;;; emacsconf-schedule.el --- Scheduling support     -*- lexical-binding: t; -*-

;; Copyright (C) 2022  Sacha Chua

;; Author: Sacha Chua <sacha@sachachua.com>
;; Keywords: calendar

;; 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 <https://www.gnu.org/licenses/>.

;;; Commentary:

;; 

;;; Code:

(defvar emacsconf-scheduling-strategies nil "List of scheduling functions.
Each function should take the info and manipulate it as needed, returning the new info.")

(defvar emacsconf-schedule-max-time 30)
(defun emacsconf-schedule-allocate-at-most (info)
  "Allocate at most `emacsconf-schedule-max-time' to the talks."
  (mapcar (lambda (o)
            (when (plist-get o :max-time)
              (plist-put o :time
                         (number-to-string
                          (min
                           (string-to-number (plist-get o :max-time))
                           emacsconf-max-time))))
            o)
          info))


(defvar emacsconf-schedule-break-time 10 "Number of minutes for break.")
(defvar emacsconf-schedule-lunch-time 45 "Number of minutes for lunch.")

(defun emacsconf-schedule-override-breaks (info)
  (mapcar (lambda (o)
            (when (string-match "BREAK" (plist-get o :title))
              (plist-put o :time (number-to-string emacsconf-schedule-break-time)))
            (when (string-match "LUNCH" (plist-get o :title))
              (plist-put o :time (number-to-string emacsconf-schedule-lunch-time)))
            o)
          info))

(defun emacsconf-schedule-prepare (&optional info)
  (emacsconf-schedule-based-on-info
   (seq-reduce (lambda (prev val) (funcall val prev))
               emacsconf-scheduling-strategies
               (or info (emacsconf-get-talk-info)))))

(defun emacsconf-schedule-summarize-breaks (&optional list)
  (setq list (or list (emacsconf-schedule-summarize)))
  (let ((list (or list (emacsconf-schedule-summarize)))
        (title-field 5))
    (append
     (cdr (seq-filter (lambda (o) (string-match "BREAK" (elt o title-field)))
                      list))
     '(hline)
     (cdr (seq-filter (lambda (o) (string-match "LUNCH" (elt o title-field)))
                 list)))))

(defun emacsconf-schedule-strategy-pack-everything-in-just-as-confirmed (&optional info)
  (let* ((emacsconf-schedule-break-time 10)
         (emacsconf-schedule-lunch-time 30)
         (emacsconf-schedule-max-time 30)
         (emacsconf-schedule-default-buffer-minutes 5)
         (emacsconf-schedule-default-buffer-minutes-for-live-q-and-a 10)
         (emacsconf-schedule-tweaked-allocations '(("indieweb" . 20)
                                                   ("maint" . 20)
                                                   ("workflows" . 20)))
         (emacsconf-scheduling-strategies '(emacsconf-schedule-allocate-buffer-time
                                            emacsconf-schedule-override-breaks
                                            emacsconf-schedule-allocate-buffer-time-at-most-max-time
                                            emacsconf-schedule-allocate-max-time
                                            emacsconf-schedule-allocate-at-most
                                            emacsconf-schedule-tweak-allocations)))
    (emacsconf-schedule-prepare info)))

(defun emacsconf-schedule-allocate-buffer-time-at-most-max-time (info)
  (mapcar (lambda (o)
            (when (plist-get o :slug)
              (plist-put o :buffer
                         (number-to-string
                          (if (string-match "live" (plist-get o :q-and-a))
                              (min (string-to-number (plist-get o :max-time))
                                   emacsconf-schedule-default-buffer-minutes-for-live-q-and-a)
                            emacsconf-schedule-default-buffer-minutes))))
            o)
          info))

(defun emacsconf-schedule-dump-sexp (info &optional include-time)
  (mapcar (lambda (o)
            (cond
             ((plist-get o :slug) (if include-time (cons (plist-get o :slug) (plist-get o :time)) (intern (plist-get o :slug))))
             ((plist-get o :fixed-time) (cons (plist-get o :title) (format-time-string "%Y-%m-%d %H:%M" (plist-get o :start-time))))
             (t (if include-time
                    (cons (plist-get o :title) (or (plist-get o :time) (plist-get o :max-time)))
                  (plist-get o :title)))))
          info))

