module Datatypes.Board (Board(..), clearLines) where

import Data.Set (Set)
import qualified Data.Set as Set

import Datatypes.Cell (Cell)

data Board = Board { width :: Int, height :: Int, filled :: Set Cell } deriving Show

empty :: Int -> Int -> Board
empty w h = Board w h Set.empty

clearLines :: Board -> (Board, Int)
clearLines b = let (newFilled, linesDeleted) = collectGarbage yCoords 0 (filled b)
                   in (b { filled = newFilled }, linesDeleted)
                   where
                       yCoords = Set.toList $ Set.map (\(x, y) -> y) (filled b)
                       countInLine l items = Set.size $ Set.filter (\(x, y) -> y == l) items
                       collectGarbage (l:ls) count items = if countInLine l items == (width b)
                                                            then collectGarbage ls (count + 1) (deleteLine l items)
                                                            else collectGarbage ls count items
                       collectGarbage [] count items = (items, count)

-- PRIVATE

deleteLine :: Int -> Set Cell -> Set Cell
deleteLine l cells = let updated = Set.filter (\(x, y) -> y /= l) cells
                         in Set.map (\(x, y) -> if y < l then (x, y + 1) else (x, y)) updated