{-# LANGUAGE RankNTypes #-}

module Importer.IQM.Parser where

import Importer.IQM.Types
import Data.Attoparsec.ByteString.Char8
import Data.Attoparsec.ByteString
import Data.ByteString.Char8 (pack)
import Data.ByteString (split, null)
import Data.Word
import Data.Int
import Unsafe.Coerce
import Control.Monad.Trans.State
import Control.Monad.Trans.Class
import Control.Monad

import Prelude as P hiding (take, null)

w8ToInt :: Integral a => a -> a -> a
w8ToInt i add = 256*i + add

parseNum :: (Integral a, Integral b) => [a] -> b
parseNum = (foldl1 w8ToInt) . map fromIntegral

int16 :: CParser Int16
int16 = do
        ret <- lift $ do
                         a <- anyWord8 :: Parser Word8
                         b <- anyWord8 :: Parser Word8
                         return $ parseNum [b,a]
        modify (+2)
        return ret
                  
int32 :: CParser Int32
int32 = do
        ret <- lift $ do
                         a <- anyWord8 :: Parser Word8
                         b <- anyWord8 :: Parser Word8
                         c <- anyWord8 :: Parser Word8
                         d <- anyWord8 :: Parser Word8
                         return $ parseNum [d,c,b,a]
        modify (+4)
        return $ ret

readHeader :: CParser IQMHeader
readHeader = do
         _ <- lift $ string (pack "INTERQUAKEMODEL\0")
         v <- int32
         -- when v /= 2 then --TODO: error something 
         size' <- int32
         flags' <- int32
         num_text' <- int32
         ofs_text' <- int32         
         num_meshes' <- int32
         ofs_meshes' <- int32         
         num_vertexarrays' <- int32
         num_vertexes' <- int32         
         ofs_vertexarrays' <- int32
         num_triangles' <- int32         
         ofs_triangles' <- int32
         ofs_adjacency' <- int32         
         num_joints' <- int32
         ofs_joints' <- int32         
         num_poses' <- int32
         ofs_poses' <- int32         
         num_anims' <- int32
         ofs_anims' <- int32         
         num_frames' <- int32
         num_framechannels' <- int32         
         ofs_frames' <- int32
         ofs_bounds' <- int32         
         num_comment' <- int32
         ofs_comment' <- int32         
         num_extensions' <- int32
         ofs_extensions' <- int32
         return IQMHeader { version = v
                , filesize           = size'
                , flags              = flags'
                , num_text           = num_text'
                , ofs_text           = ofs_text'
                , num_meshes         = num_meshes'
                , ofs_meshes         = ofs_meshes'
                , num_vertexarrays   = num_vertexarrays'
                , num_vertexes       = num_vertexes'
                , ofs_vertexarrays   = ofs_vertexarrays'
                , num_triangles      = num_triangles'
                , ofs_triangles      = ofs_triangles'
                , ofs_adjacency      = ofs_adjacency'
                , num_joints         = num_joints'
                , ofs_joints         = ofs_joints'
                , num_poses          = num_poses'
                , ofs_poses          = ofs_poses'
                , num_anims          = num_anims'
                , ofs_anims          = ofs_anims'
                , num_frames         = num_frames'
                , num_framechannels  = num_framechannels'
                , ofs_frames         = ofs_frames'
                , ofs_bounds         = ofs_bounds'
                , num_comment        = num_comment'
                , ofs_comment        = ofs_comment'
                , num_extensions     = num_extensions'
                , ofs_extensions     = ofs_extensions'
                }

readMesh :: CParser IQMMesh
readMesh = do
        name <- int32
        mat <- int32
        fv <- int32
        nv <- int32
        ft <- int32
        nt <- int32
        return IQMMesh
                { meshName              = if name == 0 then Nothing else Just (Mesh name)
                , meshMaterial          = mat
                , meshFirstVertex       = fv
                , meshNumVertexes       = nv
                , meshFirstTriangle     = ft
                , meshNumTriangles      = nt
                }

readMeshes :: Int -> CParser [IQMMesh]
readMeshes 1 = do
        m <- readMesh
        return [m]
readMeshes n = do
        m <- readMesh
        ms <- readMeshes (n-1)
        return $ m:ms

(.-) :: forall a a1 a2.
              (Num a, Integral a2, Integral a1) =>
              a1 -> a2 -> a
(.-) a b = (fromIntegral a) - (fromIntegral b)

infix 5 .-

parseIQM :: CParser IQM
parseIQM = do
        put 0
        h <- readHeader
	soFar <- get
        _ <- lift $ take $ ofs_text h .- soFar
        text <- lift $ take $ fromIntegral $ num_text h
        soFar <- get
        _ <- lift $ take $ ofs_meshes h .- soFar
        meshes' <- readMeshes (fromIntegral (num_meshes h))
        return IQM
                { header = h
                , texts = filter (not.null) (split (unsafeCoerce '\0') text)
                , meshes = meshes'
                }