;;; org-x-dag.el --- Org-in-a-DAG -*- lexical-binding: t; -*-

;; Copyright (C) 2022  Nathan Dwarshuis

;; This program 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.

;; This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;; Welcome to Dagestan, you will be smeshed...

;;; Code:

;; TODO this depends on other stuff in org-x like the file and id operations
(require 'org)
(require 'org-ml)
(require 'dash)
(require 'dag)
(require 'ht)

;;; DATE/TIME FUNCTIONS

;; current state

(defun org-x-dag-current-datetime ()
  (->> (current-time)
       (decode-time)
       (-drop 1)
       (-take 5)
       (reverse)))

(defun org-x-dag-current-date ()
  (-take 3 (org-x-dag-current-datetime)))

(defun org-x-dag-current-time ()
  (-drop 3 (org-x-dag-current-datetime)))

(defun org-x-dag-date-at-current-time (date)
  `(,@date ,@(org-x-dag-current-time)))

;; calendar interface

(defun org-x-dag-gregorian-to-date (greg)
  (-let (((m d y) greg))
    `(,y ,m ,d)))

(defun org-x-dag-date-to-gregorian (date)
  (-let (((y m d) date))
    `(,m ,d ,y)))

(defun org-x-dag-date-to-absolute (date)
  (->> (org-x-dag-date-to-gregorian date)
       (calendar-absolute-from-gregorian)))

(defun org-x-dag-absolute-to-date (abs)
  (->> (calendar-gregorian-from-absolute abs)
       (org-x-dag-gregorian-to-date)))

;; datetime operations

(defun org-x-dag-datetime< (datetime0 datetime1)
  (org-x-dag-with-times datetime0 datetime1
    (-when-let (next (->> (-zip-with #'cons datetime0 datetime1)
                          (--drop-while (= (car it) (cdr it)))
                          (car)))
      (< (car next) (cdr next)))))

(defun org-x-dag-datetime= (datetime0 datetime1)
  (org-x-dag-with-times datetime0 datetime1
    (->> (-zip-with #'cons datetime0 datetime1)
         (--drop-while (= (car it) (cdr it)))
         (not))))

(defun org-x-dag-datetime-split (datetime)
  ;; TODO this function doesn't guarantee that a short timestamp is properly
  ;; formatted
  (if (org-ml-time-is-long datetime)
      (-split-at 3 datetime)
    `(,(-take 3 datetime) nil)))

(defun org-x-dag-datetime-shift (datetime shift unit)
  (cl-flet*
      ((enc-dec-long
        (y m d H M)
        (-let (((_ M* H* d* m* y* _ _ _)
                (->> (list 0 M H d m y nil nil (current-time-zone))
                     (encode-time)
                     (decode-time))))
          (list y* m* d* H* M*)))
       (enc-dec-short
        (y m d)
        (-take 3 (enc-dec-long y m d 0 0))))
    (pcase datetime
      ((or `(,y ,m ,d) `(,y ,m ,d nil nil))
       (pcase unit
         ('month (enc-dec-short y (+ m shift) d))
         ('submonth (enc-dec-short y m (+ d shift)))))
      (`(,y ,m ,d ,H ,M)
       (pcase unit
         ('month (enc-dec-long y (+ m shift) d H M))
         ('submonth (enc-dec-long y m d H (+ M shift))))))))

(defun org-x-dag-date-diff (date0 date1)
  ""
  (pcase (list date0 date1)
    (`((,y0 ,m0 ,d0) (,y1 ,m1 ,d1))
     (- (calendar-absolute-from-gregorian `(,m0 ,d0 ,y0))
        (calendar-absolute-from-gregorian `(,m1 ,d1 ,y1))))
    (_ (error "Invalid date format(s): %S or %S" date0 date1))))

;; date <-> week

(defun org-x-dag-date-to-week-number (date)
  (-let* (((y m d) date)
          (greg (org-x-dag-date-to-gregorian date))
          (abs (calendar-absolute-from-gregorian greg))
          (daynum (calendar-day-of-week greg))
          ;; Catch the special case where the first few days of January might
          ;; belong to the previous year
          (start-year (if (and (= 1 m) (< d (1+ daynum))) (1- y) y))
          (start-greg `(1 1 ,start-year))
          (start-daynum (calendar-day-of-week start-greg))
          (start-abs (calendar-absolute-from-gregorian start-greg))
          (start-diff (if (= 0 start-daynum) 0 (- 7 start-daynum))))
    (1+ (/ (- abs start-abs start-diff) 7))))

(defun org-x-dag-week-number-to-date (year weeknum)
  (let* ((start-greg `(1 1 ,year))
         (start-abs (calendar-absolute-from-gregorian start-greg))
         (start-weeknum (calendar-day-of-week start-greg))
         (start-diff (if (= 0 start-weeknum) 0 (- 7 start-weeknum))))
    (->> (* (1- weeknum) 7)
         (+ start-abs start-diff)
         (org-x-dag-absolute-to-date))))

(defun org-x-dag-date-to-week-start (date)
  ""
  (let* ((greg (org-x-dag-date-to-gregorian date))
         (daynum (calendar-day-of-week greg)))
    (-> (calendar-absolute-from-gregorian greg)
        (- daynum)
        (org-x-dag-absolute-to-date))))

;; date <-> quarter

(defun org-x-dag-quarter-to-date (quarter)
  (-let (((y q) quarter))
    (list y (1+ (* q 3)) 1)))

(defun org-x-dag-date-to-quarter (date)
  (-let (((y m _) date))
    (list y (1+ (/ m 3)))))

(defun org-x-dag-shift-quarter (quarter n unit)
  (-let (((y q) quarter))
    (pcase unit
      (`year `(,(+ n y) ,q))
      (`quarter
       (let* ((x (+ q n))
              (q* (mod x 4))
              (y* (+ y (floor (/ x 4.0)))))
         `(,y* ,q*))))))

(defun org-x-dag-quarter-diff (quarter1 quarter2)
  (cl-flet
      ((qt-to-abs
        (q)
        (->> (org-x-dag-quarter-to-date q)
             (org-x-dag-date-to-absolute))))
    (- (qt-to-abs quarter1) (qt-to-abs quarter2))))

;;; GLOBAL STATE

;; variables to store state

(defun org-x-dag-create (d m f c)
  (list :dag d :id->meta m :file->ids f :current-date c))

(defun org-x-dag-empty ()
  (org-x-dag-create (dag-empty)
                    (ht-create #'equal)
                    (ht-create #'equal)
                    (org-x-dag-current-date)))

(defvar org-x-dag (org-x-dag-empty)
                        
  "The org-x DAG.

Each node in this DAG represents a headline with the following
characteristics:
- contained in a file as given by `org-x-dag-get-files'
- has a keyword
- either has an immediate parent with a keyword or has no parents
  with keywords

Each node is represented by a key, which is either a string
representing the headlines's ID property or a cons cell
like (FILE POS) representing the staring position in file/buffer
of the headline (aka a \"pseudo-marker\").")

(defvar org-x-dag-sync-state nil
  "An alist representing the sync state of the DAG.

The car of each cell is the file path, and the cdr is the md5 of
that file as it currently sits on disk.")

;; functions to construct nodes within state

(defun org-x-dag-build-meta (file point level todo title tags parent)
  (list :file file
        :point point
        :level level
        :todo todo
        :title title
        :tags tags
        :buffer-parent parent))

;; state lookup functions
;;
;; all functions with `org-x-dag->' or `org-x-dag-id->' depend on the value of
;; `org-x-dag'

(defun org-x-dag->metatable ()
  (plist-get org-x-dag :id->meta))

(defun org-x-dag->dag ()
  (plist-get org-x-dag :dag))

(defun org-x-dag->adjacency-list ()
  (dag-get-adjacency-list (org-x-dag->dag)))

(defun org-x-dag-id->metaprop (id prop)
  (-> (org-x-dag->metatable)
      (ht-get id)
      (plist-get prop)))

(defun org-x-dag-id->file (id)
  "Return file for ID."
  (org-x-dag-id->metaprop id :file))

(defun org-x-dag-id->point (id)
  "Return point for ID."
  (org-x-dag-id->metaprop id :point))

(defun org-x-dag-id->todo (id)
  "Return todo keyword for ID."
  (org-x-dag-id->metaprop id :todo))

(defun org-x-dag-id->title (id)
  "Return title for ID."
  (org-x-dag-id->metaprop id :title))

(defun org-x-dag-id->local-tags (id)
  "Return local tags for ID."
  (org-x-dag-id->metaprop id :tags))

(defun org-x-dag-id->is-done-p (id)
  "Return t if ID has done keywords."
  (member (org-x-dag-id->todo id) org-x-done-keywords))

(defun org-x-dag-id->is-floating-p (id)
  (-> (plist-get org-x-dag :dag)
      (dag-get-floating-nodes)
      (ht-get id)))

(defun org-x-dag-id->is-toplevel-p (id)
  (or (not (org-x-dag-id->metaprop id :buffer-parent))
      ;; TODO pretty sure this will never be used
      (org-x-dag-id->is-floating-p id)))

(defun org-x-dag-id->tags (inherit? init id)
  (cl-labels
      ((ascend
        (id tags)
        (-if-let (parent (org-x-dag-id->metaprop id :buffer-parent))
            ;; tags in the front of the list have precedence over latter tags,
            ;; so putting parent tags at the end means child tags have
            ;; precedence
            (->> (org-x-dag-id->local-tags parent)
                 (append tags)
                 (ascend parent))
          tags)))
    ;; likewise, init tags have the lowest precedence (the likely use case for
    ;; this argument is for file tags)
    (let ((local-tags (org-x-dag-id->local-tags id))
          (parent-tags (and inherit? (ascend id nil))))
      (append local-tags parent-tags init))))

(defun org-x-dag-id->bucket (inherit? id)
  (-some->> (org-x-dag-id->tags inherit? nil id)
    (--find (= (elt it 0) org-x-tag-category-prefix))
    (s-chop-prefix "_")
    (intern)))

(defun org-x-dag-id->link (id)
  (org-x-dag-with-id-in-file id
    (let ((desc (org-x-dag-id->title id)))
      (->> (org-ml-build-secondary-string! desc)
           (apply #'org-ml-build-link id :type "id")))))

(defun org-x-dag-id->link-item (id)
  (->> (org-x-dag-id->link id)
       (org-ml-build-paragraph)
       (org-ml-build-item)))

(defun org-x-dag-id->parents (id)
  (->> (plist-get org-x-dag :dag)
       (dag-get-parents id)))

(defun org-x-dag-id->split-parents (id)
  (let ((ps (org-x-dag-id->parents id)))
    (if (org-x-dag-id->is-toplevel-p id)
        `(nil ,ps)
      (let ((f (org-x-dag-id->file id)))
        ;; ASSUME there will only be one headline parent (not sure how that
        ;; wouldn't be true, but this algorithm doesn't care or know)
        (-if-let (i (--find-index (equal f (org-x-dag-id->file it)) ps))
            `(,(nth i ps) ,(-remove-at i ps))
          `(nil ,ps))))))

(defun org-x-dag-id->headline-parent (id)
  (car (org-x-dag-id->split-parents id)))

(defun org-x-dag-id->foreign-parents (id)
  (cadr (org-x-dag-id->split-parents id)))

(defun org-x-dag-id->children (id)
  (->> (plist-get org-x-dag :dag)
       (dag-get-children id)))

(defun org-x-dag-id->headline-children (id)
  (->> (org-x-dag-id->children id)
       (--filter (equal (org-x-dag-id->metaprop it :buffer-parent) id))))

(defun org-x-dag-id->all-headline-children (id)
  (->> (org-x-dag-id->headline-children id)
       (-mapcat #'org-x-dag-id->all-headline-children)
       (cons id)))

(defun org-x-dag-files->ids (files)
  (let ((filemap (plist-get org-x-dag :file->ids)))
    (--mapcat (ht-get filemap it) files)))

(defun org-x-dag-file->ids (file)
  (org-x-dag-files->ids `(,file)))

(defun org-x-dag->epg-ids ()
  (org-x-dag-file->ids (org-x-get-endpoint-goal-file)))

