path: root/lisp/battery.el

;;; battery.el --- display battery status information

;; Copyright (C) 1997-1998, 2000-2019 Free Software Foundation, Inc.

;; Author: Ralph Schleicher <rs@ralph-schleicher.de>
;; Keywords: hardware

;; 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 <https://www.gnu.org/licenses/>.

;;; Commentary:

;; There is at present support for GNU/Linux, macOS and Windows.  This
;; library supports both the `/proc/apm' file format of Linux version
;; 1.3.58 or newer and the `/proc/acpi/' directory structure of Linux
;; 2.4.20 and 2.6.  Darwin (macOS) is supported by using the `pmset'
;; program.  Windows is supported by the GetSystemPowerStatus API call.

;;; Code:

(require 'timer)
(eval-when-compile (require 'cl-lib))

(defgroup battery nil
  "Display battery status information."
  :prefix "battery-"
  :group 'hardware)

(defcustom battery-upower-device "battery_BAT1"
  "Upower battery device name."
  :version "26.1"
  :type 'string
  :group 'battery)

(defun battery--find-linux-sysfs-batteries ()
  (let ((dirs nil))
    (dolist (file (directory-files "/sys/class/power_supply/" t))
      (when (and (or (file-directory-p file)
                     (file-symlink-p file))
                 (file-exists-p (expand-file-name "capacity" file)))
        (push file dirs)))
    (nreverse dirs)))

(defcustom battery-status-function
  (cond ((and (eq system-type 'gnu/linux)
	      (file-readable-p "/proc/apm"))
	 #'battery-linux-proc-apm)
	((and (eq system-type 'gnu/linux)
	      (file-directory-p "/proc/acpi/battery"))
	 #'battery-linux-proc-acpi)
	((and (eq system-type 'gnu/linux)
	      (file-directory-p "/sys/class/power_supply/")
              (battery--find-linux-sysfs-batteries))
	 #'battery-linux-sysfs)
	((and (eq system-type 'berkeley-unix)
	      (file-executable-p "/usr/sbin/apm"))
	 #'battery-bsd-apm)
	((and (eq system-type 'darwin)
	      (condition-case nil
		  (with-temp-buffer
		    (and (eq (call-process "pmset" nil t nil "-g" "ps") 0)
			 (> (buffer-size) 0)))
		(error nil)))
	 #'battery-pmset)
	((fboundp 'w32-battery-status)
	 #'w32-battery-status))
  "Function for getting battery status information.
The function has to return an alist of conversion definitions.
Its cons cells are of the form

    (CONVERSION . REPLACEMENT-TEXT)

CONVERSION is the character code of a \"conversion specification\"
introduced by a `%' character in a control string."
  :type '(choice (const nil) function)
  :group 'battery)

(defcustom battery-echo-area-format
  "Power %L, battery %B (%p%% load, remaining time %t)"
  "Control string formatting the string to display in the echo area.
Ordinary characters in the control string are printed as-is, while
conversion specifications introduced by a `%' character in the control
string are substituted as defined by the current value of the variable
`battery-status-function'.  Here are the ones generally available:
%c Current capacity (mAh or mWh)
%r Current rate of charge or discharge
%B Battery status (verbose)
%b Battery status: empty means high, `-' means low,
   `!' means critical, and `+' means charging
%d Temperature (in degrees Celsius)
%L AC line status (verbose)
%p Battery load percentage
%m Remaining time (to charge or discharge) in minutes
%h Remaining time (to charge or discharge) in hours
%t Remaining time (to charge or discharge) in the form `h:min'"
  :type '(choice string (const nil))
  :group 'battery)

(defvar battery-mode-line-string nil
  "String to display in the mode line.")
;;;###autoload (put 'battery-mode-line-string 'risky-local-variable t)

(defcustom battery-mode-line-limit 100
  "Percentage of full battery load below which display battery status"
  :version "24.1"
  :type 'integer
  :group 'battery)

