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;;; zero-input-framework.el --- Zero Chinese input method framework -*- lexical-binding: t -*-

;; Licensed under the Apache License, Version 2.0 (the "License");
;; you may not use this file except in compliance with the License.
;; You may obtain a copy of the License at
;; Unless required by applicable law or agreed to in writing, software
;; distributed under the License is distributed on an "AS IS" BASIS,
;; See the License for the specific language governing permissions and
;; limitations under the License.

;;; Commentary:

;; zero-input-framework is a Chinese input method framework for Emacs,
;; implemented as an Emacs minor mode.
;; You can cycle zero-input-punctuation-level in current buffer by C-c , ,
;; You can change default Chinese punctuation level:
;;   (setq-default zero-input-punctuation-level zero-input-punctuation-level-full)
;; You can toggle full-width mode in current buffer by C-c , .
;; You can enable full-width mode by default:
;;   (setq-default zero-input-full-width-p t)

;;; Code:

;; dependencies

(eval-when-compile (require 'cl-lib) (require 'cl-macs))
(require 'ring)
(require 's)
(require 'zero-input-panel)

;; utils

;; this function is from ibus.el
(defun zero-input--ibus-compute-pixel-position (&optional pos window)
  "Return geometry of object at POS in WINDOW as a list like \(X Y H).
X and Y are pixel coordinates relative to top left corner of frame which
WINDOW is in.  H is the pixel height of the object.

Omitting POS and WINDOW means use current position and selected window,
  (let* ((frame (window-frame (or window (selected-window))))
	 (posn (posn-at-point (or pos (window-point window)) window))
	 (line (cdr (posn-actual-col-row posn)))
	 (line-height (and line
			   (or (window-line-height line window)
			       (and (redisplay t)
				    (window-line-height line window)))))
	 (x-y (or (posn-x-y posn)
		  (let ((geom (pos-visible-in-window-p
			       (or pos (window-point window)) window t)))
		    (and geom (cons (car geom) (cadr geom))))
		  '(0 . 0)))
	 (ax (+ (car (window-inside-pixel-edges window))
		(car x-y)))
	 (ay (+ (cadr (window-pixel-edges window))
		(or (nth 2 line-height) (cdr x-y))))
	 (height (or (car line-height)
		     (with-current-buffer (window-buffer window)
			;; `posn-object-width-height' returns an incorrect value
			;; when the header line is displayed (Emacs bug #4426).
			((and posn
			      (null header-line-format))
			 (cdr (posn-object-width-height posn)))
			((and (bound-and-true-p text-scale-mode)
			      (not (zerop (with-no-warnings
			 (round (* (frame-char-height frame)
				     (expt text-scale-mode-step
			 (frame-char-height frame)))))))
    (list ax ay height)))

(defun zero-input-get-point-position ()
  "Return current point's position (x y).
Origin (0, 0) is at screen top left corner."
  (cl-destructuring-bind (x y line-height) (zero-input--ibus-compute-pixel-position)
     ((functionp 'window-absolute-pixel-position)
      ;; introduced in emacs 26
      (cl-destructuring-bind (x . y) (window-absolute-pixel-position)
	(list x (+ y line-height))))
     ((functionp 'frame-edges)
      ;; introduced in emacs 25
      (cl-destructuring-bind (frame-x frame-y &rest rest)
	  (frame-edges nil 'inner-edges)
	(list (+ frame-x x) (+ frame-y y line-height))))
      ;; <= emacs 24, used guessed pixel size for tool-bar, menu-bar, WM title
      ;; bar. Since I can't get that from elisp.
      (list (+ (frame-parameter nil 'left)
	       (if (and (> (frame-parameter nil 'tool-bar-lines) 0)
			(eq (frame-parameter nil 'tool-bar-position) 'left))
		   96 0)
	    (+ (frame-parameter nil 'top)
	       (if (and (> (frame-parameter nil 'tool-bar-lines) 0)
			(eq (frame-parameter nil 'tool-bar-position) 'top))
		   42 0)
	       (if (> (frame-parameter nil 'menu-bar-lines) 0) (+ 30 30) 0)

(defun zero-input-cycle-list (lst item)
  "Return the object next to given ITEM in LST.

If item is the last object, return the first object in lst.
If item is not in lst, return nil."
  (let ((r (member item lst)))
     ((null r) nil)
     (t (or (cadr r)
	    (car lst))))))

;; key logic functions

;; zero-input-el version
(defvar zero-input-version nil "Zero package version.")
(setq zero-input-version "2.8.0")

;; FSM state
(defconst zero-input--state-im-off 'IM-OFF)
(defconst zero-input--state-im-waiting-input 'IM-WAITING-INPUT)
(defconst zero-input--state-im-preediting 'IM-PREEDITING)

(defconst zero-input-punctuation-level-basic 'BASIC)
(defconst zero-input-punctuation-level-full 'FULL)
(defconst zero-input-punctuation-level-none 'NONE)

(defvar-local zero-input-im nil
  "Stores current input method.

