gistfile1.el

(require 'creole)
(require 'cl)

(defun creole-extract-heading-level (heading)
  (string-to-number (save-match-data
                      (string-match
                       (rx "heading" (group (+ digit)))
                       heading)
                      (match-string 1 heading))))

(creole-extract-heading-level "heading2")text


;; Here
;; emacs -Q -L . -l creole-to-md --eval '(creole-md "ViaTodo MVP.wiki")' -f sly
(creole-structure (creole-tokenize (get-buffer "ViaTodo MVP.wiki")))



(defun creole/list->md (type items)
  (cl-loop
   for item in items
   do
   (cond
    ((listp item)
     (creole/list->md (car item) (cdr item)))
    (t (insert (format "-%s\n" item))))))

(defun creole/heading->md (heading-cons)
  (let* ((h-str (symbol-name (car heading-cons)))
         (level (save-match-data
                  (string-match
                   (rx "heading" (group (+ digit)))
                   h-str)
                  (match-string 1 h-str)))
         (h-text (if (listp (cdr heading-cons))
                     (cadr heading-cons)
                   (cdr heading-cons))))
    (dotimes (i (string-to-number level))
      (insert "#"))
    (insert h-text)
    (insert "\n")))


(defun creole-md (docbuf &optional md-buffer)
  (let ((result-buffer (or md-buffer
                           (get-buffer-create "*md-buffer*"))))
    (with-current-buffer result-buffer)
    (cl-loop for element in (creole-structure (creole-tokenize docbuf))
             do
             (let ((syntax (car element)))
               (ecase syntax
                 ((ul ol)
                  (creole/list->md syntax (cdr element)))
                 ((heading1 heading2 heading3 heading4 heading5)
                  (creole/heading->md element))
                 (preformatted (format "```\n%s```\n" (cdr element)))
                 (hr (insert "\n"))
                 (para (insert (format "\n%s\n" (cdr element)))))))))

(provide 'creole-to-md)