;;; encoded-kb.el --- handler to input multibyte characters encoded somehow

;; Copyright (C) 1997  Free Software Foundation, Inc.
;; Copyright (C) 1995, 1997, 1998, 1999, 2000, 2001, 2004, 2005
;;   National Institute of Advanced Industrial Science and Technology (AIST)
;;   Registration Number H14PRO021

;; This file is part of GNU Emacs.

;; GNU Emacs 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 2, or (at your option)
;; any later version.

;; GNU Emacs 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 GNU Emacs; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.

;;; Commentary:

;;; Code:

;; Usually this map is empty (even if Encoded-kbd mode is on), but if
;; the keyboard coding system is iso-2022-based, it defines dummy key
;; bindings for ESC $ ..., etc. so that those bindings in
;; key-translation-map take effect.
(defconst encoded-kbd-mode-map (make-sparse-keymap)
  "Keymap for Encoded-kbd minor mode.")

;; Subsidiary keymaps for handling ISO2022 escape sequences.

(defvar encoded-kbd-iso2022-esc-map
  (let ((map (make-sparse-keymap)))
    (define-key map "$" 'encoded-kbd-iso2022-esc-dollar-prefix)
    (define-key map "(" 'encoded-kbd-iso2022-designation-prefix)
    (define-key map ")" 'encoded-kbd-iso2022-designation-prefix)
    (define-key map "," 'encoded-kbd-iso2022-designation-prefix)
    (define-key map "-" 'encoded-kbd-iso2022-designation-prefix)
    map)
  "Keymap for handling ESC code in Encoded-kbd mode.")
(fset 'encoded-kbd-iso2022-esc-prefix encoded-kbd-iso2022-esc-map)

(defvar encoded-kbd-iso2022-esc-dollar-map
  (let ((map (make-sparse-keymap)))
    (define-key map "(" 'encoded-kbd-iso2022-designation-prefix)
    (define-key map ")" 'encoded-kbd-iso2022-designation-prefix)
    (define-key map "," 'encoded-kbd-iso2022-designation-prefix)
    (define-key map "-" 'encoded-kbd-iso2022-designation-prefix)
    (define-key map "@" 'encoded-kbd-iso2022-designation)
    (define-key map "A" 'encoded-kbd-iso2022-designation)
    (define-key map "B" 'encoded-kbd-iso2022-designation)
    map)
  "Keymap for handling ESC $ sequence in Encoded-kbd mode.")
(fset 'encoded-kbd-iso2022-esc-dollar-prefix
      encoded-kbd-iso2022-esc-dollar-map)

(defvar encoded-kbd-iso2022-designation-map
  (let ((map (make-sparse-keymap))
	(l charset-list)
	final-char)
    (while l
      (setq final-char (charset-iso-final-char (car l)))
      (if (> final-char 0)
	  (define-key map (char-to-string final-char)
	    'encoded-kbd-iso2022-designation))
      (setq l (cdr l)))
    map)
  "Keymap for handling ISO2022 designation sequence in Encoded-kbd mode.")
(fset 'encoded-kbd-iso2022-designation-prefix
      encoded-kbd-iso2022-designation-map)

;; Keep information of designation state of ISO2022 encoding.  When
;; Encoded-kbd mode is on, this is set to a vector of length 4, the
;; elements are character sets currently designated to graphic
;; registers 0 thru 3.

(defvar encoded-kbd-iso2022-designations nil)
(put 'encoded-kbd-iso2022-designations 'permanent-local t)

;; Keep information of invocation state of ISO2022 encoding.  When
;; Encoded-kbd mode is on, this is set to a vector of length 3,
;; graphic register numbers currently invoked to graphic plane 1 and
;; 2, and a single shifted graphic register number.

(defvar encoded-kbd-iso2022-invocations nil)
(put 'encoded-kbd-iso2022-invocations 'permanent-local t)

(defsubst encoded-kbd-last-key ()
  (let ((keys (this-single-command-keys)))
    (aref keys (1- (length keys)))))

