;; // https://adventofcode.com/2022/day/21
(defpackage :day-21
  (:use :cl))
(in-package :day-21)

(ql:quickload 'cl-ppcre)

(defun parse-integer-or-symbol (str)
  (let ((maybe-int (parse-integer str :junk-allowed t)))
    (if maybe-int
        maybe-int
        (intern (string-upcase str)))))


(defun line-to-quoted-operation (line)
  (let* ((words (ppcre:split " " (ppcre:regex-replace ":" line "")))
         (symbols (mapcar #'parse-integer-or-symbol words)))
    (cond
      ((= 4 (length symbols))
       ;; with operation
       (destructuring-bind (name operand1 op operand2)
           symbols
         `(defparameter ,name '(,op (eval ,operand1) (eval ,operand2)))))

      ((= 2 (length symbols))
       ;; just number
       (destructuring-bind (name value)
           symbols
         `(defparameter ,name ,value))))))

(defun load-file-defs (filename)
  (loop
  for line in (uiop:read-file-lines filename)
  for definition = (line-to-quoted-operation line)
  do (eval definition)))