If nil, the empty input method will be used.  In the empty input
method, only punctuation is handled.  Other keys are pass
(defvar zero-input-ims nil
  "A list of registered input methods.")

(defvar-local zero-input-buffer nil
  "Stores the associated buffer.
this is used to help with buffer focus in/out events")

(defvar-local zero-input-state zero-input--state-im-off)
(defcustom zero-input-full-width-p nil
  "Set to t to enable full-width mode.
In full-width mode, commit ascii char will insert full-width char if there is a
corresponding full-width char.  This full-width char map is
independent from punctuation map.  You can change this via
  :group 'zero-input
  :safe t
  :type 'boolean)
(make-variable-buffer-local 'zero-input-full-width-p)

(defcustom zero-input-punctuation-basic-map
  '((?, ",")
    (?, ",")
    (?. "。")				; 0x3002
    (?? "?")
    (?! "!")
    (?\\ "、")				; 0x3001
    (?: ":"))
  "Punctuation map used when `zero-input-punctuation-level' is not 'NONE."
  :group 'zero-input
  :type '(alist :key-type character :value-type (group string)))

(defcustom zero-input-punctuation-full-map
  '((?_ "——")
    (?< "《")				;0x300A
    (?> "》")				;0x300B
    (?\( "(")
    (?\) ")")
    (?\[ "【")				;0x3010
    (?\] "】")				;0x3011
    (?^ "……")
    (?~ "~")
    (?\; ";")
    (?$ "¥"))
  "Additional punctuation map used when `zero-input-punctuation-level' is 'FULL."
  :group 'zero-input
  :type '(alist :key-type character :value-type (group string)))

(defcustom zero-input-punctuation-level zero-input-punctuation-level-basic
  "Default punctuation level.

Should be one of
  :group 'zero-input
  :safe t
  :type `(choice (const :tag "zero-input-punctuation-level-basic"
		 (const :tag "zero-input-punctuation-level-full"
		 (const :tag "zero-input-punctuation-level-none"
(make-variable-buffer-local 'zero-input-punctuation-level)
(defvar zero-input-punctuation-levels (list zero-input-punctuation-level-basic
  "Punctuation levels to use when `zero-input-cycle-punctuation-level'.")
(defvar-local zero-input-double-quote-flag nil
  "Non-nil means next double quote insert close quote.

Used when converting double quote to Chinese quote.
If nil, next double quote insert open quote.
Otherwise, next double quote insert close quote.")
(defvar-local zero-input-single-quote-flag nil
  "Non-nil means next single quote insert close quote.

Used when converting single quote to Chinese quote.
If nil, next single quote insert open quote.
Otherwise, next single quote insert close quote.")
(defvar-local zero-input-recent-insert-chars (make-ring 3)
  "Store recent insert characters.

Used to handle Chinese dot in digit input.
e.g. 1。3 could be converted to 1.3.")
(defcustom zero-input-auto-fix-dot-between-numbers t
  "Non-nil means zero should change 1。3 to 1.3, H。264 to H.264."
  :type 'boolean)
(defvar-local zero-input-preedit-str "")
(defvar-local zero-input-candidates nil)
(defcustom zero-input-candidates-per-page 10
  "How many candidates to show on each page.

Change will be effective only in new `zero-input-mode' buffer."
  :type 'integer)
(defvar-local zero-input-current-page 0 "Current page number.  count from 0.")
(defvar-local zero-input-initial-fetch-size 21
  "How many candidates to fetch for the first call to GetCandidates.

It's best set to (1+ (* zero-input-candidates-per-page N)) where
N is number of pages you want to fetch in initial fetch.")
;; zero-input-fetch-size is reset to 0 when preedit-str changes.
;; zero-input-fetch-size is set to fetch-size in build-candidates-async
;; complete-func lambda.
(defvar-local zero-input-fetch-size 0 "Last GetCandidates call's fetch-size.")
(defvar zero-input-previous-page-key ?\- "Previous page key.")
(defvar zero-input-next-page-key ?\= "Next page key.")

