root/trunk/lisp/calendar/timeclock.el

;;; timeclock.el --- mode for keeping track of how much you work

;; Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
;;   Free Software Foundation, Inc.

;; Author: John Wiegley <johnw@gnu.org>
;; Created: 25 Mar 1999
;; Version: 2.6.1
;; Keywords: calendar data

;; 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, 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; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.

;;; Commentary:

;; This mode is for keeping track of time intervals.  You can use it
;; for whatever purpose you like, but the typical scenario is to keep
;; track of how much time you spend working on certain projects.
;;
;; Use `timeclock-in' when you start on a project, and `timeclock-out'
;; when you're done.  Once you've collected some data, you can use
;; `timeclock-workday-remaining' to see how much time is left to be
;; worked today (where `timeclock-workday' specifies the length of the
;; working day), and `timeclock-when-to-leave' to calculate when you're free.

;; You'll probably want to bind the timeclock commands to some handy
;; keystrokes.  At the moment, C-x t is unused:
;;
;;   (require 'timeclock)
;;
;;   (define-key ctl-x-map "ti" 'timeclock-in)
;;   (define-key ctl-x-map "to" 'timeclock-out)
;;   (define-key ctl-x-map "tc" 'timeclock-change)
;;   (define-key ctl-x-map "tr" 'timeclock-reread-log)
;;   (define-key ctl-x-map "tu" 'timeclock-update-modeline)
;;   (define-key ctl-x-map "tw" 'timeclock-when-to-leave-string)

;; If you want Emacs to display the amount of time "left" to your
;; workday in the modeline, you can either set the value of
;; `timeclock-modeline-display' to t using M-x customize, or you
;; can add this code to your .emacs file:
;;
;;   (require 'timeclock)
;;   (timeclock-modeline-display)
;;
;; To cancel this modeline display at any time, just call
;; `timeclock-modeline-display' again.

;; You may also want Emacs to ask you before exiting, if you are
;; currently working on a project.  This can be done either by setting
;; `timeclock-ask-before-exiting' to t using M-x customize (this is
;; the default), or by adding the following to your .emacs file:
;;
;;   (add-hook 'kill-emacs-query-functions 'timeclock-query-out)

;; NOTE: If you change your .timelog file without using timeclock's
;; functions, or if you change the value of any of timeclock's
;; customizable variables, you should run the command
;; `timeclock-reread-log'.  This will recompute any discrepancies in
;; your average working time, and will make sure that the various
;; display functions return the correct value.

;;; History:

;;; Code:

(defgroup timeclock nil
  "Keeping track of the time that gets spent."
  :group 'data)

;;; User Variables:

(defcustom timeclock-file (convert-standard-filename "~/.timelog")
  "*The file used to store timeclock data in."
  :type 'file
  :group 'timeclock)

(defcustom timeclock-workday (* 8 60 60)
  "*The length of a work period."
  :type 'integer
  :group 'timeclock)

(defcustom timeclock-relative t
  "*Whether to make reported time relative to `timeclock-workday'.
For example, if the length of a normal workday is eight hours, and you
work four hours on Monday, then the amount of time \"remaining\" on
Tuesday is twelve hours -- relative to an averaged work period of
eight hours -- or eight hours, non-relative.  So relative time takes
into account any discrepancy of time under-worked or over-worked on
previous days.  This only affects the timeclock modeline display."
  :type 'boolean
  :group 'timeclock)

(defcustom timeclock-get-project-function 'timeclock-ask-for-project
  "*The function used to determine the name of the current project.
When clocking in, and no project is specified, this function will be
called to determine what is the current project to be worked on.
If this variable is nil, no questions will be asked."
  :type 'function
  :group 'timeclock)

(defcustom timeclock-get-reason-function 'timeclock-ask-for-reason
  "*A function used to determine the reason for clocking out.
When clocking out, and no reason is specified, this function will be
called to determine what is the reason.
If this variable is nil, no questions will be asked."
  :type 'function
  :group 'timeclock)

