1 files changed, 50 insertions, 0 deletions
diff --git a/config/files/config-files-backup-on-save-hook.el b/config/files/config-files-backup-on-save-hook.el
new file mode 100644
index 0000000..53b96d1
--- /dev/null
+++ b/config/files/config-files-backup-on-save-hook.el
@@ -0,0 +1,50 @@
+(defvar config-files-backup-directory (file-name-concat user-emacs-directory "backups"))
+
+(unless (file-exists-p config-files-backup-directory)
+  (mkdir config-files-backup-directory))
+
+(defun config-files-format-backup-path (path number)
+  (format "%s.~%s~" path number))
+
+(defun config-files-backup-extension (path)
+  (let* ((i (string-search "." (reverse path)))
+         (extension (substring path (- (length path) i))))
+    extension))
+
+(defun config-files-backup-no-extension (path)
+  (let* ((i (string-search "." (reverse path)))
+         (no-extension (substring path 0 (- (length path) (+ i 1)))))
+    no-extension))
+
+(defun config-files-backup-number (path)
+  (let* ((extension (config-files-backup-extension path))
+         (extracted (substring extension 1 (- (length extension) 1)))
+         (as-number (unless (zerop (length extracted))
+                      (string-to-number extracted))))
+    as-number))
+
+(defun config-files-shift-path (path)
+  (let* ((without-extension (config-files-backup-no-extension path))
+         (number (config-files-backup-number path))
+         (next-number (+ number 1))
+         (shifted-path (config-files-format-backup-path
+                        without-extension
+                        next-number)))
+    shifted-path))
+
+(defun config-files-shift-backup (path)
+  (let ((next-path (config-files-shift-path path)))
+    (when (file-exists-p next-path)
+        (config-files-shift-backup next-path))
+    (rename-file path next-path)))
+
+(defun config-files-backup-before-save ()
+  (unless backup-inhibited
+    (let* ((path (buffer-file-name))
+           (backup-path (config-files-format-backup-path path 0)))
+      (when (file-exists-p path)
+        (when (file-exists-p backup-path)
+          (config-files-shift-backup backup-path))
+        (copy-file path backup-path)))))
+
+(add-hook 'before-save-hook 'config-files-backup-before-save)