evil-fcitx.el

; evil-fcitx.el -- providing auto toggling on the top of fcitx-remote
; something about fcitx-remote program:
; `$ fcitx-remote' return 0 - no input focus
;                         1 - default IME(English)
;                         2 - user's IME
; `$ fcitx-remote -c' will set IME to 1 - default IME
; `$ fcitx-remote -o' will set IME to 2 - user's IME

;;;;;;;;;; User configs

(defvar force-back-to-default-state-key "C-c C-q")

; Indicator to be displayed in mode-line, like <N>/<I> for Evil-mode
(defvar user-IME-state-indicator "[ZH]")
(defvar default-IME-state-indicator "[EN]")

; 2 is the return value of `$ fcitx-remote' when you toggle on your IME
; usaully don't need to change this
(defvar user-IME-ID "2\n")

;;;;;;;;;; End of user configs

(defvar IME-state-mode-line-tag default-IME-state-indicator)

(defun get-current-IME ()
  (if (equal (shell-command-to-string "fcitx-remote")
                         user-IME-ID)
          "user-IME"
        "default-IME"))

(defvar IME-state
  (concat (get-current-IME) "-state"))

(defun switch-to-default-IME ()
  (when (not (equal (get-current-IME) "default-IME"))
        (shell-command "fcitx-remote -c")
        (message "switch to default IME")))

(defun switch-to-user-IME ()
  (when (not (equal (get-current-IME) "user-IME"))
        (shell-command "fcitx-remote -o")
        (message "switch to user IME")))

(defun IME-state-setter (state)
  "Set IME-state and update mode-line tag"
  (setq IME-state state)
  (update-IME-mode-line-tag state))

(defun update-IME-mode-line-tag (IME-state)
  "set the IME-state-mode-line-tag right next to the evil-mode-line-tag"
  (when (listp mode-line-format)
        ; set the mode-line-tag first
        (cond
         ((equal IME-state "default-IME-state")
          (setq IME-state-mode-line-tag default-IME-state-indicator))
         ((equal IME-state "user-IME-state")
          (setq IME-state-mode-line-tag user-IME-state-indicator))
         (else
          (print "error")))
        ; then remove the tag itself
        (setq mode-line-format
                  (delq 'IME-state-mode-line-tag mode-line-format))
        ; just like the evil-refresh-mode-line
        (let ((mlpos mode-line-format)
                  pred)
          ; the position is right next to evil-mode-line-tag
           ; don't quite understand this condition
          (while (and mlpos
                                  ; some elem in the mode-line-format could be a list
                                  ; so the sym is defined like this
                                  (let ((sym (or (car-safe (car mlpos))
                                                                 (car mlpos))))
                                        (not (eq 'evil-mode-line-tag sym))))
                ; pred are the stuffs include and after the current sym
                (setq pred mlpos
                          mlpos (cdr mlpos)))
          (cond
           ((not mlpos))
           ((not nil)
                (setcdr mlpos (cons 'IME-state-mode-line-tag (cdr mlpos)))))
          (force-mode-line-update))))

; init with defulat-IME-state
(update-IME-mode-line-tag "default-IME-state")

(defun exit-insert-evil-fcitx ()
  "When exit insert with user-IME, remember it"
  (if (equal (get-current-IME) "user-IME")
          (progn
                (IME-state-setter "user-IME-state")
                (switch-to-default-IME)
                (message "IME state recorded"))
        (IME-state-setter "default-IME-state")))

(add-hook 'evil-insert-state-exit-hook
                  'exit-insert-evil-fcitx)

(defun entry-insert-evil-fcitx ()
  "When entry insert with user-IME-state, restore the user-IME"
  ; Do not show mode-line-tag in insert state
  ; Emacs cannot get IME info in real time,
  ; so it may be confusing when in insert state
  (progn
        (setq IME-state-mode-line-tag "[--]")
        (force-mode-line-update))
  (if (and (equal IME-state "user-IME-state"))
          (progn
                (switch-to-user-IME)
                ; print-msg
                (message "IME state Restored"))))

(add-hook 'evil-insert-state-entry-hook
                  'entry-insert-evil-fcitx)

(defun force-back-to-default-state()
  "Clear the IME-state and switch back to normal state"
  (interactive)
  ; This is quite ugly now, I may consider another way later
  ; clear IME-state when 1. When in User-IME-state
  ;                      2. When IME is User-IME
  (if (or (equal IME-state "user-IME-state")
                  (equal (get-current-IME) "user-IME"))
          (progn
                (switch-to-default-IME)
                (IME-state-setter "default-IME-state")
                ;(evil-normal-state)
                (message "IME-state cleared"))))

(global-set-key (kbd force-back-to-default-state-key)
                'force-back-to-default-state)

; switch back to default-IME-state after input some non-ascii chars
; as argument of find-char(backward) search(backward) replace command
(defadvice evil-find-char (after change-to-user-IME-after-find-char
                                                                  (&optional count char))
          (switch-to-default-IME))
(ad-activate 'evil-find-char)

(defadvice evil-find-char-backward (after change-to-user-IME-after-rfind-char
                                                                                  (&optional count char))
  (switch-to-default-IME))
(ad-activate 'evil-find-char-backward)

(defadvice evil-search-forward (after change-to-user-IME-state-after-search
                                      ())
  (switch-to-default-IME))
(ad-activate 'evil-search-forward)

(defadvice evil-search-backward (after change-to-user-IME-state-after-rsearch
                                      ())
  (switch-to-default-IME))
(ad-activate 'evil-search-backward)

(defadvice evil-replace (after change-to-user-IME-state-after-find-char
                                                           (beg end &optional type char))
  (switch-to-default-IME))
(ad-activate 'evil-replace)

(provide 'evil-fcitx)