;; (C) Muli Ben-Yehuda <mulix@mulix.org>, GPL'd  
;; 
;; M-x display-battery to add the battery status to your mode line, 
;; M-x display-battery-stop to remove it 
;; 
;; Code mostly copy and pasted from time.el, some bits copied from 
;; Alex Shinn's <foof@debian.org> battery.el. 
;; 
;; $Id: battery.el,v 1.1 2003/09/28 21:12:41 muli Exp $ 

(defvar display-battery-string nil)

(defvar display-battery-interval 120
  "Number of seconds to wait before updating battery info")

(defun battery-shell-command(command output-buffer)
  "Execute string COMMAND, capture output in output-buffer."
  "we need this because shell-command pipes its output to the "
  "echo area, if it has exactly one line of output?!"
  (let ((buffer (get-buffer-create
		 (or output-buffer "*Shell Command Output*")))
	(exit-status nil)
	(directory default-directory))
    (save-excursion
      (set-buffer buffer)
      (setq buffer-read-only nil)
      ;; XEmacs change
      (setq default-directory directory)
      (erase-buffer))
    (setq exit-status
	  (call-process-region (point) (point) 
			       shell-file-name nil buffer nil
			       shell-command-switch command))))

(defun display-battery()
  (interactive)

  (let ((old (get-itimer "display-battery")))
    (if old 
	(delete-itimer old)))

  (if (memq 'display-battery-string global-mode-string)
      (setq global-mode-string
	    (remove 'display-battery-string global-mode-string)))

  (or global-mode-string
      (setq global-mode-string '("")))

  (setq global-mode-string
	(append global-mode-string '(display-battery-string)))

  (display-battery-function)

  (start-itimer "display-battery" 'display-battery-function
		display-battery-interval display-battery-interval))

(defun display-battery-function()
  "Generate representing battery info"
  (save-excursion
    ;; Because we can't read /proc/apm directly, 
    ;; and shell-command is b0rked (see battery-shell-command help string)
    ;; TODO: this can barf, check exit status 
    (battery-shell-command "cat /proc/apm" "*battery*")
    (set-buffer "*battery*")
    (beginning-of-buffer)
    (setq display-battery-string
          (if (looking-at ".*[ \t]\\([0-9]+%\\)")
              (concat "Bat: " (buffer-substring (match-beginning 1)
                                                (match-end 1)) " ")
            "Bat: APM off "))))

(defun display-battery-stop()
  (interactive)
  (delete-itimer "display-battery")
  (setq display-battery-string nil))

(provide 'battery)