{-# LANGUAGE MultiParamTypeClasses  #-}
{-# LANGUAGE FlexibleInstances      #-}
{-# LANGUAGE TypeSynonymInstances   #-}
{-# LANGUAGE IncoherentInstances    #-}
{-# LANGUAGE FlexibleContexts       #-}
{-# LANGUAGE FunctionalDependencies #-}
{-# LANGUAGE EmptyDataDecls         #-}
{-# LANGUAGE ScopedTypeVariables    #-}

-----------------------------------------------------------------------------
-- |
-- Module      :  Windll
-- Copyright   :  (c) Tamar Christina 2009 - 2010
-- License     :  BSD3
-- 
-- Maintainer  :  tamar@zhox.com
-- Stability   :  experimental
-- Portability :  portable
--
-- Contains the list of native types and their mapping to their equivalent FFI types
--
-----------------------------------------------------------------------------

module WinDll.Lib.NativeMapping where

import FastString
import FastTypes

import Foreign
import Foreign.C
import Foreign.C.String
import Foreign.Marshal.Alloc
import Foreign.Marshal.Array
import Foreign.Marshal.Utils
import Foreign.Ptr
import Foreign.StablePtr

import Unsafe.Coerce

import Control.Exception (bracket)
import Control.Monad
import Control.Monad.Instances

import Data.Char
import Data.List
import Data.Word

import Data.Generics
import Data.Generics.Basics
import Data.Typeable

import WinDll.Structs.Types
import WinDll.Lib.Native

import qualified Language.Haskell.Exts as Exts


-- | Typeclase to allow Left LoaD transform. It is basically to allow a transformation to take place
--   at the last argument/return type of the function. This is because most of the functions are in IO.
class LLD m a b c | b -> c where
  lld :: m a b-> m a c
  
instance LLD (->) a b (IO b) where
  lld = (return .)

-- | A class that manages the conversion between the \normal\ and type supported by \ffi\.
--   Minimal implementation requires atleast one of the pair toNative/toFFI and fromNative/fromFFI.
--   The implementation will almost always call fromNative and toNative because all exported functions 
--   are in IO since they all might have side-effects. The only exception to this is for the defaults provided
--   in this module. 
class FFIType phi ix where
    toFFI      :: phi -> ix
    toFFI      = error "toFFI is undefined for the specified type, try toNative instead."
    
    fromFFI    :: ix -> phi
    fromFFI    = error "fromFFI is undefined for the specified type, try fromNative instead."
    
    fromList   :: CInt -> ix -> IO phi
    fromList ic = error "fromList is undefined for this type. Please add a definition or consider using one of the default ones"
    
    fromNative :: ix -> IO phi
    fromNative = return.fromFFI
    
    toNative :: phi -> IO ix
    toNative = return.toFFI
    
    freeFFI :: phi -> ix -> IO ()
    freeFFI = \_ _ -> return ();
    
-- | Default values needed to satisfy .NET marshaller when having unused structures.
-- class FFIType phi ix => FFIDefaults phi ix where
-- class Default phi where
    -- nDefault :: phi
    
-- instance Data a => Default a where 
    -- nDefault = empty
          -- where empty :: Data a => a
                -- empty = value
                  -- where
                    -- value = fromConstrB empty con
                    -- con = case dataTypeRep dat of
                             -- (AlgRep cons) -> head cons
                             -- IntRep -> mkIntegralConstr dat 0
                             -- FloatRep -> mkRealConstr dat 0
                             -- CharRep -> mkCharConstr dat 'a'
                    -- dat = dataTypeOf value    
    
-- | Wrapper functions for dealing with FunPtrs
-- wrapFn :: (FFIType (IO a) ca, FFIType b (IO cb)) => (a -> IO b) -> (ca -> IO cb)
-- wrapFn fn = fromFFI >=> fn >=> toFFI

-- unwrapFn :: (FFIType a (IO ca), FFIType (IO b) cb) => (ca -> IO cb) -> (a -> IO b)
-- unwrapFn fn a = bracket (toFFI a) (freeFFI undefined) (fn >=> fromFFI)
    
-- | Dedicated instance for ()
instance FFIType () () where
    toFFI   = id
    fromFFI = id
    
-- | Numeral values are all also already FFI values, If I've read the documentation correctly 
--   Due to GHC matching only the instance heads this instance can't unfortunately be used. (Booo bad GHC)
-- instance Num a => FFIType a a where
    -- toFFI   = id
    -- fromFFI = id
    
-- | Booleans are by default already an FFI value
instance FFIType Bool Bool where
    toFFI   = id
    fromFFI = id
    
-- | Convert booleans to Cints for use when using the ccall or stdcall conventions
instance FFIType Bool CInt where
    toFFI False = 0
    toFFI True  = 1
    fromFFI 0   = False
    fromFFI 1   = True    
    
-- | Convert booleans to Word8 to save space for use when using the ccall or stdcall conventions
instance FFIType Bool Word8 where
    toFFI False = 0
    toFFI True  = 1
    fromFFI 0   = False
    fromFFI 1   = True    
    