(defcustom battery-mode-line-format
  (cond ((eq battery-status-function 'battery-linux-proc-acpi)
	 "[%b%p%%,%d°C]")
	(battery-status-function
	 "[%b%p%%]"))
  "Control string formatting the string to display in the mode line.
Ordinary characters in the control string are printed as-is, while
conversion specifications introduced by a `%' character in the control
string are substituted as defined by the current value of the variable
`battery-status-function'.  Here are the ones generally available:
%c Current capacity (mAh or mWh)
%r Current rate of charge or discharge
%B Battery status (verbose)
%b Battery status: empty means high, `-' means low,
   `!' means critical, and `+' means charging
%d Temperature (in degrees Celsius)
%L AC line status (verbose)
%p Battery load percentage
%m Remaining time (to charge or discharge) in minutes
%h Remaining time (to charge or discharge) in hours
%t Remaining time (to charge or discharge) in the form `h:min'"
  :type '(choice string (const nil))
  :group 'battery)

(defcustom battery-update-interval 60
  "Seconds after which the battery status will be updated."
  :type 'integer
  :group 'battery)

(defcustom battery-load-low 25
  "Upper bound of low battery load percentage.
A battery load percentage below this number is considered low."
  :type 'integer
  :group 'battery)

(defcustom battery-load-critical 10
  "Upper bound of critical battery load percentage.
A battery load percentage below this number is considered critical."
  :type 'integer
  :group 'battery)

(defvar battery-update-timer nil
  "Interval timer object.")

;;;###autoload
(defun battery ()
  "Display battery status information in the echo area.
The text being displayed in the echo area is controlled by the variables
`battery-echo-area-format' and `battery-status-function'."
  (interactive)
  (message "%s" (if (and battery-echo-area-format battery-status-function)
		    (battery-format battery-echo-area-format
				    (funcall battery-status-function))
		  "Battery status not available")))

;;;###autoload
(define-minor-mode display-battery-mode
  "Toggle battery status display in mode line (Display Battery mode).

The text displayed in the mode line is controlled by
`battery-mode-line-format' and `battery-status-function'.
The mode line is be updated every `battery-update-interval'
seconds."
  :global t :group 'battery
  (setq battery-mode-line-string "")
  (or global-mode-string (setq global-mode-string '("")))
  (and battery-update-timer (cancel-timer battery-update-timer))
  (if (and battery-status-function battery-mode-line-format)
      (if (not display-battery-mode)
	  (setq global-mode-string
		(delq 'battery-mode-line-string global-mode-string))
	(add-to-list 'global-mode-string 'battery-mode-line-string t)
	(setq battery-update-timer (run-at-time nil battery-update-interval
						'battery-update-handler))
	(battery-update))
    (message "Battery status not available")
    (setq display-battery-mode nil)))

(defun battery-update-handler ()
  (battery-update)
  (sit-for 0))

(defun battery-update ()
  "Update battery status information in the mode line."
  (let* ((data (and battery-status-function (funcall battery-status-function)))
         (percentage (car (read-from-string (cdr (assq ?p data))))))
    (setq battery-mode-line-string
	  (propertize (if (and battery-mode-line-format
			       (numberp percentage)
                               (<= percentage battery-mode-line-limit))
			  (battery-format battery-mode-line-format data)
			"")
		      'face
                      (and (numberp percentage)
                           (<= percentage battery-load-critical)
                           'error)
		      'help-echo "Battery status information")))
  (force-mode-line-update))

;;; `/proc/apm' interface for Linux.

(defconst battery-linux-proc-apm-regexp
  (concat "^\\([^ ]+\\)"		; Driver version.
	  " \\([^ ]+\\)"		; APM BIOS version.
	  " 0x\\([0-9a-f]+\\)"		; APM BIOS flags.
	  " 0x\\([0-9a-f]+\\)"		; AC line status.
	  " 0x\\([0-9a-f]+\\)"		; Battery status.
	  " 0x\\([0-9a-f]+\\)"		; Battery flags.
	  " \\(-?[0-9]+\\)%"		; Load percentage.
	  " \\(-?[0-9]+\\)"		; Remaining time.
	  " \\(.*\\)"			; Time unit.
	  "$")
  "Regular expression matching contents of `/proc/apm'.")

