;;; ledger-schedule.el --- Helper code for use with the "ledger" command-line tool
;; Copyright (C) 2013 Craig Earls (enderw88 at gmail dot com)
;; This file is not part of GNU Emacs.
;; This 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, or (at your option)
;; any later version.
;;
;; This 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 module provides for automatically adding transactions to a
;; ledger buffer on a periodic basis. Recurrence expressions are
;; inspired by Martin Fowler's "Recurring Events for Calendars",
;; martinfowler.com/apsupp/recurring.pdf
;; use (fset 'VARNAME (macro args)) to put the macro definition in the
;; function slot of the symbol VARNAME. Then use VARNAME as the
;; function without have to use funcall.
(require 'ledger-init)
(defgroup ledger-schedule nil
"Support for automatically recommendation transactions."
:group 'ledger)
(defcustom ledger-schedule-buffer-name "*Ledger Schedule*"
"Name for the schedule buffer"
:type 'string
:group 'ledger-schedule)
(defcustom ledger-schedule-look-backward 7
"Number of days to look back in time for transactions."
:type 'integer
:group 'ledger-schedule)
(defcustom ledger-schedule-look-forward 14
"Number of days auto look forward to recommend transactions"
:type 'integer
:group 'ledger-schedule)
(defcustom ledger-schedule-file "~/ledger-schedule.ledger"
"File to find scheduled transactions."
:type 'file
:group 'ledger-schedule)
(defvar ledger-schedule-available nil)
(defsubst between (val low high)
(and (>= val low) (<= val high)))
(defun ledger-schedule-check-available ()
(setq ledger-schedule-available (and ledger-schedule-file
(file-exists-p ledger-schedule-file))))
(defun ledger-schedule-days-in-month (month year)
"Return number of days in the MONTH, MONTH is from 1 to 12.
If year is nil, assume it is not a leap year"
(if (between month 1 12)
(if (and year (date-leap-year-p year) (= 2 month))
29
(nth (1- month) '(31 28 31 30 31 30 31 31 30 31 30 31)))
(error "Month out of range, MONTH=%S" month)))
;; Macros to handle date expressions
(defun ledger-schedule-constrain-day-in-month (count day-of-week)
"Return a form that evaluates DATE that returns true for the COUNT DAY-OF-WEEK.
For example, return true if date is the 3rd Thursday of the
month. Negative COUNT starts from the end of the month. (EQ
COUNT 0) means EVERY day-of-week (eg. every Saturday)"
(if (and (between count -6 6) (between day-of-week 0 6))
(cond ((zerop count) ;; Return true if day-of-week matches
`(eq (nth 6 (decode-time date)) ,day-of-week))
((> count 0) ;; Positive count
(let ((decoded (gensym)))
`(let ((,decoded (decode-time date)))
(and (eq (nth 6 ,decoded) ,day-of-week)
(between (nth 3 ,decoded)
,(* (1- count) 7)
,(* count 7))))))
((< count 0)
(let ((days-in-month (gensym))
(decoded (gensym)))
`(let* ((,decoded (decode-time date))
(,days-in-month (ledger-schedule-days-in-month
(nth 4 ,decoded)
(nth 5 ,decoded))))
(and (eq (nth 6 ,decoded) ,day-of-week)
(between (nth 3 ,decoded)
(+ ,days-in-month ,(* count 7))
(+ ,days-in-month ,(* (1+ count) 7)))))))
(t
(error "COUNT out of range, COUNT=%S" count)))
(error "Invalid argument to ledger-schedule-day-in-month-macro %S %S"
count
day-of-week)))
(defun ledger-schedule-constrain-every-count-day (day-of-week skip start-date)
"Return a form that is true for every DAY skipping SKIP, starting on START.
For example every second Friday, regardless of month."
(let ((start-day (nth 6 (decode-time (eval start-date)))))
(if (eq start-day day-of-week) ;; good, can proceed
`(zerop (mod (- (time-to-days date) ,(time-to-days (eval start-date))) ,(* skip 7)))
(error "START-DATE day of week doesn't match DAY-OF-WEEK"))))
(defun ledger-schedule-constrain-date-range (month1 day1 month2 day2)
"Return a form of DATE that is true if DATE falls between MONTH1 DAY1 and MONTH2 DAY2."
