org-tree-slide.el

;;; org-tree-slide.el --- A presentation tool for org-mode
;;
;; Copyright (C) 2011-2020 Takaaki ISHIKAWA
;;
;; Author: Takaaki ISHIKAWA <takaxp at ieee dot org>
;; Version: 2.8.18
;; Package-Requires: ((emacs "24.4"))
;; Maintainer: Takaaki ISHIKAWA <takaxp at ieee dot org>
;; Twitter: @takaxp
;; URL: https://github.com/takaxp/org-tree-slide
;; Keywords: convenience, org-mode, presentation, narrowing
;;
;; Committers: Yuuki ARISAWA (@uk-ar)
;;             Eric S Fraga
;;             Eike Kettner
;;             Stefano BENNATI
;;             Matus Goljer
;;             Boruch Baum
;;
;; 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 GNU Emacs; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.
;;

;;; Commentary:

;; Requirement:
;;    org-mode 6.33x or higher version
;;    The latest version of the org-mode is recommended.
;;                      (see https://orgmode.org/)
;;
;; Usage:
;;    1. Put this elisp into your load-path
;;    2. Add (require 'org-tree-slide) in your .emacs
;;    3. Open an org-mode file
;;    4. Toggle org-tree-slide-mode (M-x org-tree-slide-mode)
;;       then Slideshow will start and you can find "TSlide" in mode line.
;;    5. `C-<'/`C->' will move between slides
;;    6. `C-x s c' will show CONTENT of the org buffer
;;       Select a heading and type `C-<', then Slideshow will start again.
;;    7. Toggle org-tree-slide-mode again to exit this minor mode
;;
;; Recommended minimum settings:
;;    (global-set-key (kbd "<f8>") 'org-tree-slide-mode)
;;    (global-set-key (kbd "S-<f8>") 'org-tree-slide-skip-done-toggle)
;;
;;  and three useful profiles are available.
;;
;;    1. Simple use
;;       M-x org-tree-slide-simple-profile
;;
;;    2. Presentation use
;;       M-x org-tree-slide-presentation-profile
;;
;;    3. TODO Pursuit with narrowing
;;       M-x org-tree-slide-narrowing-control-profile
;;
;;    Type `C-h f org-tree-slide-mode', you can find more detail.
;;
;; Note:
;;    - Make sure key maps below when you introduce this elisp.
;;    - Customize variables, M-x customize-group ENT org-tree-slide ENT
;;    - see also moom.el (https://github.com/takaxp/moom) to control Emacs frame

;;; Code:

(require 'org)
(require 'org-timer)

(defconst org-tree-slide "2.8.18"
  "The version number of the org-tree-slide.el.")

(defgroup org-tree-slide nil
  "User variables for org-tree-slide."
  :group 'org-structure)

(defcustom org-tree-slide-skip-outline-level 0
  "Skip slides if a heading level is higher than or equal to this variable.

   `0': never skip at any heading
   `1': will skip all slides and be terminated automatically.
        Not recommended to use this number.
   e.g. set `4',
   *** heading A  ; display as a slide
       entry
   **** heading B ; skip! do not display as the next slide
   **** heading C ; skip!
   *** heading D  ; display as the next slide"
  :type 'integer
  :group 'org-tree-slide)

(defcustom org-tree-slide-fold-subtrees-skipped t
  "If this flag is true, the subtrees in a slide will be displayed in fold.

When nil, the body of the subtrees will be revealed."
  :type 'boolean
  :group 'org-tree-slide)

(defcustom org-tree-slide-header t
  "The status of displaying the slide header."
  :type 'boolean
  :group 'org-tree-slide)

(defcustom org-tree-slide-content-margin-top 2
  "Specify the margin between the slide header and its content."
  :type 'integer
  :group 'org-tree-slide)

(defcustom org-tree-slide-slide-in-effect t
  "Using a visual effect of slide-in for displaying trees."
  :type 'boolean
  :group 'org-tree-slide)

(defcustom org-tree-slide-cursor-init t
  "Specify a cursor position when exit slideshow.