(defun battery-linux-proc-apm ()
  "Get APM status information from Linux (the kernel).
This function works only with the new `/proc/apm' format introduced
in Linux version 1.3.58.

The following %-sequences are provided:
%v Linux driver version
%V APM BIOS version
%I APM BIOS status (verbose)
%L AC line status (verbose)
%B Battery status (verbose)
%b Battery status, empty means high, `-' means low,
   `!' means critical, and `+' means charging
%p Battery load percentage
%s Remaining time (to charge or discharge) in seconds
%m Remaining time (to charge or discharge) in minutes
%h Remaining time (to charge or discharge) in hours
%t Remaining time (to charge or discharge) in the form `h:min'"
  (let (driver-version bios-version bios-interface line-status
	battery-status battery-status-symbol load-percentage
	seconds minutes hours remaining-time tem)
    (with-temp-buffer
      (ignore-errors (insert-file-contents "/proc/apm"))
      (when (re-search-forward battery-linux-proc-apm-regexp)
	(setq driver-version (match-string 1))
	(setq bios-version (match-string 2))
	(setq tem (string-to-number (match-string 3) 16))
	(if (not (logand tem 2))
	    (setq bios-interface "not supported")
	  (setq bios-interface "enabled")
	  (cond ((logand tem 16) (setq bios-interface "disabled"))
		((logand tem 32) (setq bios-interface "disengaged")))
	  (setq tem (string-to-number (match-string 4) 16))
	  (cond ((= tem 0) (setq line-status "off-line"))
		((= tem 1) (setq line-status "on-line"))
		((= tem 2) (setq line-status "on backup")))
	  (setq tem (string-to-number (match-string 6) 16))
	  (if (= tem 255)
	      (setq battery-status "N/A")
	    (setq tem (string-to-number (match-string 5) 16))
	    (cond ((= tem 0) (setq battery-status "high"
				   battery-status-symbol ""))
		  ((= tem 1) (setq battery-status "low"
				   battery-status-symbol "-"))
		  ((= tem 2) (setq battery-status "critical"
				   battery-status-symbol "!"))
		  ((= tem 3) (setq battery-status "charging"
				   battery-status-symbol "+")))
	    (setq load-percentage (match-string 7))
	    (setq seconds (string-to-number (match-string 8)))
	    (and (string-equal (match-string 9) "min")
		 (setq seconds (* 60 seconds)))
	    (setq minutes (/ seconds 60)
		  hours (/ seconds 3600))
	    (setq remaining-time
		  (format "%d:%02d" hours (- minutes (* 60 hours))))))))
    (list (cons ?v (or driver-version "N/A"))
	  (cons ?V (or bios-version "N/A"))
	  (cons ?I (or bios-interface "N/A"))
	  (cons ?L (or line-status "N/A"))
	  (cons ?B (or battery-status "N/A"))
	  (cons ?b (or battery-status-symbol ""))
	  (cons ?p (or load-percentage "N/A"))
	  (cons ?s (or (and seconds (number-to-string seconds)) "N/A"))
	  (cons ?m (or (and minutes (number-to-string minutes)) "N/A"))
	  (cons ?h (or (and hours (number-to-string hours)) "N/A"))
	  (cons ?t (or remaining-time "N/A")))))


;;; `/proc/acpi/' interface for Linux.

(defun battery-linux-proc-acpi ()
  "Get ACPI status information from Linux (the kernel).
This function works only with the `/proc/acpi/' format introduced
in Linux version 2.4.20 and 2.6.0.