(defcustom timeclock-get-workday-function nil
  "*A function used to determine the length of today's workday.
The first time that a user clocks in each day, this function will be
called to determine what is the length of the current workday.  If
the return value is nil, or equal to `timeclock-workday', nothing special
will be done.  If it is a quantity different from `timeclock-workday',
however, a record will be output to the timelog file to note the fact that
that day has a length that is different from the norm."
  :type '(choice (const nil) function)
  :group 'timeclock)

(defcustom timeclock-ask-before-exiting t
  "*If non-nil, ask if the user wants to clock out before exiting Emacs.
This variable only has effect if set with \\[customize]."
  :set (lambda (symbol value)
         (if value
             (add-hook 'kill-emacs-query-functions 'timeclock-query-out)
           (remove-hook 'kill-emacs-query-functions 'timeclock-query-out))
         (setq timeclock-ask-before-exiting value))
  :type 'boolean
  :group 'timeclock)

(defvar timeclock-update-timer nil
  "The timer used to update `timeclock-mode-string'.")

;; For byte-compiler.
(defvar display-time-hook)
(defvar timeclock-modeline-display)

(defcustom timeclock-use-display-time t
  "*If non-nil, use `display-time-hook' for doing modeline updates.
The advantage of this is that one less timer has to be set running
amok in Emacs' process space.  The disadvantage is that it requires
you to have `display-time' running.  If you don't want to use
`display-time', but still want the modeline to show how much time is
left, set this variable to nil.  Changing the value of this variable
while timeclock information is being displayed in the modeline has no
effect.  You should call the function `timeclock-modeline-display' with
a positive argument to force an update."
  :set (lambda (symbol value)
         (let ((currently-displaying
                (and (boundp 'timeclock-modeline-display)
                     timeclock-modeline-display)))
           ;; if we're changing to the state that
           ;; `timeclock-modeline-display' is already using, don't
           ;; bother toggling it.  This happens on the initial loading
           ;; of timeclock.el.
           (if (and currently-displaying
                    (or (and value
                             (boundp 'display-time-hook)
                             (memq 'timeclock-update-modeline
                                   display-time-hook))
                        (and (not value)
                             timeclock-update-timer)))
               (setq currently-displaying nil))
           (and currently-displaying
                (set-variable 'timeclock-modeline-display nil))
           (setq timeclock-use-display-time value)
           (and currently-displaying
                (set-variable 'timeclock-modeline-display t))
           timeclock-use-display-time))
  :type 'boolean
  :group 'timeclock
  :require 'time)

(defcustom timeclock-first-in-hook nil
  "*A hook run for the first \"in\" event each day.
Note that this hook is run before recording any events.  Thus the
value of `timeclock-hours-today', `timeclock-last-event' and the
return value of function `timeclock-last-period' are relative previous
to today."
  :type 'hook
  :group 'timeclock)

(defcustom timeclock-load-hook nil
  "*Hook that gets run after timeclock has been loaded."
  :type 'hook
  :group 'timeclock)

(defcustom timeclock-in-hook nil
  "*A hook run every time an \"in\" event is recorded."
  :type 'hook
  :group 'timeclock)

(defcustom timeclock-day-over-hook nil
  "*A hook that is run when the workday has been completed.
This hook is only run if the current time remaining is being displayed
in the modeline.  See the variable `timeclock-modeline-display'."
  :type 'hook
  :group 'timeclock)

(defcustom timeclock-out-hook nil
  "*A hook run every time an \"out\" event is recorded."
  :type 'hook
  :group 'timeclock)

(defcustom timeclock-done-hook nil
  "*A hook run every time a project is marked as completed."
  :type 'hook
  :group 'timeclock)

(defcustom timeclock-event-hook nil
  "*A hook run every time any event is recorded."
  :type 'hook
  :group 'timeclock)

(defvar timeclock-last-event nil
  "A list containing the last event that was recorded.
The format of this list is (CODE TIME PROJECT).")

(defvar timeclock-last-event-workday nil
  "The number of seconds in the workday of `timeclock-last-event'.")