(let ((decoded (gensym))
(target-month (gensym))
(target-day (gensym)))
`(let* ((,decoded (decode-time date))
(,target-month (nth 4 decoded))
(,target-day (nth 3 decoded)))
(and (and (> ,target-month ,month1)
(< ,target-month ,month2))
(and (> ,target-day ,day1)
(< ,target-day ,day2))))))
(defun ledger-schedule-is-holiday (date)
"Return true if DATE is a holiday.")
(defun ledger-schedule-scan-transactions (schedule-file)
"Scans AUTO_FILE and returns a list of transactions with date predicates.
The car of each item is a fuction of date that returns true if
the transaction should be logged for that day."
(interactive "fFile name: ")
(let ((xact-list (list)))
(with-current-buffer
(find-file-noselect schedule-file)
(goto-char (point-min))
(while (re-search-forward "^\\[\\(.*\\)\\] " nil t)
(let ((date-descriptor "")
(transaction nil)
(xact-start (match-end 0)))
(setq date-descriptors
(ledger-schedule-read-descriptor-tree
(buffer-substring-no-properties
(match-beginning 0)
(match-end 0))))
(forward-paragraph)
(setq transaction (list date-descriptors
(buffer-substring-no-properties
xact-start
(point))))
(setq xact-list (cons transaction xact-list))))
xact-list)))
(defun ledger-schedule-replace-brackets ()
"Replace all brackets with parens"
(goto-char (point-min))
(while (search-forward "]" nil t)
(replace-match ")" nil t))
(goto-char (point-min))
(while (search-forward "[" nil t)
(replace-match "(" nil t)))
(defvar ledger-schedule-descriptor-regex
(concat "\\(20[0-9][0-9]\\|[\*]\\)[/\\-]" ;; Year slot
"\\([\*EO]\\|[01][0-9]\\)[/\\-]" ;; Month slot
"\\([\*]\\|\\([0-3][0-9]\\)\\|"
"\\([0-5]"
"\\(\\(Su\\)\\|"
"\\(Mo\\)\\|"
"\\(Tu\\)\\|"
"\\(We\\)\\|"
"\\(Th\\)\\|"
"\\(Fr\\)\\|"
"\\(Sa\\)\\)\\)\\)"))
(defun ledger-schedule-read-descriptor-tree (descriptor-string)
"Take a date DESCRIPTOR-STRING and return a function of date that
returns true if the date meets the requirements"
(with-temp-buffer
;; copy the descriptor string into a temp buffer for manipulation
(let (pos)
;; Replace brackets with parens
(insert descriptor-string)
(ledger-schedule-replace-brackets)
(goto-char (point-max))
;; double quote all the descriptors for string processing later
(while (re-search-backward ledger-schedule-descriptor-regex nil t) ;; Day slot
(goto-char
(match-end 0))
(insert ?\")
(goto-char (match-beginning 0))
(insert "\"" )))
;; read the descriptor string into a lisp object the transform the
;; string descriptor into useable things
(ledger-schedule-transform-auto-tree
(read (buffer-substring-no-properties (point-min) (point-max))))))
(defun ledger-schedule-transform-auto-tree (descriptor-string-list)
"Takes a lisp list of date descriptor strings, TREE, and returns a string with a lambda function of date."