(defun org-x-dag->ltg-ids ()
  (org-x-dag-file->ids (org-x-get-lifetime-goal-file)))

(defun org-x-dag->current-date ()
  (plist-get org-x-dag :current-date))

;; (defun org-x-dag->qtp-ids ()
;;   (org-x-dag-file->ids (org-x-qtp-get-file)))

;; (defun org-x-dag->wkp-ids ()
;;   (org-x-dag-file->ids (org-x-get-weekly-plan-file)))

(defun org-x-dag-filter-ids-tags (tags ids)
  (--filter (-intersection (org-x-dag-id->tags t nil it) tags) ids))

(defun org-x-dag-date-to-quarter-tags (date)
  (-let (((y q) (org-x-dag-date-to-quarter date)))
    (list (org-x-dag-format-year-tag y)
          (org-x-dag-format-quarter-tag q))))

(defun org-x-dag-date-to-week-tags (date)
  (-let (((y _ _) date)
         (w (org-x-dag-date-to-week-number date)))
    (list (org-x-dag-format-year-tag y)
          (org-x-dag-format-week-tag w))))

(defun org-x-dag-date-to-daily-tags (date)
  (-let (((y m d) date))
    (list (org-x-dag-format-year-tag y)
          (org-x-dag-format-month-tag m)
          (org-x-dag-format-day-tag d))))

;; (defun org-x-dag-date->tagged-ids (id-getter tag-getter date)
;;   (let ((target-tags (funcall tag-getter date)))
;;     (org-x-dag-filter-ids-tags target-tags (funcall id-getter))))

(defun org-x-dag-date->tagged-ids (ids tag-getter date)
  (let ((target-tags (funcall tag-getter date)))
    (org-x-dag-filter-ids-tags target-tags ids)))

;; (defun org-x-dag-date->qtp-ids (date)
;;   (org-x-dag-date->tagged-ids #'org-x-dag->qtp-ids
;;                               #'org-x-dag-date-to-quarter-tags
;;                               date))

;; (defun org-x-dag-date->wkp-ids (date)
;;   (org-x-dag-date->tagged-ids #'org-x-dag->wkp-ids
;;                               #'org-x-dag-date-to-week-tags
;;                               date))

;; (defun org-x-dag->qtp-current-ids ()
;;   (org-x-dag-date->qtp-ids (org-x-dag->current-date)))

;; (defun org-x-dag->wkp-current-ids (date)
;;   (org-x-dag-date->wkp-ids (org-x-dag->current-date)))


;; (defun org-x-dag->dlp-ids ()
;;   (org-x-dag-file->ids (org-x-get-daily-plan-file)))

;; (defun org-x-dag-date->dlp-ids (date)
;;   (org-x-dag-date->tagged-ids #'org-x-dag->dlp-ids
;;                               #'org-x-dag-date-to-daily-tags
;;                               date))

;; (defun org-x-dag->dlp-current-ids (date)
;;   (org-x-dag-date->dlp-ids (org-x-dag->current-date)))

(defun org-x-dag-which->ids (file date-to-tag which)
  (cl-flet
      ((date-ids
        (ids date)
        (org-x-dag-date->tagged-ids ids date-to-tag date)))
    (let ((ids (org-x-dag-file->ids file)))
      (pcase which
        (`all ids)
        (`current (date-ids ids (org-x-dag->current-date)))
        (date (date-ids ids date))))))

(defun org-x-dag->qtp-ids (which)
  (org-x-dag-which->ids (org-x-qtp-get-file)
                        #'org-x-dag-date-to-quarter-tags
                        which))

(defun org-x-dag->wkp-ids (which)
  (org-x-dag-which->ids (org-x-get-weekly-plan-file)
                        #'org-x-dag-date-to-week-tags
                        which))

(defun org-x-dag->dlp-ids (which)
  (org-x-dag-which->ids (org-x-get-daily-plan-file)
                        #'org-x-dag-date-to-daily-tags
                        which))

(defun org-x-dag-partition-child-ids (files ids)
  (->> (org-x-dag-files->ids files)
       (--split-with (-intersection ids (org-x-dag-id->children it)))))

(defun org-x-dag-id->has-child-in-files-p (id files)
  (-intersection (org-x-dag-id->children id) (org-x-dag-files->ids files)))

(defun org-x-dag-id->has-parent-in-files-p (id files)
  (-intersection (org-x-dag-id->parents id) (org-x-dag-files->ids files)))

(defun org-x-dag->dlp-action-ids (which)
  (->> (org-x-dag->dlp-ids which)
       (org-x-dag-partition-child-ids (org-x-get-action-and-incubator-files))))

(defun org-x-dag->wkp-qtp-ids (which)
  (->> (org-x-dag->wkp-ids which)
       (org-x-dag-partition-child-ids (list (org-x-qtp-get-file)))))

(defun org-x-dag->qtp-goal-ids (which)
  (->> (org-x-dag->qtp-ids which)
       (org-x-dag-partition-child-ids `(,(org-x-get-lifetime-goal-file)
                                        ,(org-x-get-endpoint-goal-file)))))

;; (defun org-x-dag-date->dlp-parent-ids (date)
;;   (let ((dlp-ids (org-x-dag-date->dlp-ids date)))
;;     (->> (org-x-get-action-and-incubator-files)
;;          (org-x-dag-files->ids)
;;          (--filter (-intersection (org-x-dag-id->children it) dlp-ids)))))

(defun org-x-dag->leaf-epg-ids ()
  (-remove #'org-x-dag-id->headline-children (org-x-dag->epg-ids)))

(defun org-x-dag->leaf-ltg-ids ()
  (let ((epg-file (org-x-get-endpoint-goal-file)))
    (->> (org-x-dag->ltg-ids)
         (-remove #'org-x-dag-id->headline-children)
         (--remove (equal (org-x-dag-id->file it) epg-file)))))

(defun org-x-dag-goal-count-tasks (id)
  (->> (org-x-dag-id->children id)
       (-mapcat #'org-x-dag-id->all-headline-children)
       ;; TODO this isn't very efficient, looking up children twice
       (-remove #'org-x-dag-id->headline-children)
       (length)))

(defun org-x-dag-rank-leaf-goals (quarter ids)
  (cl-flet
      ((score
        (buckets id)
        ;; TODO what happens when I don't have a bucket?
        (let ((idx (-elem-index (org-x-dag-id->bucket t id) (reverse buckets)))
              (ntasks (org-x-dag-goal-count-tasks id)))
          (list idx ntasks))))
    (let ((bs (org-x-qtp-get-buckets quarter)))
      (org-x-dag-ids-rank (score bs it) ids))))

;; planning state

;; TODO might be less tedious to just set the date and have functions handy
;; to get the current quarter and week start
(defvar org-x-dag-selected-quarter nil
  "The current quarter to be used for planning.
Is a list like (YEAR QUARTER).")

(defvar org-x-dag-selected-week nil
  "The current week to be used for planning.
A date like (YEAR MONTH DAY).")

;; (defvar org-x-dag-week-start-index 0
;;   "The day considered to start a week (0 = Sunday).")

(defvar org-x-dag-selected-date nil
  "The current week to be used for planning.
A date like (YEAR MONTH DAY).")

;;; PLANNING

;; planning buffer tags
;;
;; use tags to encode date/time information in the buffer since it is really
;; easy to look up tags in the DAG

(defconst org-x-dag-weekly-tags
  '((0 . "SUN")
    (1 . "MON")
    (2 . "TUE")
    (3 . "WED")
    (4 . "THU")
    (5 . "FRI")
    (6 . "SAT")))

(defun org-x-dag-format-year-tag (year)
  (format "Y%d" (mod year 2000)))

(defun org-x-dag-format-quarter-tag (quarter)
  (format "Q%d" quarter))

(defun org-x-dag-format-month-tag (month)
  (format "M%02d" month))

(defun org-x-dag-format-week-tag (week)
  (format "W%02d" week))

(defun org-x-dag-format-day-of-week-tag (daynum)
  (alist-get daynum org-x-dag-weekly-tags))

(defun org-x-dag-format-day-tag (day)
  (format "D%02d" day))

;; headline lookup

(defun org-x-dag-headlines-find-tag (tag headlines)
  (--find (org-ml-headline-has-tag tag it) headlines))

(defun org-x-dag-headlines-find-year (year headlines)
  (-> (org-x-dag-format-year-tag year)
      (org-x-dag-headlines-find-tag headlines)))

(defun org-x-dag-headlines-find-quarter (quarter headlines)
  (-> (org-x-dag-format-quarter-tag quarter)
      (org-x-dag-headlines-find-tag headlines)))

(defun org-x-dag-headlines-find-week (weeknum headlines)
  (-> (org-x-dag-format-week-tag weeknum)
      (org-x-dag-headlines-find-tag headlines)))

(defun org-x-dag-headlines-find-day-of-week (daynum headlines)
  (-> (org-x-dag-format-day-of-week-tag daynum)
      (org-x-dag-headlines-find-tag headlines)))

(defun org-x-dag-headlines-find-month (month headlines)
  (-> (org-x-dag-format-month-tag month)
      (org-x-dag-headlines-find-tag headlines)))

(defun org-x-dag-headlines-find-day (day headlines)
  (-> (org-x-dag-format-day-tag day)
      (org-x-dag-headlines-find-tag headlines)))

;; headline builders

(defun org-x-dag-build-planning-headline (title tag level subheadlines)
  (apply #'org-ml-build-headline!
         :title-text title
         :tag (list tag)
         :level level
         subheadlines))

(defun org-x-dag-build-year-headline (year subheadlines)
  (let ((title (number-to-string year))
        (tag (org-x-dag-format-year-tag year)))
    (org-x-dag-build-planning-headline tag title 1 subheadlines)))

(defun org-x-dag-build-quarter-headline (quarter subheadlines)
  (let ((title (format "Quarter %d" quarter))
        (tag (org-x-dag-format-quarter-tag quarter)))
    (org-x-dag-build-planning-headline title tag 2 subheadlines)))

(defun org-x-dag-build-week-headline (year weeknum subheadlines)
  (-let* (((_ m d) (org-x-dag-week-number-to-date year weeknum))
          (m* (calendar-month-name m))
          (title (format "%s %s" m* d))
          (tag (org-x-dag-format-week-tag weeknum)))
    (org-x-dag-build-planning-headline title tag 2 subheadlines)))

(defun org-x-dag-build-month-headline (month subheadlines)
  (let ((title (calendar-month-name month))
        (tag (org-x-dag-format-month-tag month)))
    (org-x-dag-build-planning-headline title tag 2 subheadlines)))

(defun org-x-dag-build-day-headline (date subheadlines)
  (let ((title (format "%d-%02d-%02d" y m d))
        (tag (org-x-dag-format-day-tag d)))
    (org-x-dag-build-planning-headline title tag 3 subheadlines)))

(defun org-x-dag-build-day-of-week-headline (daynum subheadlines)
  (let ((title (elt calendar-day-name-array daynum))
        (tag (alist-get daynum org-x-dag-weekly-tags)))
    (org-x-dag-build-planning-headline title tag 3 subheadlines)))

;; id headline builders

(defun org-x-dag-build-planning-id-headline (title level paragraph ids)
  (let ((sec (-some-> paragraph
               (org-ml-build-paragraph!)
               (list))))
    (->> (org-ml-build-headline! :title-text title
                                 :level level
                                 :todo-keyword org-x-kw-todo
                                 :section-children sec)
         (org-x-dag-headline-add-id)
         (org-x-dag-headline-set-parent-links ids))))

(defun org-x-dag-build-qtp-headline (title paragraph ids allocation)
  (->> (org-x-dag-build-planning-id-headline title 3 paragraph ids)
       (org-ml-headline-set-node-property org-x-prop-allocate allocation)))

(defun org-x-dag-build-wkp-headline (title paragraph ids)
  (org-x-dag-build-planning-id-headline title 4 paragraph ids))

(defun org-x-dag-build-dlp-headline (title paragraph ids datetime)
  (let ((pl (org-ml-build-planning! :scheduled datetime)))
    (->> (org-x-dag-build-planning-id-headline title 4 paragraph ids)
         (org-ml-headline-set-planning pl))))