;;; concrete input method should define these functions and set them in the
;;; corresponding *-func variable.
(defun zero-input-build-candidates-default (_preedit-str _fetch-size)
  "Default implementation for `zero-input-build-candidates-func'."
(defun zero-input-can-start-sequence-default (_ch)
  "Default implementation for `zero-input-can-start-sequence-func'."
(defun zero-input-get-preedit-str-for-panel-default ()
  "Default implementation for `zero-input-get-preedit-str-for-panel-func'."
(defvar-local zero-input-build-candidates-func
  "Contains a function to build candidates from preedit-str.  The function accepts param preedit-str, fetch-size, returns candidate list.")
(defvar-local zero-input-build-candidates-async-func
  "Contains a function to build candidates from preedit-str.  The function accepts param preedit-str, fetch-size, and a complete-func that should be called on returned candidate list.")
(defvar-local zero-input-can-start-sequence-func
  "Contains a function to decide whether a char can start a preedit sequence.")
(defvar-local zero-input-handle-preedit-char-func
  "Contains a function to handle IM-PREEDITING state char insert.
The function should return t if char is handled.
This allow input method to override default logic.")
(defvar-local zero-input-get-preedit-str-for-panel-func
  "Contains a function that return preedit-str to show in zero-input-panel.")
(defvar-local zero-input-backspace-func
  "Contains a function to handle <backward> char.")
(defvar-local zero-input-handle-preedit-char-func
  "Hanlde character insert in `zero-input--state-im-preediting' mode.")
(defvar-local zero-input-preedit-start-func 'nil
  "Called when enter `zero-input--state-im-preediting' state.")
(defvar-local zero-input-preedit-end-func 'nil
  "Called when leave `zero-input--state-im-preediting' state.")

(defvar zero-input-enable-debug nil
  "Whether to enable debug.
if t, `zero-input-debug' will output debug msg in *zero-input-debug* buffer")
(defvar zero-input-debug-buffer-max-size 30000
  "Max characters in *zero-input-debug* buffer.  If reached, first half data will be deleted.")

(defun zero-input-debug (string &rest objects)
  "Log debug message in *zero-input-debug* buffer.

STRING and OBJECTS are passed to `format'"
  (if zero-input-enable-debug
      (with-current-buffer (get-buffer-create "*zero-input-debug*")
	(goto-char (point-max))
	(insert (apply 'format string objects))
	(when (> (point) zero-input-debug-buffer-max-size)
	  (insert "removing old data\n")
	  (delete-region (point-min) (/ zero-input-debug-buffer-max-size 2))))))

;; (zero-input-debug "msg1\n")
;; (zero-input-debug "msg2: %s\n" "some obj")
;; (zero-input-debug "msg3: %s\n" 24)
;; (zero-input-debug "msg4: %s %s\n" 24 1)

(defun zero-input-add-recent-insert-char (ch)
  "Insert CH to `zero-input-recent-insert-chars'."
  ;; (cl-assert (and (characterp ch) (not (stringp ch))))
  (zero-input-debug "add char to recent chars ring: %s\n" ch)
  (ring-insert zero-input-recent-insert-chars ch))

(defun zero-input-enter-preedit-state ()
  "Config keymap when enter preedit state."
  (if (functionp zero-input-preedit-start-func)
      (funcall zero-input-preedit-start-func)))

(defun zero-input-leave-preedit-state ()
  "Config keymap when leave preedit state."
  (if (functionp zero-input-preedit-end-func)
      (funcall zero-input-preedit-end-func)))

(defun zero-input-set-state (state)
  "Set zero state to given STATE."
  (zero-input-debug "set state to %s\n" state)
  (setq zero-input-state state)
  (if (eq state zero-input--state-im-preediting)

(defun zero-input-candidates-on-page (candidates)
  "Return candidates on current page for given CANDIDATES list."
  (cl-flet ((take (n lst)
	       "take the first n element from lst. if there is not
enough elements, return lst as it is."
		for lst* = lst then (cdr lst*)
		for n* = n then (1- n*)
		until (or (zerop n*) (null lst*))
		collect (car lst*)))
	    (drop (n lst)
	       "drop the first n elements from lst"
		for lst* = lst then (cdr lst*)
		for n* = n then (1- n*)
		until (or (zerop n*) (null lst*))
		finally (return lst*))))
    (take zero-input-candidates-per-page
	  (drop (* zero-input-candidates-per-page zero-input-current-page) candidates))))

(defun zero-input-show-candidates (&optional candidates)
  "Show CANDIDATES using zero-input-panel via IPC/RPC."
  (let ((candidates-on-page
	 (zero-input-candidates-on-page (or candidates
    (cl-destructuring-bind (x y) (zero-input-get-point-position)
       (funcall zero-input-get-preedit-str-for-panel-func)
       (length candidates-on-page)
       `(("in_emacs" t)
	 ("filename" ,(or (buffer-file-name) ""))
	 ("page_number" ,(1+ zero-input-current-page))
	 ("has_next_page" ,(or (> (length (or candidates zero-input-candidates)) (* zero-input-candidates-per-page (1+ zero-input-current-page))) (< zero-input-fetch-size (* zero-input-candidates-per-page (+ 2 zero-input-current-page)))))
	 ("has_previous_page" ,(> zero-input-current-page 0))
	 ("move_x" :int32 ,x)
	 ("move_y" :int32 ,y)))
      (zero-input-debug "candidates: %s\n" (s-join ", " candidates-on-page)))))

(defun zero-input-build-candidates (preedit-str fetch-size)
  "Build candidates list synchronously.