(defun encoded-kbd-iso2022-designation (ignore)
  "Do ISO2022 designation according to the current key in Encoded-kbd mode.
The following key sequence may cause multilingual text insertion."
  (let ((key-seq (this-single-command-keys))
	(prev-g0-charset (aref encoded-kbd-iso2022-designations
			       (aref encoded-kbd-iso2022-invocations 0)))
	intermediate-char final-char
	reg dimension chars charset)
    (if (= (length key-seq) 4)
	;; ESC $ <intermediate-char> <final-char>
	(setq intermediate-char (aref key-seq 2)
	      dimension 2
	      chars (if (< intermediate-char ?,) 94 96)
	      final-char (aref key-seq 3)
	      reg (mod intermediate-char 4))
      (if (= (aref key-seq 1) ?$)
	  ;; ESC $ <final-char>
	  (setq dimension 2
		chars 94
		final-char (aref key-seq 2)
		reg 0)
	;; ESC <intermediate-char> <final-char>
	(setq intermediate-char (aref key-seq 1)
	      dimension 1
	      chars (if (< intermediate-char ?,) 94 96)
	      final-char (aref key-seq 2)
	      reg (mod intermediate-char 4))))
    (aset encoded-kbd-iso2022-designations reg
	  (iso-charset dimension chars final-char)))
  "")

(defun encoded-kbd-iso2022-single-shift (ignore)
  (let ((char (encoded-kbd-last-key)))
    (aset encoded-kbd-iso2022-invocations 2 (if (= char ?\216) 2 3)))
  "")

(defun encoded-kbd-self-insert-iso2022-7bit (ignore)
  (let ((char (encoded-kbd-last-key))
	(charset (aref encoded-kbd-iso2022-designations
		       (or (aref encoded-kbd-iso2022-invocations 2)
			   (aref encoded-kbd-iso2022-invocations 0)))))
    (aset encoded-kbd-iso2022-invocations 2 nil)
    (vector (if (= (charset-dimension charset) 1)
		(make-char charset char)
	      (make-char charset char (read-char-exclusive))))))

(defun encoded-kbd-self-insert-iso2022-8bit (ignore)
  (let ((char (encoded-kbd-last-key))
	(charset (aref encoded-kbd-iso2022-designations
		       (or (aref encoded-kbd-iso2022-invocations 2)
			   (aref encoded-kbd-iso2022-invocations 1)))))
    (aset encoded-kbd-iso2022-invocations 2 nil)
    (vector (if (= (charset-dimension charset) 1)
		(make-char charset char)
	      (make-char charset char (read-char-exclusive))))))

(defun encoded-kbd-self-insert-sjis (ignore)
  (let ((char (encoded-kbd-last-key)))
    (vector
     (if (or (< char ?\xA0) (>= char ?\xE0))
	 (decode-sjis-char (+ (ash char 8) (read-char-exclusive)))
       (make-char 'katakana-jisx0201 char)))))

(defun encoded-kbd-self-insert-big5 (ignore)
  (let ((char (encoded-kbd-last-key)))
    (vector 
     (decode-big5-char (+ (ash char 8) (read-char-exclusive))))))

(defun encoded-kbd-self-insert-ccl (ignore)
  (let ((str (char-to-string (encoded-kbd-last-key)))
	(ccl (car (aref (coding-system-spec (keyboard-coding-system)) 4)))
	(vec [nil nil nil nil nil nil nil nil nil])
	result)
    (while (= (length (setq result (ccl-execute-on-string ccl vec str t))) 0)
      (dotimes (i 9) (aset vec i nil))
      (setq str (format "%s%c" str (read-char-exclusive))))
    (vector (aref result 0))))

(defun encoded-kbd-setup-keymap (keymap coding)
  ;; At first, reset the keymap.
  (define-key encoded-kbd-mode-map "\e" nil)
  ;; Then setup the keymap according to the keyboard coding system.
  (cond
   ((eq (coding-system-type coding) 1)	; SJIS
    (let ((i 128))
      (while (< i 256)
	(define-key keymap
	  (vector i) 'encoded-kbd-self-insert-sjis)
	(setq i (1+ i))))
    8)

   ((eq (coding-system-type coding) 3)	; Big5
    (let ((i 161))
      (while (< i 255)
	(define-key keymap
	  (vector i) 'encoded-kbd-self-insert-big5)
	(setq i (1+ i))))
    8)