(defun emacsconf-schedule-validate-and-summarize (schedule)
  (let ((validation-results (emacsconf-schedule-validate-time-constraints schedule))
        (sched (emacsconf-schedule-summarize schedule)))
    (append
     (list (list (format "%d talks" (length (emacsconf-filter-talks arranged)))))
     (mapcar (lambda (o) (list nil nil nil nil nil o)) validation-results)
     (if show-breaks
         (append
          (emacsconf-summarize-schedule
           (seq-filter (lambda (o) (string-match "BREAK\\|LUNCH" (plist-get o :title)))
                       schedule))
          '(hline)))
     sched nil)))

(defun emacsconf-schedule-inflate-sexp (sequence &optional info include-time)
  "Pairs with `emacsconf-schedule-dump-sexp'."
  (setq info (or info (emacsconf-get-talk-info)))
  (let ((by-assoc (mapcar (lambda (o) (cons (intern (plist-get o :slug)) o)) (emacsconf-filter-talks info))))
    (mapcar
     (lambda (seq)
       (if include-time
           (error "Not yet implemented")
         (cond
          ((eq seq 'break)
           (list :title "BREAK" :time emacsconf-schedule-break-time))
          ((eq seq 'lunch)
           (list :title "LUNCH" :time emacsconf-schedule-lunch-time))
          ((and (listp seq) (member (car seq) '(break lunch)) (stringp (cdr seq)))
           (list :title (if (eq (car seq) 'lunch) "LUNCH" "BREAK")
                 :scheduled (format-time-string (car org-time-stamp-formats) (date-to-time (cdr seq)))
                 :start-time (date-to-time (cdr seq))
                 :fixed-time t
                 :time (if (eq (car seq) 'lunch) emacsconf-schedule-lunch-time emacsconf-schedule-break-time)))
          ((and (listp seq) (member (car seq) '(break lunch)) (numberp (cdr seq)))
           (list :title (if (eq (car seq) 'lunch) "LUNCH" "BREAK")
                 :time (string-to-number (cdr seq))))
          ;; Named thing with fixed time
          ((and (listp seq) (stringp (car seq)) (stringp (cdr seq)))
           (append
            (seq-find (lambda (o) (string= (plist-get o :title) (car seq))) info)
            (list :title (car seq)
                  :scheduled (format-time-string (car org-time-stamp-formats) (date-to-time (cdr seq)))
                  :start-time (date-to-time (cdr seq))
                  :fixed-time t)))
          ;; Named thing with duration
          ((and (listp seq) (stringp (car seq)) (numberp (cdr seq)))
           (append
            (seq-find (lambda (o) (string= (plist-get o :title) (car seq))) info)
            (list :title (car seq)
                  :time (number-to-string (cdr seq)))))
          ;; Named thing
          ((stringp seq)
           (append
            (seq-find (lambda (o) (string= (plist-get o :title) seq)) info)
            (list :title seq)))
          ;; Slug with time
          ((and (listp seq) (symbolp (car seq)) (stringp (cdr seq)))
           (append (assoc-default (car seq) by-assoc)
                   (list :scheduled (format-time-string (car org-time-stamp-formats) (date-to-time (cdr seq)))
                         :start-time (date-to-time (cdr seq))
                         :fixed-time t)))
          ;; Slug with duration
          ((and (listp seq) (symbolp (car seq)) (numberp (cdr seq)))
           (append (assoc-default (car seq) by-assoc)
                   (list :override-time t
                         :time (number-to-string (cdr seq)))))
          ;; Just the slug
          ((symbolp seq)
           (assoc-default seq by-assoc))
          (t (error "Unknown %s" (prin1-to-string seq))))))
     sequence)))

