{-# LANGUAGE OverloadedStrings #-}
{-# OPTIONS_GHC -Wno-unused-do-bind #-}

module Day1 where

import Data.Semigroup
import Data.Char
import Data.String
import qualified Data.ByteString as B
import qualified Data.ByteString.Char8 as Char8
import Data.Attoparsec.Lazy
import Data.Attoparsec.ByteString.Char8 (letter_ascii)
import Data.Either (fromRight)

-- import Debug.Trace

main :: IO ()
main = do
  day1input <- lines <$> readFile "inputs/day1.input"
  putStrLn "Part 1 result:"
  print $ part1 day1input
  putStrLn "Part 2 result:"
  print $ part2 day1input

part1 :: [String] -> Sum Int
part1 = foldMap go
  where
    go :: String -> Sum Int
    go = glueFirstLast . map (\c -> read [c]) . filter isNumber

part2 :: [String] -> Sum Int
part2 = foldMap (glueFirstLast . getNumbers)

glueFirstLast :: [Int] -> Sum Int
glueFirstLast xs = Sum $ 10 * head xs + last xs

getNumbers :: String -> [Int]
getNumbers = fromRight [] . parseOnly numberParser . fromString

numberParser :: Parser [Int]
numberParser = do
  s <- concat <$> (parseN `sepBy` letter_ascii)
  pure $ concatMap toInt s
  where
    parseN = many' . choice $ map string
      ["oneight","threeight","fiveight","sevenine","nineight","eightwo","eighthree","twone"
      ,"one","two","three","four","five","six","seven","eight","nine"
      , "1","2","3","4","5","6","7","8","9"
      ]
    toInt :: B.ByteString -> [Int]
    toInt "one" = [1]
    toInt "two" = [2]
    toInt "three" = [3]
    toInt "four" = [4]
    toInt "five" = [5]
    toInt "six" = [6]
    toInt "seven" = [7]
    toInt "eight" = [8]
    toInt "nine" = [9]
    toInt "oneight" = [1,8]
    toInt "threeight" = [3,8]
    toInt "fiveight" = [5,8]
    toInt "sevenine" = [7,9]
    toInt "nineight" = [9,8]
    toInt "eighthree" = [8,3]
    toInt "eightwo" = [8,2]
    toInt "twone" = [2,1]
    toInt ss = [read $ Char8.unpack ss]