solve.hs

-- Day 7
{-# LANGUAGE BangPatterns #-}

import Data.List

while :: (a -> Bool) -> (a -> a) -> a -> a
while p f = go where go !x = if p x then go (f x) else x

cleanUpNav :: [String] -> [String]
cleanUpNav = filter (\x -> not $ "$ cd .." `isInfixOf` x || (x == "$ ls"))


getDirName :: String -> String -> String
getDirName x prefix = if prefix `isPrefixOf` x
               then last $ words x
               else ""

getUntilCommand :: [String] -> [String]
getUntilCommand [] = []
getUntilCommand (x:xs) = if head x /= '$'
                         then x:getUntilCommand xs
                         else []

getDirNameContent :: [String] -> [(String, [String])]
getDirNameContent [] = []
getDirNameContent (x:xs) = if "$ cd " `isPrefixOf` x
                           then (getDirName x "$ cd ", getUntilCommand xs) : getDirNameContent xs
                           else getDirNameContent xs

findDir :: String -> [(String, [String])] -> (String, [String])
findDir n = head . filter (\(x, _) -> x == n)

unwrapDir :: String -> [(String, [String])] -> [String]
unwrapDir dirName navStack = snd $ findDir dirName navStack

filesInNestedDir :: String -> [(String, [String])]-> [String]
filesInNestedDir x stack = if "dir" `isPrefixOf` x
                           then unwrapDir (getDirName x "dir ") stack
                           else [x]

filesForDir :: [String] -> [(String, [String])] -> [[String]]
filesForDir [x] stack = [filesInNestedDir x stack]
filesForDir (x:xs) stack = filesInNestedDir x stack : filesForDir xs stack

containsDirs :: [String] -> Bool
containsDirs l = filter ("dir" `isPrefixOf`) l /= []

goUntilNoDir :: [String] -> [(String, [String])] -> [String]
goUntilNoDir currentDir stack = if containsDirs currentDir
                                then goUntilNoDir (concat (filesForDir currentDir stack)) stack
                                else currentDir

getFilesInDirs :: [(String, [String])] -> [(String, [String])]
getFilesInDirs stack = map (\(x, y) ->
                                (x, goUntilNoDir y stack)) stack

getFileSize :: String -> Int
getFileSize = read . head . words

solve1 :: [(String, [String])] -> Int
solve1 s = sum $ filter (\x -> x <= 100000) $ map (\(_, y) -> sum $ map (getFileSize) y) s

readInput :: IO [(String, [String])]
readInput = readFile "./sample.txt" >>= return  . getDirNameContent . cleanUpNav . lines

main :: IO ()
main = readInput >>= print . solve1