(defun emacsconf-format-schedule-summary-row (o)
  (pcase emacsconf-focus
    ('status
      (list
       (plist-get o :status)
       (if (plist-get o :slug)
           (org-link-make-string (plist-get o :url)
                                 (plist-get o :slug))
         "")
       (if (plist-get o :scheduled)
           (emacsconf-format-short-time (plist-get o :scheduled))
         "")
       (or (plist-get o :time) "")
       (or (plist-get o :buffer) "")
       (org-link-make-string (org-link-heading-search-string (plist-get o :title))
                             (plist-get o :title))
       (or (plist-get o :speakers) "")
       (or (plist-get o :q-and-a) "")
       (or (plist-get o :availability) "")))
    ('time
      (list
       (if (plist-get o :slug)
           (org-link-make-string (plist-get o :url) (plist-get o :slug))
         "------")
       (if (and (plist-get o :scheduled)
                (not (plist-get o :fixed-time)))
           (emacsconf-format-short-time (plist-get o :scheduled) t)
         "")
       (or (plist-get o :time) "")
       (or (plist-get o :buffer) "")
       (if (< (string-to-number (or (plist-get o :time) ""))
              (string-to-number (or (plist-get o :max-time) "")))
           (plist-get o :max-time)
         "")
       (org-link-make-string (org-link-heading-search-string (plist-get o :title))
                             (plist-get o :title))
       (if (plist-get o :scheduled) ; time is here twice so we can easily check it against availability
           (emacsconf-format-short-time (plist-get o :scheduled))
         "")
       (or (plist-get o :availability) "")))))

(defun emacsconf-schedule-summarize (&optional info)
  (cons
   (if (eq emacsconf-focus 'time)
       (list "Slug" "Schedule" "Time" "Buffer" "Max" "Title" "Time" "Availability")
     (list "Status" "Slug" "Schedule" "Time" "Buffer" "Title" "Name" "Q&A" "Availability"))
   (mapcar #'emacsconf-schedule-format-summary-row (or info (emacsconf-get-talk-info)))))

(defun emacsconf-update-schedules-from-info (info)
  (emacsconf-schedule-update info)
  (save-window-excursion
    (save-excursion
      (mapc (lambda (talk)
              (emacsconf-go-to-talk (plist-get talk :slug))
              (org-entry-put (point) "TIME" (plist-get talk :time)))
            (emacsconf-filter-talks info)))))


(defun emacsconf-schedule-svg-track (svg base-x base-y width height start-time end-time info &optional vertical)
  (let ((scale (/ (if vertical height width)
                  (float-time (time-subtract end-time start-time)))))
    (mapc
     (lambda (o)
       (let* ((offset (floor (* scale (float-time (time-subtract (plist-get o :start-time) start-time)))))
              (size (floor (* scale (float-time (time-subtract (plist-get o :end-time) (plist-get o :start-time))))))
              (x (if vertical base-x (+ base-x offset)))
              (y (if vertical (+ base-y offset) base-y)))
         (dom-append-child
          svg
          (dom-node
           'a
           `((href . ,(plist-get o :url))
             (title . ,(plist-get o :title)))
           (dom-node
            'rect
             `((x . ,x)
               (y . ,y)
              (width . ,(if vertical width size))
              (height . ,(1- (if vertical size height)))
              (stroke . "black")
              (fill . ,(cond
                        ((string-match "BREAK\\|LUNCH" (plist-get o :title)) nil)
                        ((plist-get o :invalid) "red")
                        ((string-match "EST"
                                       (or (plist-get o :availability) ""))
                         "lightgray")
                        (t "lightgreen")))))
           (dom-node
            'g
            `((transform . ,(format "translate(%d,%d)"
                                    (+ x (if vertical width size) -2) (+ y (if vertical size height) -2))))
            (dom-node
             'text
             '((fill . "black")
               (x . 0)
               (y . 0)
               (font-size . 10)
               (transform . "rotate(-90)"))
             (svg--encode-text (or (plist-get o :slug) (plist-get o :title)))))))))
     info)))

