import           Data.Attoparsec.Text
import qualified Data.Text as T
import Prelude hiding (takeWhile, take)

data IndexedFace
        = IndexedFaceTriangle Int Int Int
        | IndexedFaceQuad     Int Int Int Int
        deriving (Show)

    -- | block of faces-lines
faces :: Parser [[(Int, IndexedFace)]]
faces = faceLine `sepBy` endOfLine

    -- | Line containing up to two indexed faces
faceLine :: Parser [(Int, IndexedFace)]
faceLine = face `sepBy` (take 6)

    -- | single indexed-face
face :: Parser (Int, IndexedFace)
face = do
      i  <- index
      v1 <- index
      v2 <- index
      v3 <- index
      v4 <- index
      case v4 of
        0  -> return (i, IndexedFaceTriangle v1 v2 v3)
        _  -> return (i, IndexedFaceQuad     v1 v2 v3 v4)

    -- | node or face index 6 wide
index :: Parser Int
index = do
      i <- take 6
      return . read . T.unpack $ i


test1 = do
      let ele = T.pack    "     1    10     1     9     0           2     1     2     9     0\n"
          r    =  parse faceLine ele
      case r of
           Partial _ -> print $ feed r (T.pack "")
           _         -> print r

test2 = do
      let eles = T.pack $ concat ["     1    10     1     9     0       2     1     2     9     0\n"
                                 ,"     3    11     9     2     0\n"
                                 ,"     4    12     8     1     0\n"
                                 ]
          r    =  parse faces eles
      case r of
           Partial _ -> print $ feed r (T.pack "")
           _         -> print r

test3 = do
      let eles = T.pack $ concat ["     1    10     1     9     0       2     1     2     9     0\n"
                                 ,"     3    11     9     2     0\n"
                                 ,"     4    12     8     1     0\n"
                                 ]
          r    =  parse faces eles
      case r of
           Partial _ -> print $ feed r (T.pack "")
           _         -> print r



test4 = do
      let eles = T.pack $ concat ["     1    10     1     9     0       2     1     2     9     0\n"
                                 ,"     3    11     9     2     0\n"
                                 ,"     4    12     8     1     0\n"
                                 ]
          r    =  parse faces eles
      case r of
           Partial _ -> print $ feed r (T.pack "")
           _         -> print r


test5 = do
      let eles = T.pack $ concat ["     1    10     1     9     0       2     1     2     9     0\n"
                                 ,"     3    11     9     2     0       4    12     8     1     0\n"
                                 ]
          r    =  parse faces eles
      case r of
           Partial _ -> print $ feed r (T.pack "")
           _         -> print r