From dccb57747efe78c498951deefff0ddba2f28050d Mon Sep 17 00:00:00 2001
From: Jim Myhrberg <contact@jimeh.me>
Date: Thu, 20 Aug 2020 22:12:49 +0100
Subject: [PATCH] feat(windows): use new windmove-swap-* functions on Emacs 27
 and later

Fallback onto buffer-move package for Emacs versions prior to 27.
---
 core/siren-core-modules.el        |  1 -
 modules/windows/siren-windmove.el | 23 ++++++++++++++++++++++-
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/core/siren-core-modules.el b/core/siren-core-modules.el
index 14b7036..3551cbf 100644
--- a/core/siren-core-modules.el
+++ b/core/siren-core-modules.el
@@ -107,7 +107,6 @@
 (require 'siren-magit)
 
 ;; Window management
-(require 'siren-buffer-move)
 (require 'siren-resize-window)
 (require 'siren-windmove)
 (require 'siren-zoom-window)
diff --git a/modules/windows/siren-windmove.el b/modules/windows/siren-windmove.el
index ef35ab8..88502ed 100644
--- a/modules/windows/siren-windmove.el
+++ b/modules/windows/siren-windmove.el
@@ -6,6 +6,9 @@
 
 ;;; Code:
 
+(when (version< emacs-version "27.0")
+  (require 'siren-buffer-move))
+
 (use-package windmove
   :straight (:type built-in)
 
@@ -14,6 +17,10 @@
   ("M-k" . siren-windmove-down)
   ("M-j" . siren-windmove-left)
   ("M-l" . siren-windmove-right)
+  ("M-K" . siren-windmove-swap-down)
+  ("M-I" . siren-windmove-swap-up)
+  ("M-J" . siren-windmove-swap-left)
+  ("M-L" . siren-windmove-swap-right)
 
   :custom
   (siren-windmove-tmux-fallback (if (getenv "TMUX") t nil))
@@ -41,7 +48,21 @@
     (interactive)
     (if (and (not (ignore-errors (windmove-right)))
              siren-windmove-tmux-fallback)
-        (shell-command "tmux select-pane -R"))))
+        (shell-command "tmux select-pane -R")))
 
+  (defun siren-windmove-swap-defun (direction)
+    "Define window swap function for DIRECTION.
+On Emacs 27.0 or later use windmove, on earlier use buffer-move package."
+    `(defun ,(intern (format "siren-windmove-swap-%s" direction)) ()
+       (interactive)
+       (,(intern (format (if (version< emacs-version "27.0")
+                             "buf-move-%s"
+                           "windmove-swap-states-%s")
+                         direction)))))
+
+  (defmacro siren-windmove-swap-defuns (directions)
+    `(progn ,@(mapcar 'siren-windmove-swap-defun directions)))
+
+  (siren-windmove-swap-defuns (up down left right)))
 (provide 'siren-windmove)
 ;;; siren-windmove.el ends here