Try to find at least FETCH-SIZE number of candidates for PREEDIT-STR.
Return a list of candidates."
  ;; (zero-input-debug "zero-input-build-candidates\n")
  (unless (functionp zero-input-build-candidates-func)
    (signal 'wrong-type-argument (list 'functionp zero-input-build-candidates-func)))
  ;; Note that zero-input-candidates and zero-input-fetch-size is updated in
  ;; async complete callback. This function only care about building the
  ;; candidates.
  (funcall zero-input-build-candidates-func preedit-str fetch-size))

(defun zero-input-build-candidates-async-default (preedit-str fetch-size complete-func)
  "Build candidate list, when done show it via `zero-input-show-candidates'.

PREEDIT-STR the preedit-str.
FETCH-SIZE try to find at least this many candidates for preedit-str.
COMPLETE-FUNC the function to call when build candidates completes."
  ;; (zero-input-debug "zero-input-build-candidates-async-default\n")
  ;; default implementation just call sync version `zero-input-build-candidates'.
  (let ((candidates (zero-input-build-candidates preedit-str fetch-size)))
    ;; update cache to make SPC and digit key selection possible.
    (funcall complete-func candidates)))

(defvar zero-input-full-width-char-map nil
  "An alist that map half-width char to full-width char.")
(setq zero-input-full-width-char-map
       ;; ascii 32 -> unicode 3000
       (cons ?\s ?\u3000)
       ;; ascii [33, 126] -> unicode [FF01, FF5E]
	for i from 33 to 126
	collect (cons (make-char 'ascii i)
		      (make-char 'unicode 0 255 (- i 32))))))

(defun zero-input-convert-ch-to-full-width (ch)
  "Convert half-width char CH to full-width.

If there is no full-width char for CH, return it unchanged."
  (let ((pair (assoc ch zero-input-full-width-char-map)))
    (if pair (cdr pair) ch)))

(defun zero-input-convert-str-to-full-width (s)
  "Convert each char in S to their full-width char if there is one."
  (concat (mapcar 'zero-input-convert-ch-to-full-width s)))

(defun zero-input-convert-str-to-full-width-maybe (s)
  "If in `zero-input-full-width-p', convert char in S to their full-width char; otherwise, return s unchanged."
  (if zero-input-full-width-p (zero-input-convert-str-to-full-width s) s))

(defun zero-input-insert-full-width-char (ch)
  "If in `zero-input-full-width-p', insert full-width char for given CH and return true, otherwise just return nil."
  (when zero-input-full-width-p
    (let ((full-width-ch (zero-input-convert-ch-to-full-width ch)))
      (insert full-width-ch)
      (zero-input-add-recent-insert-char full-width-ch)

(defun zero-input-convert-punctuation-basic (ch)
  "Convert punctuation for `zero-input-punctuation-level-basic'.

Return CH's Chinese punctuation if CH is converted.  Return nil otherwise."
  (cadr (assq ch zero-input-punctuation-basic-map)))

(defun zero-input-convert-punctuation-full (ch)
  "Convert punctuation for `zero-input-punctuation-level-full'.

Return CH's Chinese punctuation if CH is converted.  Return nil otherwise"
  (or (zero-input-convert-punctuation-basic ch)
      (cadr (assq ch zero-input-punctuation-full-map))
      (cl-case ch
	(?\" (setq zero-input-double-quote-flag (not zero-input-double-quote-flag))
	     (if zero-input-double-quote-flag "“" "”"))
	(?\' (setq zero-input-single-quote-flag (not zero-input-single-quote-flag))
	     (if zero-input-single-quote-flag "‘" "’")))))

(defun zero-input-convert-punctuation (ch)
  "Convert punctuation based on `zero-input-punctuation-level'.
Return CH's Chinese punctuation if CH is converted.  Return nil otherwise."
   ((eq zero-input-punctuation-level zero-input-punctuation-level-basic)
    (zero-input-convert-punctuation-basic ch))
   ((eq zero-input-punctuation-level zero-input-punctuation-level-full)
    (zero-input-convert-punctuation-full ch))
   (t nil)))

(defun zero-input-handle-punctuation (ch)
  "If CH is a punctuation character, insert mapped Chinese punctuation and return true; otherwise, return false."
  (let ((str (zero-input-convert-punctuation ch)))
    (when str
      (insert str)
      (mapc #'zero-input-add-recent-insert-char str)

