PointReader

module PointReader
    (
        readPoint,
        isEnd,
        isError,
        getPoint
    ) where

import Point
import Data.Text as Text

data ReadedPoint = Point Double Double | END_OF_READING | READING_ERROR deriving (Eq, Show)

readPoint :: IO (ReadedPoint)
readPoint = do
    line <- getLine
    if (line == "END") then
        return END_OF_READING
    else
        return (parseString (Prelude.filter (\c -> c /= ' ') line))

parseString :: String -> ReadedPoint
parseString line =
    let ds = Prelude.map Text.unpack (Text.splitOn (Text.pack ";") (Text.pack line))
    in if (Prelude.length ds /= 2) then
        READING_ERROR
    else let d1 = reads (ds !! 0) :: [(Double, String)]
             d2 = reads (ds !! 1) :: [(Double, String)]
         in if (Prelude.null d1 || Prelude.null d2) then
            READING_ERROR
        else
            let (x, t1) = d1 !! 0
                (y, t2) = d2 !! 0
            in if (not (Prelude.null t1) || not (Prelude.null t2)) then
                READING_ERROR
            else
                Point x y

isEnd :: ReadedPoint -> Bool
isEnd rp = rp == END_OF_READING

isError :: ReadedPoint -> Bool
isError rp = rp == READING_ERROR

getPoint :: ReadedPoint -> Point
getPoint (Point x y) = createPoint x y
getPoint rp = error ("Can't be converted to Point: " ++ show rp)