my i3-emacs integration

/**
 * Holds a keybinding, consisting of a keycode combined with modifiers and the
 * command which is executed as soon as the key is pressed (see
 * src/config_parser.c)
 *
 */
struct Binding {
    // ...

    /** Window class to use for key passthrough. Currently an exact string match. */
    struct {
        char *class;
    } passthrough;
};

/*
 * Adds a binding from config parameters given as strings and returns a
 * pointer to the binding structure. Returns NULL if the input code could not
 * be parsed.
 *
 */
Binding *configure_binding(const char *bindtype, const char *modifiers, const char *input_code,
                           const char *release, const char *border, const char *whole_window,
                           const char *exclude_titlebar, const char *command, const char *modename,
                           bool pango_markup, const char *passthrough) {
    // ...

    // XXX: should change this to be configurable, but I only care about Emacs, so.
    if (passthrough) {
        new_binding->passthrough.class = sstrdup("Emacs");
    } else {
        new_binding->passthrough.class = NULL;
    }

    return new_binding;
}

void handle_key_press(xcb_key_press_event_t *event) {
    // ...

    DLOG("PATCH: checking if we should pass keypress through\n");
    if (bind->passthrough.class) {
        xcb_generic_error_t *focus_error;
        xcb_get_input_focus_reply_t *input_focus = xcb_get_input_focus_reply(
            conn, xcb_get_input_focus(conn), &focus_error);

        if (focus_error != NULL) {
            DLOG("PATCH: could not get focused window");
            free(focus_error);
        } else {
            Con *con = con_by_window_id(input_focus->focus);
            const xcb_window_t focus = input_focus->focus;
            free(input_focus);

            const bool should_pass =
                con && con->window->class_class &&
                strcmp(con->window->class_class, bind->passthrough.class) == 0;
            if (should_pass) {
                DLOG("PATCH: forwarding keypress (%d %s %s @ %d %d)\n", focus,
                     con->name, con->window->class_class, event->event_x,
                     event->event_y);
                event->event = focus;
                xcb_send_event(conn, false, focus, XCB_EVENT_MASK_NO_EVENT,
                               (const char *)event);
                return;
            }
        }
    }

    DLOG("PATCH: handling keypress normally\n");
    CommandResult *result = run_binding(bind, NULL);
    command_result_free(result);
}

# bindsym/bindcode
state BINDING:
  # ...
  passthrough = '--passthrough'
      ->
  key = word
      -> BINDCOMMAND

state BINDCOMMAND:
  # ...
  passthrough = '--passthrough'
      ->
  command = string
      -> call cfg_binding(..., $passthrough, $command)

(defmacro nausicaa/i3-msg (&rest args)
  "Call i3-msg with ARGS."
  `(start-process "emacs-to-i3" nil "i3-msg" ,@args))

(defun nausicaa/emacs-i3-windmove (dir)
  "Select window in DIR, if it exists; if not, i3-select it."
  (let ((other-window (nausicaa/find-other-window dir)))
    (if (or (null other-window) (window-minibuffer-p other-window))
        (nausicaa/i3-msg "focus" (symbol-name dir))
      (nausicaa/do-window-select dir))))

(defun nausicaa/emacs-i3-move-window (dir)
  "Do some stuff to move window in DIR.

I should check out `evil-move-window' at some point."
  (let ((other-window (windmove-find-other-window dir)))
    (cond
     ((and other-window (not (window-minibuffer-p other-window)))
      (window-swap-states (selected-window) other-window))
     (t (nausicaa/i3-msg "move" (symbol-name dir))))))

(defun nausicaa/find-other-window (&rest args)
  "Pass ARGS through to `windmove-find-other-window'.

Exists solely so I can reuse `+popup--ignore-window-parameters-a'."
  (apply #'windmove-find-other-window args))

(defun nausicaa/do-window-select (&rest args)
  "Pass ARGS through to `windmove-do-window-select'.

Exists solely so I can reuse `+popup--ignore-window-parameters-a'."
  (apply #'windmove-do-window-select args))

(advice-add 'nausicaa/find-other-window
            :around #'+popup--ignore-window-parameters-a)
(advice-add 'nausicaa/do-window-select
            :around #'+popup--ignore-window-parameters-a)

# start a terminal
bindsym --passthrough $super+Return exec mistty-create
bindsym --passthrough $super+Control+Return exec alacritty-create

(defun nausicaa/launch-alacritty ()
  (interactive)
  (async-start-process "alacritty-create" "bash" nil "-c" "exec alacritty-create"))

(map!
 "s-<return>" #'mistty-create
 "C-s-<return>" #'nausicaa/launch-alacritty)

pkgs.writeShellApplication {
  name = "mistty-create";
  text = ''
    ${config.programs.emacs.package}/bin/emacsclient -e "(progn (other-frame-prefix) (mistty-create))"
  '';
}

pkgs.writeShellApplication {
  name = "alacritty-create";
  text = ''
    if ! ${pkgs.alacritty}/bin/alacritty msg create-window --working-directory "$PWD"; then
       env -u INSIDE_EMACS ${pkgs.alacritty}/bin/alacritty "$@" >/dev/null 2>&1 &
       disown %env
    fi
  '';
}