(defun zero-input-append-char-to-preedit-str (ch)
  "Append char CH to preedit str, update and show candidate list."
  (setq zero-input-preedit-str
	(concat zero-input-preedit-str (make-string 1 ch)))
  (zero-input-debug "appended %c, preedit str is: %s\n" ch zero-input-preedit-str)

(defun zero-input-can-start-sequence (ch)
  "Return t if char CH can start a preedit sequence."
  (if (functionp zero-input-can-start-sequence-func)
      (funcall zero-input-can-start-sequence-func ch)
    (error "`zero-input-can-start-sequence-func' is not a function")))

(defun zero-input-page-up ()
  "If not at first page, show candidates on previous page."
  (when (> zero-input-current-page 0)
    (setq zero-input-current-page (1- zero-input-current-page))

(defun zero-input-just-page-down ()
  "Just page down using existing candidates."
  (let ((len (length zero-input-candidates)))
    (when (> len (* zero-input-candidates-per-page (1+ zero-input-current-page)))
      (setq zero-input-current-page (1+ zero-input-current-page))
      (zero-input-debug "showing candidates on page %s\n" zero-input-current-page)

(defun zero-input-page-down ()
  "If there is still candidates to be displayed, show candidates on next page."
  (let ((len (length zero-input-candidates))
	(new-fetch-size (1+ (* zero-input-candidates-per-page (+ 2 zero-input-current-page)))))
    (zero-input-debug "decide whether to fetch more candidates, has %s candidates, last fetch size=%s, new-fetch-size=%s\n" len zero-input-fetch-size new-fetch-size)
    (if (and (< len new-fetch-size)
	     (< zero-input-fetch-size new-fetch-size))
	  (zero-input-debug "will fetch more candidates")
	  (funcall zero-input-build-candidates-async-func
		   #'(lambda (candidates)
		       (setq zero-input-candidates candidates)
		       (setq zero-input-fetch-size (max new-fetch-size
							(length candidates)))

(defun zero-input-handle-preedit-char-default (ch)
  "Hanlde character insert in `zero-input--state-im-preediting' state.

CH is the char user has typed."
   ((= ch ?\s)
   ((and (>= ch ?0) (<= ch ?9))
    ;; 1 commit the 0th candidate
    ;; 2 commit the 1st candidate
    ;; ...
    ;; 0 commit the 9th candidate
    (unless (zero-input-commit-nth-candidate (mod (- (- ch ?0) 1) 10))
      (zero-input-append-char-to-preedit-str ch)))
   ((= ch zero-input-previous-page-key)
   ((= ch zero-input-next-page-key)
   (t (let ((str (zero-input-convert-punctuation ch)))
	(if str
	      (zero-input-set-state zero-input--state-im-waiting-input)
	      (insert str))
	  (zero-input-append-char-to-preedit-str ch))))))

(defun zero-input-self-insert-command (n)
  "Handle character `self-insert-command'.  This includes characters and digits.

N is the argument passed to `self-insert-command'."
  (interactive "p")
  (let ((ch (elt (this-command-keys-vector) 0)))
    (zero-input-debug "user typed: %c\n" ch)
     ((eq zero-input-state zero-input--state-im-waiting-input)
      (if (zero-input-can-start-sequence ch)
	    (zero-input-debug "can start sequence, state=IM_PREEDITING\n")
	    (zero-input-set-state zero-input--state-im-preediting)
	    (zero-input-append-char-to-preedit-str ch))
	(zero-input-debug "cannot start sequence, state=IM_WAITING_INPUT\n")
	(unless (zero-input-handle-punctuation ch)
	  (unless (zero-input-insert-full-width-char ch)
	    (self-insert-command n)))))
     ((eq zero-input-state zero-input--state-im-preediting)
      (zero-input-debug "still preediting\n")
      (funcall zero-input-handle-preedit-char-func ch))
      (zero-input-debug "unexpected state: %s\n" zero-input-state)
      (self-insert-command n)))))

(defun zero-input-get-initial-fetch-size ()
  "Return initial fetch size."
   ((<= zero-input-initial-fetch-size zero-input-candidates-per-page)
    (1+ zero-input-candidates-per-page))
   ((zerop (mod zero-input-initial-fetch-size zero-input-candidates-per-page))
    (1+ zero-input-initial-fetch-size))
   (t zero-input-initial-fetch-size)))

