;;;; Copyright © 2023, Jaidyn Ann <jadedctrl@posteo.at>
;;;;
;;;; 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/>.

;;;; FLORA-SEARCH-AURORA.INPUT
;;;; All input-related voodoo goes here: Input reading, translating, parsing, etc.

(defpackage :flora-search-aurora.input
  (:use :cl)
  (:export #:read-char-plist #:normalize-char-plist
           +qwerty-layout+ +dvorak-layout+))

(in-package :flora-search-aurora.input)


;; Yup, they're hardcoded like this. Horrid, ain't it? ^_^
(defvar +qwerty-layout+
  '(#\q #\Q #\w #\W #\e #\E #\r #\R #\t #\T #\y #\Y #\u #\U #\i #\I #\o #\O #\p #\P #\[ #\{ #\] #\}
    #\a #\A #\s #\S #\d #\D #\f #\F #\g #\G #\h #\H #\j #\J #\k #\K #\l #\L #\; #\: #\' #\"
    #\z #\Z #\x #\X #\c #\C #\v #\V #\b #\B #\n #\N #\m #\M #\, #\< #\. #\> #\/ #\?))

(defvar +dvorak-layout+
  '(#\' #\" #\, #\< #\. #\> #\p #\P #\y #\Y #\f #\F #\g #\G #\c #\C #\r #\R #\l #\L #\/ #\? #\= #\+
    #\a #\A #\o #\O #\e #\E #\u #\U #\i #\I #\d #\D #\h #\H #\t #\T #\n #\N #\s #\S #\- #\_
    #\; #\: #\q #\Q #\j #\J #\k #\K #\x #\X #\b #\B #\m #\M #\w #\W #\v #\V #\z #\Z))


(defun read-char-plist (&optional (stream *standard-input*))
  "Reads a character directly from standard-input (sans buffering).
Simple terminal escape codes (like arrow-keys) are translated into
roughly-semantically-equal character representations — see the
docstring of #'escape-code-to-character for more info."
  (let* ((char-1 (read-char stream))
         (char-2 (if (eq char-1 #\ESC) (read-char-no-hang stream)))  ; Maybe escaped char or [.
         (char-3 (if (eq char-2 #\[)   (read-char-no-hang stream)))  ; Maybe end-of-sequence, or 1.
         (char-4 (if (eq char-3 #\1)   (read-char-no-hang stream)))  ; Maybe semicolon.
         (char-5 (if (eq char-4 #\;)   (read-char-no-hang stream)))  ; Maybe modifer-key.
         (char-6 (if (characterp char-5) (read-char-no-hang stream)))) ; Escaped char and EOS.
    ;; Let me explain! There are pretty much three input-cases we should care about:
    ;;   * character
    ;;   * ␛ character
    ;;   * ␛ [ character
    ;;   * ␛ [ 1 ; modifier character
    ;; This is by no means comprehensive, sorry: I didn't even try! But it suits my purposes. :-P
    (let ((the-char (or char-6 char-3 char-2 char-1))
          (modifier (case char-5
                      (#\2 'shift)
                      (#\3 'meta)
                      (#\5 'control)))
          (escaped (eq char-1 #\ESC)))
      (list :char the-char :modifier modifier :escaped escaped))))


(defun normalize-char-plist (char-plist &optional (layout +qwerty-layout+))
  "Given a character input property list (as received from read-char-plist),
massage the output into parsable, deescaped, QWERTY-according format."
  (let ((normalized (deescape-char-plist char-plist)))
    (setf (getf normalized :char)
          (qwertyize-char (getf normalized :char)
                          layout))
    normalized))


(defun qwertyize-char (char layout)
  "Given a char input in some layout, return the corresponding character in QWERTY.
Not at all comprehensive, but probably-mostly-just-good-enough. ¯\_ (ツ)_/¯"
  (or (parallel-list-item char layout +qwerty-layout+)
      char))


(defun deescape-char-plist (char-plist)
  "Translate escaped characters into somewhat-semantically-adjacent
characters, like left arrow-key (escaped D) into ← (“LEFTWARDS ARROW”)."
  (list :modifier (getf char-plist :modifier)
        :char (if (getf char-plist :escaped)
                  (case (getf char-plist :char)
                    (#\A #\↑)
                    (#\B #\↓)
                    (#\C #\→)
                    (#\D #\←)
                    (otherwise (getf char-plist :char)))
                  (getf char-plist :char))))


;;; ~ Utilities ~

(defun parallel-list-item (item-a list-a list-b &key (test #'eql))
  "Given two parallel lists and an item contained in the first list, return its
corresponding item in the other list, by index."
  (let ((index (position item-a list-a :test test)))
    (if index
        (nth index list-b))))