(defun emacsconf-schedule-svg-day (elem label width height start end tracks)
  (let* ((label-margin 15)
         (track-height (/ (- height (* 2 label-margin)) (length tracks)))
         (x 0) (y label-margin)
         (scale (/ width (float-time (time-subtract end start))))
         (time start))
    (svg-rectangle elem 0 0 width height :fill "white")
    (svg-text elem label :x 3 :y (- label-margin 3) :fill "black" :font-size "10")
    (mapc (lambda (track)
            (emacsconf-schedule-svg-track
             elem x y width track-height
             start end track)
            (setq y (+ y track-height)))
          tracks)
    ;; draw grid
    (while (time-less-p time end)
      (let ((x (* (float-time (time-subtract time start)) scale)))
        (dom-append-child
         elem
         (dom-node
          'g
          `((transform . ,(format "translate(%d,%d)" x label-margin)))
          (dom-node
           'line
           `((stroke . "lightgray")
             (x1 . 0)
             (y1 . 0)
             (x2 . 0)
             (y2 . ,(- height label-margin label-margin))))
          (dom-node
           'text
           `((fill . "darkgray")
             (x . 0)
             (y . ,(- height 2 label-margin))
             (font-size . 10)
             (text-anchor . "middle"))
           (svg--encode-text (format-time-string "%-l" time)))))
        (setq time (time-add time (seconds-to-time 3600)))))
    elem))

(defun emacsconf-schedule-svg (width height days)
  (let ((svg (svg-create width height :background "white"))
        (day-height (/ height (length days)))
        (y 0))
    (mapc
     (lambda (day)
       (let ((group (dom-node 'g `((transform . ,(format "translate(0,%d)" y))))))
         (dom-append-child svg group)
         (emacsconf-schedule-svg-day group
                                     (plist-get day :label)
                                     width day-height
                                     (date-to-time (plist-get day :start))
                                     (date-to-time (plist-get day :end))
                                     (plist-get day :tracks)))
       (setq y (+ y day-height)))
     days)
    svg))

(defun emacsconf-schedule-get-subsequence (info start &optional end)
  "START and END are regexps to match against the title in INFO."
  (seq-subseq info
              (1+ (seq-position info start
                                (lambda (o match) (string-match match (plist-get o :title)))))
              (if end
                  (seq-position info end
                                (lambda (o match) (string-match match (plist-get o :title))))
                (length info))))

;;; Schedule summary

(defun emacsconf-schedule-round-start-to-five (o)
  (let* ((start-time (plist-get o :start))
         (decoded-time (decode-time start-time "America/Toronto"))
         (duration (* (string-to-number (plist-get o :time)) 60))
         (minutes (elt decoded-time 1))
         offset end-time)
    (unless (= (mod minutes 5) 0)
      (setq offset (seconds-to-time (* 60 (- 5 (mod minutes 5))))
            end-time (time-add start-time (time-to-seconds duration)))
      (plist-put o :scheduled (format "%s-%s" (format-time-string "%Y-%m-%d %H:%M" (time-add start-time offset))
                                      (format-time-string "%H:%M" (time-add end-time offset))))
      (plist-put o :start-time (time-add start-time offset))
      (plist-put o :end-time (time-add end-time offset)))))

;(emacsconf-update-schedules #'emacsconf-round-start-to-five)
(defvar emacsconf-schedule-default-buffer-minutes-for-live-q-and-a 15)
(defvar emacsconf-schedule-default-buffer-minutes 5)
(defun emacsconf-schedule-allocate-buffer-time (info)
  (mapcar (lambda (o)
            (when (plist-get o :slug)
              (plist-put o :buffer
                         (number-to-string 
                          (if (string-match "live" (plist-get o :q-and-a))
                              emacsconf-schedule-default-buffer-minutes-for-live-q-and-a
                            emacsconf-schedule-default-buffer-minutes))))
            o)
          info))

(defun emacsconf-schedule-allocate-max-time (info)
  (mapcar (lambda (o)
            (when (plist-get o :max-time)
              (plist-put o :time (plist-get o :max-time)))
            o)
          info))

(defvar emacsconf-schedule-tweaked-allocations nil "Alist of slug . time")
(defun emacsconf-schedule-tweak-allocations (info)
  (mapcar (lambda (o)
            (let ((talk-times emacsconf-schedule-tweaked-allocations))
              (when (assoc (plist-get o :slug) emacsconf-schedule-tweaked-allocations)
                (plist-put o :time
                           (number-to-string
                            (assoc-default (plist-get o :slug) emacsconf-schedule-tweaked-allocations)))))
            o)
          info))

