#lang racket/base

(require racket/function racket/match racket/set
         parser-tools/lex
         (prefix-in : parser-tools/lex-sre)
         parser-tools/yacc)

(define-tokens kaitai-expr [boolean number string identifier])
(define-empty-tokens kaitai-empty [eof + - * / % < <= > >= == != << >> & pipe ^ not and or ? :
                                   lparen rparen lbracket comma dot rbracket])

(define (kaitai-numstr->number str)
  (match (regexp-replace* #px"_" str "")
    [(pregexp #px"^0x(.*?)$" (list _ num)) (string->number num 16)]
    [(pregexp #px"^0b(.*?)$" (list _ num)) (string->number num 2)]
    [(pregexp #px"^0o(.*?)$" (list _ num)) (string->number num 8)]
    [num (string->number num)]))

(define (kaitai-subst-string str)
  ;; racket's built in string translation works fine
  (printf "uwu ~s\n" str)
  (read (open-input-string
          (string-append "\"" (substring str 1 (sub1 (string-length str))) "\""))))

(define kaitai-lexer
  (lexer
    [(:or "true" "false") (token-boolean (string=? "true" lexeme))]
    [(:or (:: "0x" (:+ (:or numeric (char-set "abcdefABCDEF_"))))
          (:: "0b" (:+ (char-set "01_")))
          (:: "0o" (:+ (char-set "01234567_")))
          (:: (:? (char-set "+-"))
              (:+ (:or numeric "_"))
              (:? (:: "." (:* (:or numeric "_"))))
              (:? (:: (char-set "eE") (:? (char-set "+-")) (:+ (:or numeric "_"))))))
     (token-number (kaitai-numstr->number lexeme))]
    [(:or (:: "'" (:* (:- any-char "'") "\\'") "'")
          (:: "\"" (:* (:- any-char "\"") "\\\"") "\""))
     (token-string (kaitai-subst-string lexeme))]
    [whitespace (kaitai-lexer input-port)]
    ["+" (token-+)]
    ["-" (token--)]
    ["*" (token-*)]
    ["/" (token-/)]
    ["%" (token-%)]
    ["<" (token-<)]
    ["<=" (token-<=)]
    [">" (token->)]
    [">=" (token->=)]
    ["==" (token-==)]
    ["!=" (token-!=)]
    [">>" (token->>)]
    ["<<" (token-<<)]
    ["&" (token-&)]
    ["|" (token-pipe)]
    ["^" (token-^)]
    ["not" (token-not)]
    ["and" (token-and)]
    ["or" (token-or)]
    ["?" (token-?)]
    [":" (token-:)]
    ["(" (token-lparen)]
    [")" (token-rparen)]
    ["[" (token-lbracket)]
    ["," (token-comma)]
    ["." (token-dot)]
    ["]" (token-rbracket)]
    [(:: (:+ (:or alphabetic "_"))
         (:* (:or alphabetic numeric "_" "::")))
     (token-identifier lexeme)]
    [(eof) (token-eof)]))

(let ([input (open-input-string "_root._io.size.to_i & 0x08000000 != 0 + code == block_type::int32 ? 4 : 8")])
  (let loop ()
    (match (kaitai-lexer input)
      [(? (curry equal? (token-eof))) (void)]
      [x (printf "~v\n" x) (loop)])))