("workspace", I3_IPC_EVENT_WORKSPACE, "{\"change\":\"rename\"}");
 }
+
+/*
+ * Implementation of 'bar mode dock|hide|invisible|toggle [<bar_id>]'
+ *
+ */
+bool cmd_bar_mode(char *bar_mode, char *bar_id) {
+    int mode;
+    bool toggle = false;
+    if (strcmp(bar_mode, "dock") == 0)
+        mode = M_DOCK;
+    else if (strcmp(bar_mode, "hide") == 0)
+        mode = M_HIDE;
+    else if (strcmp(bar_mode, "invisible") == 0)
+        mode = M_INVISIBLE;
+    else if (strcmp(bar_mode, "toggle") == 0)
+        toggle = true;
+    else {
+        ELOG("Unknown bar mode \"%s\", this is a mismatch between code and parser spec.\n", bar_mode);
+        return false;
+    }
+
+    bool changed_sth = false;
+    Barconfig *current = NULL;
+    TAILQ_FOREACH(current, &barconfigs, configs) {
+        if (bar_id && strcmp(current->id, bar_id) != 0)
+            continue;
+
+        if (toggle)
+            mode = (current->mode + 1) % 2;
+
+        DLOG("Changing bar mode of bar_id '%s' to '%s (%d)'\n", current->id, bar_mode, mode);
+        current->mode = mode;
+        changed_sth = true;
+
+        if (bar_id)
+             break;
+    }
+
+    if (bar_id && !changed_sth) {
+        DLOG("Changing bar mode of bar_id %s failed, bar_id not found.\n", bar_id);
+        return false;
+    }
+
+    return true;
+}
+
+/*
+ * Implementation of 'bar hidden_state hide|show|toggle [<bar_id>]'
+ *
+ */
+bool cmd_bar_hidden_state(char *bar_hidden_state, char *bar_id) {
+    int hidden_state;
+    bool toggle = false;
+    if (strcmp(bar_hidden_state, "hide") == 0)
+        hidden_state = S_HIDE;
+    else if (strcmp(bar_hidden_state, "show") == 0)
+        hidden_state = S_SHOW;
+    else if (strcmp(bar_hidden_state, "toggle") == 0)
+        toggle = true;
+    else {
+        ELOG("Unknown bar state \"%s\", this is a mismatch between code and parser spec.\n", bar_hidden_state);
+        return false;
+    }
+
+    bool changed_sth = false;
+    Barconfig *current = NULL;
+    TAILQ_FOREACH(current, &barconfigs, configs) {
+        if (bar_id && strcmp(current->id, bar_id) != 0)
+            continue;
+
+        if (toggle)
+            hidden_state = (current->hidden_state + 1) % 2;
+
+        DLOG("Changing bar hidden_state of bar_id '%s' to '%s (%d)'\n", current->id, bar_hidden_state, hidden_state);
+        current->hidden_state = hidden_state;
+        changed_sth = true;
+
+        if (bar_id)
+             break;
+    }
+
+    if (bar_id && !changed_sth) {
+        DLOG("Changing bar hidden_state of bar_id %s failed, bar_id not found.\n", bar_id);
+        return false;
+    }
+
+    return true;
+}
+
+/*
+ * Implementation of 'bar (hidden_state hide|show|toggle)|(mode dock|hide|invisible|toggle) [<bar_id>]'
+ *
+ */
+void cmd_bar(I3_CMD, char *bar_type, char *bar_value, char *bar_id) {
+    bool ret;
+    if (strcmp(bar_type, "mode") == 0)
+        ret = cmd_bar_mode(bar_value, bar_id);
+    else if (strcmp(bar_type, "hidden_state") == 0)
+        ret = cmd_bar_hidden_state(bar_value, bar_id);
+    else {
+        ELOG("Unknown bar option type \"%s\", this is a mismatch between code and parser spec.\n", bar_type);
+        ret = false;
+    }
+
+    ysuccess(ret);
+    if (!ret)
+        return;
+
+    update_barconfig();
+}