gemcap/src/Network/GemServ.hs

{-|

Module      : Network.GemServ
Description : Gemini Server Stuff
Copyright   : (C) Jonathan Lamothe
License     : AGPL-3.0-or-later
Maintainer  : jonathan@jlamothe.net
Stability   : experimental
Portability : POSIX

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as
published by the Free Software Foundation, either version 3 of the
License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Affero General Public License for more details.

You should have received a copy of the GNU Affero General Public
License along with this program.  If not, see
<https://www.gnu.org/licenses/>.

-}

module Network.GemServ (
  encodeRequest,
  escapeString
) where

import Data.Char (ord)
import Data.List (intercalate)

import Network.GemServ.Types

-- | Encodes a 'Request' into a 'String'
encodeRequest :: Request -> String
encodeRequest req =
  "gemini://" ++ authority ++ "/" ++ path ++ query
  where
    authority = reqHost req ++ case reqPort req of
      Just port -> ':' : show port
      Nothing   -> ""
    path = intercalate "/" $ map escapeString $ reqPath req
    query = case reqQuery req of
      "" -> ""
      q  -> '?' : escapeString q

-- | add required escape sequences to a string
escapeString :: String -> String
escapeString = concatMap $ \ch ->
  if ch `elem` unescaped
  then [ch]
  else '%' : toHex ch
  where
    unescaped = ['0'..'9'] ++ ['A'..'Z'] ++ ['a'..'z'] ++ "~-_."
    toHex ch  = let
      n    = ord ch
      high = n `div` 16
      low  = n `mod` 16
      in [hexDigits !! high, hexDigits !! low]

hexDigits :: String
hexDigits = ['0'..'9'] ++ ['a'..'f']

--jl