;;; vc-filewise.el --- common functions for file-oriented back ends.

;; Copyright (C) 1992-1996, 1998-2014 Free Software Foundation, Inc.

;; Author:     FSF (see vc.el for full credits)
;; Maintainer: Andre Spiegel <spiegel@gnu.org>
;; Package: vc

;; This file is part of GNU Emacs.

;; GNU Emacs 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.

;; GNU Emacs 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 GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;; Common functions for file-oriented back ends - SCCS, RCS, SRC, CVS
;;
;; The main purpose of this file is so none of this code has to live
;; in the always-resident vc-hooks.  A secondary purpose is to remove
;; code specific to this class of back ends from vc.el.

;;; Code:

(eval-when-compile (require 'vc))

(defun vc-master-name (file)
  "Return the master name of FILE.
If the file is not registered, or the master name is not known, return nil."
  (or (vc-file-getprop file 'vc-name)
      ;; force computation of the property by calling
      ;; vc-BACKEND-registered explicitly
      (let ((backend (vc-backend file)))
	(if (and backend
		 (vc-filewise-registered backend file))
	    (vc-file-getprop file 'vc-name)))))

(defun vc-rename-master (oldmaster newfile templates)
  "Rename OLDMASTER to be the master file for NEWFILE based on TEMPLATES."
  (let* ((dir (file-name-directory (expand-file-name oldmaster)))
	 (newdir (or (file-name-directory newfile) ""))
	 (newbase (file-name-nondirectory newfile))
	 (masters
	  ;; List of potential master files for `newfile'
	  (mapcar
	   (lambda (s) (vc-possible-master s newdir newbase))
	   templates)))
    (when (or (file-symlink-p oldmaster)
	      (file-symlink-p (file-name-directory oldmaster)))
      (error "This is unsafe in the presence of symbolic links"))
    (rename-file
     oldmaster
     (catch 'found
       ;; If possible, keep the master file in the same directory.
       (dolist (f masters)
	 (when (and f (string= (file-name-directory (expand-file-name f)) dir))
	   (throw 'found f)))
       ;; If not, just use the first possible place.
       (dolist (f masters)
	 (and f (or (not (setq dir (file-name-directory f)))
		    (file-directory-p dir))
	      (throw 'found f)))
       (error "New file lacks a version control directory")))))

(defun vc-filewise-registered (backend file)
  "Check if FILE is registered in BACKEND using vc-BACKEND-master-templates."
  (let ((sym (vc-make-backend-sym backend 'master-templates)))
    (unless (get backend 'vc-templates-grabbed)
      (put backend 'vc-templates-grabbed t))
    (let ((result (vc-check-master-templates file (symbol-value sym))))
      (if (stringp result)
	  (vc-file-setprop file 'vc-name result)
	nil))))				; Not registered

(defun vc-check-master-templates (file templates)
  "Return non-nil if there is a master corresponding to FILE.

TEMPLATES is a list of strings or functions.  If an element is a
string, it must be a control string as required by `format', with two
string placeholders, such as \"%sRCS/%s,v\".  The directory part of
FILE is substituted for the first placeholder, the basename of FILE
for the second.  If a file with the resulting name exists, it is taken
as the master of FILE, and returned.

If an element of TEMPLATES is a function, it is called with the
directory part and the basename of FILE as arguments.  It should
return non-nil if it finds a master; that value is then returned by
this function."
  (let ((dirname (or (file-name-directory file) ""))
        (basename (file-name-nondirectory file)))
    (catch 'found
      (mapcar
       (lambda (s)
	 (let ((trial (vc-possible-master s dirname basename)))
	   (when (and trial (file-exists-p trial)
		      ;; Make sure the file we found with name
		      ;; TRIAL is not the source file itself.
		      ;; That can happen with RCS-style names if
		      ;; the file name is truncated (e.g. to 14
		      ;; chars).  See if either directory or
		      ;; attributes differ.
		      (or (not (string= dirname
					(file-name-directory trial)))
			  (not (equal (file-attributes file)
				      (file-attributes trial)))))
	       (throw 'found trial))))
       templates))))

(provide 'vc-filewise)