;
; github-wiki.l
; 5 July 2020, by Teruyoshi FUJIWARA
;

; This script makes a TOC (table of content) for Github Wiki.

; Functions:
; (github-wiki-make-toc) Makes a table of contents from wiki document.
; (github-convert-from-hiki) Converts a Hiki text to a Github Wiki format.
; (github-set-baseurl) Set a base url of git repository to support github-convert-from-hiki function.

(defvar *gh-base-name* "https://github.com/your_account/project/wiki/")

(defun github-wiki-make-toc ()
  (interactive)
  (let* ((buf-name (buffer-name (selected-buffer))) (wikiname buf-name))
    (when (string-match "^\\(.+\\)\\(\.md\\)$" wikiname)
      (setq wikiname (substitute-string (string-replace-match wikiname "\\1") " " "-")))
    
    ; pickup headings
    (grep-buffer "\\(^#+[ ]*.*\\)$")
    (goto-char (point-min))
    
    (foreach-line-buffer 'process-region wikiname)
    (goto-char (point-min))
    (insert "# 目次\n")
    (copy-region-as-kill (point-min) (point-max))
    (set-buffer buf-name)))

(defun filter-buffer (func buffunc)
  (let ((s (make-buffer-stream (selected-buffer)))
	(stack nil) line)
    (while (setq line (read-line s nil))
      (if (setq res (funcall func line))
	  (push res stack)))
    (if buffunc (funcall buffunc))
    (delete-region (point-min) (point-max))
    (insert (format nil "~{~A~%~}" (reverse stack)))))

(defun make-tmpbuf (bufname)
  (set-buffer (switch-to-buffer bufname))
  (make-local-variable 'need-not-save)
  (setq need-not-save t))

(defun grep-buffer (regexp)
  "Filter buffer with a regular expression. This command edits current buffer directly."
;  (interactive "sRegular Expression: ")
  (filter-buffer (lambda (l)
		   (if (string-match regexp l)
		       (string-replace-match l "\\1")
		     nil))
		 (lambda () (make-tmpbuf "*github-wiki-tmp*"))))

(defun end-line-of-file-p ()
;  (interactive)
  (if (next-line)
      (progn
	(previous-line)
	nil)
    t))

(defun foreach-line-buffer (func wikiname)
;  (interactive)
  (if (eq (buffer-size) 0)
      nil
    (save-excursion
      (loop
	(let ((bol) (eol))
	  (beginning-of-line)
	  (setq bol (point))
	  (goto-eol)
	  (setq eol (point))
	  (narrow-to-region bol eol)
	  (funcall func wikiname)
	  (widen))
	(next-line)
	(if (end-line-of-file-p)
	    (return)))
      t)))

(defun process-region (wikiname)
  (let ((str-orig (buffer-substring (point-min) (point-max))) (level) (title) (str))
    (string-match "^\\(#+[ ]+\\)\\(.+\\)$" str-orig)
    (setq level (string-replace-match str-orig "\\1"))
    (setq title (string-replace-match str-orig "\\2"))
    ; markdown 記述を除去
    (goto-char (point-min))
    (replace-buffer "^#+[ ]+" "" :regexp t)
    ; URLエンコードの際に除外する文字
    (goto-char (point-min))
    (replace-buffer "[・〜()（）？\"\.,．，。、\+\/:\?]" "" :regexp t)
    ; " " は "-" に置き換える
    (goto-char (point-min))
    (replace-buffer " " "-" :regexp t)
    ;
    (goto-char (point-min))
    (let ((from (point-min)) (to (point-max)))
      (downcase-region from to)
      (setq str (buffer-substring from to))
      (kill-region from to))
    (insert (convert-level level) " ")
    (insert "[" title "](")
    (insert *gh-base-name*)
    (insert (si:www-url-encode (map-internal-to-utf-8 wikiname)))
    (insert "#")
    (insert (si:www-url-encode (map-internal-to-utf-8 str)))
    (insert ")")
    ))

(defun convert-level (md)
  (string-match "^\\(#+\\)" md)
  (setq md (string-replace-match md "\\1"))
  (if (eq (length md) 1)
      "*"
    (concat (repeat-string "\t" (- (length md) 1)) "*")))

(defun github-convert-from-hiki ()
  (interactive)
  (goto-char (point-min))
  (replace-buffer "{{toc}}" "")

  (goto-char (point-min))
  (replace-buffer "<<<\\|>>>" "```" :regexp t)
  
  ;(goto-char (point-min))
  ;(replace-buffer "^###[ ]*" "\t\t1. " :regexp t)
  ;(goto-char (point-min))
  ;(replace-buffer "^##[ ]*" "\t1. " :regexp t)
  ;(goto-char (point-min))
  ;(replace-buffer "^#[ ]*" "1. " :regexp t)
  
  (goto-char (point-min))
  (replace-buffer "^!!![ ]*" "### " :regexp t)
  (goto-char (point-min))
  (replace-buffer "^!![ ]*" "## " :regexp t)
  (goto-char (point-min))
  (replace-buffer "^![ ]*" "# " :regexp t)
  )

  
(defun github-set-baseurl (url)
  (interactive "sBase URL: ")
  (let ((s (subseq url (- (length url) 1))))
    (if (string/= s "/")
	(setq *gh-base-name* (concat url "/"))
      (setq *gh-base-name* url))))