;;; org-datetree.el --- Create date entries in a tree -*- lexical-binding: t; -*-

;; Copyright (C) 2009-2024 Free Software Foundation, Inc.

;; Author: Carsten Dominik <carsten.dominik@gmail.com>
;; Keywords: outlines, hypermedia, calendar, text
;; URL: https://orgmode.org
;;
;; 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:

;; This file contains code to create entries in a tree where the
;; top-level nodes represent years, the level 2 nodes represent the
;; months, and the level 1 entries days.  It also implements
;; extensions to the datetree that allow for other levels such as
;; quarters and weeks.

;;; Code:

(require 'org-macs)
(org-assert-version)

(require 'cal-iso)
(require 'org)
(require 'org-element)

(defcustom org-datetree-add-timestamp nil
  "When non-nil, add a time stamp matching date of entry.
Added time stamp is active unless value is `inactive'."
  :group 'org-capture
  :version "24.3"
  :type '(choice
	  (const :tag "Do not add a time stamp" nil)
	  (const :tag "Add an inactive time stamp" inactive)
	  (const :tag "Add an active time stamp" active)))

;;;###autoload
(defun org-datetree-find-date-create (d &optional keep-restriction)
  "Find or create a day entry for date D.
If KEEP-RESTRICTION is non-nil, do not widen the buffer.
When it is nil, the buffer will be widened to make sure an existing date
tree can be found.  If it is the symbol `subtree-at-point', then the tree
will be built under the headline at point."
  (org-datetree-find-create-entry '(year month day) d keep-restriction))

;;;###autoload
(defun org-datetree-find-month-create (d &optional keep-restriction)
  "Find or create a month entry for date D.
Compared to `org-datetree-find-date-create' this function creates
entries grouped by year-month instead of year-month-day.
If KEEP-RESTRICTION is non-nil, do not widen the buffer.
When it is nil, the buffer will be widened to make sure an existing date
tree can be found.  If it is the symbol `subtree-at-point', then the tree
will be built under the headline at point."
  (org-datetree-find-create-entry '(year month) d keep-restriction))

;;;###autoload
(defun org-datetree-find-iso-week-create (d &optional keep-restriction)
  "Find or create an ISO week entry for date D.
Compared to `org-datetree-find-date-create' this function creates
entries grouped by year-week-day instead of year-month-day.  If
KEEP-RESTRICTION is non-nil, do not widen the buffer.  When it is
nil, the buffer will be widened to make sure an existing date
tree can be found.  If it is the symbol `subtree-at-point', then
the tree will be built under the headline at point."
  (org-datetree-find-create-entry '(year week day) d keep-restriction))

;;;###autoload
(defun org-datetree-find-create-entry
    (time-grouping d &optional keep-restriction)
  "Find or create an entry for date D.
TIME-GROUPING specifies the grouping levels of the datetree, and
should be a subset of `(year quarter month week day)'.  Weeks are
assigned to years according to ISO-8601.  If TIME-GROUPING
contains both `month' and `week', then weeks are assigned to the
month containing Thursday, for consistency with the ISO-8601
year-week rule.  If TIME-GROUPING contains `quarter' and `week'
but not `month', quarters are defined as 13-week periods;
otherwise they are defined as 3-month periods.