;;; Internal Variables:

(defvar timeclock-discrepancy nil
  "A variable containing the time discrepancy before the last event.
Normally, timeclock assumes that you intend to work for
`timeclock-workday' seconds every day.  Any days in which you work
more or less than this amount is considered either a positive or
a negative discrepancy.  If you work in such a manner that the
discrepancy is always brought back to zero, then you will by
definition have worked an average amount equal to `timeclock-workday'
each day.")

(defvar timeclock-elapsed nil
  "A variable containing the time elapsed for complete periods today.
This value is not accurate enough to be useful by itself.  Rather,
call `timeclock-workday-elapsed', to determine how much time has been
worked so far today.  Also, if `timeclock-relative' is nil, this value
will be the same as `timeclock-discrepancy'.")

(defvar timeclock-use-elapsed nil
  "Non-nil if the modeline should display time elapsed, not remaining.")

(defvar timeclock-last-period nil
  "Integer representing the number of seconds in the last period.
Note that you shouldn't access this value, but instead should use the
function `timeclock-last-period'.")

(defvar timeclock-mode-string nil
  "The timeclock string (optionally) displayed in the modeline.
The time is bracketed by <> if you are clocked in, otherwise by [].")

(defvar timeclock-day-over nil
  "The date of the last day when notified \"day over\" for.")

;;; User Functions:

;;;###autoload
(defun timeclock-modeline-display (&optional arg)
  "Toggle display of the amount of time left today in the modeline.
If `timeclock-use-display-time' is non-nil (the default), then
the function `display-time-mode' must be active, and the modeline
will be updated whenever the time display is updated.  Otherwise,
the timeclock will use its own sixty second timer to do its
updating.  With prefix ARG, turn modeline display on if and only
if ARG is positive.  Returns the new status of timeclock modeline
display (non-nil means on)."
  (interactive "P")
  ;; cf display-time-mode.
  (setq timeclock-mode-string "")
  (or global-mode-string (setq global-mode-string '("")))
  (let ((on-p (if arg
                  (> (prefix-numeric-value arg) 0)
                (not timeclock-modeline-display))))
    (if on-p
        (progn
          (or (memq 'timeclock-mode-string global-mode-string)
              (setq global-mode-string
                    (append global-mode-string '(timeclock-mode-string))))
          (unless (memq 'timeclock-update-modeline timeclock-event-hook)
            (add-hook 'timeclock-event-hook 'timeclock-update-modeline))
          (when timeclock-update-timer
            (cancel-timer timeclock-update-timer)
            (setq timeclock-update-timer nil))
          (if (boundp 'display-time-hook)
              (remove-hook 'display-time-hook 'timeclock-update-modeline))
          (if timeclock-use-display-time
              (progn
                ;; Update immediately so there is a visible change
                ;; on calling this function.
                (if display-time-mode (timeclock-update-modeline)
                  (message "Activate `display-time-mode' or turn off \
`timeclock-use-display-time' to see timeclock information"))
                (add-hook 'display-time-hook 'timeclock-update-modeline))
            (setq timeclock-update-timer
                  (run-at-time nil 60 'timeclock-update-modeline))))
      (setq global-mode-string
            (delq 'timeclock-mode-string global-mode-string))
      (remove-hook 'timeclock-event-hook 'timeclock-update-modeline)
      (if (boundp 'display-time-hook)
          (remove-hook 'display-time-hook
                       'timeclock-update-modeline))
      (when timeclock-update-timer
        (cancel-timer timeclock-update-timer)
        (setq timeclock-update-timer nil)))
    (force-mode-line-update)
    (setq timeclock-modeline-display on-p)))

;; This has to be here so that the function definition of
;; `timeclock-modeline-display' is known to the "set" function.
(defcustom timeclock-modeline-display nil
  "Toggle modeline display of time remaining.
You must modify via \\[customize] for this variable to have an effect."
  :set (lambda (symbol value)
         (setq timeclock-modeline-display
               (timeclock-modeline-display (or value 0))))
  :type 'boolean
  :group 'timeclock
  :require 'timeclock)