(defun zero-input-preedit-str-changed ()
  "Called when preedit str is changed and not empty.  Update and show candidate list."
  (setq zero-input-fetch-size 0)
  (setq zero-input-current-page 0)
  (let ((new-fetch-size (zero-input-get-initial-fetch-size)))
    (funcall zero-input-build-candidates-async-func
	     zero-input-preedit-str new-fetch-size
	     #'(lambda (candidates)
		 (setq zero-input-candidates candidates)
		 (setq zero-input-fetch-size (max new-fetch-size (length candidates)))
		 (zero-input-show-candidates candidates)))))

(defun zero-input-backspace-default ()
  "Handle backspace key in `zero-input--state-im-preediting' state."
  (let ((len (length zero-input-preedit-str)))
    (if (> len 1)
	  (setq zero-input-preedit-str
		(substring zero-input-preedit-str 0 (1- len)))
      (zero-input-set-state zero-input--state-im-waiting-input)

(defun zero-input-backspace ()
  "Handle backspace key in `zero-input--state-im-preediting' state."
  (unless (eq zero-input-state zero-input--state-im-preediting)
    (error "Error: zero-input-backspace called in non preediting state"))
  (zero-input-debug "zero-input-backspace\n")
  (funcall zero-input-backspace-func))

(defun zero-input-commit-text (text)
  "Commit given TEXT, reset preedit str, hide candidate list."
  (zero-input-debug "commit text: %s\n" text)
  (insert text)
  ;; insert last 3 characters (if possible) to zero-input-recent-insert-chars
  (mapc #'zero-input-add-recent-insert-char
	(if (>= (length text) 3) (substring text -3) text))
  (setq zero-input-preedit-str "")
  (setq zero-input-candidates nil)
  (setq zero-input-current-page 0)

(defun zero-input-return ()
  "Handle RET key press in `zero-input--state-im-preediting' state."
  (unless (eq zero-input-state zero-input--state-im-preediting)
    (error "Error: zero-input-return called in non preediting state"))
  (zero-input-debug "zero-input-return\n")
  (zero-input-set-state zero-input--state-im-waiting-input)
  (zero-input-commit-text (zero-input-convert-str-to-full-width-maybe zero-input-preedit-str)))

(defun zero-input-commit-nth-candidate (n)
  "Commit Nth candidate and return true if it exists; otherwise, return false."
  (let ((candidate (nth n (zero-input-candidates-on-page zero-input-candidates))))
    (if candidate
	  (zero-input-set-state zero-input--state-im-waiting-input)
	  (zero-input-commit-text candidate)

(defun zero-input-commit-preedit-str ()
  "Commit current preedit-str."
  (zero-input-set-state zero-input--state-im-waiting-input)
  (zero-input-commit-text (zero-input-convert-str-to-full-width-maybe zero-input-preedit-str)))

(defun zero-input-commit-first-candidate-or-preedit-str ()
  "Commit first candidate if there is one, otherwise commit preedit str."
  (unless (zero-input-commit-nth-candidate 0)

(defun zero-input-hide-candidate-list ()
  "Hide candidate list."
  (zero-input-debug "hide candidate list\n"))

(defun zero-input-reset ()
  "Reset zero states."
  (zero-input-debug "zero-input-reset\n")
  (zero-input-set-state zero-input--state-im-waiting-input)
  (setq zero-input-preedit-str "")
  (setq zero-input-candidates nil)
  (setq zero-input-current-page 0)
  (while (not (ring-empty-p zero-input-recent-insert-chars))
    (ring-remove zero-input-recent-insert-chars))

(defun zero-input-focus-in ()
  "A hook function, run when focus in a buffer."
  (when (eq zero-input-state zero-input--state-im-preediting)
    (zero-input-show-candidates zero-input-candidates)

(defun zero-input-focus-out ()
  "A hook function, run when focus out a buffer."
  (when (eq zero-input-state zero-input--state-im-preediting)

(defun zero-input-buffer-list-changed ()
  "A hook function, run when buffer list has changed.  This includes user has switched buffer."
  (if (eq (car (buffer-list)) zero-input-buffer)

;; minor mode

(defvar zero-input-mode-map
  (let ((map (make-sparse-keymap)))
    ;; build zero-input-prefix-map
    (defvar zero-input-prefix-map (define-prefix-command 'zero-input-prefix-map))
    (let ((bindings '(("," zero-input-cycle-punctuation-level)
		      ("." zero-input-toggle-full-width))))
      (dolist (b bindings)
	(define-key zero-input-prefix-map (car b) (cadr b))))
    ;; mount zero-input-prefix-map in C-c , prefix key.
    (define-key map (kbd "C-c ,") zero-input-prefix-map)

    ;; other keybindings
    (define-key map [remap self-insert-command]
  "Keymap for `zero-input-mode'.")

