From 0810857131fb2cc7103dbf26d5ed48d21c151829 Mon Sep 17 00:00:00 2001
From: Jim Myhrberg <contact@jimeh.me>
Date: Sat, 30 May 2020 17:01:21 +0100
Subject: [PATCH] feat(windows): Integrate windmove with tmux

When Emacs is launched within Tmux, and a windmove command fails (due to
it reaching the left/right/top/bottom edge of frame, instead trigger a
Tmux pane switch in that direction.

This allows a nearly seamless window/pane switching experience between
Emacs and Tmux.

It does require the following configuration in Tmux to work properly:

    # Enable smart pane switching that's Emacs aware.
    is_emacs='echo "#{pane_current_command}" | grep -iqE "(^|\/)emacs$"'

    # Use Alt-[i/k/j/l] keys without prefix key to switch panes if current pane is
    # not running Emacs. If the pane is running Emacs, let Emacs receive the
    # keybindings instead.
    bind -n M-i if-shell "$is_emacs" "send-keys M-i" "select-pane -U"
    bind -n M-k if-shell "$is_emacs" "send-keys M-k" "select-pane -D"
    bind -n M-j if-shell "$is_emacs" "send-keys M-j" "select-pane -L"
    bind -n M-l if-shell "$is_emacs" "send-keys M-l" "select-pane -R"
    bind -T copy-mode M-i if-shell "$is_emacs" "send-keys M-i" "select-pane -U"
    bind -T copy-mode M-k if-shell "$is_emacs" "send-keys M-k" "select-pane -D"
    bind -T copy-mode M-j if-shell "$is_emacs" "send-keys M-j" "select-pane -L"
    bind -T copy-mode M-l if-shell "$is_emacs" "send-keys M-l" "select-pane -R"
    bind -T copy-mode-vi M-i if-shell "$is_emacs" "send-keys M-i" "select-pane -U"
    bind -T copy-mode-vi M-k if-shell "$is_emacs" "send-keys M-k" "select-pane -D"
    bind -T copy-mode-vi M-j if-shell "$is_emacs" "send-keys M-j" "select-pane -L"
    bind -T copy-mode-vi M-l if-shell "$is_emacs" "send-keys M-l" "select-pane -R"
---
 modules/windows/siren-windmove.el | 39 +++++++++++++++++++++++++++----
 1 file changed, 34 insertions(+), 5 deletions(-)

diff --git a/modules/windows/siren-windmove.el b/modules/windows/siren-windmove.el
index 4123bd7..ef35ab8 100644
--- a/modules/windows/siren-windmove.el
+++ b/modules/windows/siren-windmove.el
@@ -8,11 +8,40 @@
 
 (use-package windmove
   :straight (:type built-in)
-  :config
-  (global-set-key (kbd "M-k") (siren-ignore-error-wrapper 'windmove-down))
-  (global-set-key (kbd "M-i") (siren-ignore-error-wrapper 'windmove-up))
-  (global-set-key (kbd "M-j") (siren-ignore-error-wrapper 'windmove-left))
-  (global-set-key (kbd "M-l") (siren-ignore-error-wrapper 'windmove-right)))
+
+  :bind
+  ("M-i" . siren-windmove-up)
+  ("M-k" . siren-windmove-down)
+  ("M-j" . siren-windmove-left)
+  ("M-l" . siren-windmove-right)
+
+  :custom
+  (siren-windmove-tmux-fallback (if (getenv "TMUX") t nil))
+
+  :init
+  (defun siren-windmove-up ()
+    (interactive)
+    (if (and (not (ignore-errors (windmove-up)))
+             siren-windmove-tmux-fallback)
+        (shell-command "tmux select-pane -U")))
+
+  (defun siren-windmove-down ()
+    (interactive)
+    (if (and (not (ignore-errors (windmove-down)))
+             siren-windmove-tmux-fallback)
+        (shell-command "tmux select-pane -D")))
+
+  (defun siren-windmove-left ()
+    (interactive)
+    (if (and (not (ignore-errors (windmove-left)))
+             siren-windmove-tmux-fallback)
+        (shell-command "tmux select-pane -L")))
+
+  (defun siren-windmove-right ()
+    (interactive)
+    (if (and (not (ignore-errors (windmove-right)))
+             siren-windmove-tmux-fallback)
+        (shell-command "tmux select-pane -R"))))
 
 (provide 'siren-windmove)
 ;;; siren-windmove.el ends here