(defsubst timeclock-time-to-date (time)
  "Convert the TIME value to a textual date string."
  (format-time-string "%Y/%m/%d" time))

;;;###autoload
(defun timeclock-in (&optional arg project find-project)
  "Clock in, recording the current time moment in the timelog.
With a numeric prefix ARG, record the fact that today has only that
many hours in it to be worked.  If arg is a non-numeric prefix arg
\(non-nil, but not a number), 0 is assumed (working on a holiday or
weekend).  *If not called interactively, ARG should be the number of
_seconds_ worked today*.  This feature only has effect the first time
this function is called within a day.

PROJECT is the project being clocked into.  If PROJECT is nil, and
FIND-PROJECT is non-nil -- or the user calls `timeclock-in'
interactively -- call the function `timeclock-get-project-function' to
discover the name of the project."
  (interactive
   (list (and current-prefix-arg
              (if (numberp current-prefix-arg)
                  (* current-prefix-arg 60 60)
                0))))
  (if (equal (car timeclock-last-event) "i")
      (error "You've already clocked in!")
    (unless timeclock-last-event
      (timeclock-reread-log))
    ;; Either no log file, or day has rolled over.
    (unless (and timeclock-last-event
                 (equal (timeclock-time-to-date
                         (cadr timeclock-last-event))
                        (timeclock-time-to-date (current-time))))
      (let ((workday (or (and (numberp arg) arg)
                         (and arg 0)
                         (and timeclock-get-workday-function
                              (funcall timeclock-get-workday-function))
                         timeclock-workday)))
        (run-hooks 'timeclock-first-in-hook)
        ;; settle the discrepancy for the new day
        (setq timeclock-discrepancy
              (- (or timeclock-discrepancy 0) workday))
        (if (not (= workday timeclock-workday))
            (timeclock-log "h" (number-to-string
                                (/ workday (if (zerop (% workday (* 60 60)))
                                               60 60.0) 60))))))
    (timeclock-log "i" (or project
                           (and timeclock-get-project-function
                                (or find-project (interactive-p))
                                (funcall timeclock-get-project-function))))
    (run-hooks 'timeclock-in-hook)))

;;;###autoload
(defun timeclock-out (&optional arg reason find-reason)
  "Clock out, recording the current time moment in the timelog.
If a prefix ARG is given, the user has completed the project that was
begun during the last time segment.

REASON is the user's reason for clocking out.  If REASON is nil, and
FIND-REASON is non-nil -- or the user calls `timeclock-out'
interactively -- call the function `timeclock-get-reason-function' to
discover the reason."
  (interactive "P")
  (or timeclock-last-event
      (error "You haven't clocked in!"))
  (if (equal (downcase (car timeclock-last-event)) "o")
      (error "You've already clocked out!")
    (timeclock-log
     (if arg "O" "o")
     (or reason
         (and timeclock-get-reason-function
              (or find-reason (interactive-p))
              (funcall timeclock-get-reason-function))))
    (run-hooks 'timeclock-out-hook)
    (if arg
        (run-hooks 'timeclock-done-hook))))

;; Should today-only be removed in favour of timeclock-relative? - gm
(defsubst timeclock-workday-remaining (&optional today-only)
  "Return the number of seconds until the workday is complete.
The amount returned is relative to the value of `timeclock-workday'.
If TODAY-ONLY is non-nil, the value returned will be relative only to
the time worked today, and not to past time."
  (let ((discrep (timeclock-find-discrep)))
    (if discrep
        (- (if today-only (cadr discrep)
             (car discrep)))
      0.0)))