;; buffer manipulation

(defun org-x-dag-qtp-to-children (qt-plan)
  (-let* (((&plist :categories :goals) qt-plan)
          ;; TODO what happens if there are no categories?
          (sec (-some->> categories
                 (--map-indexed (org-ml-build-item!
                                 :bullet it-index
                                 :paragraph (symbol-name it)))
                 (apply #'org-ml-build-plain-list)
                 (org-ml-build-drawer org-x-drwr-categories)
                 (org-ml-build-section))))
    (if sec (cons sec goals) goals)))

(defun org-x-dag-qtp-from-children (children)
  ;; ignore properties, planning, etc
  (-let* (((sec goals) (if (org-ml-is-type 'section (car children))
                           `(,(car children) ,(cdr children))
                         `(nil ,children)))
          (cats (-some->> sec
                  (--find (org-x--is-drawer-with-name org-x-drwr-categories it))
                  (org-x-qtp-drawer-to-categories))))
    (list :categories cats :goals goals)))

(defun org-x-dag-qtp-get (quarter)
  (org-x-with-file (org-x-qtp-get-file)
    (-let (((year qnum) quarter))
      (->> (org-ml-parse-subtrees 'all)
           (org-x-dag-headlines-find-year year)
           (org-ml-headline-get-subheadlines)
           (org-x-dag-headlines-find-quarter qnum)
           (org-ml-get-children)
           (org-x-dag-qtp-from-children)))))

(defun org-x-dag-qtp-set (quarter qt-plan)
  (cl-flet
      ((build-yr-headline
        (year qnum children)
        (->> (org-x-dag-build-quarter-headline qnum children)
             (list)
             (org-x-dag-build-year-headline year))))
    (org-x-with-file (org-x-qtp-get-file)
      (-let* (((year qnum) quarter)
              (sts (org-ml-parse-subtrees 'all))
              (children (org-x-dag-qtp-to-children qt-plan)))
        (-if-let (st-yr (org-x-dag-headlines-find-year year sts))
            (-if-let (st-qt (->> (org-ml-headline-get-subheadlines st-yr)
                                 (org-x-dag-headlines-find-quarter qnum)))
                (org-ml-update* (org-ml-set-children children it) st-qt)
              (org-ml-update*
                (-snoc it (org-x-dag-build-quarter-headline qnum children))
                st-yr))
          (let ((end (1+ (org-ml-get-property :end (-last-item sts)))))
            (org-ml-insert end (build-yr-headline year qnum children))))))))

(defmacro org-x-dag-qtp-map (quarter form)
  (declare (indent 1))
  `(let ((it (org-x-dag-qtp-get ,quarter)))
     (org-x-dag-qtp-set ,quarter ,form)))

(defun org-x-dag-qtp-get-key (key quarter)
  (plist-get (org-x-dag-qtp-get quarter) key))

(defun org-x-dag-qtp-set-key (quarter key xs)
  (org-x-dag-qtp-map quarter
    (plist-put it key xs)))

(defun org-x-qtp-get-buckets (quarter)
  (org-x-dag-qtp-get-key :categories quarter))

(defun org-x-qtp-get-goals (quarter)
  (org-x-dag-qtp-get-key :goals quarter))

(defun org-x-qtp-get-goal-ids (quarter)
  (->> (org-x-qtp-get-goals quarter)
       (--map (org-ml-headline-get-node-property "ID" it))))

(defun org-x-qtp-get-goal-parent-ids (quarter)
  (->> (org-x-qtp-get-goals quarter)
       (-mapcat #'org-x-dag-headline-get-parent-links)))

(defun org-x-qtp-set-categories (quarter categories)
  (org-x-dag-qtp-set-key quarter :categories categories))

(defun org-x-qtp-set-goals (quarter goals)
  (org-x-dag-qtp-set-key quarter :goals goals))

(defmacro org-x-qtp-map-categories (quarter form)
  `(let ((it (org-x-qtp-get-buckets ,quarter)))
     (org-x-qtp-set-categories ,quarter ,form)))

(defmacro org-x-qtp-map-goals (quarter form)
  `(let ((it (org-x-qtp-get-goals ,quarter)))
     (org-x-qtp-set-goals ,quarter ,form)))

(defun org-x-qtp-add-goal (quarter headline)
  (org-x-qtp-map-goals quarter (cons headline it)))

(defun org-x-dag-headline-add-id (headline)
  (org-ml-headline-set-node-property "ID" (org-id-new) headline))

(defun org-x-qtp-add-goal-ids (quarter ids title allocation)
  (->> (org-x-dag-build-qtp-headline title nil ids allocation)
       (org-x-qtp-add-goal quarter)))

(defun org-x-dag-weekly-headlines-to-alist (headlines)
  (->> (-map #'car org-x-dag-weekly-tags)
       (--map (->> (org-x-dag-headlines-find-day-of-week it headlines)
                   (org-ml-headline-get-subheadlines)
                   (cons it)))))

(defun org-x-dag-weekly-alist-to-headlines (plan)
  (--map (-let (((daynum . hls) it))
           (org-x-dag-build-day-of-week-headline daynum hls))
         plan))

(defun org-x-dag-wkp-get (week)
  (org-x-with-file (org-x-get-weekly-plan-file)
    (-let (((year weeknum) week))
      (->> (org-ml-parse-subtrees 'all)
           (org-x-dag-headlines-find-year year)
           (org-ml-headline-get-subheadlines)
           (org-x-dag-headlines-find-week weeknum)
           (org-ml-headline-get-subheadlines)
           (org-x-dag-weekly-headlines-to-alist)))))

(defun org-x-dag-wkp-set (week plan)
  (cl-flet*
      ((build-yr-headline
        (year weeknum children)
        (->> (org-x-dag-build-week-headline year weeknum children)
             (list)
             (org-x-dag-build-year-headline year))))
    (org-x-with-file (org-x-get-weekly-plan-file)
      (-let* (((year weeknum) week)
              (sts (org-ml-parse-subtrees 'all))
              (children (org-x-dag-weekly-alist-to-headlines plan)))
        (-if-let (st-yr (org-x-dag-headlines-find-year year sts))
            (-if-let (st-wk (->> (org-ml-headline-get-subheadlines st-yr)
                                 (org-x-dag-headlines-find-week weeknum)))
                (org-ml-update* (org-ml-set-children children it) st-wk)
              (org-ml-update*
                (-snoc it (org-x-dag-build-week-headline year weeknum children))
                st-yr))
          (let ((end (1+ (org-ml-get-property :end (-last-item sts)))))
            (org-ml-insert end (build-yr-headline year weeknum children))))))))

(defmacro org-x-dag-wkp-map (week form)
  (declare (indent 1))
  (let ((w (make-symbol "--week")))
    `(let* ((,w ,week)
            (it (org-x-dag-wkp-get ,w)))
       (org-x-dag-wkp-set ,w ,form))))

(defun org-x-dag-wkp-day-get (week daynum)
  (alist-get daynum (org-x-dag-wkp-get week)))

(defun org-x-dag-wkp-day-set (week daynum headlines)
  (org-x-dag-wkp-map week
    (--replace-where (= daynum (car it)) (cons daynum headlines) it)))

(defmacro org-x-dag-wkp-day-map (week daynum form)
  (declare (indent 2))
  (let ((w (make-symbol "--week"))
        (d (make-symbol "--daynum")))
    `(let* ((,w ,week)
            (,d ,daynum)
            (it (org-x-dag-wkp-day-get ,w ,d)))
       (org-x-dag-wkp-day-set ,w ,d ,form))))

(defun org-x-dag-wkp-day-add (week daynum headline)
  (org-x-dag-wkp-day-map week daynum (cons headline it)))

(defun org-x-dag-wkp-add-goal (week daynum title ids desc)
  (->> (org-x-dag-build-wkp-headline title desc ids)
       (org-x-dag-wkp-day-add week daynum)))

;; TODO not DRY
(defun org-x-dag-dlp-get (date)
  (org-x-with-file (org-x-get-weekly-plan-file)
    (-let (((y m d) date))
      (->> (org-ml-parse-subtrees 'all)
           (org-x-dag-headlines-find-year y)
           (org-ml-headline-get-subheadlines)
           (org-x-dag-headlines-find-week m)
           (org-ml-headline-get-subheadlines)
           (org-x-dag-headlines-find-day d)))))

(defun org-x-dag-dlp-set (date headlines)
  (cl-flet*
      ((build-mo-headline
        (date headlines)
        (-let (((_ m _) date))
          (->> (org-x-dag-build-day-headline date headlines)
               (list)
               (org-x-dag-build-month-headline m))))
       (build-yr-headline
        (date headlines)
        (-let* (((y _ _) date))
          (->> (build-mo-headline date headlines)
               (list)
               (org-x-dag-build-year-headline y)))))
    (org-x-with-file (org-x-get-daily-plan-file)
      (-let (((y m d) date)
             (sts (org-ml-parse-subtrees 'all)))
        (-if-let (st-yr (org-x-dag-headlines-find-year y sts))
            (-if-let (st-mo (->> (org-ml-headline-get-subheadlines st-yr)
                                 (org-x-dag-headlines-find-month m)))
                (-if-let (st-day (->> (org-ml-headline-get-subheadlines st-mo)
                                      (org-x-dag-headlines-find-day d)))
                    (org-ml-update* (org-ml-set-children headlines it) st-day)
                  (org-ml-update*
                    (-snoc it (org-x-dag-build-day-headline date headlines))
                    st-mo))
              (org-ml-update*
                (-snoc it (build-mo-headline date headlines))
                st-yr))
          (let ((end (1+ (org-ml-get-property :end (-last-item sts)))))
            (org-ml-insert end (build-yr-headline date headlines))))))))

(defmacro org-x-dag-dlp-map (date form)
  (declare (indent 1))
  (let ((d (make-symbol "--date")))
    `(let* ((,d ,date)
            (it (org-x-dag-dlp-get ,d)))
       (org-x-dag-dlp-set ,d ,form))))

(defun org-x-dag-dlp-add (date headline)
  (org-x-dag-dlp-map date (cons headline it)))

(defun org-x-dag-dlp-add-task (date title ids time)
  (let ((datetime `(,@date ,@time)))
    (->> (org-x-dag-build-dlp-headline title nil ids datetime)
         (org-x-dag-dlp-add date))))

;;; BUFFER SCANNING

(defun org-x-dag-get-local-property (prop)
  (car (org--property-local-values prop nil)))

(defun org-x-dag-get-link-property ()
  (-some->> (org-x-dag-get-local-property org-x-prop-goal)
    (s-split ";")
    (--map (->> (s-trim it)
                (s-match "^\\[\\[id:\\(.*\\)\\]\\[.*\\]\\]$")
                (cadr)))))

(defun org-x-dag-get-parent-links ()
  (cl-flet
      ((match-id
        (s)
        (->> (s-match "id:\\([^][]\\{36\\}\\)" s)
             (cadr)
             (substring-no-properties))))
    (save-excursion
      (let ((re (concat
                 "^[ \t]*:X_PARENT_LINKS:[ \t]*\n"
                 "\\(\\(?:^- .*?\n\\)*?\\)"
                 "[ \t]*:END:[ \t]*$"))
            (end (save-excursion (outline-next-heading))))
        (-some->> (and (re-search-forward re end t) (match-string 1))
          (s-trim)
          (s-split "\n")
          (-map #'match-id))))))

(defun org-x-dag-line-regexp (kws)
  (let ((level-re "\\(\\*+\\)")
        (kw-re (format "\\(%s\\)?" (s-join "\\|" kws)))
        (title-re "\\(.*?\\)?")
        (tag-re "\\(?:\\([[:alnum:]_@#%%:]+\\):\\)?"))
    (format "^%s[ ]+%s%s%s[ ]*$" level-re kw-re title-re tag-re)))

(defun org-x-dag-get-buffer-nodes (file kws)
  "Return a list of nodes from FILE.

