(with-eval-after-load "ox"
  (require 'org-custom-translation))

#+TITLE: むかしのはなし
#+AUTHOR: おおむかしのかたりべ
#+CUSTOM_TRANSLATION: ja Author さくしゃ
#+CUSTOM_TRANSLATION: ja Created つくったにちじ

むかしむかしあるところにおじいさんとおばあさんがいました。

めでたしめでたし。

#+CUSTOM_TRANSLATION: "Figure %d:" ""

これは何かの写真です。

#+CAPTION: 何かの写真
[[file:example-1.jpg]]

これは別の写真です。

#+CAPTION: 別の写真
[[file:example-2.jpg]]

;;; org-custom-translation.el --- Customize export translations -*- lexical-binding: t; -*-

;; Copyright (C) 2024 AKIYAMA Kouhei

;; Author: AKIYAMA Kouhei <misohena@gmail.com>
;; Keywords: 

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

;; This program 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 General Public License for more details.

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

;;; Commentary:

;; Change the translation dictionary used during export from the
;; in-buffer options.

;; Add the export option "#+CUSTOM_TRANSLATION:" to temporarily change
;; org-export-dictionary during export.

;; * Preparation
;; Put the following in your init.el.
;;   (with-eval-after-load "ox"
;;     (require 'org-custom-translation))

;; * Option Syntax
;; #+CUSTOM_TRANSLATION: [<language>] <src> <dst>

;; * Examples
;; Translate to Japanese romanization.
;; #+CUSTOM_TRANSLATION: ja Author Sakusha
;; #+CUSTOM_TRANSLATION: ja Date Hizuke

;; Remove figure number.
;; #+CUSTOM_TRANSLATION: "Figure %d:" ""

;;; Code:

(require 'cl-lib)
(require 'ox)

(defun org-custom-translation-split-option-value (str)
  (cl-loop with index = 0
           while (progn
                   (string-match
                    " *\\(\\(\"\\([^\"]*\\)\"\\)\\|\\([^ \t\"]+\\)\\)\\|"
                    str index)
                   (match-beginning 1))
           collect (or (match-string 3 str)
                       (match-string 4 str))
           do (setq index (match-end 0))))

(defun org-custom-translation-make-dictionary (lines current-language)
  (cl-loop for line in lines
           for values = (org-custom-translation-split-option-value line)
           when (>= (length values) 2)
           collect (let ((lang (if (>= (length values) 3)
                                   (pop values)
                                 current-language))
                         (src (car values))
                         (dst (cadr values)))
                     (list src (list lang :default dst)))))

(defun org-custom-translation-override-dictionary (options)
  (setq-local
   org-export-dictionary
   (append
    (org-custom-translation-make-dictionary
     ;;(cdar (org-collect-keywords '("CUSTOM_TRANSLATION")))
     (when-let ((lines-str (plist-get options :custom-translation)))
       (split-string lines-str "\n"))
     (or (plist-get options :language) org-export-default-language))
    org-export-dictionary)))

(defun org-custom-translation-filter-options (options _backend &rest _rest)
  (org-custom-translation-override-dictionary options)
  options)

(defun org-custom-translation-add-export-option ()
  (setf (alist-get :custom-translation org-export-options-alist)
        '("CUSTOM_TRANSLATION" nil nil newline)))

(defun org-custom-translation-setup ()
  (org-custom-translation-add-export-option)
  (add-to-list 'org-export-filter-options-functions
               'org-custom-translation-filter-options))

(org-custom-translation-setup)

(provide 'org-custom-translation)
;;; org-custom-translation.el ends here