-- | JSON utilities
module Json where

import Data.Aeson
import Data.Aeson.Types (parse)
import Data.Text        (unpack)
import Data.List        (intercalate)

import qualified Data.Vector       as V
import qualified Data.Aeson.KeyMap as K
import qualified Data.Aeson.Key    as K

-- | Gets the JSON value of a key
(|.) :: Object -> Key -> Value
obj |. key = case parse (.: key) obj of
  Success val -> val
  Error err -> toJSON err


-- | Gets the 'String' value of a key
(|:) :: Object -> Key -> String
obj |: key = repr (obj |. key)


-- | Creates a 'String' representation of a 'Value'
repr :: Value -> String
repr obj = repr' obj 0 where
  repr' val lev =
    case val of
      Array  x -> intercalate ", " $ mapl (\i -> repr' i lev) x
      Object x -> newline lev $ concat $ map (dump x lev) $ K.keys x
      String x -> unpack x
      Number x -> show x
      Bool   x -> show x
      Null     -> "null"
  mapl f v = V.toList (V.map f v)
  newline n = if n /= 0 then id else drop 1
  indent l = '\n' : (concat . replicate l) "  "
  dump o l k = concat [indent l, K.toString k, ": ", repr' (o |. k) (l+1)]


-- | Pretty print a JSON 'Value'
pprint :: Value -> IO ()
pprint = putStrLn . repr