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

;; Copyright (C) 1997, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
;;   Free Software Foundation, Inc.
;; Copyright (C) 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004,
;;   2005, 2006, 2007, 2008
;;   National Institute of Advanced Industrial Science and Technology (AIST)
;;   Registration Number H14PRO021
;; Copyright (C) 2003
;;   National Institute of Advanced Industrial Science and Technology (AIST)
;;   Registration Number H13PRO009

;; 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 3 of the License, 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.  If not, see <http://www.gnu.org/licenses/>.

;;; 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
;; input-decode-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 (coding-system-get (keyboard-coding-system) :ccl-decoder))
	(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))))


;; Decode list of codes in CODE-LIST by CHARSET and return the decoded
;; characters.  If CODE-LIST is too short for the dimension of
;; CHARSET, read new codes and append them to the tail of CODE-LIST.
;; Return nil if CODE-LIST can't be decoded.

(defun encoded-kbd-decode-code-list (charset code-list)
  (let ((dimension (charset-dimension charset))
	code)
    (while (> dimension (length code-list))
      (nconc code-list (list (read-char-exclusive))))
    (setq code (car code-list))
    (if (= dimension 1)
	(decode-char charset code)
      (setq code-list (cdr code-list)
	    code (logior (lsh code 8) (car code-list)))
      (if (= dimension 2)
	  (decode-char charset code)
	(setq code-list (cdr code-list)
	      code (logior (lsh code 8) (car code-list)))
	(if (= dimension 3)
	    (decode-char charset code)
	  ;; As Emacs can't handle full 32-bit integer, we must give a
	  ;; cons of higher and lower 16-bit codes to decode-char.
	  (setq code (cons (lsh code -8)
			   (logior (lsh (car code-list) 8) (cadr code-list))))
	  (decode-char charset code))))))

(defun encoded-kbd-self-insert-charset (ignore)
  (let ((charset-list
	 (coding-system-get (keyboard-coding-system) :charset-list))
	(code-list (list (encoded-kbd-last-key)))
	tail char)
    (while (and charset-list (not char))
      (setq char (encoded-kbd-decode-code-list (car charset-list) code-list)
	    charset-list (cdr charset-list)))
    (if char
	(vector char)
      (setq unread-command-events (cdr code-list))
      (vector (car code-list)))))

(defun encoded-kbd-self-insert-utf-8 (arg)
  (interactive "p")
  (let* ((lead (encoded-kbd-last-key))
         (char lead)
         len event)
    (cond ((< char #xE0)
	   (setq len 1 char (logand char #x1F)))
	  ((< char #xF0)
	   (setq len 2 char (logand char #x0F)))
	  ((< char #xF8)
	   (setq len 3 char (logand char #x07)))
	  (t
	   (setq len 4 char 0)))
    (while (> len 0)
      (setq event (read-char-exclusive))
      (if (and (>= event #x80) (< event #xc0))
          ;; Valid utf-8 sequence.
          (setq char (logior (lsh char 6) (- event #x80))
                len (1- len))
        ;; Invalid utf-8 sequence.  Might be because Quail got involved
        ;; in-between and the bytes we thought we were reading were actually
        ;; latin-1 chars.  Let's presume that `event' is the second "byte",
        ;; i.e. there weren't any "apprently correct" between `lead' and
        ;; `event': it's easy to recover in this case, and the more general
        ;; case seems pretty unlikely.
        ;; FIXME: We should really do encoded-kbd decoding before processing
        ;; input-methods.
        (push event unread-command-events)
        (setq char lead)
        (setq len 0)))
    (vector char)))

(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) 'shift-jis)
    (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) 'charset)
    (dolist (elt (mapcar
		  #'(lambda (x) 
		      (let ((dim (charset-dimension x))
			    (code-space (get-charset-property x :code-space)))
			(cons (aref code-space (* (1- dim) 2))
			      (aref code-space (1+ (* (1- dim) 2))))))
		  (coding-system-get coding :charset-list)))
      (let ((from (max (car elt) 128))
	    (to (cdr elt)))
	(while (<= from to)
	  (define-key keymap
	    (vector from) 'encoded-kbd-self-insert-charset)
	  (setq from (1+ from)))))
    8)