(defun emacsconf-schedule-based-on-info (info)
  (let (current-time end-time duration) 
    (mapcar
     (lambda (talk)
       (when (plist-get talk :fixed-time)
         (setq current-time (plist-get talk :start-time)))
       (when (and (plist-get talk :time) 
                  (not (string= (plist-get talk :status) "CANCELLED")))
         (setq duration (* (string-to-number (plist-get talk :time)) 60)
               end-time (time-add current-time (seconds-to-time duration)))
         (plist-put talk :scheduled
                    (format "<%s-%s>" (format-time-string "%Y-%m-%d %a %H:%M" current-time)
                            (format-time-string "%H:%M" end-time)))
         (plist-put talk :start-time current-time)
         (plist-put talk :end-time end-time)
         (setq current-time (time-add end-time (* (string-to-number (or (plist-get talk :buffer) "0")) 60))))
       talk)
     info)))

(defun emacsconf-schedule-update (&optional modify-func)
  "Schedule the talks based on TIME and BUFFER.
Talks with a FIXED_TIME property are not moved."
  (interactive)
  (save-excursion
    (org-with-wide-buffer
     (let (current-time end-time duration) 
       (org-map-entries
        (lambda ()
          (when (or (org-entry-get (point) "TIME") (org-entry-get (point) "FIXED_TIME"))
            (let ((talk (emacsconf-get-talk-info-for-subtree)))
              (when (org-entry-get (point) "FIXED_TIME")
                (setq current-time (plist-get talk :start-time)))
              (when (and (plist-get talk :time) 
                         (not (string= (plist-get talk :status) "CANCELLED")))
                (setq duration (* (string-to-number (plist-get talk :time)) 60)
                      end-time (time-add current-time (seconds-to-time duration)))
                (org-set-property "SCHEDULED" (format "%s-%s" (format-time-string "%Y-%m-%d %H:%M" current-time)
                                                      (format-time-string "%H:%M" end-time)))
                (when (functionp modify-func)
                  (funcall modify-func))
                (setq end-time (time-add (org-get-scheduled-time (point)) (seconds-to-time duration)))
                (setq current-time (time-add end-time (* (string-to-number (or (plist-get talk :buffer) "0")) 60))))))))))))

(defun emacsconf-schedule-validate-time-constraints (&optional info)
  (interactive)
  (let* ((info (or info (emacsconf-get-talk-info)))
         (results (delq nil
                        (append
                         (mapcar
                          (lambda (o)
                            (apply #'emacsconf-schedule-check-time
                                   (car o)
                                   (emacsconf-search-talk-info (car o) info)
                                   (cdr o)))
                          emacsconf-time-constraints)
                         (mapcar
                          (lambda (o)
                            (let (result
                                  (constraint (emacsconf-schedule-get-time-constraint o)))
                              (when constraint
                                (setq result (apply #'emacsconf-schedule-check-time
                                                      (plist-get o :slug)
                                                      o
                                                      constraint))
                                (when result (plist-put o :invalid result))
                                result)))
                          info)))))
    (if (called-interactively-p 'any)
        (message "%s" (string-join results "\n"))
      results)))

(defun emacsconf-schedule-check-time (label o &optional from-time to-time)
  "FROM-TIME and TO-TIME should be strings like HH:MM in EST.
Both start and end time are tested."
  (let* ((start-time (format-time-string "%H:%M" (plist-get o :start-time)))
         (end-time (format-time-string "%H:%M" (plist-get o :end-time)))
         result)
    (setq result
          (or
           (and (null o) (format "%s: Not found" label))
           (and from-time (string< start-time from-time)
                (format "%s: Starts at %s before %s" label start-time from-time))
           (and to-time (string< to-time end-time)
                (format "%s: Ends at %s after %s" label end-time to-time))))
    (when result (plist-put o :invalid result))
    result))

(defun emacsconf-schedule-get-time-constraint (o)
  (unless (string-match "after the event" (or (plist-get o :q-and-a) ""))
    (let ((avail (or (plist-get o :availability) ""))
          hours)
      (when (string-match "\\([<>]\\)=? *\\([0-9]+:[0-9]+\\) *EST" avail)
        (if (string= (match-string 1 avail) ">")
            (list (match-string 2 avail) nil)
          (list nil (match-string 2 avail)))))))

(provide 'emacsconf-schedule)
;;; emacsconf-schedule.el ends here