;; use funcall to use the lambda function spit out here
(if (consp descriptor-string-list)
(let (result)
(while (consp descriptor-string-list)
(let ((newcar (car descriptor-string-list)))
(if (consp newcar)
(setq newcar (ledger-schedule-transform-auto-tree (car descriptor-string-list))))
;; newcar may be a cons now, after ledger-schedule-transfrom-auto-tree
(if (consp newcar)
(push newcar result)
;; this is where we actually turn the string descriptor into useful lisp
(push (ledger-schedule-compile-constraints newcar) result)) )
(setq descriptor-string-list (cdr descriptor-string-list)))
;; tie up all the clauses in a big or and lambda, and return
;; the lambda function as list to be executed by funcall
`(lambda (date)
,(nconc (list 'or) (nreverse result) descriptor-string-list)))))
(defun ledger-schedule-compile-constraints (descriptor-string)
"Return a list with the year, month and day fields split"
(let ((fields (split-string descriptor-string "[/\\-]" t))
constrain-year constrain-month constrain-day)
(setq constrain-year (ledger-schedule-constrain-year (nth 0 fields)))
(setq constrain-month (ledger-schedule-constrain-month (nth 1 fields)))
(setq constrain-day (ledger-schedule-constrain-day (nth 2 fields)))
(list 'and constrain-year constrain-month constrain-day)))
(defun ledger-schedule-constrain-year (str)
(let ((year-match t))
(cond ((string= str "*")
year-match)
((/= 0 (setq year-match (string-to-number str)))
`(eq (nth 5 (decode-time date)) ,year-match))
(t
(error "Improperly specified year constraint: %s" str)))))
(defun ledger-schedule-constrain-month (str)
(let ((month-match t))
(cond ((string= str "*")
month-match) ;; always match
((/= 0 (setq month-match (string-to-number str)))
(if (between month-match 1 12) ;; no month specified, assume 31 days.
`(eq (nth 4 (decode-time date)) ,month-match)
(error "ledger-schedule-constrain-numerical-month: month out of range %S" month-match)))
(t
(error "Improperly specified month constraint: %s" str)))))
(defun ledger-schedule-constrain-day (str)
(let ((day-match t))
(cond ((string= str "*")
t)
((/= 0 (setq day-match (string-to-number str)))
`(eq (nth 3 (decode-time date)) ,day-match))
(t
(error "Improperly specified day constraint: %s" str)))))
(defun ledger-schedule-parse-date-descriptor (descriptor)
"Parse the date descriptor, return the evaluator"
(ledger-schedule-compile-constraints descriptor))
(defun ledger-schedule-list-upcoming-xacts (candidate-items early horizon)
"Search CANDIDATE-ITEMS for xacts that occur within the period today - EARLY to today + HORIZON"
(let ((start-date (time-subtract (current-time) (days-to-time early)))
test-date items)
(loop for day from 0 to (+ early horizon) by 1 do
(setq test-date (time-add start-date (days-to-time day)))
(dolist (candidate candidate-items items)
(if (funcall (car candidate) test-date)
(setq items (append items (list (list test-date (cadr candidate))))))))
items))
(defun ledger-schedule-already-entered (candidate buffer)
(let ((target-date (format-time-string date-format (car candidate)))
(target-payee (cadr candidate)))
nil))
(defun ledger-schedule-create-auto-buffer (candidate-items early horizon ledger-buf)
"Format CANDIDATE-ITEMS for display."
(let ((candidates (ledger-schedule-list-upcoming-xacts candidate-items early horizon))
(schedule-buf (get-buffer-create ledger-schedule-buffer-name))
(date-format (or (cdr (assoc "date-format" ledger-environment-alist))
ledger-default-date-format)))
(with-current-buffer schedule-buf
(erase-buffer)
(dolist (candidate candidates)
(if (not (ledger-schedule-already-entered candidate ledger-buf))
(insert (format-time-string date-format (car candidate) ) " " (cadr candidate) "\n")))
(ledger-mode))
(length candidates)))
(defun ledger-schedule-upcoming (file look-backward look-forward)
"Generate upcoming transaction
FILE is the file containing the scheduled transaction,
default to `ledger-schedule-file'.
LOOK-BACKWARD is the number of day in the past to look at
default to `ledger-schedule-look-backward'
LOOK-FORWARD is the number of day in the futur to look at
default to `ledger-schedule-look-forward'
Use a prefix arg to change the default value"
(interactive (if current-prefix-arg
(list (read-file-name "Schedule File: " () ledger-schedule-file t)
(read-number "Look backward: " ledger-schedule-look-backward)
(read-number "Look forward: " ledger-schedule-look-forward))
(list ledger-schedule-file ledger-schedule-look-backward ledger-schedule-look-forward)))
(ledger-schedule-create-auto-buffer
(ledger-schedule-scan-transactions file)
look-backward
look-forward
(current-buffer))
(pop-to-buffer ledger-schedule-buffer-name))
(provide 'ledger-schedule)
;;; ledger-schedule.el ends here