Begin Day 4, implement parser

[adventofcode2018.git] / day04 / guards.hs

import qualified Data.Map.Strict as M
import Text.ParserCombinators.ReadP 
import Control.Applicative ((<|>))

main :: IO ()
main = do
    shifts <- map parse . lines <$> getContents
    print "a"

type GID = Int

data Status = Begin | Awake | Asleep deriving (Show)   
data Date = Date Int Int Int deriving (Show)
data Time = Time Int Int deriving (Show)

data Shift = Shift Status GID Date Time deriving (Show)

parse :: String -> Shift
parse = fst . head . readP_to_S go
    where digit :: ReadP Char
          digit = satisfy (\char -> char >= '0' && char <= '9')
          stGet :: String -> Status
          stGet "wakes up" = Awake
          stGet "falls asleep" = Asleep
          stGet "Guard #" = Begin
          go :: ReadP Shift
          go = do
            char '['
            year <- read <$> count 4 digit
            char '-'
            month <- read <$> count 2 digit
            char '-'
            day <- read <$> count 2 digit
            char ' '
            hour <- read <$> count 2 digit
            char ':'
            minute <- read <$> count 2 digit
            string "] "
            rt <- string "Guard #" <|> string "wakes up" <|> string "falls asleep"
            gid <- option (-1) (read <$> many1 digit)
            optional $ string " begins shift"
            eof
            let d = Date year month day
            let t = Time hour minute
            return (Shift (stGet rt) gid d t)