hasql/library/Hasql/Settings.hs

module Hasql.Settings where

import Hasql.Prelude
import qualified Data.ByteString as B
import qualified Data.ByteString.Lazy.Builder as BB
import qualified Data.ByteString.Lazy.Builder.ASCII as BB
import qualified Data.ByteString.Lazy as BL



-- | 
-- All settings encoded in a single byte-string according to 
-- <http://www.postgresql.org/docs/9.4/static/libpq-connect.html#LIBPQ-CONNSTRING the PostgreSQL format>.
type Settings =
  ByteString

-- |
-- Encode a host, a port, a user, a password and a database into the PostgreSQL settings byte-string.
{-# INLINE settings #-}
settings :: ByteString -> Word16 -> ByteString -> ByteString -> ByteString -> Settings
settings host port user password database =
  BL.toStrict $ BB.toLazyByteString $ mconcat $ intersperse (BB.char7 ' ') $ catMaybes $
  [
    mappend (BB.string7 "host=") . BB.byteString <$> 
    mfilter (not . B.null) (pure host)
    ,
    mappend (BB.string7 "port=") . BB.word16Dec <$> 
    mfilter (/= 0) (pure port)
    ,
    mappend (BB.string7 "user=") . BB.byteString <$> 
    mfilter (not . B.null) (pure user)
    ,
    mappend (BB.string7 "password=") . BB.byteString <$> 
    mfilter (not . B.null) (pure password)
    ,
    mappend (BB.string7 "dbname=") . BB.byteString <$> 
    mfilter (not . B.null) (pure database)
  ]