;;; gadialog.el --- major mode for editing gadialog dialog files -*- lexical-binding: t -*-

;; Copyright (C) 2019 by Oleksandr Gavenko <gavenkoa@gmail.com>

;; You can do anything with this file without any warranty.

;; Author: Oleksandr Gavenko <gavenkoa@gmail.com>
;; Maintainer: Oleksandr Gavenko <gavenkoa@gmail.com>
;; Created: 2019
;; Version: 0.17
;; Keywords: dict, dictionary

;;; Commentary:
;;
;; Mode can be installed by:
;;
;;   (autoload 'gadialog-mode "gadialog")
;;
;; File association can be registered by:
;;
;;   (add-to-list 'auto-mode-alist (cons "\\.gadialog$" 'gadialog-mode))

;;; Code:

(defvar gadialog-font-lock-keywords
  '(("^# [1-9][0-9]*" . font-lock-type-face)
    ("^## [1-9][0-9]*" . font-lock-warning-face)
    ("^- " . font-lock-keyword-face)))

(defvar gadialog-syntax-table
  (let ((table (make-syntax-table text-mode-syntax-table)))
    (modify-syntax-entry ?' "w" table)
    table))

(defun gadialog-next-num ()
  (save-excursion
    (goto-char (point-min))
    (let (beg end num)
      (catch 'return
        (when (looking-at "## \\([1-9][0-9]*\\)")
          (setq beg (match-beginning 1)
                end (match-end 1))
          (setq num (string-to-number (buffer-substring beg end)))
          (delete-region beg end)
          (goto-char beg)
          (setq num (1+ num))
          (insert (int-to-string num))
          (throw 'return num))
        (insert "## 1\n")
        1))))

(defun gadialog-cleaup-whitespaves-forward ()
  (while (memq (char-before) '(?\  ?\n ?\t))
    (delete-char -1)))

(defun gadialog-insert-template ()
  (interactive)
  (forward-line 0)
  (when (looking-at "# ")
    (forward-line 1))
  (unless (re-search-forward "^# " (+ (point) 10240) t)
    (goto-char (point-max)))
  (forward-line 0)
  (gadialog-cleaup-whitespaves-forward)
  (insert "\n# ")
  (insert (int-to-string (gadialog-next-num)))
  (insert "\n- \n")
  (backward-char))

(defun gadialog-insert-sentence ()
  (interactive)
  (forward-line 1)
  (while (not (or (eobp)
                  (memq (char-after) (list ?- ?#))))
    (forward-line 1))
  (gadialog-cleaup-whitespaves-forward)
  (insert "\n- \n")
  (backward-char))


(define-derived-mode gadialog-mode fundamental-mode "gadialog"
  (setq font-lock-defaults '(gadialog-font-lock-keywords))
  (define-key (current-local-map) [C-return] 'gadialog-insert-template)
  (define-key (current-local-map) [S-return] 'gadialog-insert-sentence)
  (set-syntax-table gadialog-syntax-table)
  (setq paragraph-start "[#-]"))

(provide 'gadialog)

;;; gadialog.el ends here