Non-nil: the cursor will move automatically to the head of buffer.
nil: keep the same position."
  :type 'boolean
  :group 'org-tree-slide)

(defcustom org-tree-slide-slide-in-blank-lines 10
  "Specify the number of blank lines, the slide will move from this line."
  :type 'integer
  :group 'org-tree-slide)

(defcustom org-tree-slide-slide-in-waiting 0.02
  "Specify the duration waiting the next update of overlay."
  :type 'float
  :group 'org-tree-slide)

(defcustom org-tree-slide-heading-emphasis nil
  "Specify to use a custom face heading, or not."
  :type 'boolean
  :group 'org-tree-slide)

(defcustom org-tree-slide-never-touch-face nil
  "If t, do NOT touch any face setting."
  :type 'boolean
  :group 'org-tree-slide)

(defcustom org-tree-slide-skip-done nil
  "Specify to show TODO item only or not."
  :type 'boolean
  :group 'org-tree-slide)

(defcustom org-tree-slide-skip-comments t
  "Specify to skip COMMENT item or not."
  :type 'boolean
  :group 'org-tree-slide)

(defcustom org-tree-slide-activate-message
  "Hello! This is org-tree-slide :-)"
  "Message in mini buffer when \"org-tree-slide\" is activated."
  :type 'string
  :group 'org-tree-slide)

(defcustom org-tree-slide-deactivate-message
  "Quit, Bye!"
  "Message in mini buffer when \"org-tree-slide\" is deactivated."
  :type 'string
  :group 'org-tree-slide)

(defcustom org-tree-slide-modeline-display 'outside
  "Specify how to display the slide number in mode line.

   'lighter: shown in lighter (update info actively, then it's slow)
   'outside: update infomation when moving to the next/previous slide
   nil: nothing to be shown"
  :type 'symbol
  :group 'org-tree-slide)

(defcustom org-tree-slide-indicator
  '(:next "   Next >>" :previous "<< Previous" :content "<<  CONTENT  >>")
  "Specify the indication messages for changing slides.
The specified string for NEXT will be used in `org-tree-slide-move-next-tree',
PREVIOUS will be used in `org-tree-slide-move-previous-tree'.
CONTENT will be used in `org-tree-slide-content'.
If you want to show anything, just specify nil."
  :type 'plist
  :group 'org-tree-slide)

(defvar org-tree-slide-mode-map
  (let ((map (make-sparse-keymap)))
    (define-key map (kbd "C-x s c") 'org-tree-slide-content)
    ;;    (define-key map (kbd "C-x s r") 'org-tree-slide-resume) ;; TODO
    (define-key map (kbd "C-<") 'org-tree-slide-move-previous-tree)
    (define-key map (kbd "C->") 'org-tree-slide-move-next-tree)
    map)
  "The keymap for `org-tree-slide'.")

(defcustom org-tree-slide-heading-level-1
  '(outline-1 :height 1.5 bold)
  "Level 1."
  :group 'org-tree-slide)

(defcustom org-tree-slide-heading-level-2
  '(outline-2 :height 1.4 bold)
  "Level 2."
  :group 'org-tree-slide)

(defcustom org-tree-slide-heading-level-3
  '(outline-3 :height 1.3 bold)
  "Level 3."
  :group 'org-tree-slide)

(defcustom org-tree-slide-heading-level-4
  '(outline-4 :height 1.2 bold)
  "Level 4."
  :group 'org-tree-slide)

(defvar-local org-tree-slide-heading-level-1-cookie nil)
(defvar-local org-tree-slide-heading-level-2-cookie nil)
(defvar-local org-tree-slide-heading-level-3-cookie nil)
(defvar-local org-tree-slide-heading-level-4-cookie nil)

(defvar org-tree-slide-mode nil)
(defvar org-tree-slide-play-hook nil
  "A hook run when `org-tree-slide--play' is evaluated to start the slideshow.")
(defvar org-tree-slide-stop-hook nil
  "A hook run when `org-tree-slide--stop' is evaluated to stop the slideshow.")
(defvar org-tree-slide-before-narrow-hook nil
  "A hook run before evaluating `org-tree-slide--display-tree-with-narrow'.")
(defvar org-tree-slide-after-narrow-hook nil
  "A hook run after evaluating `org-tree-slide--display-tree-with-narrow'.")
(defvar org-tree-slide-before-move-next-hook nil
  "A hook run before moving to the next slide.")
(defvar org-tree-slide-before-move-previous-hook nil
  "A hook run before moving to the previous slide.")
(defvar org-tree-slide-before-content-view-hook nil
  "A hook run before showing the content.")

;;;###autoload
(define-minor-mode org-tree-slide-mode
  "A presentation tool for org-mode.

Usage:
  - Set minimal recommendation settings in .emacs
    (global-set-key (kbd \"<f8>\") 'org-tree-slide-mode)
    (global-set-key (kbd \"S-<f8>\") 'org-tree-slide-skip-done-toggle)
  - Open an org file
  - Type <f8> to start org-tree-slide-mode
  - Type C-< / C-> to move between trees
  - To exit this minor mode, just type <f8> again.

