import Data.List
import Data.List.Split
import Data.Char (isDigit)

main :: IO ()
main = do
    input <- readFile "5/riley.txt"
    let x = parse <$> lines input
    print $ f x
    print $ g x
    where
        f = solve . filter (not . diagonal)
        g = solve

-- | Extract all the numbers from the given string
parse :: String -> [Int]
parse = map read . wordsBy (not . isDigit)

-- | Determine if the given line is diagonal.
diagonal :: [Int] -> Bool
diagonal [ x1, y1, x2, y2 ] = x1 /= x2 && y1 /= y2

solve :: [[Int]] -> Int
solve = length . filter ((>= 2) . length) . group . sort . (>>= range)

-- | Transform a line to a list of points on that line.
range :: [Int] -> [(Int,Int)]
range [ x1, y1, x2, y2 ]
    | x1 == x2  = [ (x1,y) | y <- ys ]
    | y1 == y2  = [ (x,y1) | x <- xs ]
    | otherwise = zip xs ys
    where xs = gen x1 x2
          ys = gen y1 y2

-- | Generate a list of numbers from `a` to `b`.
gen :: Int -> Int -> [Int]
gen a b | a > b     = [ b .. a ]
        | otherwise = reverse [ a .. b ]