;;; planner-multi-plan.el --- Tasks and notes with more than one plan page

;;; Commentary:

;; Tasks and notes can have links of the form
;; (WikiLinkOne,WikiLinkTwo,WikiLinkThree).

(defun planner-format-task
  (task-info &optional category priority status description link-text link)
  "Return a string containing TASK-INFO ready to be inserted into a page.
Non-nil values of CATEGORY, PRIORITY, STATUS, DESCRIPTION, LINK-TEXT,
and LINK override TASK-INFO."
  (format planner-task-format
          (or category (planner-task-category task-info))
          (or priority (planner-task-priority task-info) "")
          (or status (planner-task-status task-info))
          (or description (planner-task-description task-info))
          (let ((text (or link-text
                          (and link (planner-make-link link))
                          (planner-task-link-text task-info))))
            (if (and text (not (equal text "")))
                (concat " ("
                        text
                        ")")
              ""))))

(defun planner-update-task-on-page (page info &optional no-create)
  "On PAGE, update or create a task based on INFO.
If NO-CREATE is non-nil, do not create it if the task is not yet
there."
  (setq page (emacs-wiki-wiki-link-target page))
  (unless (and no-create (not (assoc page (planner-file-alist))))
    (planner-find-file page)
    (if (planner-find-task info)
        (unless (planner-tasks-equal-p info (planner-current-task-info))
          (delete-region (line-beginning-position)
                         (min (point-max) (1+ (line-end-position))))
          (insert (planner-format-task info
                                       nil nil nil nil
                                       (planner-task-link-text info)) "\n"))
      (unless no-create
        (planner-seek-task-creation-point)
        (insert (planner-format-task info nil nil nil nil
                                     (planner-task-link-text info))
                "\n")))))

;; We put this in a separate function so that we can change it
;; easily
(defsubst planner-multi-plan-split-string (link)
  "Return a list of links in LINK.
LINK should be a string of the form link1,link2,link3 where links
can be extended links or simple wiki links."
  (and link (split-string link ",")))

(defsubst planner-multi-plan-create-string (list)
  "Return LIST as a link-text string."
  (mapconcat 'identity list ","))

(defun planner-multi-plan-delete-matching (regexp list)
  "Remove all elements that match REGEXP from LIST."
  (delq nil
        (mapcar
         (lambda (item)
           (unless (string-match regexp (emacs-wiki-wiki-link-target item))
             item))
         list)))

(defun planner-multi-plan-schedule (list new-date)
  "Change or set the date for LIST to NEW-DATE."
  (setq list (planner-multi-plan-delete-matching planner-date-regexp list))
  (if new-date
      (cons new-date list)
    list))

;; Go to the next page in a sequence
(defun planner-multi-plan-next-page (page list)
  "Return the page following PAGE in LIST, or nil if not found."
  (let ((tail (member page list)))
    (when tail
      (if (= (length tail) 1) ; Last
          (car list) ; Return the first item
        (cadr tail)))))

;; Update a task on all the pages
(defun planner-multi-plan-update-task-at-point ()
  "Update the current task on all the pages linked to it."
  (interactive)
  (let* ((info (planner-current-task-info))
         (links (planner-multi-plan-split-string
                 (planner-task-link info))))
    (mapcar
     (lambda (page)
       (planner-update-task-on-page page info))
     links)))

(defun planner-multi-plan-copy-or-move-task (&optional date)
  "Copy or move the current task to DATE.
Tasks are moved if they are rescheduled from a date page to
another date page."
  (let ((info (planner-current-task-info))
)        new-links)
    (setq new-links
          (planner-multi-plan-schedule
           (planner-multi-plan-split-string
            (planner-task-link info))))
    (mapcar
     (lambda (page)
       (if (string-match planner-date-regexp page)
           (progn
             ;; Delete it from the page

             )
         ;; Update the task
         ))
    
             
    (unless info (error "No task on line"))
    ;; Delete it from any date pages
    
  ;; Update the linked plan pages
  ;; Create a new item
  )
(provide 'planner-multi-plan)

;;; planner-multi-plan.el ends here