Profiles:

  - [ Simple ]
 => M-x `org-tree-slide-simple-profile'

    1. No header display
    2. No slide-in effect
    3. The cursor will move to the head of buffer when exit
    4. No slide number display in mode line
    5. Display every type of tree

  - [ Presentation ]
 => M-x `org-tree-slide-presentation-profile'

    1. Display header
    2. Enable slide-in effect
    3. The cursor will move to the head of buffer when exit
    4. Display slide number in mode line
    5. Display every type of tree

  - [ TODO Pursuit with narrowing ]
 => M-x `org-tree-slide-narrowing-control-profile'

    1. No header display
    2. No slide-in effect
    3. The cursor will keep the same position when exit
    4. Display slide number in mode line
    5. Display TODO trees only
"
  :init-value nil
  :lighter (:eval (org-tree-slide--update-modeline))
  :keymap org-tree-slide-mode-map
  :group 'org-tree-slide
  :require 'org
  (if org-tree-slide-mode
      (org-tree-slide--setup)
    (org-tree-slide--abort)))

;;;###autoload
(defun org-tree-slide-play-with-timer ()
  "Start slideshow with setting a count down timer."
  (interactive)
  (org-timer-set-timer)
  (unless (org-tree-slide--active-p)
    (org-tree-slide-mode)))

;;;###autoload
(defun org-tree-slide-without-init-play ()
  "Start slideshow without the init play.  Just enter \"org-tree-slide-mode\"."
  (interactive)
  (org-tree-slide-mode)
  (widen)
  (org-overview)
  (goto-char 1))

(defvar org-tree-slide-content--pos nil
  "Where to return when toggling function `org-tree-slide-content'.")

;;;###autoload
(defun org-tree-slide-content ()
  "Change the display for viewing content of the org file during the slide view mode is active."
  (interactive)
  (when (org-tree-slide--active-p)
    (cond
     (org-tree-slide-content--pos
      ;; (widen)
      (goto-char org-tree-slide-content--pos)
      (org-tree-slide--display-tree-with-narrow)
      (goto-char org-tree-slide-content--pos)
      (setq org-tree-slide-content--pos nil))
     (t
      (setq org-tree-slide-content--pos
            (max (1+ (point-min)) (point)))
      (run-hooks 'org-tree-slide-before-content-view-hook)
      (widen)
      (org-tree-slide--hide-slide-header)
      (org-tree-slide--move-to-the-first-heading)
      (org-overview)
      (cond ((eq 0 org-tree-slide-skip-outline-level)
             (org-content))
            ((< 2 org-tree-slide-skip-outline-level)
             (org-content (1- org-tree-slide-skip-outline-level))))
      ;;  (goto-char (point-min))
      (redisplay)
      (goto-char org-tree-slide-content--pos)
      (let ((msg (plist-get org-tree-slide-indicator :content))
            (message-log-max nil))
        (when msg
          (message "%s" msg)))))))

;;;###autoload
(defun org-tree-slide-move-next-tree ()
  "Display the next slide."
  (interactive)
  (when (org-tree-slide--active-p)
    (let ((msg (plist-get org-tree-slide-indicator :next))
          (message-log-max nil))
      (when msg
        (message "%s" msg)))
    (cond
     ;; displaying a slide, not the contents
     ((and (buffer-narrowed-p)
           (org-tree-slide--last-tree-p (point)))
      (org-tree-slide-content))
     ((or
       (or (and (org-tree-slide--before-first-heading-p)
                (not (org-at-heading-p)))
           (and (= (point-at-bol) 1) (not (buffer-narrowed-p))))
       (or (org-tree-slide--first-heading-with-narrow-p)
           (not (org-at-heading-p))))
      (run-hooks 'org-tree-slide-before-move-next-hook)
      (widen)
      (org-tree-slide--outline-next-heading)
      (org-tree-slide--display-tree-with-narrow))
     ;; stay the same slide (for CONTENT MODE, on the subtrees)
     (t (org-tree-slide--display-tree-with-narrow)))))

;;;###autoload
(defun org-tree-slide-move-previous-tree ()
  "Display the previous slide."
  (interactive)
  (when (org-tree-slide--active-p)
    (let ((msg (plist-get org-tree-slide-indicator :previous))
          (message-log-max nil))
      (when msg
        (message "%s" msg)))
    (org-tree-slide--hide-slide-header)		; for at the first heading
    (run-hooks 'org-tree-slide-before-move-previous-hook)
    (widen)
    (cond
     ((org-tree-slide--before-first-heading-p)
      (message "before first heading (org-tree-slide)" ))
     ((not (org-at-heading-p))
      (org-tree-slide--outline-previous-heading)
      (org-tree-slide--outline-previous-heading))
     (t (org-tree-slide--outline-previous-heading)))
    (org-tree-slide--display-tree-with-narrow)
    ;; To avoid error of missing header in Emacs24
    (if (= emacs-major-version 24)
        (goto-char (point-min)))))

;;;###autoload
(defun org-tree-slide-simple-profile ()
  "Set variables for simple use.

