-----------------------------------------------------------------------------
-- |
-- Module      :  Data.Show
-- Copyright   :  (c) 2020-2021 EMQ Technologies Co., Ltd.
-- License     :  BSD-style (see the LICENSE file)
--
-- Maintainer  :  Feng Lee, feng@emqx.io
--                Yang M, yangm@emqx.io
-- Stability   :  experimental
-- Portability :  portable
--
-- The Show typeclass.
--
-----------------------------------------------------------------------------
module Data.Show
  ( class Show, show, showAny
  ) where

import Data.Maybe (Maybe(..))
import Data.Unit (Unit)
import Data.List ((++))
import Data.Binary as B
import Data.Ordering (Ordering(..))

class Show a where
  show :: a -> String

instance Show Atom where
  show = showAtomImpl

instance Show Boolean where
  show true = "true"
  show false = "false"

instance Show Integer where
  show = showIntImpl

instance Show Float where
  show f = showFloatImpl f

instance Show Char where
  show c = showCharImpl c

instance Show [Char] where
  show x = "\"" ++ x ++ "\""

else instance Show a => Show [a] where
  show x = "[" ++ showListImpl x ++ "]"

instance Show Unit where
  show _ = "unit"

instance Show a => Show (Maybe a) where
  show Nothing = "Nothing"
  show (Just x) = "Just " ++ show x

instance Show Binary where
  show x = show (B.toList x)

instance Show Ordering where
  show LT = "LT"
  show GT = "GT"
  show EQ = "EQ"

foreign import showAtomImpl :: Atom -> String
foreign import showIntImpl :: Integer -> String
foreign import showFloatImpl :: Float -> String
foreign import showCharImpl :: Char -> String

foreign import showAny :: forall a. a -> String

showListImpl :: forall a. (Show a) => [a] -> String
showListImpl [] = ""
showListImpl [x] = show x
showListImpl [x | xs] = show x ++ ", " ++ showListImpl xs

instance (Show a, Show b) => Show (a, b) where
  show (a', b') = "(" ++ show a' ++ ", " ++ show b' ++ ")"