module Network.Salvia.Handlers.Dispatching (
    Dispatcher
  , ListDispatcher
  , hDispatch
  , hListDispatch
  ) where

import Control.Monad.State

import Network.Salvia.Httpd

type Dispatcher     a b = a -> Handler b   -> Handler b -> Handler b
type ListDispatcher a b = [(a, Handler b)] -> Handler b -> Handler b

hDispatch :: (Show c, Show a) => (Context -> c) -> (a -> c -> Bool) -> Dispatcher a b
hDispatch f match a handler _default = do
  ctx <- gets f
  if a `match` ctx
    then handler
    else _default

hListDispatch :: Dispatcher a b -> ListDispatcher a b
hListDispatch disp = flip $ foldr $ uncurry disp