  `org-tree-slide-header'            => nil
  `org-tree-slide-slide-in-effect'   => nil
  `org-tree-slide-heading-emphasis'  => nil
  `org-tree-slide-cursor-init'       => t
  `org-tree-slide-modeline-display'  => nil
  `org-tree-slide-skip-done'         => nil
  `org-tree-slide-skip-comments'     => t"
  (interactive)
  (setq org-tree-slide-header nil)
  (setq org-tree-slide-slide-in-effect nil)
  (setq org-tree-slide-heading-emphasis nil)
  (setq org-tree-slide-cursor-init t)
  (setq org-tree-slide-modeline-display nil)
  (setq org-tree-slide-skip-done nil)
  (setq org-tree-slide-skip-comments t)
  (message "simple profile: ON"))

;;;###autoload
(defun org-tree-slide-presentation-profile ()
  "Set variables for presentation use.

  `org-tree-slide-header'            => t
  `org-tree-slide-slide-in-effect'   => t
  `org-tree-slide-heading-emphasis'  => nil
  `org-tree-slide-cursor-init'       => t
  `org-tree-slide-modeline-display'  => 'outside
  `org-tree-slide-skip-done'         => nil
  `org-tree-slide-skip-comments'     => t"
  (interactive)
  (setq org-tree-slide-header t)
  (setq org-tree-slide-slide-in-effect t)
  (setq org-tree-slide-heading-emphasis nil)
  (setq org-tree-slide-cursor-init t)
  (setq org-tree-slide-modeline-display 'outside)
  (setq org-tree-slide-skip-done nil)
  (setq org-tree-slide-skip-comments t)
  (message "presentation profile: ON"))

;;;###autoload
(defun org-tree-slide-narrowing-control-profile ()
  "Set variables for TODO pursuit with narrowing.

  `org-tree-slide-header'            => nil
  `org-tree-slide-slide-in-effect'   => nil
  `org-tree-slide-heading-emphasis'  => nil
  `org-tree-slide-cursor-init'       => nil
  `org-tree-slide-modeline-display'  => 'lighter
  `org-tree-slide-skip-done'         => t
  `org-tree-slide-skip-comments'     => t"
  (interactive)
  (setq org-tree-slide-header nil)
  (setq org-tree-slide-slide-in-effect nil)
  (setq org-tree-slide-heading-emphasis nil)
  (setq org-tree-slide-cursor-init nil)
  (setq org-tree-slide-modeline-display 'lighter)
  (setq org-tree-slide-skip-done t)
  (setq org-tree-slide-skip-comments t)
  (message "narrowing control profile: ON"))

;;;###autoload
(defun org-tree-slide-display-header-toggle ()
  "Toggle displaying the slide header."
  (interactive)
  (setq org-tree-slide-header (not org-tree-slide-header))
  (unless org-tree-slide-header
    (org-tree-slide--hide-slide-header))
  (org-tree-slide--display-tree-with-narrow))

;;;###autoload
(defun org-tree-slide-slide-in-effect-toggle ()
  "Toggle using slide-in effect."
  (interactive)
  (setq org-tree-slide-slide-in-effect (not org-tree-slide-slide-in-effect))
  (org-tree-slide--display-tree-with-narrow))

;;;###autoload
(defun org-tree-slide-heading-emphasis-toggle ()
  "Toggle applying emphasis to heading."
  (interactive)
  (setq org-tree-slide-heading-emphasis (not org-tree-slide-heading-emphasis))
  (org-tree-slide--apply-custom-heading-face org-tree-slide-heading-emphasis))

(defvar org-tree-slide--previous-line 0)

;;;###autoload
(defun org-tree-slide-skip-done-toggle ()
  "Toggle show TODO item only or not."
  (interactive)
  (setq org-tree-slide-skip-done (not org-tree-slide-skip-done))
  (setq org-tree-slide--previous-line -1) ; to update modeline intentionally
  (when org-tree-slide-header
    (org-tree-slide--show-slide-header))
  (if org-tree-slide-skip-done
      (message "TODO Pursuit: ON") (message "TODO Pursuit: OFF")))

;;;###autoload
(defun org-tree-slide-skip-comments-toggle ()
  "Toggle show COMMENT item or not."
  (interactive)
  (setq org-tree-slide-skip-comments (not org-tree-slide-skip-comments))
  (if org-tree-slide-skip-comments
      (message "COMMENT: HIDE") (message "COMMENT: SHOW")))

;;; Internal functions ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(defvar org-tree-slide--slide-number nil)
(make-variable-buffer-local 'org-tree-slide--slide-number)

(defvar org-tree-slide--lighter " TSlide"
  "Lighter for `org-tree-slide'.
This is displayed by default if `org-tree-slide-modeline-display' is nil.")