-- | Convert booleans to Int8 to save space for use when using the ccall or stdcall conventions
instance FFIType Bool Int8 where
    toFFI False = 0
    toFFI True  = 1
    fromFFI 0   = False
    fromFFI 1   = True
    
-- | A StorablePtr instance
instance FFIType (StablePtr a) (StablePtr a) where
   fromFFI   = id
   toFFI     = id
   freeFFI _ = freeStablePtr     
   
-- | A FunPtr instance
instance FFIType (FunPtr a) (FunPtr a) where
   fromFFI   = id
   toFFI     = id
   freeFFI _ = freeHaskellFunPtr 
   
-- | Tranform functions to and from the correct types
instance (FFIType a b, FFIType c d) => FFIType (a -> c) (b -> d) where
   toFFI   f x = toFFI (f (fromFFI x))
   fromFFI f x = fromFFI (f (toFFI x))

-- | I decided to use a CAString because on windows this gives me a constant 16 value
instance FFIType String CWString where
    toNative   = newCWString
    fromNative = peekCWString 
    
-- | Intermediate conversion instance for storing values of arrays
instance (Storable a, FFIType b a) => FFIType [b] (Ptr a) where
    toNative   = newArray . map toFFI
    fromList x = fmap (map fromFFI) . peekArray (fromFFI x)
    
-- | Another simple identityy instance, I really need to get that overlapping instances
--   looked at.
instance FFIType CWchar CWchar where
    toFFI   = id
    fromFFI = id
        
-- | Another simple identityy instance, I really need to get that overlapping instances
--   looked at.
instance FFIType CWString CWString where
    toFFI   = id
    fromFFI = id
            
-- | Another simple identityy instance, I really need to get that overlapping instances
--   looked at.
instance FFIType CInt CInt where
    toFFI   = id
    fromFFI = id
            
-- | Another simple identityy instance, I really need to get that overlapping instances
--   looked at.
instance FFIType CDouble CDouble where
    toFFI   = id
    fromFFI = id
            
-- | Another simple identityy instance, I really need to get that overlapping instances
--   looked at.
instance FFIType CLLong CLLong where
    toFFI   = id
    fromFFI = id
    
-- | Convert between FastString and CWString
instance FFIType FastString CWString where
    toFFI   = toFFI.unpackFS
    fromFFI = mkFastString.fromFFI
    
-- | Fix integers from the machine dependend values to fixed 32bit values
instance FFIType Int CInt where
    toFFI   = fromIntegral
    fromFFI = fromIntegral

-- | Instance for unboxed integers, which are first boxed then returned
-- instance FFIType FastInt CInt where
--    toFFI   = toFFI . iBox
--    fromFFI = iUnbox . fromFFI
    
-- | Fix float instances
instance FFIType Float CFloat where
    toFFI   = realToFrac
    fromFFI = realToFrac
    
-- | Any class implementing Storable has implemented enough to be considered a FFIType
instance Storable a => FFIType a (Ptr a) where
    toNative      = new
    fromNative    = peek
    
-- | Cover lists to array convertion IF the type is also an FFI type
instance Storable a => FFIType [a] (Ptr a) where
    toNative      = newArray            --fmap castPtr . new -- newArray
    fromList      = peekArray . fromFFI --const (peek . castPtr) --peekArray
    -- | Intermediate conversion instance for storing values of arrays
    
-- | One way instance for returning lists as the result of a function call.
--   We assume to have an int* as an argument and then fill that in with the
--   length
instance (FFIType a b, Storable b) => FFIType [a] (Ptr CInt -> IO (Ptr b)) where
    toNative  lst = let ln = length lst
                    in return $ \t -> do poke t (toFFI ln)
                                         toNative lst
    fromNative fn = do ptr <- malloc
                       lst <- fn ptr
                       ln  <- peek ptr
                       val <- fromList ln lst
                       free ptr
                       free lst
                       return $ val

-- | Simplistic instance of Storable for list.
--   untested but (new [(1::Int)..10] >>=return.castPtr >>= peekArray 10 :: IO [Int]) works   
instance Storable a => Storable [a] where
   sizeOf    _ = 4
   alignment _ = 4
   poke     ptr value = do newptr <- newArray value
                           copyArray (castPtr ptr) newptr (length value)
   peekElemOff ptr c  = do val <- peekArray c (castPtr ptr)
                           free ptr
                           return val
    
-- | Convertion instance for Integer types to CLLongs (long long)
instance (Num a,Integral a) => FFIType Integer a where
    toFFI   = fromInteger
    fromFFI = toInteger
    
-- | Instance for Functor classes
instance (Functor f, FFIType a b) => FFIType (f a) (f b) where
    toFFI   = fmap toFFI
    fromFFI = fmap fromFFI  
    