A node will only be returned if the headline to which it points
has a valid (meaning in KWS) keyword and either its parent has a
valid keyword or none of its parents have valid keywords."
  (let ((more t)
        (line-re (org-x-dag-line-regexp kws))
        cur-path this-point this-key this-level this-todo has-todo this-parent
        this-tags this-meta all-tags this-file-links this-links acc acc-meta
        this-parent-key)
    ;; TODO add org-mode sanity check
    (goto-char (point-min))
    ;; If not on a headline, check for a property drawer with links in it
    (unless (= ?* (following-char))
      (setq this-file-links (org-x-dag-get-parent-links)))
    ;; loop through all headlines
    (while (re-search-forward line-re nil t)
      ;; Keep track of how 'deep' we are in a given org-tree using a stack. The
      ;; stack will have members like (LEVEL KEY TAGS) where LEVEL is the level
      ;; of the headline and KEY is the node key if it has a keyword, and TAGS
      ;; is a list of tags for the headlines. Only add a node to the accumulator
      ;; if it has a keyword and an ID property, and only include its parent
      ;; headline if the parent also has a keyword.
      (setq this-point (car (match-data))
            this-level (length (match-string 1))
            this-todo (match-string 2)
            this-title (-if-let (s (match-string 3)) (s-trim s) "")
            this-tags (-some-> (match-string-no-properties 4)
                        (split-string ":" t))
            this-key nil
            this-links nil)
      ;; Adjust the stack so that the top headline is the parent of the
      ;; current headline
      (while (and cur-path (<= this-level (nth 0 (car cur-path))))
        (!cdr cur-path))
      (setq this-parent (car cur-path)
            this-parent-key (nth 1 this-parent))
      ;; Add the current headline to accumulator if it has a keyword, but only
      ;; if its parent has a keyword or none of its parents have keywords
      (when (and this-todo
                 (or this-parent-key (--none-p (nth 1 it) cur-path))
                 (setq this-key (org-x-dag-get-local-property "ID")))
        ;; If parent is not a todo and we want tag inheritance, store all
        ;; tags above this headline (including file tags)
        (setq all-tags (if (and (not this-parent-key) org-use-tag-inheritance)
                           (->> cur-path
                                (--mapcat (nth 2 it))
                                (append this-tags org-file-tags))
                         this-tags)
              this-links (or (org-x-dag-get-parent-links)
                             (if this-parent-key
                                 (-some->> (--first (nth 3 it) cur-path)
                                   (nth 3))
                               this-file-links))
              this-meta (org-x-dag-build-meta file
                                              this-point
                                              this-level
                                              this-todo
                                              this-title
                                              all-tags
                                              this-parent-key))
        (!cons (cons this-key this-meta) acc-meta)
        (!cons (cons this-key `(,(nth 1 this-parent) ,@this-links)) acc))
      ;; Add current headline to stack
      (!cons (list this-level this-key this-tags this-links) cur-path))
    (list (nreverse acc) (nreverse acc-meta))))

(defun org-x-dag-get-file-nodes (file)
  "Return all nodes in FILE in one pass."
  (org-x-with-file file
    (org-x-dag-get-buffer-nodes file org-todo-keywords-1)))

;;; DAG SYNCHRONIZATION/CONSTRUCTION

(defun org-x-dag-get-files ()
  "Return a list of all files to be used in the DAG."
  `(,(org-x-get-lifetime-goal-file)
    ,(org-x-get-endpoint-goal-file)
    ,(org-x-qtp-get-file)
    ,(org-x-get-weekly-plan-file)
    ,(org-x-get-daily-plan-file)
    ,@(org-x-get-action-and-incubator-files)))

(defun org-x-dag-get-md5 (path)
  "Get the md5 checksum of PATH."
  (org-x-with-file path (buffer-hash)))

(defun org-x-dag-get-sync-state ()
  "Return the sync state.

The returned value will be a list like (TO-REMOVE TO-INSERT
TO-UPDATE) which will contain the file paths the should be
removed from, added to, or edited within the DAG respectively."
  (cl-flet
      ((lookup-md5
        (path)
        (alist-get path org-x-dag-sync-state nil nil #'equal)))
    (-let* ((existing-files (org-x-dag-get-files))
            (state-files (-map #'car org-x-dag-sync-state))
            (to-remove (-difference state-files existing-files))
            ((&alist 'to-insert 'to-update 'no-change)
             (->> (--map (cons it (org-x-dag-get-md5 it)) existing-files)
                  (--group-by (-let* (((path . new-md5) it)
                                      (old-md5 (lookup-md5 path)))
                                (cond
                                 ((null old-md5) 'to-insert)
                                 ((equal old-md5 new-md5) 'no-change)
                                 (t 'to-update)))))))
      (list to-remove to-insert to-update no-change))))

(defun org-x-dag-read-files (files)
  (cl-flet
      ((append-results
        (acc file)
        (-let* (((acc-ids acc-meta acc-filemaps) acc)
                ((ids metas) (org-x-dag-get-file-nodes file))
                (filemap (cons file (-map #'car ids))))
          (list (append ids acc-ids)
                (append metas acc-meta)
                (cons filemap acc-filemaps)))))
    (-reduce-from #'append-results nil files)))

(defun org-x-dag-update-ht (to-remove to-insert ht)
  (--each to-remove
    (ht-remove ht it))
  (--each to-insert
    (ht-set ht (car it) (cdr it))))

(defun org-x-dag-update-dag (to-insert to-remove)
  (let* ((dag (org-x-dag->dag))
         (dag* (if (dag-is-empty-p dag) (dag-alist-to-dag to-insert)
                 (dag-edit-nodes to-remove to-insert dag))))
    (plist-put org-x-dag :dag dag*)))

;; TODO there is a HUGE DIFFERENCE between a 'key' (the things in the hash table
;; the look things up) and a 'node' (which is a cons cell, the car of which is a
;; 'key' and the cdr of which is a 'relation'). These names suck, but the point
;; is we need to distinguish between them otherwise really strange things happen
(defun org-x-dag-update (to-remove to-insert to-update)
  "Update the DAG given files to add and remove.

TO-REMOVE, TO-INSERT, and TO-UPDATE are lists of files to remove
from, add to, and update with the DAG."
  (-let* (((&plist :id->meta :file->ids) org-x-dag)
          (files2rem (append to-update to-remove))
          (files2ins (append to-update to-insert))
          (ids2rem (org-x-dag-files->ids files2rem))
          ((ids2ins meta2ins fms2ins) (org-x-dag-read-files files2ins)))
    (org-x-dag-update-ht ids2rem meta2ins id->meta)
    (org-x-dag-update-ht files2rem fms2ins file->ids)
    (org-x-dag-update-dag ids2ins ids2rem)))

(defun org-x-dag-sync (&optional force)
  "Sync the DAG with files from `org-x-dag-get-files'.

If FORCE is non-nil, sync no matter what."
  (when force
    (setq org-x-dag-sync-state nil
          org-x-dag (org-x-dag-empty)))
  ;; TODO verify integrity somewhere in here
  (-let (((to-remove to-insert to-update no-change) (org-x-dag-get-sync-state)))
    (org-x-dag-update to-remove (-map #'car to-insert) (-map #'car to-update))
    (setq org-x-dag-sync-state (append to-insert to-update no-change))
    nil))

;; NODE FORMATTING

(defconst org-x-dag-tag-prefix-order (list org-x-tag-misc-prefix
                                           org-x-tag-resource-prefix
                                           org-x-tag-location-prefix
                                           org-x-tag-category-prefix)
  "Order in which tags should appear in the agenda buffer (from right to left.")

(defun org-x-dag-collapse-tags (tags)
  "Return TAGS with duplicates removed.

In the case of mutually exclusive tags, only the first tag
encountered will be returned."
  (-let (((x non-x) (--separate (memq (elt it 0) org-x-exclusive-prefixes) tags)))
    (->> (--group-by (elt it 0) x)
         (--map (car (cdr it)) )
         (append (-uniq non-x))
         ;; this removes the 'inherited' property on some of the tags, which
         ;; makes the agenda look cleaner (to me) since there are no
         ;; double-colons to separate inherited from non-inherited
         ;;
         ;; NOTE: this appears to have no effect on `org-agenda-tags' (eg the
         ;; inherited tags still show up in the menu properly)
         (-map #'substring-no-properties))))

(defun org-x-dag-sort-tags (tags)
  (cl-flet
      ((get-ranking
        (tag)
        (-if-let (i (-elem-index (elt tag 0) org-x-dag-tag-prefix-order))
            (1+ i)
          0)))
    (->> (--map (cons it (get-ranking it)) tags)
         (--sort (< (cdr it) (cdr other)))
         (-map #'car))))

(defun org-x-dag-prepare-tags (tags)
  (->> (org-x-dag-collapse-tags tags)
       (org-x-dag-sort-tags)))

(defun org-x-dag-add-default-props (item id)
  (org-add-props item nil
    'x-id id
    'help-echo (org-x-dag-help-echo)
    'org-not-done-regexp org-not-done-regexp
    'org-todo-regexp org-todo-regexp
    'org-complex-heading-regexp org-complex-heading-regexp
    'mouse-face 'highlight))

(defun org-x-dag-id->formatted-level (id)
  (-> (org-x-dag-id->metaprop id :level)
      (org-reduced-level)
      (make-string ?\s)))

(defun org-x-dag-help-echo ()
  (->> (or (buffer-file-name (buffer-base-buffer))
           (buffer-name (buffer-base-buffer)))
       (abbreviate-file-name)
       (format "mouse-2 or RET jump to Org file %S")))

(defun org-x-dag-headlines-get-regexp (re)
  (let ((end (save-excursion (outline-next-heading))))
    (-when-let (p (save-excursion (re-search-forward re end t)))
      (list (1- (match-beginning 1)) (match-string 1)))))

(defun org-x-dag-timestamp-to-absolute (ts)
  (->> (org-ml-get-properties '(:month-start :day-start :year-start) ts)
       (calendar-absolute-from-gregorian)))

;; TODO 'modulus' only applies to the repeater
(defun org-ml-timestamp-extract-modulus (modtype ts)
  "Return the modulus of timestamp TS for MODTYPE."
  (cl-flet
      ((convert-value
        (islongp value unit)
        (pcase unit
          ('year (* 12 value))
          ('month value)
          (_ (if islongp
                 ;; TODO make these messages not suck
                 (pcase unit
                   ('week (* 7 1440 value))
                   ('day (* 1440 value))
                   ('hour (* 60 value))
                   ('minute value)
                   (_ (error)))
               (pcase unit
                 ('week (* 7 value))
                 ('day value)
                 ((or 'hour 'minute) (message "WARNING: ..."))
                 (_ (error)))))))
       (convert-unit
        (unit)
        (if (memq unit '(year month)) 'month 'submonth)))
    (-let* ((props (pcase modtype
                     ('warning '(:warning-value :warning-unit :warning-type))
                     ('repeater '(:repeater-value :repeater-unit :repeater-type))))
            (islongp (->> (org-ml-timestamp-get-start-time ts)
                          (org-ml-time-is-long))))
      (-when-let ((value unit type) (org-ml-get-properties props ts))
        (let ((v (convert-value islongp value unit))
              (u (convert-unit unit)))
          `(,v ,u ,type))))))

(defun org-x-dag-partition-timestamp (ts)
  (list :datetime (org-ml-timestamp-get-start-time ts)
        :pos (org-ml-get-property :begin ts)
        :repeater (org-ml-timestamp-extract-modulus 'repeater ts)
        :warning (org-ml-timestamp-extract-modulus 'warning ts)))

(defmacro org-x-dag-with-times (datetime0 datetime1 form)
  ;; ASSUME all digits in this comparison are on the calendar/clock (eg day 32
  ;; does not 'rollover' to day 1 on the next month)
  (declare (indent 2))
  `(if (or (and (org-ml-time-is-long ,datetime0)
                (org-ml-time-is-long ,datetime1))
           (not (or (org-ml-time-is-long ,datetime0)
                    (org-ml-time-is-long ,datetime1))))
       ,form
     (error "Datetimes are invalid lengths: %S and %S" ,datetime0 ,datetime1)))

(defun org-x-dag-repeater-get-next (sel-datetime datetime shift shifttype reptype)
  "Return the next timestamp repeater of DATETIME."
  (pcase reptype
    ('catch-up
     ;; Next time is a multiple of repeater in the future relative to the base
     ;; time; shift one interval at a time since they may not be spaced evenly
     ;; (DST, leap year, different days in each month, etc). Think of this like
     ;; a path function from p-chem; shifting 3 months once might be different
     ;; than shifting by 1 month three times.
     (let ((next datetime)
           (pastp t))
       (while pastp
         (setq next (org-x-dag-datetime-shift next shift shifttype)
               pastp (org-x-dag-datetime< next sel-datetime)))
       next))
    ('restart
     ;; Next time is one repeater interval after now
     ;;
     ;; ASSUME cur needs to match the length of time
     (org-x-dag-datetime-shift sel-datetime shift shifttype))
    ('cumulate
     ;; Next time is one repeater interval after the base timestamp
     (org-x-dag-datetime-shift datetime shift shifttype))))

(defun org-x-dag-unfold-timestamp (cur datetime rep future-limit)
  "Return all timestamps associated with DATETIME.