(defun org-tree-slide--line-number-at-pos ()
  "Return the line number when widen."
  (save-excursion
    (save-restriction
      (widen)
      (line-number-at-pos))))

(defun org-tree-slide--update-modeline ()
  "Update mode line."
  (when (org-tree-slide--active-p)
    (cond
     ((equal org-tree-slide-modeline-display 'lighter)
      (setq org-tree-slide--slide-number
            (format " %s" (org-tree-slide--count-slide (point))))
      (setq org-tree-slide--previous-line (org-tree-slide--line-number-at-pos))
      org-tree-slide--slide-number)
     ;; just return the current org-tree-slide--slide-number quickly.
     ((equal org-tree-slide-modeline-display 'outside)
      org-tree-slide--slide-number)
     (t
      org-tree-slide--lighter))))

(defvar org-tree-slide--header-overlay nil
  "Flag to check the status of overlay for a slide header.")

(defvar org-tree-slide--header-face-autoconfig nil)
(defun org-tree-slide--setup ()
  "Setup."
  (when (org-tree-slide--active-p)
    (org-tree-slide--play)))

(defun org-tree-slide--abort ()
  "Abort."
  (when (equal major-mode 'org-mode)
    (org-tree-slide--stop)))

(defun org-tree-slide--play ()
  "Start slide view with the first tree of the org mode buffer."
  (run-hooks 'org-tree-slide-play-hook)
  (if (org-tree-slide--all-skip-p)
      (let ((org-tree-slide-deactivate-message
             "[notice] Terminated. Skipped all slides."))
        (org-tree-slide--stop))
    (org-tree-slide--apply-local-header-to-slide-header)
    (when org-tree-slide-heading-emphasis
      (org-tree-slide--apply-custom-heading-face t))
    (when (or org-tree-slide-cursor-init
              (org-tree-slide--before-first-heading-p))
      (org-tree-slide--move-to-the-first-heading))
    (org-tree-slide--beginning-of-tree)
    (when (org-tree-slide--heading-skip-p)
      (org-tree-slide--outline-next-heading))
    (org-tree-slide--display-tree-with-narrow)
    (when org-tree-slide-activate-message
      (message "%s" org-tree-slide-activate-message))))

(defvar org-tree-slide-startup "overview"
  "If you have \"#+startup:\" line in your org buffer, the org buffer will be shown with corresponding status (content, showall, overview:default).")

(defun org-tree-slide--stop ()
  "Stop the slide view, and redraw the orgmode buffer with #+STARTUP:."
  (widen)
  (org-show-siblings)
  (when (or org-tree-slide-cursor-init (org-tree-slide--before-first-heading-p))
    (goto-char (point-min))
    (org-overview)
    (cond ((equal "content" org-tree-slide-startup)
           (message "CONTENT: %s" org-tree-slide-startup)
           (org-content))
          ((equal "showall" org-tree-slide-startup)
           (message "SHOW ALL: %s" org-tree-slide-startup)
           (org-cycle '(64)))
          (t nil)))
  (org-tree-slide--hide-slide-header)
  (when org-timer-start-time
    (org-timer-stop))
  (when org-tree-slide-heading-emphasis
    (org-tree-slide--apply-custom-heading-face nil))
  (run-hooks 'org-tree-slide-stop-hook)
  (when org-tree-slide-deactivate-message
    (message "%s" org-tree-slide-deactivate-message)))

(defun org-tree-slide--display-tree-with-narrow ()
  "Show a tree with narrowing and also set a header at the head of slide."
  (run-hooks 'org-tree-slide-before-narrow-hook)
  (when (equal org-tree-slide-modeline-display 'outside)
    (setq org-tree-slide--slide-number
          (format " %s" (org-tree-slide--count-slide (point))))
    (setq org-tree-slide--previous-line (org-tree-slide--line-number-at-pos)))
  (goto-char (point-at-bol))
  (unless (org-tree-slide--before-first-heading-p)
    (hide-subtree)	; support CONTENT (subtrees are shown)
    (org-show-entry)
    ;; If this is the last level to be displayed, show the full content
    (if (and (not org-tree-slide-fold-subtrees-skipped)
             (org-tree-slide--heading-level-skip-p (1+ (org-outline-level))))
        (org-tree-slide--show-subtree)
      (show-children))
    ;;    (org-cycle-hide-drawers 'all) ; disabled due to performance reduction
    (org-narrow-to-subtree))
  (when org-tree-slide-slide-in-effect
    (org-tree-slide--slide-in org-tree-slide-slide-in-blank-lines))
  (when org-tree-slide-header
    (org-tree-slide--show-slide-header))
  (run-hooks 'org-tree-slide-after-narrow-hook))

