module Json.Render (
  render,
) where

import           Json.SimpleJson (JsValue(..))

render :: JsValue -> String
render JsNull         = "null"
render (JsBool True)  = "true"
render (JsBool False) = "false"
render (JsNumber x)   = show x
render (JsString x)   = show x
render other          = renderWithIndent 0 other

renderWithIndent :: Int -> JsValue -> String

renderWithIndent n (JsArray xs) = "[" ++ "\n"
                               ++ renderContent (n + 2) xs
                               ++ indent n "]"
  where renderContent n = unlines
                        . punctuate ","
                        . map (indent n . renderWithIndent n)

renderWithIndent n (JsObject ps) = "{" ++ "\n"
                                ++ renderContent (n + 2) ps
                                ++ indent n "}"
  where renderContent n = unlines
                        . punctuate ","
                        . map (indent n . renderPair n)
        renderPair n (k, v) = prefix ++ renderWithIndent n v
          where prefix = show k ++ ": "

renderWithIndent _ other = render other

spaces :: Int -> String
spaces n = replicate n ' '

tabs :: Int -> String
tabs = concat . replicate 2 . spaces

indent :: Int -> String -> String
indent n s = spaces n ++ s

punctuate :: String -> [String] -> [String]
punctuate p []  = []
punctuate p [x] = [x]
punctuate p (x:xs) = (x ++ p) : punctuate p xs