;;; text-conf.el --- My configurations about plain text files. -*- lexical-binding: t; -*-

(require 'text-mode)

;; (declare-function #'center-buffer-on "center-buffer" nil)
;; (declare-function #'center-buffer-off "center-buffer" nil)
;; (declare-function #'center-buffer-toggle "center-buffer" nil)

;; (define-key text-mode-map (vector 'f8) nil)

;;;###autoload
(defvar insert-section-heading-history nil
  "The history of inserted section heading strings")

;;;###autoload
(defun insert-section-heading (custom-heading)
  "Insert a heading line below.

If CUSTOM-HEADING is non-nil, then use a custom heading.

The user can input any string as a basic constituent of a
heading. The inputed string will be repeated (floor N M) times,
where N is the length of the current line and M is the lenght of
the input string. After this repeat the first (remainder N M)
characters of the input string will be inserted as well to cover
exactly the current ilne."
  (interactive "P")
  (let* ((current-length (- (point-at-eol)
                            (point-at-bol)))
         (heading (cond
                   ((null custom-heading) "-")
                   (t (read-string "Enter a custom heading: "
                                   nil insert-section-heading-history
                                   "-" t))))
         (floor-length (floor current-length (length heading)))
         (remainder (% current-length (length heading)))
         (remainder-string (substring heading 0 remainder))
         (index 0))
    (save-excursion
      (goto-char (line-end-position))
      (newline)
      (while (< index floor-length)
        (message "index: %s" index)
        (message "floor: %s" floor-length)
        (insert heading)
        (setq index (1+ index)))
      (insert remainder-string))))

;;;###autoload
(defvar make-block-history nil
  "The history of block quote descriptions.")

;;;###autoload
(defun make-block (&optional description)
  "Surround the current line or the region in a block.

If DESCRIPTION is non-nil, ask for a description and put the
DESCRIPTION above the block."
  (interactive "P")
  (let* ((beg (cond
               ((use-region-p)
                (region-beginning))
               ((line-beginning-position))))
         (end (cond
               ((use-region-p)
                (region-end))
               ((line-end-position))))
         (end-marker (set-marker (make-marker) (1+ end)))
         (fill-line (make-string fill-column ?=))
         (header (cond
                  (description
                   (list fill-line
                         "\n"
                         (center-string-in-width
                          (read-string "Description of the block: "
                                       nil make-block-history nil t)
                          fill-column)
                         "\n"
                         fill-line))
                  (t (list fill-line)))))
    (save-excursion
      (goto-char beg)
      (while (<= (point) (1- (marker-position end-marker)))
        (center-line)
        (forward-line 1))
      (goto-char beg)
      (mapc #'insert header)
      (newline)
      (goto-char (1- (marker-position end-marker)))
      (set-marker end-marker nil)
      (newline)
      (insert fill-line))))

;;;###autoload
(defun durand-next-page (&optional arg)
  "Move forward ARG pages and narrow to page.
The only differences with `narrow-to-page' are that a nil
argument means 1, and that after narrowing this moves the cursor
to the beginning."
  (interactive "p")
  (narrow-to-page arg)
  (goto-char (point-min)))

;;;###autoload
(defun durand-previous-page (&optional arg)
  "Move backward ARG pages and narrow to page.
Pass (- (prefix-numeric-value arg)) to `durand-next-page'."
  (interactive "p")
  (durand-next-page (- (prefix-numeric-value arg))))

(define-key text-mode-map (vector ?\s-m) #'durand-previous-page)
(define-key text-mode-map (vector ?\s-ù) #'durand-next-page)

(provide 'text-conf)
;;; text-conf.el ends here.