(defun org-tree-slide--show-subtree ()
  "Show everything after this heading at deeper levels except COMMENT items."
  (save-excursion
    (outline-back-to-heading)
    (outline-map-region
     (lambda ()
       (if (org-tree-slide--heading-skip-comment-p)
           (hide-subtree)
         (show-subtree)
         (org-cycle-hide-drawers 'all)))
     (point)
     (progn (outline-end-of-subtree)
            (if (eobp) (point-max) (1+ (point)))))))

(defun org-tree-slide--outline-next-heading ()
  "Go to the next heading."
  (org-tree-slide--outline-select-method
   (if (outline-next-heading)
       (if (org-tree-slide--heading-skip-p)
           'skip
         nil)
     'last)
   'next))

(defun org-tree-slide--outline-previous-heading ()
  "Go to the previous heading."
  (org-tree-slide--outline-select-method
   (if (outline-previous-heading)
       (if (org-tree-slide--heading-skip-p)
           'skip
         nil)
     'first)
   'previous))

(defun org-tree-slide--outline-select-method (action direction)
  "Control heading selection with ACTION and DIRECTION."
  (cond ((and (equal action 'last)
              (equal direction 'next))
         (when (org-tree-slide--heading-skip-p)
           (org-tree-slide-content))) ;; would be not reached here.
        ((and (equal action 'first)
              (equal direction 'previous))
         (org-tree-slide--move-to-the-first-heading))
        ((and (equal action 'skip)
              (equal direction 'next))
         (org-tree-slide--outline-next-heading)) ;; find next again
        ((and (equal action 'skip)
              (equal direction 'previous))
         (org-tree-slide--outline-previous-heading)) ;; find previous again
        (t
         nil)))

(defun org-tree-slide--heading-skip-p ()
  "This method assume the cursor exist at the heading.
** COMMENT         ; t
   hoge            ; nil
   hoge            ; nil
*** hoge           ; nil"
  (or (org-tree-slide--heading-done-skip-p)
      (org-tree-slide--heading-level-skip-p)
      (org-tree-slide--heading-skip-comment-p)))

(defun org-tree-slide--heading-level-skip-p (&optional heading-level)
  "Check the current heading should be skipped or not based on outline level.
If HEADING-LEVEL is non-nil, the provided outline level is checked."
  (and (> org-tree-slide-skip-outline-level 0)
       (<= org-tree-slide-skip-outline-level
           (or heading-level (org-outline-level)))))

(defun org-tree-slide--heading-done-skip-p ()
  "Return t, if the current heading is already done."
  (and org-tree-slide-skip-done
       (not
        (looking-at
         ;; 6.33x does NOT support org-outline-regexp-bol
         (concat "^\\*+ " org-not-done-regexp)))))

(defun org-tree-slide--heading-skip-comment-p ()
  "Return t, if the current heading is commented."
  (and org-tree-slide-skip-comments
       (looking-at (concat "^\\*+ " org-comment-string))))

(defun org-tree-slide--slide-in (blank-lines)
  "Apply slide in.  The slide will be moved from BLANK-LINES below to top."
  (let ((min-line -1))
    (when org-tree-slide-header
      (setq min-line org-tree-slide-content-margin-top))
    (while (< min-line blank-lines)
      (org-tree-slide--set-slide-header blank-lines)
      (sit-for org-tree-slide-slide-in-waiting)
      (setq blank-lines (1- blank-lines)))))

(defvar org-tree-slide-title nil
  "If you have \"#+title:\" line in your org buffer, it wil be used as a title of the slide.  If the buffer has no \"#+title:\" line, the name of current buffer will be displayed.")

(defvar org-tree-slide-email nil
  "If you have \"#+email:\" line in your org buffer, it will be used as an address of the slide.")

(defvar org-tree-slide-author nil
  "If you have \"#+author:\" line in your org buffer, it will be used as a name of the slide author.")

(defvar org-tree-slide-date nil
  "If you have \"#+date:\" line in your org buffer, it will be used as the date.")

(defcustom org-tree-slide-breadcrumbs " > "
  "Display breadcrumbs in the slide header.