If REP is nil, return a singleton list just containing DATETIME.
If REP is non-nil, return DATETIME and all repeaters up until
FUTURE-LIMIT in a list."
  ;; ASSUME pts and future-limit are both long or short timestamps
  (unless (org-x-dag-datetime< future-limit datetime)
    (pcase rep
      (`nil `(,datetime))
      (`(,value ,unit ,reptype)
       (->> (org-x-dag-repeater-get-next cur datetime value unit reptype)
            (--unfold (unless (org-x-dag-datetime< future-limit it)
                        (cons it (org-x-dag-datetime-shift it value unit))))
            (cons datetime))))))

(defun org-x-dag-get-scheduled-at (sel-date pts)
  (-let* (((&plist :datetime d :repeater r) pts)
          (islongp (org-ml-time-is-long d))
          (future-limit (if islongp `(,@sel-date 23 59) sel-date))
          (sel-datetime (if islongp (org-x-dag-date-at-current-time sel-date) sel-date)))
    (org-x-dag-unfold-timestamp sel-datetime d r future-limit)))

(defun org-x-dag-get-deadlines-at (sel-date pts)
  (-let* (((&plist :datetime d :repeater r :warning w) pts)
          (islongp (org-ml-time-is-long d))
          ((warn-shift warn-shifttype)
           (if w w
             (let ((f (if islongp 1440 1)))
               `(,(* f org-deadline-warning-days) submonth))))
          (sel-datetime (if islongp (org-x-dag-date-at-current-time sel-date) sel-date))
          (future-limit (org-x-dag-datetime-shift sel-datetime warn-shift warn-shifttype)))
    (org-x-dag-unfold-timestamp sel-datetime d r future-limit)))

(defun org-x-dag-headline-get-planning ()
  (let ((end (save-excursion (outline-next-heading))))
    (save-excursion
      (when (re-search-forward org-planning-line-re end t)
        ;; TODO this is rather slow since I'm using a general org-ml parsing
        ;; function; I'm also not even using the match results from the planning
        ;; line re, which might be useful
        (-let* ((pl (org-ml-parse-this-element)))
          (->> (org-ml-get-properties '(:deadline :scheduled) pl)
               (--map (-some-> it (org-x-dag-partition-timestamp)))))))))

(defun org-x-dag-format-tag-node (category tags key)
  ;; ASSUME I don't use subtree-level categories
  (-let* (;; (category (org-get-category))
          (tags* (org-x-dag-prepare-tags tags))
          (todo-state (org-x-dag-id->todo key))
          ;; TODO the only reason this format thing is here is to satisfy
          ;; `org-agenda-format-item' (which I should probably just rewrite)
          (head (format "%s %s" todo-state (org-x-dag-id->title key)))
          (level (org-x-dag-id->formatted-level key))
          (marker (org-agenda-new-marker))
          ;; no idea what this function actually does
          ((ts . ts-type) (org-agenda-entry-get-agenda-timestamp (point)))
          (item (org-agenda-format-item "" head level category tags*))
          (priority (org-get-priority item)))
    (-> (org-x-dag-add-default-props item key)
        (org-add-props nil
            ;; face
            'face 'default
            'done-face 'org-agenda-done
            'undone-face 'default
            ;; marker
            'org-hd-marker marker
            'org-marker marker
            ;; headline stuff
            'todo-state todo-state
            'priority priority
            'ts-date ts
            ;; misc
            'type (concat "tagsmatch" ts-type)))))

(defun org-x-dag-format-item (id extra category tags time)
  (let* ((tags* (org-x-dag-prepare-tags tags))
         (level (org-x-dag-id->formatted-level id))
         (todo-state (org-x-dag-id->todo id))
         (head (format "%s %s" todo-state (org-x-dag-id->title id)))
         (time-str (-some->> time (apply #'format "%02i:%02i ")))
         (item (org-agenda-format-item extra head level category tags* time-str))
         ;; TODO why am I getting the priority after sending the headline
         ;; through some crazy formatting function?
         (priority (org-get-priority item)))
    (-> (org-x-dag-add-default-props item id)
        (org-add-props nil
            'todo-state todo-state
            'priority priority))))

(defun org-x-dag-planning-props (id face pos date ts-date type)
  (list
   ;; face
   'face (if (org-x-dag-id->is-done-p id) 'org-agenda-done face)
   'undone-face face
   'done-face 'org-agenda-done
   ;; marker
   'org-hd-marker (org-agenda-new-marker)
   'org-marker (org-agenda-new-marker pos)
   ;; headline stuff
   'date (org-x-dag-date-to-absolute date)
   'ts-date (org-x-dag-date-to-absolute ts-date)
   'type type))

(defun org-x-dag-format-scheduled-node (sel-date pos datetime category tags id)
  (-let* (((this-date this-time) (org-x-dag-datetime-split datetime))
          (diff (org-x-dag-date-diff this-date sel-date))
          (pastp (< diff 0))
          (todayp (= diff 0))
          ;; hopefully this is right...if it is this seems silly
          (extra (-let (((today past) org-agenda-scheduled-leaders))
                   (cond (todayp today)
                         (pastp (format past (- diff)))
                         (t "")))) ;; This should never actually be used
          (face (cond (pastp 'org-scheduled-previously)
                      (todayp 'org-scheduled-today)
                      (t 'org-scheduled)))
          ((date type) (if pastp `(,this-date "past-scheduled")
                         `(,sel-date "scheduled")))
          (props (org-x-dag-planning-props id face pos date this-date type)))
    ;; NOTE: I don't care about habits, no need to consider them
    (-> (org-x-dag-format-item id extra category tags this-time)
        (org-add-props props))))

(defun org-x-dag-format-deadline-node (sel-date pos datetime category tags id)
  (-let* (((this-date this-time) (org-x-dag-datetime-split datetime))
          (diff (org-x-dag-date-diff this-date sel-date))
          (pastp (< diff 0))
          (futurep (< 0 diff))
          (extra (-let* (((now future past) org-agenda-deadline-leaders))
                   (cond
                    (futurep (format future diff))
                    (pastp (format past diff))
                    (t now))))
          ;; TODO the stock deadline formatter uses the warning time to
          ;; determine this based on percentage; I'm lazy and don't feel like
          ;; doing that (now) but I might in the future
          (face (cond
                 ((< 5 diff) 'org-upcoming-distant-deadline)
                 ((< 1 diff) 'org-upcoming-deadline)
                 (t 'org-warning)))
          ((date type) (if futurep `(,sel-date "upcoming-deadline")
                         `(,this-date "deadline")))
          (props (org-x-dag-planning-props id face pos date this-date type)))
    (-> (org-x-dag-format-item id extra category tags this-time)
        (org-add-props props))))

;;; ID FUNCTIONS

;; ranking

(defmacro org-x-dag-ids-rank (form ids)
  (declare (indent 1))
  `(cl-labels
       ((compare
         (a b)
         (cond
          ((not (or a b)) t)
          ((= (car a) (car b)) (compare (cdr a) (cdr b)))
          (t (> (car a) (car b))))))
     (->> (--map (cons it ,form) ,ids)
          (--sort (compare (cdr it) (cdr other))))))
  
(defmacro org-x-dag-ids-rank-by-children (form ids)
  `(org-x-dag-ids-rank
       (let ((it (org-x-dag-id->children it)))
         ,form)
     ,ids))

(defmacro org-x-dag-ids-rank-by-parents (form ids)
  `(org-x-dag-ids-rank
       (let ((it (org-x-dag-id->parents it)))
         ,form)
     ,ids))

;; reductions

;; TODO this is a naive approach that will effectively expand the dag into
;; a tree for nodes that share common children/parents. I might want to handle
;; these special cases in a better way (example, 'summation' could count nodes
;; multiple times, which may or may not make sense)
(defmacro org-x-dag--id-reduce (id-getter branch-form leaf-form init id)
  (declare (indent 1))
  (let ((cs (make-symbol "--children")))
    `(cl-labels
         ((reduce
           (acc it)
           (-if-let (,cs (,id-getter ,id))
               (--reduce-from (reduce acc it) ,branch-form ,cs)
             ,leaf-form)))
       (reduce ,init ,id))))

(defmacro org-x-dag-id-reduce-down (branch-form leaf-form init id)
  `(org-x-dag--id-reduce org-x-dag-id->children
     ,branch-form ,leaf-form ,init ,id))

(defmacro org-x-dag-id-reduce-up (branch-form leaf-form init id)
  `(org-x-dag--id-reduce org-x-dag-id->parents
     ,branch-form ,leaf-form ,init ,id))

;;; HEADLINE PREDICATES
;;
;; The following are predicates that require the point to be above the
;; headline in question

(defun org-x-headline-has-timestamp (re want-time)
  (let ((end (save-excursion (outline-next-heading))))
    (-when-let (p (save-excursion (re-search-forward re end t)))
      (if want-time (org-2ft (match-string 1)) p))))

(defun org-x-dag-headline-is-deadlined-p (want-time)
  (org-x-headline-has-timestamp org-deadline-time-regexp want-time))

(defun org-x-dag-headline-is-scheduled-p (want-time)
  (org-x-headline-has-timestamp org-scheduled-time-regexp want-time))

(defun org-x-dag-headline-is-closed-p (want-time)
  (org-x-headline-has-timestamp org-closed-time-regexp want-time))

(defun org-x-dag-is-created-p (want-time)
  (save-excursion
    (-when-let (ts (org-x-dag-get-local-property org-x-prop-created))
      (if want-time (org-2ft ts) t))))

(defun org-x-dag-headline-is-iterator-p ()
  (save-excursion
    (->> (org-x-dag-get-local-property org-x-prop-parent-type)
         (equal org-x-prop-parent-type-iterator))))

(defconst org-x-headline-task-status-priorities
  '((:archivable . -1)
    (:complete . -1)
    (:expired . 0)
    (:done-unclosed . 0)
    (:undone-closed . 0)
    (:active . 1)
    (:inert . 2)))

(defconst org-x-project-status-priorities
  '((:archivable . -1)
    (:complete . -1)
    (:scheduled-project . 0)
    (:invalid-todostate . 0)
    (:undone-complete . 0)
    (:done-incomplete . 0)
    (:stuck . 0)
    (:wait . 1)
    (:held . 2)
    (:active . 3)
    (:inert . 4)))

(defun org-x-dag-time-is-archivable-p (epochtime)
  (< (- (float-time) epochtime) (* 60 60 24 org-x-archive-delay)))

;;; STATUS DETERMINATION

(defmacro org-x-dag-with-id (key &rest body)
  (declare (indent 1))
  `(progn
     (goto-char (org-x-dag-id->point ,key))
     ,@body))

(defmacro org-x-dag-with-id-in-file (id &rest body)
  (declare (indent 1))
  `(org-x-with-file (org-x-dag-id->file ,id)
     (org-x-dag-with-id ,id ,@body)))

(defun org-x-headline-get-task-status-0 (kw)
  (if (member kw org-x-done-keywords)
      (-if-let (c (org-x-dag-headline-is-closed-p t))
          (if (org-x-dag-time-is-archivable-p c)
              :archivable
            :complete)
        :done-unclosed)
    (cond
     ((org-x-headline-is-expired-p) :expired)
     ((org-x-headline-is-inert-p) :inert)
     ((org-x-dag-headline-is-closed-p nil) :undone-closed)
     (t :active))))

