;; Save-visited-files.el - save opened files across sessions

;; Copyright (C) 2009 Nathaniel Flath <nflath@email.com>
;; Version: 1.1
;;
;; Commentary Save-visited-files is a lightweight version of
;; Desktop.el that only save the files you have open(currently).  This
;; was created because I couldn't ever get Desktop to work and wanted
;; to persist open files across sessions.  This file is the result.
;;
;; To install, put this file somewhere in your load-path and add the
;; following to your .emacs file:
;;
;; (require 'save-visited-files)
;; (turn-on-save-visited-files-mode)
;;
;; This will load the set of saved files on startup, as well as
;; updating this list whenever the auto-save-timer is run.  This does
;; not wait to save on closing emacs because I wanted it to be useful
;; even if emacs crashed.  To save the visited files at any time, you
;; can call M-x save-visited-files-save.  M-x
;; save-visited-files-restore will open all files saved this way.  To
;; turn off the saving of files, you need to run (turn-off-save-visited-files-mode)
;;
;;
;; Changelog:
;; 1.1
;;  * Improvements/rewriting by Ryan Thomson
;;  ** Use auto-save-hook instead of a periodic timer
;;  ** More consistent naming conventions
;;  ** Customization ability via M-x customize-group save-visited-files
;;  ** Better handling of the temp buffer
;; 1.0
;;  * Initial Release
;;
;; Code:


(defcustom save-visited-files-location "~/.emacs.d/persistence/emacs-visited-files"
  "Location of the file that contains the list of previously visited files"
  :type 'file
  :group 'save-visited-files)

(defcustom save-visited-files-auto-restore nil
  "If t, restore visited files the first time save-visited-files-mode is activated"
  :type 'boolean
  :group 'save-visited-files)

(defvar save-visited-files-already-restored nil
  "If t, then files have already been restored")

(defun save-visited-files-save (&optional location)
  "Save the list of currently visited files"
  (interactive)
  (save-window-excursion
    (setq location (or location save-visited-files-location))
    (switch-to-buffer "*Save Visited*")
    (ignore-errors
      (erase-buffer)
      (mapcar '(lambda (x) (insert x "\n"))
              (remove-if '(lambda (x)
                            (or (string-equal location x)
                                (eq nil x))) (mapcar 'buffer-file-name (buffer-list))))
      (write-file location nil))
    (kill-buffer (get-buffer "*Save Visited*"))))

(defun save-visited-files-restore (&optional location)
  "Restore all files that were saved by save-visited-files-save."
  (interactive)
  (save-window-excursion
    (setq location (or location save-visited-files-location))
    (find-file location)
    (ignore-errors
      (save-window-excursion
        (beginning-of-buffer)
        (while (not (eq (point) (point-max)))
          (let ((point (point)))
            (end-of-line)
            (ignore-errors
              (save-window-excursion
                (find-file (buffer-substring point (point)))))
            (next-line)
            (beginning-of-line)))))
    (kill-buffer (current-buffer))))

(defun turn-on-save-visited-files-mode ()
  "Turns save-visited-files-mode on"
  (interactive)
  (add-hook 'auto-save-hook 'save-visited-files-save)
  (add-hook 'kill-emacs-hook 'save-visited-files-save)
  (setq save-visited-files-mode t)
  (unless save-visited-files-already-restored
    (when save-visited-files-auto-restore
      (save-visited-files-restore)))
  (setq save-visited-files-already-restored t))

(defun turn-off-save-visited-files-mode ()
  "Turns save-visited-files-mode off"
  (interactive)
  (remove-hook 'auto-save-hook 'save-visited-files-save)
  (remove-hook 'kill-emacs-hook 'save-visited-files-save)
  (setq save-visited-files-mode nil))

(defun save-visited-files-mode (&optional arg)
  "If arg is nonnn-nil, enable save-visited-files-mode if positive, disable otherwise. With no arg, toggle save-visited-files-mode."
  (interactive)
  (setq arg (or arg (if save-visited-files-mode 0 1)))
  (if (> arg 0)
      (progn
        (turn-on-save-visited-files-mode)
        (message "Save visited files mode enabled"))
    (turn-off-save-visited-files-mode)
    (message "Save visited files mode disabled")))

(defcustom save-visited-files-mode nil
  "If t, enable save-visited-files-mode"
  :type 'boolean
  :group 'save-visited-files
  :set #'(lambda (sym val) (save-visited-files-mode (if val 1 0))))

(when save-visited-files-mode
  (turn-on-save-visited-files-mode))

(provide 'save-visited-files)