If non-nil, it should be a string used as a delimiter used to
concat the headers."
  :type '(choice (const :tag "Don't display breadcrumbs" nil)
                 (string :tag "Delimiter"))
  :group 'org-tree-slide)

(defcustom org-tree-slide-breadcrumbs-hide-todo-state t
  "If non-nil, hide TODO states in the breadcrumbs."
  :type 'boolean
  :group 'org-tree-slide)

(defun org-tree-slide--apply-local-header-to-slide-header ()
  "Form the header."
  (save-excursion
    (org-tree-slide--move-to-the-first-heading)
    (let ((limit (point)))
      (org-tree-slide--set-header-var-by-regxep
       'org-tree-slide-title "#\\+TITLE:[ \t]*\\(.*\\)$" limit)
      (org-tree-slide--set-header-var-by-regxep
       'org-tree-slide-author "#\\+AUTHOR:[ \t]*\\(.*\\)$" limit)
      (org-tree-slide--set-header-var-by-regxep
       'org-tree-slide-email "#\\+EMAIL:[ \t]*\\(.*\\)$" limit)

                                        ; Use the date header or the current date if there isn't one
      (setq org-tree-slide-date nil)
      (org-tree-slide--set-header-var-by-regxep
       'org-tree-slide-date "#\\+DATE:[ \t]*\\(.*\\)$" limit)
      (if (not org-tree-slide-date)
          (setq org-tree-slide-date
                (format-time-string "%Y-%m-%d")))

      (org-tree-slide--set-header-var-by-regxep
       'org-tree-slide-startup "#\\+STARTUP:[ \t]*\\(.*\\)$" limit))))

(defun org-tree-slide--set-header-var-by-regxep (header-variable regexp limit)
  "Set HEADER-VARIABLE using REGEXP.  LIMIT is used to change searching bound."
  (goto-char 1)
  (set header-variable
       (if (re-search-forward regexp limit t) (match-string 1) nil)))

(defface org-tree-slide-header-overlay-face '((t :inherit default))
  "Face for org-tree-slide--header-overlay"
  :group 'org-tree-slide)

(defun org-tree-slide--get-parents (&optional delim)
  "Get parent headlines and concat them with DELIM."
  (setq delim (or delim " > "))
  (save-excursion
    (save-restriction
      (widen)
      (let ((parents nil))
        (while (org-up-heading-safe)
          (push (org-get-heading
                 'no-tags
                 org-tree-slide-breadcrumbs-hide-todo-state)
                parents))
        (mapconcat 'identity parents delim)))))

(defun org-tree-slide--set-slide-header (blank-lines)
  "Set the header with overlay.

Some number of BLANK-LINES will be shown below the header."
  (org-tree-slide--hide-slide-header)
  (setq org-tree-slide--header-overlay
        (make-overlay (point-min) (+ 1 (point-min))))
  (overlay-put org-tree-slide--header-overlay 'after-string " ")
  (overlay-put org-tree-slide--header-overlay
               'face
               'org-tree-slide-header-overlay-face)
  (if org-tree-slide-header
      (overlay-put org-tree-slide--header-overlay 'display
                   (concat (if org-tree-slide-title org-tree-slide-title
                             (buffer-name))
                           "\n"
                           org-tree-slide-date "  "
                           (when org-tree-slide-author
                             (concat org-tree-slide-author "  "))
                           (when org-tree-slide-email
                             (concat "<" org-tree-slide-email ">"))
                           (when org-tree-slide-breadcrumbs
                             (concat "\n" (org-tree-slide--get-parents
                                           org-tree-slide-breadcrumbs)))
                           (org-tree-slide--get-blank-lines blank-lines)))
    (overlay-put org-tree-slide--header-overlay 'display
                 (org-tree-slide--get-blank-lines blank-lines))))

(defun org-tree-slide--get-blank-lines (lines)
  "Return breaks by LINES."
  (let ((breaks ""))
    (while (< 0 lines)
      (setq lines (1- lines))
      (setq breaks (concat breaks "\n")))
    breaks))

(defun org-tree-slide--show-slide-header (&optional lines)
  "Show header.  When LINES is nil, the default value is 2."
  (org-tree-slide--set-slide-header (or lines org-tree-slide-content-margin-top)))

(defun org-tree-slide--hide-slide-header ()
  "Hide header."
  (when org-tree-slide--header-overlay
    (delete-overlay org-tree-slide--header-overlay)))

(defun org-tree-slide--move-to-the-first-heading ()
  "Go to the first heading.  Narrowing will be canceled.
If no heading in the buffer, Return nil and stay top of the buffer.
Otherwise, return the point.  This doesn't check whether skipping or not."
  (widen)
  (goto-char 1)
  (if (looking-at "^\\*+ ")
      (progn
        (beginning-of-line)
        (point))
    (outline-next-heading)))