The following %-sequences are provided:
%c Current capacity (mAh)
%r Current rate
%B Battery status (verbose)
%b Battery status, empty means high, `-' means low,
   `!' means critical, and `+' means charging
%d Temperature (in degrees Celsius)
%L AC line status (verbose)
%p Battery load percentage
%m Remaining time (to charge or discharge) in minutes
%h Remaining time (to charge or discharge) in hours
%t Remaining time (to charge or discharge) in the form `h:min'"
  (let ((design-capacity 0)
	(last-full-capacity 0)
	full-capacity
	(warn 0)
	(low 0)
	capacity rate rate-type charging-state minutes hours)
    ;; ACPI provides information about each battery present in the system in
    ;; a separate subdirectory.  We are going to merge the available
    ;; information together since displaying for a variable amount of
    ;; batteries seems overkill for format-strings.
    (with-temp-buffer
      (dolist (dir (ignore-errors (directory-files "/proc/acpi/battery/"
						   t "\\`[^.]")))
	(erase-buffer)
	(ignore-errors (insert-file-contents (expand-file-name "state" dir)))
	(when (re-search-forward "present: +yes$" nil t)
	  (and (re-search-forward "charging state: +\\(.*\\)$" nil t)
	       (member charging-state '("unknown" "charged" nil))
	       ;; On most multi-battery systems, most of the time only one
	       ;; battery is "charging"/"discharging", the others are
	       ;; "unknown".
	       (setq charging-state (match-string 1)))
	  (when (re-search-forward "present rate: +\\([0-9]+\\) \\(m[AW]\\)$"
				   nil t)
	    (setq rate (+ (or rate 0) (string-to-number (match-string 1))))
	    (when (> rate 0)
	      (setq rate-type (or (and rate-type
				     (if (string= rate-type (match-string 2))
					 rate-type
				       (error
					"Inconsistent rate types (%s vs. %s)"
					rate-type (match-string 2))))
				  (match-string 2)))))
	  (when (re-search-forward "remaining capacity: +\\([0-9]+\\) m[AW]h$"
				   nil t)
	    (setq capacity
		  (+ (or capacity 0) (string-to-number (match-string 1))))))
	(goto-char (point-max))
	(ignore-errors (insert-file-contents (expand-file-name "info" dir)))
	(when (re-search-forward "present: +yes$" nil t)
	  (when (re-search-forward "design capacity: +\\([0-9]+\\) m[AW]h$"
				   nil t)
	    (cl-incf design-capacity (string-to-number (match-string 1))))
	  (when (re-search-forward "last full capacity: +\\([0-9]+\\) m[AW]h$"
				   nil t)
	    (cl-incf last-full-capacity (string-to-number (match-string 1))))
	  (when (re-search-forward
		 "design capacity warning: +\\([0-9]+\\) m[AW]h$" nil t)
	    (cl-incf warn (string-to-number (match-string 1))))
	  (when (re-search-forward "design capacity low: +\\([0-9]+\\) m[AW]h$"
				   nil t)
	    (cl-incf low (string-to-number (match-string 1)))))))
    (setq full-capacity (if (> last-full-capacity 0)
			    last-full-capacity design-capacity))
    (and capacity rate
	 (setq minutes (if (zerop rate) 0
			 (floor (* (if (string= charging-state
						"charging")
				       (- full-capacity capacity)
				     capacity)
				   60)
				rate))
	       hours (/ minutes 60)))
    (list (cons ?c (or (and capacity (number-to-string capacity)) "N/A"))
	  (cons ?L (or (battery-search-for-one-match-in-files
			(mapcar (lambda (e) (concat e "/state"))
				(ignore-errors
				  (directory-files "/proc/acpi/ac_adapter/"
						   t "\\`[^.]")))
			"state: +\\(.*\\)$" 1)

		       "N/A"))
	  (cons ?d (or (battery-search-for-one-match-in-files
			(mapcar (lambda (e) (concat e "/temperature"))
				(ignore-errors
				  (directory-files "/proc/acpi/thermal_zone/"
						   t "\\`[^.]")))
			"temperature: +\\([0-9]+\\) C$" 1)