;;;###autoload
(defun timeclock-status-string (&optional show-seconds today-only)
  "Report the overall timeclock status at the present moment.
If SHOW-SECONDS is non-nil, display second resolution.
If TODAY-ONLY is non-nil, the display will be relative only to time
worked today, ignoring the time worked on previous days."
  (interactive "P")
  (let ((remainder (timeclock-workday-remaining
                    (or today-only
                        (not timeclock-relative))))
        (last-in (equal (car timeclock-last-event) "i"))
        status)
    (setq status
          (format "Currently %s since %s (%s), %s %s, leave at %s"
                  (if last-in "IN" "OUT")
                  (if show-seconds
                      (format-time-string "%-I:%M:%S %p"
                                          (nth 1 timeclock-last-event))
                    (format-time-string "%-I:%M %p"
                                        (nth 1 timeclock-last-event)))
                  (or (nth 2 timeclock-last-event)
                      (if last-in "**UNKNOWN**" "workday over"))
                  (timeclock-seconds-to-string remainder show-seconds t)
                  (if (> remainder 0)
                      "remaining" "over")
                  (timeclock-when-to-leave-string show-seconds today-only)))
    (if (interactive-p)
        (message "%s" status)
      status)))

;;;###autoload
(defun timeclock-change (&optional arg project)
  "Change to working on a different project.
This clocks out of the current project, then clocks in on a new one.
With a prefix ARG, consider the previous project as finished at the
time of changeover.  PROJECT is the name of the last project you were
working on."
  (interactive "P")
  (timeclock-out arg)
  (timeclock-in nil project (interactive-p)))

;;;###autoload
(defun timeclock-query-out ()
  "Ask the user whether to clock out.
This is a useful function for adding to `kill-emacs-query-functions'."
  (and (equal (car timeclock-last-event) "i")
       (y-or-n-p "You're currently clocking time, clock out? ")
       (timeclock-out))
  ;; Unconditionally return t for `kill-emacs-query-functions'.
  t)

;;;###autoload
(defun timeclock-reread-log ()
  "Re-read the timeclock, to account for external changes.
Returns the new value of `timeclock-discrepancy'."
  (interactive)
  (setq timeclock-discrepancy nil)
  (timeclock-find-discrep)
  (if (and timeclock-discrepancy timeclock-modeline-display)
      (timeclock-update-modeline))
  timeclock-discrepancy)

(defun timeclock-seconds-to-string (seconds &optional show-seconds
                                            reverse-leader)
  "Convert SECONDS into a compact time string.
If SHOW-SECONDS is non-nil, make the resolution of the return string
include the second count.  If REVERSE-LEADER is non-nil, it means to
output a \"+\" if the time value is negative, rather than a \"-\".
This is used when negative time values have an inverted meaning (such
as with time remaining, where negative time really means overtime)."
  (if show-seconds
      (format "%s%d:%02d:%02d"
              (if (< seconds 0) (if reverse-leader "+" "-") "")
              (truncate (/ (abs seconds) 60 60))
              (% (truncate (/ (abs seconds) 60)) 60)
              (% (truncate (abs seconds)) 60))
    (format "%s%d:%02d"
            (if (< seconds 0) (if reverse-leader "+" "-") "")
            (truncate (/ (abs seconds) 60 60))
            (% (truncate (/ (abs seconds) 60)) 60))))

(defsubst timeclock-currently-in-p ()
  "Return non-nil if the user is currently clocked in."
  (equal (car timeclock-last-event) "i"))

;;;###autoload
(defun timeclock-workday-remaining-string (&optional show-seconds
                                                     today-only)
  "Return a string representing the amount of time left today.
Display second resolution if SHOW-SECONDS is non-nil.  If TODAY-ONLY
is non-nil, the display will be relative only to time worked today.
See `timeclock-relative' for more information about the meaning of
\"relative to today\"."
  (interactive)
  (let ((string (timeclock-seconds-to-string
                 (timeclock-workday-remaining today-only)
                 show-seconds t)))
    (if (interactive-p)
        (message "%s" string)
      string)))

(defsubst timeclock-workday-elapsed ()
  "Return the number of seconds worked so far today.
If RELATIVE is non-nil, the amount returned will be relative to past
time worked.  The default is to return only the time that has elapsed
so far today."
  (let ((discrep (timeclock-find-discrep)))
    (if discrep
        (nth 2 discrep)
      0.0)))

