;;; wiki.el -- A wikitext mode -*- lexical-binding: t -*-

;; Copyright (C) 2023 Free Software Foundation.

;; Author: Yuchen Pei <id@ypei.org>
;; Package-Requires: ((emacs "28.2"))

;; This file is part of dotted.

;; dotted is free software: you can redistribute it and/or modify it under
;; the terms of the GNU Affero General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; dotted 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 Affero General
;; Public License for more details.

;; You should have received a copy of the GNU Affero General Public
;; License along with dotted.  If not, see <https://www.gnu.org/licenses/>.

;;; Commentary:

;; A wikitext mode.

;;; Code:
(require 'wiki-faces)

(defvar wiki-link-re
  (rx (seq "[["
	         ;; Target
	         (group
	          (one-or-more
             (not (any "[|]"))))
		       ;; Label (optional)
		       (opt (seq "|" (group (+? anything))))
		       "]]"))
  ;; "\\(\\[\\[\\)\\([^][|]+\\)\\(|\\)\\([^][|]+\\)\\(\\]\\]\\)"
  )

(defvar wiki-font-lock-keywords
  (list
   (cons "^======.*======\\ *$" 'wiki-level-6)
   (cons "^=====.*=====\\ *$" 'wiki-level-5)
   (cons "^====.*====\\ *$" 'wiki-level-4)
   (cons "^===.*===\\ *$" 'wiki-level-3)
   (cons "^==.*==\\ *$" 'wiki-level-2)
   (cons "^=.*=\\ *$" 'wiki-level-1)
   (cons "^----+\\ *$" 'wiki-hr-face)
   (cons "'''''[^ \t\n].*?[^ \t\n]'''''" 'wiki-bold-italic)
   (cons "'''[^ \t\n'].*?[^ \t\n']'''" 'wiki-bold)
   (cons "''[^ \t\n'].*?[^ \t\n']''" 'wiki-italic)
   (cons "^ .*$" 'wiki-pre-face)
   ;; FIXME: not working, need to do something like `org-activate-links'
   (cons "\\(\\[\\[\\)\\([^][|]+\\)\\(|\\)\\([^][|]+\\)\\(\\]\\]\\)"
         '((1 invisible)
           (2 invisible)
           (3 invisible)
           (4 wiki-link)
           (5 invisible)))
   ))
(defvar wiki-font-lock-keywords nil)

(defvar wiki-outline-regexp "=+.*=+\ *$")

(defun wiki-outline-level ()
  (when (looking-at "\\(=+\\).*\\(=+\\)\ *$")
    (min (length (match-string 1))
         (length (match-string 2))
         6)))

;; `org-activate-links'
(defun wiki-activate-links ()
  (save-excursion
    (goto-char (point-min))
    (while (re-search-forward wiki-link-re nil t)
      (let ((start (match-beginning 0))
            (end (match-end 0))
            (visible-start (or (match-beginning 2) (match-beginning 1)))
            (visible-end (or (match-end 2) (match-end 1)))
            )
        (put-text-property start visible-start 'invisible t)
        (put-text-property visible-start visible-end 'font-lock-face 'wiki-link)
        (put-text-property visible-end end 'invisible t)
        (add-text-properties (1- visible-start) visible-start
                             '(rear-nonsticky invisible))
        (add-text-properties (1- visible-start) visible-start
                             '(rear-nonsticky invisible))
        ))))

(define-derived-mode wiki-mode outline-mode "Wiki"
  "A wikitext mode."

  (setq-local comment-start "<!--")
  (setq-local comment-end "-->")

  ;; FIXME: this should not be necessary in outline mode
  (setq-local font-lock-defaults '(wiki-font-lock-keywords t nil nil nil))
  (setq-local outline-regexp wiki-outline-regexp)
  (setq-local outline-level 'wiki-outline-level)
  (wiki-activate-links))

(provide 'wiki)
;;; wiki.el ends here