		       "N/A"))
	  (cons ?r (or (and rate (concat (number-to-string rate) " "
					 rate-type)) "N/A"))
	  (cons ?B (or charging-state "N/A"))
	  (cons ?b (or (and (string= charging-state "charging") "+")
		       (and capacity (< capacity low) "!")
		       (and capacity (< capacity warn) "-")
		       ""))
	  (cons ?h (or (and hours (number-to-string hours)) "N/A"))
	  (cons ?m (or (and minutes (number-to-string minutes)) "N/A"))
	  (cons ?t (or (and minutes
			    (format "%d:%02d" hours (- minutes (* 60 hours))))
		       "N/A"))
	  (cons ?p (or (and full-capacity capacity
			    (> full-capacity 0)
			    (number-to-string
			     (floor (* 100 capacity) full-capacity)))
		       "N/A")))))


;;; `/sys/class/power_supply/BATN' interface for Linux.

(defun battery-linux-sysfs ()
  "Get ACPI status information from Linux kernel.
This function works only with the new `/sys/class/power_supply/'
format introduced in Linux version 2.4.25.

The following %-sequences are provided:
%c Current capacity (mAh or mWh)
%r Current rate
%B Battery status (verbose)
%d Temperature (in degrees Celsius)
%p Battery load percentage
%L AC line status (verbose)
%m Remaining time (to charge or discharge) in minutes
%h Remaining time (to charge or discharge) in hours
%t Remaining time (to charge or discharge) in the form `h:min'"
  (let (charging-state temperature hours
        ;; Some batteries report charges and current, other energy and power.
        ;; In order to reliably be able to combine those data, we convert them
        ;; all to energy/power (since we can't combine different charges if
        ;; they're not at the same voltage).
	(energy-full 0.0)
	(energy-now 0.0)
	(power-now 0.0)
	(voltage-now 10.8))    ;Arbitrary default, in case the info is missing.
    ;; SysFS provides information about each battery present in the
    ;; system in a separate subdirectory.  We are going to merge the
    ;; available information together.
    (with-temp-buffer
      (dolist (dir (ignore-errors
                     (battery--find-linux-sysfs-batteries)))
	(erase-buffer)
	(ignore-errors (insert-file-contents
			(expand-file-name "uevent" dir)))
	(goto-char (point-min))
	(when (re-search-forward
	       "POWER_SUPPLY_VOLTAGE_NOW=\\([0-9]*\\)$" nil t)
	  (setq voltage-now (/ (string-to-number (match-string 1)) 1000000.0)))
	(goto-char (point-min))
	(when (re-search-forward "POWER_SUPPLY_PRESENT=1$" nil t)
	  (goto-char (point-min))
	  (and (re-search-forward "POWER_SUPPLY_STATUS=\\(.*\\)$" nil t)
	       (member charging-state '("Unknown" "Full" nil))
	       (setq charging-state (match-string 1)))
	  (goto-char (point-min))
	  (when (re-search-forward
                 "POWER_SUPPLY_\\(CURRENT\\|POWER\\)_NOW=\\([0-9]*\\)$"
                 nil t)
	    (cl-incf power-now
		     (* (string-to-number (match-string 2))
			(if (eq (char-after (match-beginning 1)) ?C)
			    voltage-now 1))))
	  (goto-char (point-min))
	  (when (re-search-forward "POWER_SUPPLY_TEMP=\\([0-9]*\\)$" nil t)
	    (setq temperature (match-string 1)))
	  (goto-char (point-min))
	  (let (full-string now-string)
	    ;; Sysfs may list either charge (mAh) or energy (mWh).
	    ;; Keep track of both, and choose which to report later.
	    (cond ((and (re-search-forward
			 "POWER_SUPPLY_CHARGE_FULL=\\([0-9]*\\)$" nil t)
			(setq full-string (match-string 1))
			(re-search-forward
			 "POWER_SUPPLY_CHARGE_NOW=\\([0-9]*\\)$" nil t)
			(setq now-string (match-string 1)))
		   (cl-incf energy-full (* (string-to-number full-string)
                                           voltage-now))
		   (cl-incf energy-now  (* (string-to-number now-string)
                                           voltage-now)))
		  ((and (progn (goto-char (point-min)) t)
			(re-search-forward
			 "POWER_SUPPLY_ENERGY_FULL=\\([0-9]*\\)$" nil t)
			(setq full-string (match-string 1))
			(re-search-forward
			 "POWER_SUPPLY_ENERGY_NOW=\\([0-9]*\\)$" nil t)
			(setq now-string (match-string 1)))
		   (cl-incf energy-full (string-to-number full-string))
		   (cl-incf energy-now  (string-to-number now-string)))))
	  (goto-char (point-min))
	  (unless (zerop power-now)
	    (let ((remaining (if (string= charging-state "Discharging")
				 energy-now
			       (- energy-full energy-now))))
	      (setq hours (/ remaining power-now)))))))
    (list (cons ?c (cond ((or (> energy-full 0) (> energy-now 0))
			  (number-to-string (/ energy-now voltage-now)))
			 (t "N/A")))
	  (cons ?r (if (> power-now 0.0)
		       (format "%.1f" (/ power-now 1000000.0))
		     "N/A"))
	  (cons ?m (if hours (format "%d" (* hours 60)) "N/A"))
	  (cons ?h (if hours (format "%d" hours) "N/A"))
	  (cons ?t (if hours
		       (format "%d:%02d" hours (* (- hours (floor hours)) 60))
		     "N/A"))
	  (cons ?d (or temperature "N/A"))
	  (cons ?B (or charging-state "N/A"))
	  (cons ?p (cond ((and (> energy-full 0) (> energy-now 0))
			  (format "%.1f"
				  (/ (* 100 energy-now) energy-full)))
			 (t "N/A")))
	  (cons ?L (cond
                    ((battery-search-for-one-match-in-files
                      (list "/sys/class/power_supply/AC/online"
                            "/sys/class/power_supply/ACAD/online"
                            "/sys/class/power_supply/ADP1/online")
                      "1" 0)
                     "AC")
                    ((battery-search-for-one-match-in-files
                      (list "/sys/class/power_supply/AC/online"
                            "/sys/class/power_supply/ACAD/online"
                            "/sys/class/power_supply/ADP1/online")
                      "0" 0)
                     "BAT")
                    (t "N/A"))))))


