{-# LANGUAGE FlexibleInstances     #-}
{-# LANGUAGE InstanceSigs          #-}
{-# LANGUAGE MultiParamTypeClasses #-}

module HaskellWorks.Data.Json.Type
  ( JsonType(..)
  , JsonTypeAt(..)
  ) where

import Data.Char
import Data.String
import Data.Word8
import HaskellWorks.Data.Bits.BitWise
import HaskellWorks.Data.Drop
import HaskellWorks.Data.Json.Backend.Standard.Cursor.Generic
import HaskellWorks.Data.Json.Internal.Word8
import HaskellWorks.Data.Positioning
import HaskellWorks.Data.RankSelect.Base.Rank0
import HaskellWorks.Data.RankSelect.Base.Rank1
import HaskellWorks.Data.RankSelect.Base.Select1
import Prelude                                                hiding (drop)

import qualified Data.ByteString                  as BS
import qualified HaskellWorks.Data.BalancedParens as BP

{-# ANN module ("HLint: Reduce duplication" :: String) #-}

data JsonType
  = JsonTypeArray
  | JsonTypeBool
  | JsonTypeNull
  | JsonTypeNumber
  | JsonTypeObject
  | JsonTypeString
  deriving (Eq, Show)

class JsonTypeAt a where
  jsonTypeAtPosition :: Position -> a -> Maybe JsonType
  jsonTypeAt :: a -> Maybe JsonType

instance (BP.BalancedParens w, Rank0 w, Rank1 w, Select1 v, TestBit w) => JsonTypeAt (GenericCursor String v w) where
  jsonTypeAtPosition p k = case drop (toCount p) (cursorText k) of
    c:_ | fromIntegral (ord c) == _bracketleft      -> Just JsonTypeArray
    c:_ | fromIntegral (ord c) == _f                -> Just JsonTypeBool
    c:_ | fromIntegral (ord c) == _t                -> Just JsonTypeBool
    c:_ | fromIntegral (ord c) == _n                -> Just JsonTypeNull
    c:_ | wIsJsonNumberDigit (fromIntegral (ord c)) -> Just JsonTypeNumber
    c:_ | fromIntegral (ord c) == _braceleft        -> Just JsonTypeObject
    c:_ | fromIntegral (ord c) == _quotedbl         -> Just JsonTypeString
    _                                               -> Nothing

  jsonTypeAt k = jsonTypeAtPosition p k
    where p   = lastPositionOf (select1 ik (rank1 bpk (cursorRank k)))
          ik  = interests k
          bpk = balancedParens k

instance (BP.BalancedParens w, Rank0 w, Rank1 w, Select1 v, TestBit w) => JsonTypeAt (GenericCursor BS.ByteString v w) where
  jsonTypeAtPosition p k = case BS.uncons (drop (toCount p) (cursorText k)) of
    Just (c, _) | c == _bracketleft    -> Just JsonTypeArray
    Just (c, _) | c == _f              -> Just JsonTypeBool
    Just (c, _) | c == _t              -> Just JsonTypeBool
    Just (c, _) | c == _n              -> Just JsonTypeNull
    Just (c, _) | wIsJsonNumberDigit c -> Just JsonTypeNumber
    Just (c, _) | c == _braceleft      -> Just JsonTypeObject
    Just (c, _) | c == _quotedbl       -> Just JsonTypeString
    _                                  -> Nothing

  jsonTypeAt k = jsonTypeAtPosition p k
    where p   = lastPositionOf (select1 ik (rank1 bpk (cursorRank k)))
          ik  = interests k
          bpk = balancedParens k