module Commons where

import GHC.IO.Handle (isEOF)
import Data.Array (Array, listArray, (!), indices)
import Data.List.Unique (sortUniq)


type Image = [(Int, Int)]
type ExpansionArray = Array Int Int


parseLine :: Int -> Int -> String -> Image
parseLine _ _ [] = []
parseLine row column ('#': t) = (column, row): parseLine row (column + 1) t
parseLine row column (_: t) = parseLine row (column + 1) t

parseImage :: Int -> Image -> IO Image
parseImage row image = do done <- isEOF
                          if done
                             then return image
                             else do line <- getLine
                                     parseImage (row + 1) (image ++ parseLine row 1 line)

parse :: IO Image
parse = parseImage 1 []


getExpansionArray :: Int -> Int -> Int -> [Int] -> [Int]
getExpansionArray _ _ _ [] = []
getExpansionArray i expOffset expInc (h: t)
  | i == h = i + expOffset: getExpansionArray (i + 1) expOffset expInc t
  | i < h  = i + expOffset: getExpansionArray (i + 1) (expOffset + expInc) expInc (h: t)

getExpansionArrays :: Int -> Image -> (ExpansionArray, ExpansionArray)
getExpansionArrays expInc image = let expX = getExpansionArray 1 0 expInc $ sortUniq . map fst $ image
                                      expY = getExpansionArray 1 0 expInc $ sortUniq . map snd $ image
                                  in (listArray (1, length expX) expX, listArray (1, length expY) expY)

getDistancesGalaxy :: Image -> (ExpansionArray, ExpansionArray) -> (Int, Int) -> [Int]
getDistancesGalaxy [] _ _ = []
getDistancesGalaxy ((x0, y0): t) (expX, expY) (x1, y1) =
  abs ((expX ! x0) - (expX ! x1)) + abs ((expY ! y0) - (expY ! y1)): getDistancesGalaxy t (expX, expY) (x1, y1)

getDistances :: Image -> (ExpansionArray, ExpansionArray) -> [[Int]]
getDistances [] _ = []
getDistances (h: t) (expX, expY) = getDistancesGalaxy t (expX, expY) h: getDistances t (expX, expY)