(declare-function dbus-get-property "dbus.el"
                  (bus service path interface property))

;;; `upowerd' interface.
(defsubst battery-upower-prop (pname &optional device)
  (dbus-get-property
   :system
   "org.freedesktop.UPower"
   (concat "/org/freedesktop/UPower/devices/" (or device battery-upower-device))
   "org.freedesktop.UPower"
   pname))

(defun battery-upower ()
  "Get battery status from dbus Upower interface.
This function works only in systems with `upowerd' daemon
running.

The following %-sequences are provided:
%c Current capacity (mWh)
%p Battery load percentage
%r Current rate
%B Battery status (verbose)
%L AC line status (verbose)
%s Remaining time (to charge or discharge) in seconds
%m Remaining time (to charge or discharge) in minutes
%h Remaining time (to charge or discharge) in hours
%t Remaining time (to charge or discharge) in the form `h:min'"
  (let ((percents (battery-upower-prop "Percentage"))
        (time-to-empty (battery-upower-prop "TimeToEmpty"))
        (time-to-full (battery-upower-prop "TimeToFull"))
        (state (battery-upower-prop "State"))
        (online (battery-upower-prop "Online" "line_power_ACAD"))
        (energy (battery-upower-prop "Energy"))
        (energy-rate (battery-upower-prop "EnergyRate"))
        (battery-states '((0 . "unknown") (1 . "charging")
                          (2 . "discharging") (3 . "empty")
                          (4 . "fully-charged") (5 . "pending-charge")
                          (6 . "pending-discharge")))
        seconds minutes hours remaining-time)
    (cond ((and online time-to-full)
           (setq seconds time-to-full))
          ((and (not online) time-to-empty)
           (setq seconds time-to-empty)))
    (when seconds
      (setq minutes (/ seconds 60)
            hours (/ minutes 60)
	    remaining-time (format "%d:%02d" hours (mod minutes 60))))
    (list (cons ?c (or (and energy
                            (number-to-string (round (* 1000 energy))))
                       "N/A"))
          (cons ?p (or (and percents (number-to-string (round percents)))
                       "N/A"))
          (cons ?r (or (and energy-rate
                            (concat (number-to-string energy-rate) " W"))
                       "N/A"))
          (cons ?B (or (and state (cdr (assoc state battery-states)))
                       "unknown"))
          (cons ?L (or (and online "on-line") "off-line"))
          (cons ?s (or (and seconds (number-to-string seconds)) "N/A"))
          (cons ?m (or (and minutes (number-to-string minutes)) "N/A"))
          (cons ?h (or (and hours (number-to-string hours)) "N/A"))
          (cons ?t (or remaining-time "N/A")))))


