{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE OverloadedLists #-}
{-# LANGUAGE TypeSynonymInstances #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE DefaultSignatures #-}
{-# LANGUAGE DataKinds #-}

module Data.Adnot.Class where

import           Data.Adnot.Type
import           Data.Adnot.Emit
import           Data.Int
import           Data.Word
import qualified Data.ByteString.Lazy as BSL
import qualified Data.Foldable as F
import qualified Data.List.NonEmpty as NE
import qualified Data.Map.Lazy as ML
import qualified Data.Map.Strict as MS
import qualified Data.Sequence as Seq
import qualified Data.Text as T
import qualified Data.Text.Lazy as TL
import qualified Data.Vector as V
import           GHC.Generics
import           GHC.TypeLits (KnownSymbol)

encode :: ToAdnot a => a -> BSL.ByteString
encode = encodeValue . toAdnot

class GenToAdnot f where
  genToAdnot :: f p -> Value

instance (GenToAdnot l, GenToAdnot r) => GenToAdnot (l :+: r) where
  genToAdnot (L1 x) = genToAdnot x
  genToAdnot (R1 y) = genToAdnot y

instance ToAdnot x => GenToAdnot (K1 i x) where
  genToAdnot (K1 x) = toAdnot x

instance (GatherSequence f, Constructor name) => GenToAdnot (C1 name f) where
  genToAdnot (M1 x) = Sum (T.pack (conName c)) (V.fromList (gatherSequence x))
    where c :: M1 c name f ()
          c = undefined

instance (GenToAdnot f) => GenToAdnot (S1 name f) where
  genToAdnot (M1 x) = genToAdnot x

instance (GenToAdnot f) => GenToAdnot (D1 name f) where
  genToAdnot (M1 x) = genToAdnot x

instance (GatherSequence l, GatherSequence r) => GenToAdnot (l :*: r) where
  genToAdnot x = List (V.fromList (gatherSequence x))

class GatherRecord f where
  gatherRecord :: f p -> [(T.Text, Value)]

instance (GatherRecord l, GatherRecord r) => GatherRecord (l :*: r) where
  gatherRecord (x :*: y) = gatherRecord x ++ gatherRecord y

instance (GenToAdnot f, Selector name) => GatherRecord (S1 name f) where
  gatherRecord (M1 x) = [(T.pack (selName s), genToAdnot x)]
    where s :: S1 name f ()
          s = undefined

instance GatherRecord U1 where
  gatherRecord U1 = []

class GatherSequence f where
  gatherSequence :: f p -> [Value]

instance GatherSequence U1 where
  gatherSequence U1 = []

instance (GatherSequence l, GatherSequence r) => GatherSequence (l :*: r) where
  gatherSequence (x :*: y) = gatherSequence x ++ gatherSequence y

instance ToAdnot x => GatherSequence (K1 i x) where
  gatherSequence (K1 x) = [toAdnot x]

instance GenToAdnot f => GatherSequence (S1 name f) where
  gatherSequence (M1 x) = [genToAdnot x]

instance GenToAdnot f => GatherSequence (D1 name f) where
  gatherSequence (M1 x) = [genToAdnot x]

instance GenToAdnot U1 where
  genToAdnot U1 = List []

genericToAdnot :: (GenToAdnot (Rep t), Generic t) => t -> Value
genericToAdnot x = genToAdnot (from x)

class ToAdnot a where
  toAdnot :: a -> Value

  default toAdnot :: (Generic a, GenToAdnot (Rep a)) => a -> Value
  toAdnot = genericToAdnot

-- * Integral types
instance ToAdnot Int where
  toAdnot n = Integer (fromIntegral n)

instance ToAdnot Integer where
  toAdnot n = Integer n

instance ToAdnot Int8 where
  toAdnot n = Integer (fromIntegral n)

instance ToAdnot Int16 where
  toAdnot n = Integer (fromIntegral n)

instance ToAdnot Int32 where
  toAdnot n = Integer (fromIntegral n)

instance ToAdnot Int64 where
  toAdnot n = Integer (fromIntegral n)

instance ToAdnot Word where
  toAdnot n = Integer (fromIntegral n)

instance ToAdnot Word8 where
  toAdnot n = Integer (fromIntegral n)

instance ToAdnot Word16 where
  toAdnot n = Integer (fromIntegral n)

instance ToAdnot Word32 where
  toAdnot n = Integer (fromIntegral n)

instance ToAdnot Word64 where
  toAdnot n = Integer (fromIntegral n)

-- * Rational/Floating types
instance ToAdnot Double where
  toAdnot d = Double d

instance ToAdnot Float where
  toAdnot d = Double (fromRational (toRational d))

-- * String types
instance {-# INCOHERENT #-} ToAdnot String where
  toAdnot s = String (T.pack s)

instance ToAdnot T.Text where
  toAdnot s = String s

instance ToAdnot TL.Text where
  toAdnot s = String (TL.toStrict s)

instance ToAdnot Char where
  toAdnot c = String (T.singleton c)

-- * List types
instance ToAdnot a => ToAdnot [a] where
  toAdnot ls = List (fmap toAdnot (V.fromList ls))

instance ToAdnot a => ToAdnot (V.Vector a) where
  toAdnot ls = List (fmap toAdnot ls)

instance ToAdnot a => ToAdnot (Seq.Seq a) where
  toAdnot ls = List (V.fromList (F.toList (fmap toAdnot ls)))

instance ToAdnot a => ToAdnot (NE.NonEmpty a) where
  toAdnot ls = List (V.fromList (F.toList (fmap toAdnot ls)))

-- * Mapping types
instance ToAdnot a => ToAdnot (MS.Map T.Text a) where
  toAdnot ls = Product (fmap toAdnot ls)

-- * Tuples
instance ToAdnot () where
  toAdnot () = List []

instance (ToAdnot a, ToAdnot b) => ToAdnot (a, b) where
  toAdnot (a, b) = List [toAdnot a, toAdnot b]

instance (ToAdnot a, ToAdnot b, ToAdnot c) => ToAdnot (a, b, c) where
  toAdnot (a, b, c) = List [toAdnot a, toAdnot b, toAdnot c]

instance (ToAdnot a, ToAdnot b, ToAdnot c, ToAdnot d)
         => ToAdnot (a, b, c, d) where
  toAdnot (a, b, c, d) = List [toAdnot a, toAdnot b, toAdnot c, toAdnot d]

-- Some common Haskell algebraic data types
instance ToAdnot a => ToAdnot (Maybe a) where
  toAdnot Nothing = Sum "Nothing" []
  toAdnot (Just x) = Sum "Just" [toAdnot x]

instance (ToAdnot a, ToAdnot b) => ToAdnot (Either a b) where
  toAdnot (Left x)  = Sum "Left" [toAdnot x]
  toAdnot (Right y) = Sum "Right" [toAdnot y]

instance ToAdnot Bool where
  toAdnot True  = Symbol "True"
  toAdnot False = Symbol "False"

-- * Parsing

type ParseError = String
type Parser a = Either ParseError a

withSum :: String -> (T.Text -> Array -> Parser a) -> Value -> Parser a
withSum n k val = case val of
  Sum t as -> k t as
  _        -> Left ("Expected sum in " ++ n)

class FromAdnot a where
  parseAdnot :: Value -> Parser a