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sync-file-el.el

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+;;; sync-file.el --- a viewing mode for books and novels.  -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2019 Robert Rose
+
+;; Author: Robert Rose <overclucker@gmail.com>
+;; Keywords: lisp sync file
+;; Version: 0.0.1
+;; Package-Requires ((emacs "24"))
+
+;; This program is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; Allows you to syncronize files by newest file date. Directories arent currently handled,
+;; as I have no need for that functionaliity at this point. Parent directories will always
+;; be created if they dont exist. Some conditions that may occur haven't been covered, such
+;; as write permissions and attributes. If one of the files is a regular file and the other
+;; is a directory, strange behaviours may occur. Another thing to note is that file names
+;; can make use of TRAMP, which makes remote sync and root file access possible.
+;; e.g.,
+;; (let ((files
+;;        '(("~/foo/file1.txt" . "/ssh:use@host:~/foo/file1.txt")
+;; 	    ("~/foo/file2.txt" . "/ssh:use@host:~/foo/file2.txt")
+;; 	    ("~/foo/file3.txt" . "/ssh:use@host:~/foo/file3.txt")) ))
+;;   (sync-files files))
+
+;;; Code:
+
+(defun copy-file-make-parents (name newname)
+  "Copy file and make parent directories if neccessary."
+  (let* ((parent (file-name-directory (file-name-directory newname))))
+    (unless (file-directory-p parent)
+      (make-directory parent t))
+    (copy-file name newname t)))
+
+(defun sync-file (f1 f2)
+  "Syncronize newest to oldest file. Parent directories will be created."
+  (cond ((and (file-exists-p f1) (file-exists-p f2))
+	 (cond ((file-newer-than-file-p f1 f2)
+		(copy-file f1 f2 t))
+	       ((file-newer-than-file-p f2 f1)
+		(copy-file f2 f1 t)) ))
+	((and (file-exists-p f1) (not (file-exists-p f2)))
+	 (copy-file-make-parents f1 f2) )
+	((and (file-exists-p f2) (not (file-exists-p f1)))
+	 (copy-file-make-parents f2 f1)) ))
+
+(defun sync-files (files)
+  "Syncronize newest to oldest files. Parent directories will be created.
+`files' should be in the form (cons f1 f2)."
+  (dolist (file files)
+     (sync-file (car file) (cdr file))))
+
+(provide 'sync-file)
+
+;;; sync-file.el ends here