;;; `apm' interface for BSD.
(defun battery-bsd-apm ()
  "Get APM status information from BSD apm binary.
The following %-sequences are provided:
%L AC line status (verbose)
%B Battery status (verbose)
%b Battery status, empty means high, `-' means low,
 `!' means critical, and `+' means charging
%P Advanced power saving mode state (verbose)
%p Battery charge percentage
%s Remaining battery charge time in seconds
%m Remaining battery charge time in minutes
%h Remaining battery charge time in hours
%t Remaining battery charge time in the form `h:min'"
  (let* ((os-name (car (split-string
                        ;; FIXME: Can't we use something like `system-type'?
                        (shell-command-to-string "/usr/bin/uname"))))
         (apm-flag (pcase os-name
                     ("OpenBSD" "mP")
                     ("FreeBSD" "st")
                     (_         "ms")))
         (apm-cmd (concat "/usr/sbin/apm -abl" apm-flag))
         (apm-output (split-string (shell-command-to-string apm-cmd)))
         (indices (pcase os-name
                    ;; FreeBSD's manpage documents that multiple
                    ;; outputs are ordered by "the order in which
                    ;; they're listed in the manpage", which is alphabetical
                    ;; and is also the order in which we pass them.
                    ("FreeBSD" '((ac . 0)
                                 (battery-status . 1)
                                 (battery-percent . 2)
                                 (apm-mode . 3)
                                 (battery-life . 4)))
                    ;; For NetBSD and OpenBSD, the manpage doesn't document
                    ;; the order.  The previous code used this order, so let's
                    ;; assume it's right.
                    (_         '((ac . 3)
                                 (battery-status . 0)
                                 (battery-percent . 1)
                                 (apm-mode . 4)
                                 (battery-life . 2)))))
         ;; Battery status
         (battery-status
          (pcase (string-to-number
                  (nth (alist-get 'battery-status indices) apm-output))
            (0 '("high" . ""))
            (1 '("low" . "-"))
            (2 '("critical" . "!"))
            (3 '("charging" . "+"))
            (4 '("absent" . nil))))
         ;; Battery percentage
         (battery-percentage
          (nth (alist-get 'battery-percent indices) apm-output))
         ;; Battery life
         (battery-life (nth (alist-get 'battery-life indices) apm-output))
         ;; AC status
         (line-status
          (pcase (string-to-number (nth (alist-get 'ac indices) apm-output))
            (0 "disconnected")
            (1 "connected")
            (2 "backup power")))
         ;; Advanced power savings mode
         (apm-mode
          (let ((apm (string-to-number
                      (nth (alist-get 'apm-mode indices) apm-output))))
            (if (string= os-name "OpenBSD")
                (pcase apm
                  (0 "manual")
                  (1 "automatic")
		  (2 "cool running"))
	      (if (eql apm 1) "on" "off"))))
	 seconds minutes hours remaining-time)
    (unless (member battery-life '("unknown" "-1"))
      (if (member os-name '("OpenBSD" "NetBSD"))
	  (setq minutes (string-to-number battery-life)
		seconds (* 60 minutes))
	(setq seconds (string-to-number battery-life)
	      minutes (truncate seconds 60)))
      (setq hours (truncate minutes 60)
	    remaining-time (format "%d:%02d" hours (mod minutes 60))))
    (list (cons ?L (or line-status "N/A"))
	  (cons ?B (or (car battery-status) "N/A"))
	  (cons ?b (or (cdr battery-status) "N/A"))
	  (cons ?p (if (string= battery-percentage "255")
		       "N/A"
		     battery-percentage))
	  (cons ?P (or apm-mode "N/A"))
	  (cons ?s (or (and seconds (number-to-string seconds)) "N/A"))
	  (cons ?m (or (and minutes (number-to-string minutes)) "N/A"))
	  (cons ?h (or (and hours (number-to-string hours)) "N/A"))
	  (cons ?t (or remaining-time "N/A")))))