(defun org-tree-slide--apply-custom-heading-face (status)
  "Change status of heading face.  If STATUS is nil, apply the default values."
  (unless org-tree-slide-never-touch-face
    (cond
     (status
      (setq
       org-tree-slide-heading-level-1-cookie
       (face-remap-add-relative 'org-level-1 org-tree-slide-heading-level-1)
       org-tree-slide-heading-level-2-cookie
       (face-remap-add-relative 'org-level-2 org-tree-slide-heading-level-2)
       org-tree-slide-heading-level-3-cookie
       (face-remap-add-relative 'org-level-3 org-tree-slide-heading-level-3)
       org-tree-slide-heading-level-4-cookie
       (face-remap-add-relative 'org-level-4 org-tree-slide-heading-level-4)))
     (t
      (face-remap-remove-relative org-tree-slide-heading-level-1-cookie)
      (face-remap-remove-relative org-tree-slide-heading-level-2-cookie)
      (face-remap-remove-relative org-tree-slide-heading-level-3-cookie)
      (face-remap-remove-relative org-tree-slide-heading-level-4-cookie)))))

(defun org-tree-slide--count-slide (&optional pos)
  "Return formatted the slide number.  If POS is nil, `point' will be used."
  (save-excursion
    (save-restriction
      (widen)
      (goto-char (point-min))
      (let ((count 0)
            (current-slide 0)
            (current-point (or pos (point))))
        (when (and (looking-at "^\\*+ ") (not (org-tree-slide--heading-skip-p)))
          (setq count 1)
          (setq current-slide 1))
        (while (outline-next-heading)
          (when (not (org-tree-slide--heading-skip-p))
            (setq count (1+ count))
            (when (>= current-point (point))
              (setq current-slide (1+ current-slide)))))
        (cond
         ((= count 0) "[-/-]") ; no headings
         ((= current-slide 0) (format "[-/%d]" count)) ; before first heading
         (t
          (format "[%d/%d]" current-slide count)))))))

(defun org-tree-slide--last-point-at-bot ()
  "Return nil, if no heading is the last tree.  Otherwise, return the point.
Searching the last point will start from the current cursor position.
Move point to an appropriate position before searching by call this function."
  (save-excursion
    (save-restriction
      (widen)
      (unless (org-tree-slide--before-first-heading-p)
        (org-tree-slide--beginning-of-tree)
        (if (org-tree-slide--heading-skip-p)
            (when (outline-previous-heading)
              (org-tree-slide--last-point-at-bot))
          (point))))))

(defun org-tree-slide--beginning-of-tree ()
  "Move point to beginning of tree.
If the cursor exist before first heading, do nothing."
  (unless (org-tree-slide--before-first-heading-p)
    (beginning-of-line)
    (unless (org-at-heading-p)
      (org-tree-slide--outline-previous-heading))))

(defun org-tree-slide--active-p ()
  "Return nil, if the current `major-mode' is not `org-mode'."
  (and org-tree-slide-mode (equal major-mode 'org-mode)))

(defun org-tree-slide--before-first-heading-p ()
  "Extension of `org-before-first-heading-p' to support org 6.33x.
#+TITLE: title     ; t
#+STARTUP: content ; t
* first            ; t
  hoge             ; nil
** second          ; nil
** third           ; nil"
  (and (org-before-first-heading-p) (not (buffer-narrowed-p))))

(defun org-tree-slide--first-heading-with-narrow-p ()
  "Check the current point is on the first heading with narrowing.
** first           ; t
   hoge            ; nil
   hoge            ; nil
*** second         ; nil
    hoge           ; nil
*** third          ; nil"
  (and (buffer-narrowed-p) (= (point-at-bol) (point-min))))

(defun org-tree-slide--all-skip-p ()
  "Check the buffer has at least one slide to be shown."
  (save-excursion
    (save-restriction
      (widen)
      (goto-char (1+ (buffer-size)))
      (unless (org-tree-slide--last-point-at-bot)
        t))))

(defun org-tree-slide--last-tree-p (target)
  "Check if the TARGET point is in the last heading or it's body.
If every heading is specified as skip, return nil.
** n-1             ; nil
** n               ; t
   hoge            ; t"
  (save-excursion
    (save-restriction
      (widen)
      (goto-char target)
      (org-tree-slide--beginning-of-tree)
      (let ((p (point))
            (v (goto-char (1+ (buffer-size))))
            (l (org-tree-slide--last-point-at-bot)))
        (if l
            (= p l)
          nil)))))

(provide 'org-tree-slide)

;;; org-tree-slide.el ends here