;;; gaphrase.el --- major mode for editing gaphrase 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: 0.1

;; Keywords: dict, dictionary

;;; Commentary:

;;

;; Mode can be installed by:

;;

;;   (autoload 'gaphrase-mode "gaphrase")

;;

;; File association can be registered by:

;;

;;   (add-to-list 'auto-mode-alist (cons "\\.gaphrase$" 'gaphrase-mode))

;;; Code:

(defvar gaphrase-font-lock-keywords

  '(("^\\(__\\)\n\n" (1 font-lock-type-face))

    ("^\\(__\n?[^\n]+\\)" (1 highlight))

    ("^- " . font-lock-keyword-face)))

(defvar font-lock-beg)

(defvar font-lock-end)

(defun gaphrase-font-lock-extend-region ()

  ;; (gaphrase-font-lock-extend-region--debug)

  (save-excursion

    (goto-char font-lock-beg)

    (forward-line 0)

    (unless (looking-at "__")

      (re-search-backward "^__" (- (point) 10240) t))

    (if (= (point) font-lock-beg)

        nil

      (setq font-lock-beg (point)))))

(defun gaphrase-font-lock-extend-region--debug ()

  (save-excursion

    (let ( beg end )

      (goto-char font-lock-beg)

      (beginning-of-line)

      (setq beg (buffer-substring-no-properties (point) font-lock-beg))

      (goto-char font-lock-end)

      (end-of-line)

      (setq end (buffer-substring-no-properties font-lock-end (point)))

      (message "lines: %d, %s ## %s" (count-lines font-lock-beg font-lock-end) beg end))))

(defun gaphrase-insert-template ()

  (interactive)

  (forward-line 0)

  (unless (looking-at "__")

    (re-search-backward "^__" (- (point) 10240) t))

  (forward-line 1)

  (unless (re-search-forward "^__" (+ (point) 10240) t)

    (goto-char (point-max)))

  (forward-line 0)

  (while (memq (char-before) '(?\  ?\n ?\t))

    (delete-char -1))

  (insert "\n__\n\n- \n")

  (backward-char))

(define-derived-mode gaphrase-mode fundamental-mode "gaphrase"

  (setq font-lock-defaults '(gaphrase-font-lock-keywords))

  (setq font-lock-extend-region-functions (list #'gaphrase-font-lock-extend-region))

  (define-key (current-local-map) [C-return] 'gaphrase-insert-template))

(provide 'gaphrase)

;;; gaphrase.el ends here