;;;###autoload
(defun timeclock-workday-elapsed-string (&optional show-seconds)
  "Return a string representing the amount of time worked today.
Display seconds resolution if SHOW-SECONDS is non-nil.  If RELATIVE is
non-nil, the amount returned will be relative to past time worked."
  (interactive)
  (let ((string (timeclock-seconds-to-string (timeclock-workday-elapsed)
                                             show-seconds)))
    (if (interactive-p)
        (message "%s" string)
      string)))

(defsubst timeclock-time-to-seconds (time)
  "Convert TIME to a floating point number."
  (+ (* (car time) 65536.0)
     (cadr time)
     (/ (or (car (cdr (cdr time))) 0) 1000000.0)))

(defsubst timeclock-seconds-to-time (seconds)
  "Convert SECONDS (a floating point number) to an Emacs time structure."
  (list (floor seconds 65536)
        (floor (mod seconds 65536))
        (floor (* (- seconds (ffloor seconds)) 1000000))))

;; Should today-only be removed in favour of timeclock-relative? - gm
(defsubst timeclock-when-to-leave (&optional today-only)
  "Return a time value representing the end of today's workday.
If TODAY-ONLY is non-nil, the value returned will be relative only to
the time worked today, and not to past time."
  (timeclock-seconds-to-time
   (- (timeclock-time-to-seconds (current-time))
      (let ((discrep (timeclock-find-discrep)))
        (if discrep
            (if today-only
                (cadr discrep)
              (car discrep))
          0.0)))))

;;;###autoload
(defun timeclock-when-to-leave-string (&optional show-seconds
                                                 today-only)
  "Return a string representing the end of today's workday.
This string is relative to the value of `timeclock-workday'.  If
SHOW-SECONDS is non-nil, the value printed/returned will include
seconds.  If TODAY-ONLY is non-nil, the value returned will be
relative only to the time worked today, and not to past time."
  ;; Should today-only be removed in favour of timeclock-relative? - gm
  (interactive)
  (let* ((then (timeclock-when-to-leave today-only))
         (string
          (if show-seconds
              (format-time-string "%-I:%M:%S %p" then)
            (format-time-string "%-I:%M %p" then))))
    (if (interactive-p)
        (message "%s" string)
      string)))

(defun timeclock-make-hours-explicit (old-default)
  "Specify all workday lengths in `timeclock-file'.
OLD-DEFAULT hours are set for every day that has no number indicated."
  (interactive "P")
  (if old-default (setq old-default (prefix-numeric-value old-default))
    (error "timelog-make-hours-explicit requires an explicit argument"))
  (let ((extant-timelog (find-buffer-visiting timeclock-file))
        current-date)
    (with-current-buffer (find-file-noselect timeclock-file t)
      (unwind-protect
          (save-excursion
            (save-restriction
              (widen)
              (goto-char (point-min))
              (while (progn (skip-chars-forward "\n") (not (eobp)))
                ;; This is just a variant of `timeclock-moment-regexp'.
                (unless (looking-at
                         (concat "^\\([bhioO]\\) \\([0-9]+/[0-9]+/[0-9]+\\) "
                                 "\\([0-9]+:[0-9]+:[0-9]+\\)"))
                  (error "Can't parse `%s'" timeclock-file))
                (let ((this-date (match-string 2)))
                  (unless (or (and current-date
                                   (string= this-date current-date))
                              (string= (match-string 1) "h"))
                    (insert (format "h %s %s %s\n" (match-string 2)
                                    (match-string 3) old-default)))
                  (if (string-match "^[ih]" (match-string 1)) ; ignore logouts
                      (setq current-date this-date)))
                (forward-line))
              (save-buffer)))
        (unless extant-timelog (kill-buffer (current-buffer)))))))

;;; Internal Functions:

(defvar timeclock-project-list nil)
(defvar timeclock-last-project nil)