-- -- | Instance for Functor classes directly to pointers
{- instance (Functor f, FFIType a b,Storable (f b)) => FFIType (f a) (Ptr (f b)) where
    toNative     x = new (toFFI x)
    fromNative _ x = fmap fromFFI (peek x)
 -}
        
instance FFIType Char CChar where
    toFFI   = castCharToCChar
    fromFFI = castCCharToChar
    
instance FFIType Rational CDouble where
    toFFI   = fromRational
    fromFFI = toRational
    

instance FFIType Char CWchar where
    toFFI     = head.charsToCWchars.(:[])
        where 
           charsToCWchars = foldr utf16Char [] . map ord
             where
              utf16Char c wcs
                | c < 0x10000 = fromIntegral c : wcs
                | otherwise   = let c' = c - 0x10000 in
                                fromIntegral (c' `div` 0x400 + 0xd800) :
                                fromIntegral (c' `mod` 0x400 + 0xdc00) : wcs
    fromFFI   = head.cWcharsToChars.(:[])
        where 
            cWcharsToChars = map chr . fromUTF16 . map fromIntegral
                 where
                  fromUTF16 (c1:c2:wcs)
                    | 0xd800 <= c1 && c1 <= 0xdbff && 0xdc00 <= c2 && c2 <= 0xdfff =
                      ((c1 - 0xd800)*0x400 + (c2 - 0xdc00) + 0x10000) : fromUTF16 wcs
                  fromUTF16 (c:wcs) = c : fromUTF16 wcs
                  fromUTF16 [] = []
    
-- | Tuples are not FFI compatible, As such i'll translate them to a build in tuple datatype
--   .
--   This function translates the embedded types of a Ty to the correct forms using the 
--   function translate' (see below)
translate :: Defs -> Type -> Type
translate defs = everywhere (mkT inner)
    where inner :: Exts.Name -> Exts.Name
          inner (Exts.Ident  s) = Exts.Ident  (translate' defs s)
          inner (Exts.Symbol s) = Exts.Symbol (translate' defs s)
          
-- | Translate everything but applied types. e.g. Foo Token -> FooPtr Token
--   And lists, since lists are implicitly an applied type:
--   e.g [Token] -->> [] Token -->> Ptr Token
translatePartial :: Defs -> Type -> Type
translatePartial defs (Exts.TyForall a b c) = Exts.TyForall a b (translatePartial defs c)
translatePartial defs (Exts.TyFun      a b) = Exts.TyFun (translatePartial defs a) (translatePartial defs b)
translatePartial defs (Exts.TyTuple    a b) = Exts.TyTuple a (map (translatePartial defs) b)
translatePartial defs (Exts.TyList       a) = Exts.TyList $ case isSimpleType a of
                                                              True  -> translatePrimitive defs a
                                                              False -> a
translatePartial defs (Exts.TyApp      a b) = case findStrings' a of
                                                ("IO":_) -> Exts.TyApp (translatePartial defs a) (translatePartial defs b)
                                                _        -> Exts.TyApp (translatePartial defs a) b
translatePartial defs (Exts.TyParen      a) = Exts.TyParen (translatePartial defs a)
translatePartial defs (Exts.TyInfix  a b c) = Exts.TyInfix (translatePartial defs a) b (translatePartial defs c)
translatePartial defs (Exts.TyKind     a b) = Exts.TyKind (translatePartial defs a) b
translatePartial defs                     x = translate defs x

-- | Check to see if the next type is a Simple type. e.g. A TyVar or TyCon
isSimpleType :: Type -> Bool
isSimpleType (Exts.TyApp _  _ ) = False
isSimpleType (Exts.TyParen  a ) = isSimpleType a
-- isSimpleType (Exts.TyList   _ ) = False
isSimpleType _                  = True

-- | Contrary to translate translatePrimitive will only transform the defined
--   primitive types in the \convList\ below. This is because while a transformed
--   signature should only be partially transformed till the first application (Since that'll be
--   the main pointer) we should pre-transform the primitive types into their well known static forms.
translatePrimitive :: Defs -> Type -> Type
translatePrimitive defs = everywhere (mkT inner)
    where inner :: Exts.Name -> Exts.Name
          inner (Exts.Ident  s) = Exts.Ident  (translateP defs s)
          inner (Exts.Symbol s) = Exts.Symbol (translateP defs s)
          
-- | Helper function to define translatePrimitive. It attemps to lookup the type in \convList\ but
--   in the case where it's not found the search query is returned.
translateP :: Defs -> String -> String
translateP convList x = 
   let sType = all isLower x
   in if sType then x else maybe x id (lookup x convList)

-- | Translate Partial Form, This is basically translatePrimitive . translatePartial
translatePForm :: Defs -> Type -> Type
translatePForm df = translatePrimitive df . translatePartial df
               
-- |  Look up the FFI type representation of the given type. Moreover when the type is not found
-- it is assumed to be a new structure and it is assumed to be a pointer value.
translate' :: Defs -> String -> String
translate' convList x = let sType = all isLower x
                        in if sType then x else ((flip maybe id . (++ "Ptr")) `ap` (flip lookup convList)) x
          
-- | Remove all spaces from a sentence
trim :: String -> String
trim = filter (/=' ')
    
-- | A function to split a list of elements by the given seperator
split :: Eq a => [a] -> a -> [[a]]
split []     _             = [[]]
split (x:xs) t | t==x      = [] : (split xs t)
               | otherwise = let (f:fs) = split xs t
                             in (x:f):fs