{-# LANGUAGE
    FlexibleInstances
  , MultiParamTypeClasses
  , OverloadedStrings
  , TemplateHaskell
  , UnicodeSyntax
  #-}
-- |An internal module for HTTP version numbers.
module Network.HTTP.Lucu.HttpVersion
    ( HttpVersion(..)
    )
    where
import Control.Applicative
import Control.Applicative.Unicode
import Data.Ascii (Ascii, AsciiBuilder)
import Data.Attoparsec.Char8
import Data.Attoparsec.Parsable
import Data.ByteString (ByteString)
import Data.Convertible.Base
import Data.Convertible.Instances.Ascii ()
import Data.Convertible.Utils
import Data.Monoid.Unicode
import Prelude hiding (min)
import Prelude.Unicode

-- |An HTTP version consists of major and minor versions.
data HttpVersion
    = HttpVersion !Int !Int
      deriving (Eq, Show)

instance Ord HttpVersion where
    (HttpVersion majA minA) `compare` (HttpVersion majB minB)
        | majA > majB = GT
        | majA < majB = LT
        | minA > minB = GT
        | minA < minB = LT
        | otherwise   = EQ

instance ConvertSuccess HttpVersion Ascii where
    {-# INLINE convertSuccess #-}
    convertSuccess = convertSuccessVia ((⊥) ∷ AsciiBuilder)

instance ConvertSuccess HttpVersion AsciiBuilder where
    {-# INLINE convertSuccess #-}
    convertSuccess v
        = case v of
            -- Optimisation for special cases.
            HttpVersion 1 0 → cs ("HTTP/1.0" ∷ Ascii)
            HttpVersion 1 1 → cs ("HTTP/1.1" ∷ Ascii)
            -- General (but almost never occuring) cases.
            HttpVersion maj min
                → cs ("HTTP/" ∷ Ascii)     ⊕
                  convertUnsafe (show maj) ⊕
                  cs ("."     ∷ Ascii)     ⊕
                  convertUnsafe (show min)

deriveAttempts [ ([t| HttpVersion |], [t| Ascii        |])
               , ([t| HttpVersion |], [t| AsciiBuilder |])
               ]

instance Parsable ByteString HttpVersion where
    {-# INLINEABLE parser #-}
    parser = string "HTTP/"
             *>
             (HttpVersion <$> decimal ⊛ (char '.' *> decimal))