(defun timeclock-completing-read (prompt alist &optional default)
  "A version of `completing-read' that works on both Emacs and XEmacs."
  (if (featurep 'xemacs)
      (let ((str (completing-read prompt alist)))
        (if (or (null str) (= (length str) 0))
            default
          str))
    (completing-read prompt alist nil nil nil nil default)))

(defun timeclock-ask-for-project ()
  "Ask the user for the project they are clocking into."
  (timeclock-completing-read
   (format "Clock into which project (default %s): "
           (or timeclock-last-project
               (car timeclock-project-list)))
   (mapcar 'list timeclock-project-list)
   (or timeclock-last-project
       (car timeclock-project-list))))

(defvar timeclock-reason-list nil)

(defun timeclock-ask-for-reason ()
  "Ask the user for the reason they are clocking out."
  (timeclock-completing-read "Reason for clocking out: "
                             (mapcar 'list timeclock-reason-list)))

(defun timeclock-update-modeline ()
  "Update the `timeclock-mode-string' displayed in the modeline.
The value of `timeclock-relative' affects the display as described in
that variable's documentation."
  (interactive)
  (let ((remainder
         (if timeclock-use-elapsed
             (timeclock-workday-elapsed)
           (timeclock-workday-remaining (not timeclock-relative))))
        (last-in (equal (car timeclock-last-event) "i")))
    (when (and (< remainder 0)
               (not (and timeclock-day-over
                         (equal timeclock-day-over
                                (timeclock-time-to-date
                                 (current-time))))))
      (setq timeclock-day-over
            (timeclock-time-to-date (current-time)))
      (run-hooks 'timeclock-day-over-hook))
    (setq timeclock-mode-string
          (propertize
           (format " %c%s%c "
                   (if last-in ?< ?[)
                   (timeclock-seconds-to-string remainder nil t)
                   (if last-in ?> ?]))
           'help-echo "timeclock: time remaining"))))

(put 'timeclock-mode-string 'risky-local-variable t)

(defun timeclock-log (code &optional project)
  "Log the event CODE to the timeclock log, at the time of call.
If PROJECT is a string, it represents the project which the event is
being logged for.  Normally only \"in\" events specify a project."
  (let ((extant-timelog (find-buffer-visiting timeclock-file)))
    (with-current-buffer (find-file-noselect timeclock-file t)
      (save-excursion
        (save-restriction
          (widen)
          (goto-char (point-max))
          (if (not (bolp))
              (insert "\n"))
          (let ((now (current-time)))
            (insert code " "
                    (format-time-string "%Y/%m/%d %H:%M:%S" now)
                    (or (and (stringp project)
                             (> (length project) 0)
                             (concat " " project))
                        "")
                    "\n")
            (if (equal (downcase code) "o")
                (setq timeclock-last-period
                      (- (timeclock-time-to-seconds now)
                         (timeclock-time-to-seconds
                          (cadr timeclock-last-event)))
                      timeclock-discrepancy
                      (+ timeclock-discrepancy
                         timeclock-last-period)))
            (setq timeclock-last-event (list code now project)))))
      (save-buffer)
      (unless extant-timelog (kill-buffer (current-buffer)))))
  (run-hooks 'timeclock-event-hook))

(defvar timeclock-moment-regexp
  (concat "\\([bhioO]\\)\\s-+"
          "\\([0-9]+\\)/\\([0-9]+\\)/\\([0-9]+\\)\\s-+"
          "\\([0-9]+\\):\\([0-9]+\\):\\([0-9]+\\)[ \t]*" "\\([^\n]*\\)"))

(defsubst timeclock-read-moment ()
  "Read the moment under point from the timelog."
  (if (looking-at timeclock-moment-regexp)
      (let ((code (match-string 1))
            (year (string-to-number (match-string 2)))
            (mon  (string-to-number (match-string 3)))
            (mday (string-to-number (match-string 4)))
            (hour (string-to-number (match-string 5)))
            (min  (string-to-number (match-string 6)))
            (sec  (string-to-number (match-string 7)))
            (project (match-string 8)))
        (list code (encode-time sec min hour mday mon year) project))))