(defun zero-input-enable-preediting-map ()
  "Enable preediting keymap in `zero-input-mode-map'."
  (zero-input-debug "zero-input-enable-preediting-map\n")
  (define-key zero-input-mode-map (kbd "<backspace>") 'zero-input-backspace)
  (define-key zero-input-mode-map (kbd "RET") 'zero-input-return)
  (define-key zero-input-mode-map (kbd "<escape>") 'zero-input-reset))

(defun zero-input-disable-preediting-map ()
  "Disable preediting keymap in `zero-input-mode-map'."
  (zero-input-debug "zero-input-disable-preediting-map\n")
  (define-key zero-input-mode-map (kbd "<backspace>") nil)
  (define-key zero-input-mode-map (kbd "RET") nil)
  (define-key zero-input-mode-map (kbd "<escape>") nil))

(defun zero-input-modeline-string ()
  "Build `zero-input-mode' modeline string aka lighter.

If full-width mode is enabled, show ZeroF;
Otherwise, show Zero."
  (if zero-input-full-width-p " ZeroF" " Zero"))
(define-minor-mode zero-input-mode
  "a Chinese input method framework written as an emacs minor mode.

  (:eval (zero-input-modeline-string))
  ;; local variables and variable init
  (make-local-variable 'zero-input-candidates-per-page)
  (make-local-variable 'zero-input-full-width-mode)
  (zero-input-set-im zero-input-im)
  ;; hooks
  (add-hook 'focus-in-hook 'zero-input-focus-in)
  (add-hook 'focus-out-hook 'zero-input-focus-out)
  (setq zero-input-buffer (current-buffer))
  (add-hook 'post-self-insert-hook #'zero-input-post-self-insert-command nil t)
  (add-hook 'buffer-list-update-hook 'zero-input-buffer-list-changed))

(defun zero-input-post-self-insert-command (&optional ch)
  "Run after a regular `self-insert-command' is run by zero-input.

Argument CH the character that was inserted."
  ;; `zero-input-auto-fix-dot-between-numbers' is the only feature that
  ;; requires this ring, so for now if it is nil, no need to maintain the ring
  ;; for `self-insert-command'.
  (if (and zero-input-mode zero-input-auto-fix-dot-between-numbers)
      (let ((ch (or ch (elt (this-command-keys-vector) 0))))
	(zero-input-add-recent-insert-char ch)
	;; if user typed "[0-9A-Z]。[0-9 ]", auto convert “。” to “.”
	(cl-flet ((my-digit-char-p (ch) (and (>= ch ?0) (<= ch ?9)))
		  (my-capital-letter-p (ch) (and (>= ch ?A) (<= ch ?Z))))
	  ;; ring-ref index 2 is least recent inserted char.
	  (when (and (let ((ch (ring-ref zero-input-recent-insert-chars 2)))
		       (or (my-digit-char-p ch)
			   (my-capital-letter-p ch)))
		     (equal ? (ring-ref zero-input-recent-insert-chars 1))
		     (let ((ch (ring-ref zero-input-recent-insert-chars 0)))
		       (or (my-digit-char-p ch)
			   (eq ch ?\s))))
	    (delete-char -2)
	    (insert "." (car (ring-elements zero-input-recent-insert-chars))))))))

;; IM developer API

(defun zero-input-register-im (im-name im-functions-alist)
  "(Re)register an input method in zero.

After registration, you can use `zero-input-set-default-im' and
`zero-input-set-im' to select input method to use.

IM-NAME should be a symbol.
IM-FUNCTIONS-ALIST should be a list of form
  '((:virtual-function-name . implementation-function-name))

virtual functions                   corresponding variable
:build-candidates                   `zero-input-build-candidates-func'
:can-start-sequence                 `zero-input-can-start-sequence-func'
:handle-preedit-char                `zero-input-handle-preedit-char-func'
:get-preedit-str-for-panel          `zero-input-get-preedit-str-for-panel-func'
:handle-backspace                   `zero-input-backspace-func'
:init                               nil
:shutdown                           nil
:preedit-start                      `zero-input-preedit-start-func'
:preedit-end                        `zero-input-preedit-end-func'

registered input method is saved in `zero-input-ims'"
  ;; add or replace entry in `zero-input-ims'
  (unless (stringp im-name)
    (signal 'wrong-type-argument (list 'stringp im-name)))
  (setq zero-input-ims (delq (assoc im-name zero-input-ims) zero-input-ims))
  (setq zero-input-ims (push (cons im-name im-functions-alist) zero-input-ims)))

;; Built-in empty input method. It only handles Chinese punctuation.
(zero-input-register-im "empty" nil)

;; public API

(defun zero-input-toggle-full-width ()
  "Toggle `zero-input-full-width-p' on/off."
  (setq zero-input-full-width-p (not zero-input-full-width-p))
  (message (if zero-input-full-width-p
	       "Enabled full-width mode"
	     "Enabled half-width mode")))

(defun zero-input-set-punctuation-level (level)
  "Set `zero-input-punctuation-level'.

