;;; my-org-pukiwiki.el --- Simple Org to PukiWiki exporter -*- lexical-binding: t; -*-

(require 'subr-x)

(defgroup my-org-pukiwiki nil
  "Simple Org to PukiWiki exporter."
  :group 'tools)

(defcustom my-org-pukiwiki-coding-system 'japanese-shift-jis
  "Output coding system."
  :type 'coding-system
  :group 'my-org-pukiwiki)

(defun my-org-pukiwiki--metadata-p (line)
  (string-match-p
   "^#\\+\\(TITLE\\|AUTHOR\\|OPTIONS\\|DATE\\|EMAIL\\|LANGUAGE\\|KEYWORDS\\):"
   line))

(defun my-org-pukiwiki--heading (line)
  (if (string-match "^\\(\\*+\\)[ \t]+\\(.*\\)$" line)
      (let* ((level (length (match-string 1 line)))
             (title (match-string 2 line)))
        (cond
         ((= level 1) (concat "* " title))
         ((= level 2) (concat "** " title))
         ((= level 3) (concat "*** " title))
         (t (concat "'''" title "'''"))))
    line))

(defun my-org-pukiwiki--list (line)
  (cond
   ((string-match "^[ \t]*-[ \t]+\\(.*\\)$" line)
    (concat "-" (match-string 1 line)))
   ((string-match "^[ \t]*[0-9]+\\.[ \t]+\\(.*\\)$" line)
    (concat "+" (match-string 1 line)))
   (t line)))

(defun my-org-pukiwiki--table-separator-p (line)
  (string-match-p "^[ \t]*|[-+| \t]+|[ \t]*$" line))

(defun my-org-pukiwiki--table (line)
  (cond
   ((my-org-pukiwiki--table-separator-p line)
    nil)
   ((string-match-p "^[ \t]*|" line)
    (let ((s (string-trim line)))
      (setq s (replace-regexp-in-string "=" "" s))
      (if (string-match-p "|[ \t]*キー[ \t]*|\\|[ \t]*関数[ \t]*|\\|[ \t]*機能[ \t]*|" s)
          (concat s "h")
        s)))
   (t line)))

(defun my-org-pukiwiki--inline (line)
  (setq line
        (replace-regexp-in-string
         "=\\([^=\n]+\\)="
         "''\\1''"
         line))
  (setq line
        (replace-regexp-in-string
         "~\\([^~\n]+\\)~"
         "''\\1''"
         line))
  line)

(defun my-org-pukiwiki--link (line)
  ;; [[file:foo.png]]
  (setq line
        (replace-regexp-in-string
         "\\[\\[file:\\([^]]+\\)\\]\\]"
         "#ref(\\1)"
         line))
  ;; [[https://example.org][label]]
  (setq line
        (replace-regexp-in-string
         "\\[\\[\\([^]]+\\)\\]\\[\\([^]]+\\)\\]\\]"
         "[[\\2>\\1]]"
         line))
  ;; [[https://example.org]]
  (setq line
        (replace-regexp-in-string
         "\\[\\[\\(https?://[^]]+\\)\\]\\]"
         "[[\\1]]"
         line))
  line)

(defun my-org-pukiwiki--sjis-safe (text)
  (let ((s text))
    (setq s (replace-regexp-in-string "–\\|—\\|―" "--" s))
    (setq s (replace-regexp-in-string "“\\|”" "\"" s))
    (setq s (replace-regexp-in-string "‘\\|’" "'" s))
    (setq s (replace-regexp-in-string "…" "..." s))
    (setq s (replace-regexp-in-string "⏳" "Busy" s))
    (setq s (replace-regexp-in-string "→" "->" s))
    (setq s (replace-regexp-in-string "←" "<-" s))
    (setq s (replace-regexp-in-string "⇒" "=>" s))
    (setq s (replace-regexp-in-string "├──" "+-" s))
    (setq s (replace-regexp-in-string "└──" "+-" s))
    (setq s (replace-regexp-in-string "│" "|" s))
    s))

(defun my-org-pukiwiki-convert-string (text)
  "Convert Org TEXT to PukiWiki text."
  (let ((lines (split-string text "\n"))
        (out nil)
        (in-block nil))
    (dolist (line lines)
      (cond
       ;; src/example block start
       ((string-match-p "^#\\+begin_\\(src\\|example\\)" line)
        (setq in-block t))

       ;; src/example block end
       ((string-match-p "^#\\+end_\\(src\\|example\\)" line)
        (setq in-block nil))

       ;; preformatted block: leading half-width space
       (in-block
        (push (concat " " line) out))

       ;; skip Org metadata
       ((my-org-pukiwiki--metadata-p line)
        nil)

       ;; skip caption/name lines
       ((string-match-p "^#\\+\\(CAPTION\\|NAME\\):" line)
        nil)

       ;; normal line
       (t
        (setq line (my-org-pukiwiki--heading line))
        (setq line (my-org-pukiwiki--list line))
        (setq line (my-org-pukiwiki--table line))
        (when line
          (setq line (my-org-pukiwiki--inline line))
          (setq line (my-org-pukiwiki--link line))
          (push line out)))))
    (my-org-pukiwiki--sjis-safe
     (string-join (nreverse out) "\n"))))

(defun my-org-pukiwiki-export-buffer ()
  "Convert current Org buffer and show result in *PukiWiki*."
  (interactive)
  (let ((text (my-org-pukiwiki-convert-string (buffer-string))))
    (with-current-buffer (get-buffer-create "*PukiWiki*")
      (erase-buffer)
      (insert text)
      (goto-char (point-min))
      (pop-to-buffer (current-buffer)))))

(defun my-org-pukiwiki-export-file (&optional file)
  "Export current Org buffer to a Shift-JIS PukiWiki file."
  (interactive)
  (let* ((src (buffer-file-name))
         (dst (or file
                  (if src
                      (concat (file-name-sans-extension src) ".pukiwiki")
                    "output.pukiwiki")))
         (text (my-org-pukiwiki-convert-string (buffer-string)))
         (coding-system-for-write my-org-pukiwiki-coding-system))
    (with-temp-file dst
      (insert text))
    (message "Exported PukiWiki: %s" dst)))

(defun my-org-pukiwiki-copy-to-clipboard ()
  "Convert current Org buffer to PukiWiki text and copy it to kill-ring."
  (interactive)
  (let ((text (my-org-pukiwiki-convert-string (buffer-string))))
    (kill-new text)
    (message "Copied PukiWiki text to clipboard")))

(provide 'my-org-pukiwiki)

;;; my-org-pukiwiki.el ends here