   ((eq (coding-system-type coding) 'iso-2022)
    (let ((flags (coding-system-get coding :flags))
	  (designation (coding-system-get coding :designation)))
      (if (memq 'locking-shift flags)
	  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 designation i)
	      (if (charsetp (aref designation i))
		  (aset encoded-kbd-iso2022-designations
			i (aref designation i))
		(if (charsetp (car-safe (aref designation i)))
		    (aset encoded-kbd-iso2022-designations
			  i (car (aref designation i)))))))
	(aset encoded-kbd-iso2022-invocations 0 0)
	(if (aref encoded-kbd-iso2022-designations 1)
	    (aset encoded-kbd-iso2022-invocations 1 1))
	(when (memq 'designation flags)
	  (define-key encoded-kbd-mode-map "\e" 'encoded-kbd-iso2022-esc-prefix)
	  (define-key keymap "\e" 'encoded-kbd-iso2022-esc-prefix))
	(when (or (aref designation 2) (aref designation 3))
	  (define-key keymap
	    [?\216] 'encoded-kbd-iso2022-single-shift)
	  (define-key keymap
	    [?\217] 'encoded-kbd-iso2022-single-shift))
	(or (eq (aref designation 0) 'ascii)
	    (dotimes (i 96)
	      (define-key keymap
		(vector (+ 32 i)) 'encoded-kbd-self-insert-iso2022-7bit)))
	(if (memq '7-bit flags)
	    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)
			   '((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))

   ((eq (coding-system-type coding) 'utf-8)
    (let ((i #xC0))
      (while (< i 256)
	(define-key keymap
	  (vector i) 'encoded-kbd-self-insert-utf-8)
	(setq i (1+ i))))
    8)

   (t
    nil)))

;;;###autoload
(defun encoded-kbd-setup-display (display)
  "Set up a `input-decode-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 input-decode-map.
	(let ((m input-decode-map)
              (child nil))
          (while (keymapp m)
            (if (not (equal (keymap-prompt m) "encoded-kb"))
                (progn
                  (setq child m)
                  (setq m (keymap-parent m)))
              ;; We've found an encoded-kb map, but maybe the prompt we get
              ;; is really inherited from the encoded-kb map.
              (let (mp)
                (while (and (keymapp (setq mp (keymap-parent m)))
                            (equal (keymap-prompt mp) "encoded-kb"))
                  (setq child m)
                  (setq m mp))
                ;; (assert (equal (keymap-prompt m) "encoded-kb"))
                ;; (assert (eq mp (keymap-parent m)))
                ;; (assert (not (and (keymapp mp)
                ;;                   (equal (keymap-prompt mp) "encoded-kb"))))
                ;; (assert (eq m (if child
                ;;                   (keymap-parent child) input-decode-map)))
                ;; We can finally do the actual removal.
                (if child
                    (set-keymap-parent child mp)
                  (setq input-decode-map mp))
                (setq m mp))))))

      (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)
            ;; Place `keymap' as the immediate parent of input-decode-map
            ;; rather than on top, so that later `define-key' on
            ;; input-decode-map don't end up accidentally changing our
            ;; part of the keymap, which would lead to bugs when/if we later
            ;; on remove that part.
            (set-keymap-parent keymap (keymap-parent input-decode-map))
            (set-keymap-parent input-decode-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.
        (let ((old (terminal-parameter nil 'encoded-kbd-saved-input-meta-mode)))
          (when (and old (not (equal (nth 2 (current-input-mode)) old)))
            (set-input-meta-mode old))
          (set-terminal-parameter
           nil 'encoded-kbd-saved-input-meta-mode nil))))))

(provide 'encoded-kb)

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