(defun org-x-dag-get-max-index (ys xs)
  "Return the member of XS that has the highest index in YS."
  (--max-by (> (-elem-index it ys) (-elem-index other ys)) xs))

(defmacro org-x-dag-descend-into-project (keys parent-tags codetree task-form
                                               callback)
  (declare (indent 2))
  (let ((allowed-codes (-map #'car codetree))
        (trans-tbl (--mapcat (-let (((a . bs) it))
                               (--map (cons it a) bs))
                             codetree)))
    `(cl-flet
         ((get-project-or-task-status
           (key)
           (-if-let (children (org-x-dag-id->headline-children key))
               (let* ((tags (org-x-dag-id->tags nil ,parent-tags key))
                      (child-results (funcall ,callback key tags children))
                      ;; ASSUME the car of the results will be the toplevel
                      ;; key/status pair for this (sub)project
                      (top-status (plist-get (car child-results) :status))
                      (top-status* (if (member top-status ',allowed-codes)
                                       top-status
                                     (alist-get top-status ',trans-tbl))))
                 (cons top-status* child-results))
             (let ((it-kw (org-x-dag-id->todo key)))
               (org-x-dag-with-id key
                 (-> ,task-form
                     (nth ',allowed-codes)
                     (list)))))))
       (let* ((results (-map #'get-project-or-task-status ,keys))
              (status (->> (-map #'car results)
                           (org-x-dag-get-max-index ',allowed-codes))))
         (cons status (-mapcat #'cdr results))))))

(defun org-x-dag-headline-get-project-status (key tags children)
  ;; ASSUME children will always be at least 1 long
  (org-x-dag-with-id key
    (let ((keyword (org-x-dag-id->todo key)))
      (-let (((status . child-results)
              (cond
               ((org-x-dag-headline-is-scheduled-p nil)
                (list :scheduled-project))
               ((equal keyword org-x-kw-hold)
                (list (if (org-x-headline-is-inert-p) :inert :held)))
               ((member keyword org-x--project-invalid-todostates)
                (list :invalid-todostate))
               ((equal keyword org-x-kw-canc)
                (list (if (org-x-headline-is-archivable-p) :archivable :complete)))
               ((equal keyword org-x-kw-done)
                (org-x-dag-descend-into-project children tags
                  ((:archivable)
                   (:complete)
                   (:done-incomplete :stuck :inert :held :wait :active
                                     :scheduled-project :invalid-todostate
                                     :undone-complete))
                  (if (member it-kw org-x-done-keywords)
                      (if (org-x-headline-is-archivable-p) 0 1)
                    2)
                  #'org-x-dag-headline-get-project-status))
               ((equal keyword org-x-kw-todo)
                (org-x-dag-descend-into-project children tags
                  ((:undone-complete :complete :archivable)
                   (:stuck :scheduled-project :invalid-todostate
                           :done-incomplete)
                   (:held)
                   (:wait)
                   (:inert)
                   (:active))
                  (cond
                   ((and (not (member it-kw org-x-done-keywords))
                         (org-x-headline-is-inert-p))
                    4)
                   ((equal it-kw org-x-kw-todo)
                    (if (org-x-dag-headline-is-scheduled-p nil) 5 1))
                   ((equal it-kw org-x-kw-hold)
                    2)
                   ((equal it-kw org-x-kw-wait)
                    3)
                   ((equal it-kw org-x-kw-next)
                    5)
                   (t 0))
                  #'org-x-dag-headline-get-project-status))
               (t (error "Invalid keyword detected: %s" keyword)))))
        (cons (list :key key :status status :tags tags) child-results)))))

(defun org-x-dag-headline-get-iterator-project-status (key children)
  (org-x-dag-with-id key
    (let* ((kw (org-x-dag-id->todo key))
           (status
            (cond
             ((or (member kw org-x--project-invalid-todostates)
                  (org-x-dag-headline-is-scheduled-p nil))
              (list :project-error))
             ((equal kw org-x-kw-canc)
              (list :empt))
             ;; TODO this is a bit awkward since I don't care about the child statuses
             ;; and I don't care about tags
             ((equal kw org-x-kw-done)
              (org-x-dag-descend-into-project children nil
                ((:empt)
                 (:project-error :unscheduled :actv))
                (if (member it-kw org-x-done-keywords) 0 1)
                ;; TODO this has an argument mismatch
                #'org-x-dag-headline-get-iterator-project-status))
             ((equal kw org-x-kw-todo)
              (org-x-dag-descend-into-project children nil
                ((:unscheduled :project-error)
                 (:empt)
                 (:actv))
                ;; TODO this triggers a compiler warning because I don't use
                ;; `it-kw'
                (let ((ts (org-x-dag-headline-is-scheduled-p t)))
                  (cond
                   ((not ts) 0)
                   ((> org-x-iterator-active-future-offset (- ts (float-time))) 1)
                   (t 2)))
                #'org-x-dag-headline-get-iterator-project-status))
             (t (error "Invalid keyword detected: %s" kw)))))
      status)))

(defun org-x-dag-headline-get-iterator-task-status (key)
  (org-x-dag-with-id key
    (if (org-x-dag-id->is-done-p key) :empt
      (-if-let (ts (or (org-x-dag-headline-is-scheduled-p t)
                       (org-x-dag-headline-is-deadlined-p t)))
          (if (< org-x-iterator-active-future-offset (- ts (float-time)))
              :actv
            :empt)
        :unscheduled))))

(defun org-x-dag-headline-get-iterator-status (key)
  (cl-flet
      ((get-status
        (key)
        (-if-let (children (org-x-dag-id->headline-children key))
            (->> children
                 (org-x-dag-headline-get-iterator-project-status key)
                 (car))
          (org-x-dag-headline-get-iterator-task-status key))))
    (->> (org-x-dag-id->headline-children key)
         (-map #'get-status)
         (org-x-dag-get-max-index org-x--iter-statuscodes))))

;;; SCANNERS
;;
;; Not sure what to call these, they convert the DAG to a list of agenda strings

(defmacro org-x-dag-with-files (files pre-form form)
  (declare (indent 2))
  (let* ((lookup-form '(ht-get file->ids it-file))
         (pre-form* (if pre-form
                        `(--filter ,pre-form ,lookup-form)
                      lookup-form)))
    `(-let (((&plist :file->ids) org-x-dag))
       (cl-flet
           ((proc-file
             (it-file)
             (-when-let (keys ,pre-form*)
               (org-x-with-file it-file
                 ;; NOTE there are other ways in org to get the category; the
                 ;; only one I ever cared about was the filename. Very simple,
                 ;; category = filename. Done
                 (let ((it-category (f-base it-file)))
                   (--mapcat ,form keys))))))
         (-non-nil (-mapcat #'proc-file ,files))))))

(defun org-x-dag-scan-projects ()
  (cl-flet*
      ((format-result
        (cat result)
        (-let* (((&plist :key :status :tags) result)
                (priority (alist-get status org-x-project-status-priorities)))
          (when (>= priority 0)
            (org-x-dag-with-id key
              (-> (org-x-dag-format-tag-node cat tags key)
                  (org-add-props nil
                      'x-toplevelp (org-x-dag-id->is-toplevel-p key)
                      'x-status status
                      'x-priority priority))))))
       (format-key
        (cat key)
        (let ((tags (org-x-dag-id->tags t nil key)))
          ;; TODO don't hardcode these things
          (org-x-dag-with-id key
            (unless (or (member org-x-tag-incubated tags)
                        (org-x-dag-headline-is-iterator-p))
              (-some->> (org-x-dag-id->headline-children key)
                (org-x-dag-headline-get-project-status key tags)
                (--map (format-result cat it))))))))
    (org-x-dag-with-files (org-x-get-action-files)
        (and (org-x-dag-id->is-toplevel-p it)
             (not (org-x-dag-id->is-done-p it)))
      (format-key it-category it))))

(defun org-x-dag-scan-projects-with-goals ()
  (cl-flet
      ((split-parent-goals
        (s)
        (let ((id (get-text-property 1 'x-id s)))
          (-if-let (goal-ids (org-x-dag-id->foreign-parents id))
              (--map (org-add-props (copy-seq s) nil 'x-goal-id it) goal-ids)
            (list (org-add-props s nil 'x-goal-id nil))))))
    (->> (org-x-dag-scan-projects)
         (--filter (org-x-dag-id->is-toplevel-p (get-text-property 1 'x-id it)))
         (-mapcat #'split-parent-goals))))

(defun org-x-dag-scan-iterators ()
  (cl-flet*
      ((format-result
        (tags cat key)
        (-let ((status (org-x-dag-headline-get-iterator-status key)))
          (org-x-dag-with-id key
            (-> (org-x-dag-format-tag-node cat tags key)
                (org-add-props nil
                    'x-status status))))))
    (org-x-dag-with-files (org-x-get-action-files)
        (org-x-dag-id->is-toplevel-p it)
      (let ((tags (org-x-dag-id->tags t nil it)))
        (unless (member org-x-tag-incubated tags)
          (org-x-dag-with-id it
            (when (org-x-dag-headline-is-iterator-p)
              (list (format-result tags it-category it)))))))))
  
(defun org-x-dag-get-task-nodes (id)
  (declare (indent 2))
  (cl-labels
      ((descend
        (children)
        ;; TODO don't hardcode this
        (->> (--remove (member (org-x-dag-id->todo it)
                               (list org-x-kw-canc org-x-kw-hold))
                       children)
             (--mapcat (-if-let (cs (org-x-dag-id->headline-children it))
                           (descend cs)
                         (list it))))))
    (-some-> (org-x-dag-id->headline-children id)
      (descend))))

;; TODO this includes tasks underneath cancelled headlines
(defun org-x-dag-scan-tasks ()
  (cl-flet
      ((format-key
        (category is-standalone key)
        (let ((tags (org-x-dag-id->tags t nil key)))
          ;; filter out incubators
          (org-x-dag-with-id key
            (unless (or (member org-x-tag-incubated tags)
                        (org-x-dag-headline-is-scheduled-p nil)
                        (org-x-dag-headline-is-deadlined-p nil))
              (let* ((s (org-x-headline-get-task-status-0 (org-x-dag-id->todo key)))
                     (p (alist-get s org-x-headline-task-status-priorities)))
                (unless (= p -1)
                  (-> (org-x-dag-format-tag-node category tags key)
                      (org-add-props nil
                          'x-is-standalone is-standalone
                          'x-status s)))))))))
    (org-x-dag-with-files (org-x-get-action-files)
        (org-x-dag-id->is-toplevel-p it)
      (-if-let (project-tasks (org-x-dag-get-task-nodes it))
          (--map (format-key it-category nil it) project-tasks)
        (list (format-key it-category t it))))))

;; TODO this is hella slow...increases runtime by 25% (also super redundant)
(defun org-x-dag-id->goals (id)
  (let ((goal-files (list (org-x-get-lifetime-goal-file)
                          (org-x-get-endpoint-goal-file))))
    (cl-labels
        ((get
          (id)
          (let ((parents (org-x-dag-id->parents id)))
            (-if-let (goal-ids (--filter (member (org-x-dag-id->file it) goal-files) parents))
                goal-ids
              (-mapcat #'get parents)))))
      (get id))))

(defun org-x-dag-scan-tasks-with-goals ()
  (cl-flet
      ((split-parent-goals
        (s)
        (let ((id (get-text-property 1 'x-id s)))
          ;; ASSUME all foreign parents are actually goals
          ;; TODO this isn't a great assumption
          (-if-let (goal-ids (org-x-dag-id->foreign-parents id))
              (--map (org-add-props s nil 'x-goal-id it) goal-ids)
            (list (org-add-props s nil 'x-goal-id nil))))))
    (->> (org-x-dag-scan-tasks)
         (-mapcat #'split-parent-goals))))

