module Network.HTTP.Lucu.ContentCoding
    ( acceptEncodingListP
    , normalizeCoding
    , unnormalizeCoding
    , orderAcceptEncodings
    )
    where

import           Data.Char
import           Data.Maybe
import           Network.HTTP.Lucu.Parser
import           Network.HTTP.Lucu.Parser.Http


acceptEncodingListP :: Parser [(String, Maybe Double)]
acceptEncodingListP = allowEOF $! listOf accEncP

      
accEncP :: Parser (String, Maybe Double)
accEncP = do coding <- token
             qVal   <- option Nothing
                       $ do string ";q="
                            q <- qvalue
                            return $ Just q
             return (normalizeCoding coding, qVal)


normalizeCoding :: String -> String
normalizeCoding coding
    = case map toLower coding of
        "x-gzip"     -> "gzip"
        "x-compress" -> "compress"
        other        -> other


unnormalizeCoding :: String -> String
unnormalizeCoding coding
    = case map toLower coding of
        "gzip"     -> "x-gzip"
        "compress" -> "x-compress"
        other        -> other


orderAcceptEncodings :: (String, Maybe Double) -> (String, Maybe Double) -> Ordering
orderAcceptEncodings (_, q1) (_, q2)
    = fromMaybe 0 q1 `compare` fromMaybe 0 q2