LEVEL the level to set to."
  (if (not (member level (list zero-input-punctuation-level-basic
      (error "Level not supported: %s" level)
    (setq zero-input-punctuation-level level)))

(defun zero-input-set-punctuation-levels (levels)
  "Set `zero-input-punctuation-levels'.

`zero-input-cycle-punctuation-level' will cycle current
`zero-input-punctuation-level' among defined LEVELS."
  (dolist (level levels)
    (if (not (member level (list zero-input-punctuation-level-basic
	(error "Level not supported: %s" level)))
  (setq zero-input-punctuation-levels levels))

(defun zero-input-cycle-punctuation-level ()
  "Cycle `zero-input-punctuation-level' among `zero-input-punctuation-levels'."
  (setq zero-input-punctuation-level
	(zero-input-cycle-list zero-input-punctuation-levels zero-input-punctuation-level))
  (message "punctuation level set to %s" zero-input-punctuation-level))

(defun zero-input-set-im (&optional im-name)
  "Select zero input method for current buffer.

IM-NAME (a string) should be a registered input method in zero-input."
  ;; when switch away from an IM, run last IM's :shutdown function.
  (if zero-input-im
      (let ((shutdown-func (cdr (assq :shutdown (cdr (assoc zero-input-im zero-input-ims))))))
	(if (functionp shutdown-func)
	    (funcall shutdown-func))))
   ((null im-name)
    ;; TODO is there an easier way to provide auto complete in mini buffer?
    ;; I used a recursive call to the same function.
    (let ((im-name-str (completing-read "Set input method to: " zero-input-ims)))
      (if (s-blank? im-name-str)
	  (error "Input method name is required")
	(zero-input-set-im im-name-str))))
   ((symbolp im-name)
    ;; symbol is allowed for backward compatibility.
    (zero-input-set-im (symbol-name im-name)))
   (t (let* ((im-slot (assoc im-name zero-input-ims))
	     (im-functions (cdr im-slot)))
	(if im-slot
	      (zero-input-debug "switching to %s input method" im-name)
	      ;; TODO create a macro to reduce code duplication and human
	      ;; error.
	      ;; TODO do some functionp check for the slot functions. if check
	      ;; fail, keep (or revert to) the old IM.
	      (setq zero-input-build-candidates-func
		    (or (cdr (assq :build-candidates im-functions))
	      (setq zero-input-build-candidates-async-func
		    (or (cdr (assq :build-candidates-async im-functions))
	      (setq zero-input-can-start-sequence-func
		    (or (cdr (assq :can-start-sequence im-functions))
	      (setq zero-input-handle-preedit-char-func
		    (or (cdr (assq :handle-preedit-char im-functions))
	      (setq zero-input-get-preedit-str-for-panel-func
		    (or (cdr (assq :get-preedit-str-for-panel im-functions))
	      (setq zero-input-backspace-func
		    (or (cdr (assq :handle-backspace im-functions))
	      (setq zero-input-preedit-start-func
		    (cdr (assq :preedit-start im-functions)))
	      (setq zero-input-preedit-end-func
		    (cdr (assq :preedit-end im-functions)))
	      (unless (functionp zero-input-backspace-func)
		(signal 'wrong-type-argument
			(list 'functionp zero-input-backspace-func)))
	      ;; when switch to a IM, run its :init function
	      (let ((init-func (cdr (assq :init im-functions))))
		(if (functionp init-func)
		    (funcall init-func)))
	      (setq zero-input-im im-name))
	  (error "Input method %S not registered in zero" im-name))))))

(defun zero-input-set-default-im (im-name)
  "Set given IM-NAME as default zero input method."
  ;; symbol is allowed for backward compatibility.
  (unless (or (stringp im-name) (symbolp im-name))
    (signal 'wrong-type-argument (list 'string-or-symbolp im-name)))
  (let ((im-name-str (if (symbolp im-name) (symbol-name im-name) im-name)))
    (setq-default zero-input-im im-name-str)
    (unless (assoc im-name-str zero-input-ims)
      (warn "Input method %s is not registered with zero-input" im-name-str))))

(defun zero-input-on ()
  "Turn on `zero-input-mode'."
  (zero-input-mode 1))

(defun zero-input-off ()
  "Turn off `zero-input-mode'."
  (zero-input-mode -1))
(define-obsolete-function-alias 'zero-input-toggle 'zero-input-mode
  "Zero-input v2.0.2" "Toggle `zero-input-mode'.")

(provide 'zero-input-framework)

;;; zero-input-framework.el ends here