If KEEP-RESTRICTION is non-nil, do not widen the buffer.  When it
is nil, the buffer will be widened to make sure an existing date
tree can be found.  If it is the symbol `subtree-at-point', then
the tree will be built under the headline at point."
  (let* ((year (calendar-extract-year d))
	 (month (calendar-extract-month d))
	 (day (calendar-extract-day d))
         (time (org-encode-time 0 0 0 day month year))
         (iso-date (calendar-iso-from-absolute
		    (calendar-absolute-from-gregorian d)))
         (week (nth 0 iso-date))
         (nominal-year
          (if (memq 'week time-grouping)
              (nth 2 iso-date)
            year))
         (nominal-month
          (if (memq 'week time-grouping)
              (calendar-extract-month
               ;; anchor on Thurs, to be consistent with weekyear
               (calendar-gregorian-from-absolute
                (calendar-iso-to-absolute
                 `(,week 4 ,nominal-year))))
            month))
         (quarter (if (and (memq 'week time-grouping)
                           (not (memq 'month time-grouping)))
                      (min 4 (1+ (/ (1- week) 13)))
                    (1+ (/ (1- nominal-month) 3)))))
    (org-datetree-find-create-hierarchy
     (append
      (when (memq 'year time-grouping)
        (list (list (number-to-string nominal-year)
                    (org-datetree--compare-fun-from-regex
                     "\\([12][0-9]\\{3\\}\\)"))))
      (when (memq 'quarter time-grouping)
        (list (list (format "%d-Q%d" nominal-year quarter)
                    (org-datetree--compare-fun-from-regex
                     "\\([12][0-9]\\{3\\}-Q[1-4]\\)"))))
      (when (memq 'month time-grouping)
        (list (list (format-time-string
                     "%Y-%m %B" (org-encode-time 0 0 0 1 nominal-month
                                                 nominal-year))
                    (org-datetree--compare-fun-from-regex
                     "\\([12][0-9]\\{3\\}-[01][0-9]\\) \\w+"))))
      (when (memq 'week time-grouping)
        (list (list (format-time-string "%G-W%V" time)
                    (org-datetree--compare-fun-from-regex
                     "\\([12][0-9]\\{3\\}-W[0-5][0-9]\\)"))))
      (when (memq 'day time-grouping)
        ;; Use regular date instead of ISO-week year/month
        (list (list (format-time-string
                     "%Y-%m-%d %A" (org-encode-time 0 0 0 day month year))
                    (org-datetree--compare-fun-from-regex
                     "\\([12][0-9]\\{3\\}-[01][0-9]-[0123][0-9]\\) \\w+")))))
     keep-restriction
     ;; Support the old way of tree placement, using a property
     (cond
      ((seq-set-equal-p time-grouping '(year month day))
       "DATE_TREE")
      ((seq-set-equal-p time-grouping '(year month))
       "DATE_TREE")
      ((seq-set-equal-p time-grouping '(year week day))
       "WEEK_TREE")))
    (when (memq 'day time-grouping)
      (when org-datetree-add-timestamp
        (save-excursion
          (end-of-line)
          (insert "\n")
          (org-indent-line)
          (org-insert-timestamp
           (org-encode-time 0 0 0 day month year)
           nil
           (eq org-datetree-add-timestamp 'inactive)))))))

(defun org-datetree--compare-fun-from-regex (sibling-regex)
  "Construct comparison function based on regular expression.
SIBLING-REGEX should be a regex that matches the headline and its
siblings, with 1 match group.  Headlines are compared by the
lexicographic ordering of match group 1."
  (lambda (sibling-title new-title)
    (let ((target-match (and (string-match sibling-regex new-title)
                             (match-string 1 new-title)))
          (sibling-match (and (string-match sibling-regex sibling-title)
                              (match-string 1 sibling-title))))
      (cond
       ((not (and target-match sibling-match)) nil)
       ((string< sibling-match target-match) -1)
       ((string> sibling-match target-match) 1)
       (t 0)))))

(defun org-datetree-find-create-hierarchy
    (hier-pairs &optional keep-restriction legacy-prop)
  "Insert a new entry into a datetree from the entry's full date hierarchy.
HIER-PAIRS is a list whose first entry corresponds to the outermost element
(e.g. year) and last entry corresponds to the innermost (e.g. day).
Each entry of the list is a pair, the car is the headline for that level
(e.g. \"2024\" or \"2024-12-28\"), and the cadr is a string
comparison function for sorting each headline among its siblings.
The comparison function should take 2 arguments, corresponding to
the titles of 2 headlines, and return a negative number of the
first headline precedes the second, a positive number of the
second has precedence, 0 if the headlines are at the same time,
or `nil' if a headline isn't a valid datetree subheading.  For
example, HIER-PAIRS could look like

   ((\"2024\" compare-year-fun)
    (\"2024-12 December\" compare-month-fun)
    (\"2024-12-28 Saturday\" compare-day-fun))

where compare-month-fun would be some function where
(compare-month-fun \"2024-12-December\" \"2024-12-November\") is
negative, and (compare-month-fun \"2024-12-December\" \"Potato\")
is nil.

If KEEP-RESTRICTION is non-nil, do not widen the buffer.
When it is nil, the buffer will be widened to make sure an existing date
tree can be found.  If it is the symbol `subtree-at-point', then the tree
will be built under the headline at point.

If LEGACY-PROP is non-nil, the tree is located by searching for a
headline with property LEGACY-PROP, supporting the old way of
tree placement via a property."
  (let (tree)
    (save-restriction
      ;; get the datetree base and narrow to it
      (if (eq keep-restriction 'subtree-at-point)
          (progn
	    (unless (org-at-heading-p) (error "Not at heading"))
	    (widen)
	    (org-narrow-to-subtree)
            (setq tree (car (org-element-contents (org-element-parse-buffer 'headline)))))
        (unless keep-restriction (widen))
        ;; Support the old way of tree placement, using a property
        (let ((prop (and legacy-prop (org-find-property legacy-prop))))
          (if prop
              (progn
                (goto-char prop)
	        (org-narrow-to-subtree)
                (setq tree (car (org-element-contents (org-element-parse-buffer 'headline)))))
            (setq tree (org-element-parse-buffer)))))
      (cl-loop
       for pair in hier-pairs
       do
       (setq tree
             (org-datetree--find-create-subheading
              (cadr pair) (car pair) tree)))
      tree)))

