(defpackage #:aoc-2023/1.2
  (:use #:cl)
  (:export #:main))

(in-package #:aoc-2023/1.2)

(defparameter *numbers* '(("one" . 1)
                          ("two" . 2)
                          ("three" . 3)
                          ("four" . 4)
                          ("five" . 5)
                          ("six" . 6)
                          ("seven" . 7)
                          ("eight" . 8)
                          ("nine" . 9)))

(defun digits-to-integer (a b)
  (values (parse-integer (format NIL "~A~A" a b))))

(defun line-value (line)
  (let* ((first-i (position-if #'digit-char-p line))
         (last-i (position-if #'digit-char-p line :from-end T))
         (first-val (when first-i (aref line first-i)))
         (last-val (when last-i (aref line last-i))))
    (loop :for (str . num) :in *numbers*
          :for first := (search str line)
          :for last := (search str line :from-end T)
          :when first
            :do (when (or (null first-i)
                          (< first first-i))
                  (setf first-i first)
                  (setf first-val num))
                (when (or (null last-i)
                          (> last last-i))
                  (setf last-i last)
                  (setf last-val num)))
    (digits-to-integer first-val last-val)))

(defun main ()
  (format T
          "~A~%"
          (loop :for line := (read-line T NIL)
                :while line
                :unless (string= line "")
                  :sum (line-value line))))

(eval-when (:execute)
  (main))