(defun org-x-dag-scan-incubated ()
  (cl-flet
      ((format-key
        (category key)
        (let ((tags (org-x-dag-id->tags t nil key)))
          (when (member org-x-tag-incubated tags)
            (org-x-dag-with-id key
              (let* ((sch (org-x-dag-headline-is-scheduled-p t))
                     (dead (org-x-dag-headline-is-deadlined-p t))
                     (is-project (org-x-dag-id->headline-children key)))
                (-> (org-x-dag-format-tag-node category tags key)
                    (org-add-props nil
                        'x-project-p is-project
                        'x-scheduled sch
                        'x-deadlined dead))))))))
    (org-x-dag-with-files (org-x-get-action-and-incubator-files)
        (and (org-x-dag-id->is-toplevel-p it)
             (not (org-x-dag-id->is-done-p it)))
      (list (format-key it-category it)))))

(defun org-x-dag-scan-archived ()
  (cl-flet
      ((format-key
        (category key)
        (let ((tags (org-x-dag-id->tags t nil key)))
          (unless (member org-x-tag-incubated tags)
            (org-x-dag-with-id key
              (-let (((is-archivable is-project)
                      (-if-let (children (org-x-dag-id->headline-children key))
                          (-> (org-x-dag-headline-get-project-status key tags children)
                              (alist-get org-x-project-status-priorities)
                              (eq :archivable)
                              (list t))
                        (-> (org-x-headline-get-task-status-0 (org-x-dag-id->todo key))
                            (alist-get org-x-headline-task-status-priorities)
                            (eq :archivable)
                            (list t)))))
                (when is-archivable
                  (-> (org-x-dag-format-tag-node category tags key)
                      (org-add-props nil
                          'x-project-p is-project)))))))))
    (org-x-dag-with-files (org-x-get-action-files)
        (org-x-dag-id->is-toplevel-p it)
      (org-x-dag-with-id it
        (if (org-x-dag-headline-is-iterator-p)
            (->> (org-x-dag-id->headline-children it)
                 (--map (format-key it-category it)))
          (list (format-key it-category it)))))))

(defun org-x-dag-scan-ltgs ()
  (let ((child-files (append (list (org-x-get-lifetime-goal-file)
                                   (org-x-get-endpoint-goal-file))
                             (org-x-get-action-files))))
    (cl-flet
        ((format-id
          (category id)
          (let ((toplevelp (org-x-dag-id->is-toplevel-p id))
                (has-children (->> (org-x-dag-id->children id)
                                   (--any-p (member (org-x-dag-id->file it)
                                                    child-files))))
                (tags (org-x-dag-id->tags t nil id)))
            (-> (org-x-dag-format-tag-node category tags id)
                (org-add-props nil
                    'x-goal-status (list :type 'ltg
                                         :childlessp (not has-children)
                                         :toplevelp toplevelp
                                         :parentlessp nil))))))
      (org-x-dag-with-files (list (org-x-get-lifetime-goal-file))
          nil
        (org-x-dag-with-id it
          (list (format-id it-category it)))))))

(defun org-x-dag-scan-epgs ()
  (let ((child-files (cons (org-x-get-endpoint-goal-file)
                           (org-x-get-action-files)))
        (parent-files (list (org-x-get-endpoint-goal-file)
                            (org-x-get-lifetime-goal-file))))
    (cl-flet
        ((format-id
          (category id)
          (let ((toplevelp (org-x-dag-id->is-toplevel-p id))
                (has-children (->> (org-x-dag-id->children id)
                                   (--any-p (member (org-x-dag-id->file it)
                                                    child-files))))
                (has-parents (->> (org-x-dag-id->parents id)
                                  (--any-p (member (org-x-dag-id->file it)
                                                   parent-files))))
                (tags (org-x-dag-id->tags t nil id)))
            (-> (org-x-dag-format-tag-node category tags id)
                (org-add-props nil
                    'x-goal-status (list :type 'epg
                                         :childlessp (not has-children)
                                         :toplevelp toplevelp
                                         :parentlessp (not has-parents)))))))
      (org-x-dag-with-files (list (org-x-get-endpoint-goal-file))
          nil
        (org-x-dag-with-id it
          (list (format-id it-category it)))))))

(defun org-x-dag-scan-goals ()
  (append (org-x-dag-scan-ltgs) (org-x-dag-scan-epgs)))

(defun org-x-dag-scan-errors ()
  (cl-flet
      ((format-id
        (category id)
        (org-x-dag-with-id id
          (-when-let (error-type
                      (if (org-x-dag-headline-is-iterator-p)
                          (unless (org-x-dag-get-local-property "ARCHIVE")
                            :missing-archive)
                        (-if-let (created (org-x-dag-is-created-p t))
                            (when (<= (float-time) created)
                              :future-created)
                          :missing-created)))
            (-> (org-x-dag-format-tag-node category nil id)
                (org-add-props nil
                    'x-error error-type))))))
    (org-x-dag-with-files (org-x-dag-get-files)
        (not (org-x-dag-id->is-done-p it))
      (org-x-dag-with-id it
        (list (format-id it-category it))))))

(defun org-x-dag-scan-agenda (sel-date)
  (cl-flet*
      ((format-timestamps
        (todayp sel-date cat id pts get-datetimes-fun format-datetime-fun)
        (-when-let (datetimes (funcall get-datetimes-fun sel-date pts))
          (let ((tags (org-x-dag-id->tags t nil id)))
            (unless (member org-x-tag-incubated tags)
              (-let (((&plist :pos) pts)
                     (donep (org-x-dag-id->is-done-p id)))
                (--> datetimes
                     (--remove (and donep (not (org-x-dag-datetime= (-take 3 it) sel-date))) it)
                     (if (not todayp) (--remove (org-x-dag-datetime< (-take 3 it) sel-date) it) it)
                     (--map (funcall format-datetime-fun sel-date pos it cat tags id) it)))))))
       (format-id
        (todayp cat id)
        (org-x-dag-with-id id
          (-when-let (res (org-x-dag-headline-get-planning))
            (-let (((dead sched) res))
              (append
               (when dead
                 (format-timestamps todayp sel-date cat id dead
                                    #'org-x-dag-get-deadlines-at
                                    #'org-x-dag-format-deadline-node))
               (when sched
                 (format-timestamps todayp sel-date cat id sched
                                    #'org-x-dag-get-scheduled-at
                                    #'org-x-dag-format-scheduled-node))))))))
    (org-x-dag-with-files (org-x-get-action-files)
        nil
      (let ((todayp (= (org-x-dag-date-to-absolute sel-date) (org-today))))
        (format-id todayp it-category it)))))

(defun org-x-dag-scan-quarterly-plan ()
  (let ((week-file (list (org-x-get-weekly-plan-file)))
        (current-quarter (->> (org-x-dag->current-date)
                              (org-x-dag-date-to-quarter))))
    (cl-flet
        ((format-id
          (id)
          (org-x-dag-with-id id
            (let ((alloc (-some->> (org-x-dag-get-local-property org-x-prop-allocate)
                           (org-x-dag-allocation-fraction current-quarter)))
                  (assignedp (org-x-dag-id->has-child-in-files-p id week-file))
                  (tags (->> (org-x-dag-id->parents id)
                             (--mapcat (org-x-dag-id->tags id nil it))
                             (--filter (= (elt it 0) org-x-tag-category-prefix)))))
              (-> (org-x-dag-format-tag-node "goal" tags id)
                  (org-add-props nil
                      'x-assignedp assignedp
                      ;; override face
                      'face (if assignedp 'org-warning 'default)
                      'x-alloc (or alloc 0)))))))
      (org-x-with-file (org-x-qtp-get-file)
        (-map #'format-id (org-x-dag->qtp-ids 'current))))))

(defun org-x-dag-scan-weekly-plan ()
  (let ((daily-file (list (org-x-get-daily-plan-file))))
    (cl-flet
        ((format-id
          (id)
          (org-x-dag-with-id id
            ;; TODO this assigned thing needs to be limited in scope to the
            ; the current ids of the time period in question
            (let* ((assignedp (org-x-dag-id->has-child-in-files-p id daily-file))
                   (day (-some->> (org-x-dag-id->tags t nil id)
                          ;; TODO I guess this works...could be more precise
                          (--filter (s-matches-p "[A-Z]\\{3\\}" it))
                          (car)))
                   (daynum (car (rassoc day org-x-dag-weekly-tags))))
              (-> (org-x-dag-format-tag-node "goal" nil id)
                  (org-add-props nil
                      'x-assignedp assignedp
                      'x-day-of-week (format "%d. %s" daynum day)
                      ;; override face
                      'face (if assignedp 'org-warning 'default)))))))
      (org-x-with-file (org-x-get-weekly-plan-file)
        (-map #'format-id (org-x-dag->wkp-ids 'current))))))

;; (cl-flet
;;     ((format-id
;;       (category id)
;;       (-> (org-x-dag-format-tag-node category nil id)
;;           (org-add-props nil))))
;;   (org-x-dag-with-files (list (org-x-qtp-get-file))
;;       nil
;;     (org-x-dag-with-id it
;;       (list (format-id it-category it))))))

;;; AGENDA VIEWS

;; (defun org-x-dag-show-tasks (_match)
;;   (org-x-dag-sync t)
;;   ;; hack to make the loop only run once
;;   (let ((org-agenda-files (list (car (org-x-get-action-files)))))
;;     (nd/with-advice
;;         (('org-scan-tags :override (lambda (&rest _) (org-x-dag-scan-tasks))))
;;       (org-tags-view '(4) "TODO"))))

(defun org-x-dag-show-nodes (get-nodes)
  (org-x-dag-sync)
  (let* ((org-tags-match-list-sublevels org-tags-match-list-sublevels)
         (completion-ignore-case t))
    (catch 'exit
      (org-agenda-prepare (concat "DAG-TAG"))
      (org-compile-prefix-format 'tags)
      (org-set-sorting-strategy 'tags)
      (let ((org-agenda-redo-command `(org-x-dag-show-nodes ',get-nodes))
            (rtnall (funcall get-nodes)))
        (org-agenda--insert-overriding-header
          (with-temp-buffer
            (insert "Headlines with TAGS match: \n")
            (add-text-properties (point-min) (1- (point))
                                 (list 'face 'org-agenda-structure))
            (buffer-string)))
        (org-agenda-mark-header-line (point-min))
        (when rtnall
          (insert (org-agenda-finalize-entries rtnall 'tags) "\n"))
        (goto-char (point-min))
        (or org-agenda-multi (org-agenda-fit-window-to-buffer))
        (add-text-properties
         (point-min) (point-max)
         `(org-agenda-type tags
                           org-last-args (,get-nodes)
                           org-redo-cmd ,org-agenda-redo-command
                           org-series-cmd ,org-cmd))
        (org-agenda-finalize)
        (setq buffer-read-only t)))))

;; make the signature exactly like `org-agenda-list' ...for now
(defun org-x-dag-show-daily-nodes (&optional _ start-day _ _)
  (org-x-dag-sync)
  (-let ((completion-ignore-case t)
         ;; TODO not sure if this if thing is actually necessary
         ((arg start-day span with-hour) (or org-agenda-overriding-arguments
                                     (list nil start-day 'day nil))))
    (catch 'exit
      (org-agenda-prepare "DAG-DAILY")
      (org-compile-prefix-format 'agenda)
      (org-set-sorting-strategy 'agenda)
      (-let* ((today (org-today))
              (sd (or start-day today))
              (org-agenda-redo-command
               `(org-x-dag-show-daily-nodes 'nil ,start-day ',span ,with-hour))
              ((m d y) (calendar-gregorian-from-absolute sd))
              (rtnall (org-x-dag-scan-agenda `(,y ,m ,d))))
        (setq-local org-starting-day sd)
        (setq-local org-arg-loc arg)
        ;; TODO just day (for now)
        (setq-local org-agenda-current-span span)
        (org-agenda--insert-overriding-header
          (with-temp-buffer
            (insert (format "Agenda for %d-%02d-%02d: \n" y m d))
            (add-text-properties (point-min) (1- (point))
                                 (list 'face 'org-agenda-structure))
            (buffer-string)))
        (org-agenda-mark-header-line (point-min))
        ;; TODO handle time grid here somehow
        (-some--> (org-agenda-add-time-grid-maybe rtnall 1 (= sd today))
          (org-agenda-finalize-entries it 'agenda)
          (insert it "\n"))
        (goto-char (point-min))
        (or org-agenda-multi (org-agenda-fit-window-to-buffer))
        (add-text-properties
         (point-min) (point-max)
         `(org-agenda-type agenda
                           org-last-args (,arg ,start-day ,span)
                           org-redo-cmd ,org-agenda-redo-command
                           org-series-cmd ,org-cmd))
        (org-agenda-finalize)
        (setq buffer-read-only t)))))