(defun org-datetree--find-create-subheading
    (compare-fun new-title tree)
  "Find datetree subheading, or create it if it doesn't exist.
After insertion, move point to beginning of the subheading, and
narrow to its subtree.  NEW-TITLE is the subheading to be found
or created.  TREE is the parent headline, or an element of type
`org-data' if NEW-TITLE is to be at level 1.  COMPARE-FUN is a
function of 2 arguments for comparing headline titles; it should
return a negative number if the first headline precedes the
second, a positive number if the second number has precedence, 0
if the headlines are at the same time, and `nil' if a headline
isn't a valid datetree subheading at this level."
  (let* ((level (if (eq (org-element-type tree) 'org-data)
                    1
                  (1+ (org-element-property :level tree))))
         (sibling (org-element-map tree 'headline
                    (lambda (d)
                      (when (= (org-element-property :level d) level)
                        (let ((compare-result
                               (funcall compare-fun
                                        (org-element-property :raw-value d)
                                        new-title)))
                          (and compare-result (>= compare-result 0) d))))
                    nil t)))
    ;; go to headline, or first successor sibling, or end of buffer
    (if sibling
        (goto-char (org-element-property :begin sibling))
      (goto-char (point-max))
      (unless (bolp) (insert "\n")))
    (if (and sibling
             (= 0 (funcall compare-fun
                           (org-element-property :raw-value sibling)
                           new-title)))
        ;; narrow and return the matched headline
        (progn
          (org-narrow-to-subtree)
          sibling)
      ;; insert new headline, narrow, and return it
      (delete-region (save-excursion (skip-chars-backward " \t\n") (point)) (point))
      (when (org--blank-before-heading-p) (insert "\n"))
      (insert
       (format "\n%s %s\n"
               (make-string (if org-odd-levels-only (1- (* 2 level)) level) ?*)
               new-title))
      (forward-line -1)
      (org-narrow-to-subtree)
      (org-element-at-point))))

(defun org-datetree-file-entry-under (txt d)
  "Insert a node TXT into the date tree under date D."
  (org-datetree-find-date-create d)
  (let ((level (org-get-valid-level (funcall outline-level) 1)))
    (org-end-of-subtree t t)
    (org-back-over-empty-lines)
    (org-paste-subtree level txt)))

(defun org-datetree-cleanup ()
  "Make sure all entries in the current tree are under the correct date.
It may be useful to restrict the buffer to the applicable portion
before running this command, even though the command tries to be smart."
  (interactive)
  (goto-char (point-min))
  (let ((dre (concat "\\<" org-deadline-string "\\>[ \t]*\\'"))
	(sre (concat "\\<" org-scheduled-string "\\>[ \t]*\\'")))
    (while (re-search-forward org-ts-regexp nil t)
      (catch 'next
	(let ((tmp (buffer-substring
		    (max (line-beginning-position)
			 (- (match-beginning 0) org-ds-keyword-length))
		    (match-beginning 0))))
	  (when (or (string-suffix-p "-" tmp)
		    (string-match dre tmp)
		    (string-match sre tmp))
	    (throw 'next nil))
	  (let* ((dct (decode-time (org-time-string-to-time (match-string 0))))
		 (date (list (nth 4 dct) (nth 3 dct) (nth 5 dct)))
		 (year (nth 2 date))
		 (month (car date))
		 (day (nth 1 date))
		 (pos (point))
		 (hdl-pos (progn (org-back-to-heading t) (point))))
	    (unless (org-up-heading-safe)
	      ;; No parent, we are not in a date tree.
	      (goto-char pos)
	      (throw 'next nil))
	    (unless (looking-at "\\*+[ \t]+[0-9]+-[0-1][0-9]-[0-3][0-9]")
	      ;; Parent looks wrong, we are not in a date tree.
	      (goto-char pos)
	      (throw 'next nil))
	    (when (looking-at (format "\\*+[ \t]+%d-%02d-%02d" year month day))
	      ;; At correct date already, do nothing.
	      (goto-char pos)
	      (throw 'next nil))
	    ;; OK, we need to refile this entry.
	    (goto-char hdl-pos)
	    (org-cut-subtree)
	    (save-excursion
	      (save-restriction
		(org-datetree-file-entry-under (current-kill 0) date)))))))))

(provide 'org-datetree)

;; Local variables:
;; generated-autoload-file: "org-loaddefs.el"
;; End:

;;; org-datetree.el ends here