;;; `pmset' interface for Darwin (macOS).

(defun battery-pmset ()
  "Get battery status information using `pmset'.

The following %-sequences are provided:
%L Power source (verbose)
%B Battery status (verbose)
%b Battery status, empty means high, `-' means low,
   `!' means critical, and `+' means charging
%p Battery load percentage
%h Remaining time in hours
%m Remaining time in minutes
%t Remaining time in the form `h:min'"
  (let (power-source load-percentage battery-status battery-status-symbol
	remaining-time hours minutes)
    (with-temp-buffer
      (ignore-errors (call-process "pmset" nil t nil "-g" "ps"))
      (goto-char (point-min))
      (when (re-search-forward "\\(?:Currentl?y\\|Now\\) drawing from '\\(AC\\|Battery\\) Power'" nil t)
	(setq power-source (match-string 1))
	(when (re-search-forward "^ -InternalBattery-0\\([ \t]+(id=[0-9]+)\\)*[ \t]+" nil t)
	  (when (looking-at "\\([0-9]\\{1,3\\}\\)%")
	    (setq load-percentage (match-string 1))
	    (goto-char (match-end 0))
	    (cond ((looking-at "; charging")
		   (setq battery-status "charging"
			 battery-status-symbol "+"))
		  ((< (string-to-number load-percentage) battery-load-critical)
		   (setq battery-status "critical"
			 battery-status-symbol "!"))
		  ((< (string-to-number load-percentage) battery-load-low)
		   (setq battery-status "low"
			 battery-status-symbol "-"))
		  (t
		   (setq battery-status "high"
			 battery-status-symbol "")))
	    (when (re-search-forward "\\(\\([0-9]+\\):\\([0-9]+\\)\\) remaining"  nil t)
	      (setq remaining-time (match-string 1))
	      (let ((h (string-to-number (match-string 2)))
		    (m (string-to-number (match-string 3))))
		(setq hours (number-to-string (+ h (if (< m 30) 0 1)))
		      minutes (number-to-string (+ (* h 60) m)))))))))
    (list (cons ?L (or power-source "N/A"))
	  (cons ?p (or load-percentage "N/A"))
	  (cons ?B (or battery-status "N/A"))
	  (cons ?b (or battery-status-symbol ""))
	  (cons ?h (or hours "N/A"))
	  (cons ?m (or minutes "N/A"))
	  (cons ?t (or remaining-time "N/A")))))


;;; Private functions.

(defun battery-format (format alist)
  "Substitute %-sequences in FORMAT."
  (replace-regexp-in-string
   "%."
   (lambda (str)
     (let ((char (aref str 1)))
       (if (eq char ?%) "%"
	 (or (cdr (assoc char alist)) ""))))
   format t t))

(defun battery-search-for-one-match-in-files (files regexp match-num)
  "Search REGEXP in the content of the files listed in FILES.
If a match occurred, return the parenthesized expression numbered by
MATCH-NUM in the match.  Otherwise, return nil."
  (with-temp-buffer
    (catch 'found
      (dolist (file files)
	(and (ignore-errors (insert-file-contents file nil nil nil 'replace))
	     (re-search-forward regexp nil t)
	     (throw 'found (match-string match-num)))))))


(provide 'battery)

;;; battery.el ends here