;;; PARENT LINK FUNCTONS

(defconst org-x-drwr-parent-links "X_PARENT_LINKS")

(defun org-x-dag-build-parent-link-drawer (ids)
  (->> (-map #'org-x-dag-id->link-item ids)
       (apply #'org-ml-build-plain-list)
       (org-ml-build-drawer org-x-drwr-parent-links)))

(defun org-x-dag-section-get-parent-links (children)
  (cl-flet
      ((parse-item
        (item)
        (let ((first (car (org-ml-item-get-paragraph item))))
          (if (and (org-ml-is-type 'link first)
                   (equal (org-ml-get-property :type first) "id"))
              (org-ml-get-property :path first)
            (error "Invalid link node: %S" first)))))
    (-when-let (first (->> children
                           (--find (org-x--is-drawer-with-name org-x-drwr-parent-links it))
                           (org-ml-get-children)
                           (car)))
      (if (org-ml-is-type 'plain-list first)
          (->> (org-ml-get-children first)
               (-map #'parse-item))
        (error "Invalid parent link drawer")))))

(defun org-x-dag-section-set-parent-links (ids children)
  (-if-let (i (--find-index (org-x--is-drawer-with-name org-x-drwr-parent-links it)
                            children))
      (let ((d (nth i children)))
        (-if-let (pl (-some->> (-map #'org-x-dag-id->link-item ids)
                       (apply #'org-ml-build-plain-list)))
            (-replace-at i (org-ml-set-children (list pl) d) children)
          (-remove-at i children)))
    (if ids (cons (org-x-dag-build-parent-link-drawer ids) children) children)))

(defmacro org-x-dag-section-map-parent-links* (form children)
  (let ((c (make-symbol "--headline")))
    `(let* ((,c ,children)
            (it (org-x-dag-section-get-parent-links ,c)))
       (org-x-dag-section-set-parent-links ,form ,c))))

(defun org-x-dag-section-add-parent-link (id children)
  (org-x-dag-section-map-parent-links* (cons id it) children))

(defun org-x-dag-section-remove-parent-link (id children)
  (org-x-dag-section-map-parent-links*
   (--remove-first (equal it id) it)
   children))

(defun org-x-dag-headline-get-parent-links (headline)
  (->> headline
       (org-ml-headline-get-contents (org-x-logbook-config))
       (org-x-dag-section-get-parent-links)))

(defun org-x-dag-headline-set-parent-links (ids headline)
  (org-ml-headline-map-contents* (org-x-logbook-config)
    (org-x-dag-section-set-parent-links ids it)
    headline))

(defmacro org-x-dag-headline-map-parent-links* (form headline)
  (let ((h (make-symbol "--headline")))
    `(let* ((,h ,headline)
            (it (org-x-dag-headline-get-parent-links ,h)))
       (org-x-dag-headline-set-parent-links ,form ,h))))

;; TODO not DRY
(defun org-x-dag-headline-add-parent-link (id headline)
  (org-x-dag-headline-map-parent-links* (cons id it) headline))

(defun org-x-dag-headline-remove-parent-link (id headline)
  (org-x-dag-headline-map-parent-links*
   (--remove-first (equal it id) it)
   headline))

;;; ALLOCATION

(pcase-defmacro regexp (capture regexp)
  `(and x (let ,capture (s-match ,regexp x))))

;; this function can also be used to check the format of an allocation during
;; assignment
(defun org-x-dag-allocation-fraction (quarter allocation)
  (cl-flet
      ((hhmm-to-mins
        (H M)
        (let ((H* (string-to-number H))
              (M* (string-to-number M)))
          (+ (* 60.0 H*) M*))))
    (let* ((qt-days (-> (org-x-dag-shift-quarter quarter 1 'quarter)
                        (org-x-dag-quarter-diff quarter)
                        (float)))
           (qt-mins (* qt-days 1440))
           (hhmm-regexp "\\(2[0-4]\\|[0-1][0-9]\\|[0-9]\\):\\([0-6][0-9]\\)"))
      (pcase allocation
        ;; match 'X%' where X is a flat percent of the quarter
        ((regexp `(,_ ,percent) "^\\([0-9]+\\)%$")
         (/ (string-to-number percent) 100.0))
        ;; match 'H:M' where H is hours and M is minutes (both clock digits)
        ((regexp `(,_ ,H ,M) (format "^%s$" hhmm-regexp))
         (/ (hhmm-to-mins H M) 1440.0))
        ;; match 'H:M/Dd' where H/M are like above and D is number of days
        ;; per quarter
        ((regexp `(,_ ,H ,M ,d) (format "^%s/\\([0-9]+\\)d$" hhmm-regexp))
         (let ((d* (string-to-number d))
               (mins (hhmm-to-mins H M)))
           (/ (* mins d*) qt-mins)))
        (e (error "Invalid allocation: %s" e))))))

;;; INTERACTIVE FUNCTIONS

(defun org-x-dag-add-id-to-this-headline (id)
  (org-ml-update-this-headline*
    (org-x-dag-headline-add-parent-link id it)))

(defun org-x-dag-read-id (ids cur-ids)
  (cl-flet
      ((make-cell
        (id type)
        (-let ((title (org-x-dag-id->title id))
               (presentp (not (eq type 'toadd)))
               (prefix (pcase type
                         (`present ?*)
                         (`noexist ?!)
                         (`toadd ?\s))))
          (list (format "%c %s" prefix title)
                :id id
                :title title
                :presentp presentp))))
    (let* ((present (--map (list it 'present) (-intersection cur-ids ids)))
           (noexist (--map (list it 'noexist) (-difference cur-ids ids)))
           (toadd (--map (list it 'toadd) (-difference ids cur-ids)))
           (mapper (->> (append present noexist toadd)
                        (--map (apply #'make-cell it))
                        (--sort (plist-get (cdr it) :presentp)))))
      (print (-map #'cdr mapper))
      (alist-get (completing-read "Node: " mapper) mapper nil nil #'equal))))

(defun org-x-dag-this-headline-choose-id (toplevel-allowed? legal-files msg ids)
  (cl-flet
      ((update-nodes
        (link-getter remover adder ids children)
        (-let* ((cur-ids (funcall link-getter children))
                ((&plist :id i :presentp p) (org-x-dag-read-id ids cur-ids)))
          (funcall (if p remover adder) i children))))
    (if (not (member (buffer-file-name) legal-files)) (message "Not in %s" msg)
      (if (org-before-first-heading-p)
          (if (not toplevel-allowed?) (message "Cannot set toplevel drawer.")
            (org-ml-update-this-section*
              ;; TODO org-ml shouldn't require this, just map the children
              ;; directly
              (org-ml-map-children*
                (update-nodes #'org-x-dag-section-get-parent-links
                              #'org-x-dag-section-remove-parent-link
                              #'org-x-dag-section-add-parent-link
                              ids it)
                it)))
        (org-ml-update-this-headline*
          (update-nodes #'org-x-dag-headline-get-parent-links
                        #'org-x-dag-headline-remove-parent-link
                        #'org-x-dag-headline-add-parent-link
                        ids it))))))

(defun org-x-dag-link-ltg-to-epg ()
  (interactive)
  (let ((ids (org-x-dag->ltg-ids))
        (legal (list (org-x-get-endpoint-goal-file))))
    (org-x-dag-this-headline-choose-id nil legal "endpoint goal file" ids)))

(defun org-x-dag-link-goal-to-qtp ()
  (interactive)
  (let ((ids (append (org-x-dag->ltg-ids) (org-x-dag->epg-ids)))
        (legal (list (org-x-qtp-get-file))))
    (org-x-dag-this-headline-choose-id nil legal "quarterly plan file" ids)))

(defun org-x-dag-link-action-to-goal ()
  (interactive)
  (let ((ids (append (org-x-dag->ltg-ids) (org-x-dag->epg-ids)))
        (legal (org-x-get-action-and-incubator-files)))
    ;; TODO this won't work on the toplevel section
    (org-x-dag-this-headline-choose-id t legal "an action/incubator file" ids)))

;;; AGENDA VIEWS

(defun org-x-dag-agenda-run-series (name files cmds)
  (declare (indent 2))
  (catch 'exit
    (let ((org-agenda-buffer-name (format "*Agenda: %s*" name)))
      (org-agenda-run-series name `((,@cmds) ((org-agenda-files ',files)))))))

(defun org-x-dag-agenda-call (buffer-name header-name type match files settings)
  (declare (indent 5))
  (let* ((n (or header-name buffer-name))
         (s `((org-agenda-overriding-header ,n) ,@settings)))
    (org-x-dag-agenda-run-series buffer-name files `((,type ,match ,s)))))

;; TODO the tags in the far column are redundant
(defun org-x-dag-agenda-quarterly-plan ()
  (interactive)
  (let ((match ''org-x-dag-scan-quarterly-plan)
        (files (org-x-get-action-files))
        (header (->> (org-x-dag->current-date)
                     (org-x-dag-date-to-quarter)
                     (apply #'format "Quarterly Plan: %d Q%d"))))
    (org-x-dag-agenda-call "Quarterly Plan" nil #'org-x-dag-show-nodes match files
      `((org-agenda-todo-ignore-with-date t)
        (org-agenda-overriding-header ,header)
        (org-agenda-sorting-strategy '(user-defined-up category-keep))
        ;; TODO add allocation (somehow)
        (org-agenda-prefix-format '((tags . "  ")))
        (org-super-agenda-groups
         '((:auto-map
            (lambda (line)
              (let ((bucket (car (get-text-property 1 'tags line))))
                (--> (-map #'cdr org-x-life-categories)
                     (--find (equal (plist-get it :tag) bucket) it)
                     (plist-get it :desc)))))))))))

(defun org-x-dag-agenda-weekly-plan ()
  (interactive)
  (let* ((match ''org-x-dag-scan-weekly-plan)
         (files (org-x-get-action-files))
         (date (org-x-dag->current-date))
         (header (->> (org-x-dag-date-to-week-number date)
                      (format "Weekly Plan: %d W%02d" (car date)))))
    (org-x-dag-agenda-call "Weekly Plan" nil #'org-x-dag-show-nodes match files
      `((org-agenda-todo-ignore-with-date t)
        (org-agenda-overriding-header ,header)
        (org-agenda-sorting-strategy '(user-defined-up category-keep))
        (org-agenda-prefix-format '((tags . "  ")))
        (org-super-agenda-groups
         '((:auto-map
            (lambda (line)
              (get-text-property 1 'x-day-of-week line)))))))))

(defun org-x-dag-agenda-tasks-by-goal ()
  (interactive)
  (let ((match ''org-x-dag-scan-tasks-with-goals)
        (files (org-x-get-action-files)))
    (nd/org-agenda-call "Tasks by Goal" nil #'org-x-dag-show-nodes match files
      `((org-agenda-todo-ignore-with-date t)
        (org-agenda-sorting-strategy '(user-defined-up category-keep))
        (org-super-agenda-groups
         '((:auto-map
            (lambda (line)
              (-if-let (i (get-text-property 1 'x-goal-id line))
                  (->> (org-x-dag-id->title i)
                       (substring-no-properties))
                "0. Unlinked")))))))))

;; TODO this is just toplevel projects (for now)
;; TODO wetter than Seattle
(defun org-x-dag-agenda-projects-by-goal ()
  (interactive)
  (let ((match ''org-x-dag-scan-projects-with-goals)
        (files (org-x-get-action-files)))
    (nd/org-agenda-call "Projects by Goal" nil #'org-x-dag-show-nodes match files
      `((org-agenda-todo-ignore-with-date t)
        (org-agenda-sorting-strategy '(user-defined-up category-keep))
        (org-super-agenda-groups
         '((:auto-map
            (lambda (line)
              (-if-let (i (get-text-property 1 'x-goal-id line))
                  (->> (org-x-dag-id->title i)
                       (substring-no-properties))
                "0. Unlinked")))))))))

(provide 'org-x-dag)
;;; org-x-dag.el ends here