module Main (main) where

import System.Environment.Blank ( getArgs )
import Common
import Task1 (task1)
import Task2 (task2)

main :: IO ()
main = do
  args <- getArgs
  case args of
    ["1", file] -> do
      equations <- readEquationsFromFile file
      print $ task1 equations
    ["2", file] -> do
      equations <- readEquationsFromFile file
      print $ task2 equations
    _ -> error "Usage: <1|2> <input file>"

readEquationsFromFile :: String -> IO [Equation]
readEquationsFromFile file = do
  content <- readFile file
  return $ map parseLine $ lines content

parseLine :: String -> Equation
parseLine line = fromWords $ words line
  where
    fromWords :: [String] -> Equation
    fromWords (firstWord:args) = (read $ reverse $ dropFirst $ reverse firstWord, map read args)
      where
        dropFirst :: String -> String
        dropFirst (_:xs) = xs
        dropFirst x = x
    fromWords parts = error $ "Illegal line: " ++ unwords parts