Types.hs

-- |Types used by request handlers.
module Web.Seacat.RequestHandler.Types
    ( FileInfo(..)
    , PathInfo(..)
    , module Web.Seacat.RequestHandler.Types
    ) where

import Control.Applicative((<$>))
import Control.Monad.Trans.Reader (ReaderT, ask)
import Data.ByteString.Lazy.Char8 (ByteString)
import Data.ConfigFile (ConfigParser)
import Data.Text (Text)
import Database.Persist.Sql (SqlPersistM)
import Network.Wai (Request, Response)
import Network.Wai.Parse (FileInfo(..))
import Web.Routes.PathInfo (PathInfo(..))

-- |Type to represent a Seacat request
data Cry r = Cry
    { _req    :: Request
    -- ^ The underlying WAI request.

    , _params :: [(Text, Text)]
    -- ^ The parameters, parsed once before the top-level handler is
    -- called.

    , _files  :: [(Text, FileInfo ByteString)]
    -- ^ The files, stored in memory as lazy bytestrings, and parsed
    -- out of the request once at the beginning.

    , _conf :: ConfigParser
    -- ^ The contents of the configuration file

    , _mkurl :: MkUrl r
    -- ^ The URL building function
    }

-- |Function to make URLs from some routing type
type MkUrl r = r -> [(Text, Text)] -> Text

-- |Function which handles a request
type RequestProcessor r = ReaderT (Cry r) SqlPersistM

-- |`RequestProcessor` specialised to producing a `Response`. All
-- routes should go to a function of type `PathInfo r => Handler r`.
type Handler r = RequestProcessor r Response

-- |Get the configuration from a `RequestProcessor`
askConf :: PathInfo r => RequestProcessor r ConfigParser
askConf = _conf <$> askCry

-- |Get the URL maker from a `RequestProcessor`
askMkUrl :: PathInfo r => RequestProcessor r (MkUrl r)
askMkUrl = _mkurl <$> askCry

-- |Get the seacat request from a `RequestProcessor`
askCry :: PathInfo r => RequestProcessor r (Cry r)
askCry = ask

-- |Get the WAI request from a `RequestProcessor`
askReq :: PathInfo r => RequestProcessor r Request
askReq = _req <$> askCry