(defun timeclock-last-period (&optional moment)
  "Return the value of the last event period.
If the last event was a clock-in, the period will be open ended, and
growing every second.  Otherwise, it is a fixed amount which has been
recorded to disk.  If MOMENT is non-nil, use that as the current time.
This is only provided for coherency when used by
`timeclock-discrepancy'."
  (if (equal (car timeclock-last-event) "i")
      (- (timeclock-time-to-seconds (or moment (current-time)))
         (timeclock-time-to-seconds
          (cadr timeclock-last-event)))
    timeclock-last-period))

(defsubst timeclock-entry-length (entry)
  (- (timeclock-time-to-seconds (cadr entry))
     (timeclock-time-to-seconds (car entry))))

(defsubst timeclock-entry-begin (entry)
  (car entry))

(defsubst timeclock-entry-end (entry)
  (cadr entry))

(defsubst timeclock-entry-project (entry)
  (nth 2 entry))

(defsubst timeclock-entry-comment (entry)
  (nth 3 entry))


(defsubst timeclock-entry-list-length (entry-list)
  (let ((length 0))
    (while entry-list
      (setq length (+ length (timeclock-entry-length (car entry-list))))
      (setq entry-list (cdr entry-list)))
    length))

(defsubst timeclock-entry-list-begin (entry-list)
  (timeclock-entry-begin (car entry-list)))

(defsubst timeclock-entry-list-end (entry-list)
  (timeclock-entry-end (car (last entry-list))))

(defsubst timeclock-entry-list-span (entry-list)
  (- (timeclock-time-to-seconds (timeclock-entry-list-end entry-list))
     (timeclock-time-to-seconds (timeclock-entry-list-begin entry-list))))

(defsubst timeclock-entry-list-break (entry-list)
  (- (timeclock-entry-list-span entry-list)
     (timeclock-entry-list-length entry-list)))

(defsubst timeclock-entry-list-projects (entry-list)
  (let (projects)
    (while entry-list
      (let ((project (timeclock-entry-project (car entry-list))))
        (if projects
            (add-to-list 'projects project)
          (setq projects (list project))))
      (setq entry-list (cdr entry-list)))
    projects))


(defsubst timeclock-day-required (day)
  (or (car day) timeclock-workday))

(defsubst timeclock-day-length (day)
  (timeclock-entry-list-length (cdr day)))

(defsubst timeclock-day-debt (day)
  (- (timeclock-day-required day)
     (timeclock-day-length day)))

(defsubst timeclock-day-begin (day)
  (timeclock-entry-list-begin (cdr day)))

(defsubst timeclock-day-end (day)
  (timeclock-entry-list-end (cdr day)))

(defsubst timeclock-day-span (day)
  (timeclock-entry-list-span (cdr day)))

(defsubst timeclock-day-break (day)
  (timeclock-entry-list-break (cdr day)))

(defsubst timeclock-day-projects (day)
  (timeclock-entry-list-projects (cdr day)))

(defmacro timeclock-day-list-template (func)
  `(let ((length 0))
     (while day-list
       (setq length (+ length (,(eval func) (car day-list))))
       (setq day-list (cdr day-list)))
     length))

(defun timeclock-day-list-required (day-list)
  (timeclock-day-list-template 'timeclock-day-required))

(defun timeclock-day-list-length (day-list)
  (timeclock-day-list-template 'timeclock-day-length))

(defun timeclock-day-list-debt (day-list)
  (timeclock-day-list-template 'timeclock-day-debt))

(defsubst timeclock-day-list-begin (day-list)
  (timeclock-day-begin (car day-list)))

(defsubst timeclock-day-list-end (day-list)
  (timeclock-day-end (car (last day-list))))

(defun timeclock-day-list-span (day-list)
  (timeclock-day-list-template 'timeclock-day-span))

(defun timeclock-day-list-break (day-list)
  (timeclock-day-list-template 'timeclock-day-break))