#| -*-Scheme-*-

Copyright (C) 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994,
    1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
    2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016,
    2017, 2018, 2019, 2020, 2021, 2022 Massachusetts Institute of
    Technology

This file is part of MIT/GNU Scheme.

MIT/GNU Scheme 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 2 of the License, or (at
your option) any later version.

MIT/GNU Scheme 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 MIT/GNU Scheme; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301,
USA.

|#

;;;; Mode-line notifications (e.g. presence of mail, load average)

(declare (usual-integrations))

(define-variable notify-show-time
  "If true, the notifier displays the current time."
  #t
  boolean?)

(define (notifier:time)
  (let ((time (get-decoded-time)))
    (let ((hour (decoded-time/hour time))
	  (minute (decoded-time/minute time)))
      (string-append (write-to-string
		      (cond ((zero? hour) 12)
			    ((< hour 13) hour)
			    (else (- hour 12))))
		     (if (< minute 10) ":0" ":")
		     (write-to-string minute)
		     (if (< hour 12) "am" "pm")))))

(define-variable notify-show-date
  "If true, the notifier displays the current date."
  #f
  boolean?)

(define (notifier:date)
  (let ((time (get-decoded-time)))
    (string-append (vector-ref
		    '#("Mon" "Tue" "Wed" "Thu" "Fri" "Sat" "Sun")
		    (decoded-time/day-of-week time))
		   (vector-ref
		    '#("??" " Jan " " Feb " " Mar " " Apr " " May " " Jun "
			    " Jul " " Aug " " Sep " " Oct " " Nov " " Dec ")
		    (decoded-time/month time))
		   (write-to-string (decoded-time/day time)))))

(define-variable notify-show-load
  "If true, the notifier displays the load average."
  #f
  boolean?)

(define (notifier:load-average)
  (let ((temporary-buffer (temporary-buffer "*uptime*")))
    (let ((start (buffer-start temporary-buffer)))
      (shell-command #f start #f #f "uptime")
      (let ((result
	     (if (re-search-forward
		  ".*load average:[ ]*\\([0-9.]*\\),"
		  start 
		  (buffer-end temporary-buffer))
		 (extract-string (re-match-start 1)
				 (re-match-end 1))
		 "")))
	(kill-buffer temporary-buffer)
	result))))

(define-variable notify-show-mail
  "If true, the notifier displays your mail status."
  #t
  boolean?)

(define-variable notify-mail-present
  "A string to be displayed in the modeline when mail is present.
Ignored if notify-show-mail is false."
  "Mail"
  string?)

(define-variable notify-mail-not-present
  "A string to be displayed in the modeline when mail is not present.
Ignored if notify-show-mail is false."
  ""
  string?)

(define-variable mail-notify-directory
  "Directory in which MAIL-NOTIFY checks for mail."
  #f
  (lambda (object) (or (not object) (file-directory? object))))

(define (notifier:mail-present)
  (if (not (ref-variable mail-notify-directory))
      (begin
	(guarantee-rmail-variables-initialized)
	(set-variable! mail-notify-directory rmail-spool-directory)))
  (if (let ((pathname
	     (merge-pathnames (ref-variable mail-notify-directory)
			      (current-user-name))))
	(and (file-exists? pathname)
	     (> (file-length pathname) 0)))
      (ref-variable notify-mail-present)
      (ref-variable notify-mail-not-present)))

(define (notifier:set-mail-string! string)
  ;; STRING is either #F, meaning use the internal mail notifier, or a
  ;; string.  A null string means no mail, and a non-null string means
  ;; new mail is available.
  (without-interrupts
   (lambda ()
     (set! override-notifier-mail-string string)
     (if (not notifier-thread-registration)
	 (set-variable! global-mode-string string #f))
     (global-window-modeline-event!))))

(define-variable notify-interval
  "How often the notifier updates the modeline, in seconds."
  60
  exact-nonnegative-integer?)

(define notifier-elements
  (list (cons (ref-variable-object notify-show-date) notifier:date)
	(cons (ref-variable-object notify-show-time) notifier:time)
	(cons (ref-variable-object notify-show-load) notifier:load-average)))

(define (notifier:get-string window)
  window
  (string-append-separated notifier-element-string
			   (if override-notifier-mail-string
			       (if (string-null? override-notifier-mail-string)
				   (ref-variable notify-mail-not-present)
				   (ref-variable notify-mail-present))
			       notifier-mail-string)))

(define (update-notifier-strings! element mail)
  (set! notifier-element-string element)
  (set! notifier-mail-string mail)
  (global-window-modeline-event!))

(define notifier-element-string "")
(define notifier-mail-string "")
(define override-notifier-mail-string #f)
(define mail-notify-hook-installed? #f)
(define notifier-thread-registration #f)

(define-command run-notifier
  "Run the notifier.
The notifier maintains a simple display in the modeline,
which can show various things including time, load average, and mail status."
  ()
  (lambda ()
    (if (and (not mail-notify-hook-installed?)
	     (command-defined? rmail))
	(begin
	  (add-event-receiver!
	   (ref-variable rmail-new-mail-hook)
	   (lambda ()
	     (update-notifier-strings!
	      notifier-element-string
	      (if (ref-variable notify-show-mail)
		  (ref-variable notify-mail-not-present)
		  ""))))
	  (set! mail-notify-hook-installed? #t)
	  unspecific))
    ((ref-command kill-notifier))
    (set-variable! global-mode-string `("" ,notifier:get-string))
    (set! notifier-thread-registration
	  (start-standard-polling-thread (* (ref-variable notify-interval #f)
					    1000)
					 notifier
					 (cons 'notifier current-editor)))
    unspecific))

(define (notifier)
  (update-notifier-strings!
   (reduce-right string-append-separated
		 ""
		 (map (lambda (element)
			(if (and (car element)
				 (variable-value (car element)))
			    ((cdr element))
			    ""))
		      notifier-elements))
   (if (and mail-notify-hook-installed?
	    (ref-variable notify-show-mail))
       (notifier:mail-present)
       ""))
  #t)

(define-command kill-notifier
  "Kill the current notifier, if any."
  ()
  (lambda ()
    (without-interrupts
     (lambda ()
       (if notifier-thread-registration
	   (begin
	     (stop-standard-polling-thread notifier-thread-registration)
	     (set! notifier-thread-registration #f)
	     unspecific))))
    (update-notifier-strings! "" "")
    (set-variable! global-mode-string override-notifier-mail-string #f)))