   ((eq (coding-system-type coding) 2) ; ISO-2022
    (let ((flags (coding-system-flags coding))
	  use-designation)
      (if (aref flags 8)
	  nil				; Don't support locking-shift.
	(setq encoded-kbd-iso2022-designations (make-vector 4 nil)
	      encoded-kbd-iso2022-invocations (make-vector 3 nil))
	(dotimes (i 4)
	  (if (aref flags i)
	      (if (charsetp (aref flags i))
		  (aset encoded-kbd-iso2022-designations
			i (aref flags i))
		(setq use-designation t)
		(if (charsetp (car-safe (aref flags i)))
		    (aset encoded-kbd-iso2022-designations
			  i (car (aref flags i)))))))
	(aset encoded-kbd-iso2022-invocations 0 0)
	(if (aref encoded-kbd-iso2022-designations 1)
	    (aset encoded-kbd-iso2022-invocations 1 1))
	(when use-designation
	  (define-key encoded-kbd-mode-map "\e" 'encoded-kbd-iso2022-esc-prefix)
	  (define-key keymap "\e" 'encoded-kbd-iso2022-esc-prefix))
	(when (or (aref flags 2) (aref flags 3))
	  (define-key keymap
	    [?\216] 'encoded-kbd-iso2022-single-shift)
	  (define-key keymap
	    [?\217] 'encoded-kbd-iso2022-single-shift))
	(or (eq (aref flags 0) 'ascii)
	    (dotimes (i 96)
	      (define-key keymap
		(vector (+ 32 i)) 'encoded-kbd-self-insert-iso2022-7bit)))
	(if (aref flags 7)
	    t
	  (dotimes (i 96)
	    (define-key keymap
	      (vector (+ 160 i)) 'encoded-kbd-self-insert-iso2022-8bit))
	  8))))

   ((eq (coding-system-type coding) 4)	; CCL-base
    (let ((valid-codes (or (coding-system-get coding 'valid-codes)
			   '((128 . 255))))
	  elt from to valid)
      (while valid-codes
	(setq elt (car valid-codes) valid-codes (cdr valid-codes))
	(if (consp elt)
	    (setq from (car elt) to (cdr elt))
	  (setq from (setq to elt)))
	(while (<= from to)
	  (if (>= from 128)
	      (define-key keymap
		(vector from) 'encoded-kbd-self-insert-ccl))
	  (setq from (1+ from))))
      8))

   (t
    nil)))

;;;###autoload
(defun encoded-kbd-setup-display (display)
  "Set up a `key-translation-map' for `keyboard-coding-system' on DISPLAY.

DISPLAY may be a display id, a frame, or nil for the selected frame's display."
  (let ((frame (if (framep display) display (car (frames-on-display-list display)))))
    (when frame
      (with-selected-frame frame
	;; Remove any previous encoded-kb keymap from key-translation-map.
	(let ((m local-key-translation-map))
	  (if (equal (keymap-prompt m) "encoded-kb")
	      (setq local-key-translation-map (keymap-parent m))
	    (while (keymap-parent m)
	      (if (equal (keymap-prompt (keymap-parent m)) "encoded-kb")
		  (set-keymap-parent m (keymap-parent (keymap-parent m))))
	      (setq m (keymap-parent m)))))

	(if (keyboard-coding-system)
	    ;; We are turning on Encoded-kbd mode.
	    (let ((coding (keyboard-coding-system))
		  (keymap (make-sparse-keymap "encoded-kb"))
		  (cim (current-input-mode))
		  result)
	      (set-keymap-parent keymap local-key-translation-map)
	      (setq local-key-translation-map keymap)
	      (unless (terminal-parameter nil 'encoded-kbd-saved-input-meta-mode)
		(set-terminal-parameter nil 'encoded-kbd-saved-input-mode (nth 2 cim)))
	      (setq result (and coding (encoded-kbd-setup-keymap keymap coding)))
	      (if result
		  (when (and (eq result 8)
			     (memq (nth 2 cim) '(t nil)))
		    (set-input-meta-mode 'use-8th-bit))
		(set-terminal-parameter nil 'encoded-kbd-saved-input-meta-mode nil)
		(error "Unsupported coding system in Encoded-kbd mode: %S"
		       coding)))
	  ;; We are turning off Encoded-kbd mode.
	  (when (and (terminal-parameter nil 'encoded-kbd-saved-input-meta-mode)
		     (not (equal (nth 2 (current-input-mode))
				 (terminal-parameter nil 'encoded-kbd-saved-input-meta-mode))))
	    (set-input-meta-mode (terminal-parameter nil 'encoded-kbd-saved-input-meta-mode)))
	  (set-terminal-parameter nil 'saved-input-meta-mode nil))))))

(provide 'encoded-kb)

;;; arch-tag: 76f0f9b3-65e7-45c3-b692-59509a87ad44
;;; encoded-kb.el ends here