{-# LANGUAGE
    UnicodeSyntax
  #-}
-- |The entry point of Lucu httpd.
module Network.HTTP.Lucu.Httpd
    ( FallbackHandler
    , runHttpd
    )
    where
import Control.Concurrent
import Control.Exception
import Control.Monad
import Control.Monad.Unicode
import Data.Maybe
import Network.BSD
import Network.Socket
import Network.HTTP.Lucu.Config
import Network.HTTP.Lucu.Interaction
import Network.HTTP.Lucu.RequestReader
import Network.HTTP.Lucu.Resource.Tree
import Network.HTTP.Lucu.ResponseWriter
import Network.HTTP.Lucu.SocketLike as SL

-- |This is the entry point of Lucu httpd. It listens to a socket and
-- waits for clients. 'runHttpd' never stops by itself so the only way
-- to stop it is to raise an exception in the thread running it.
--
-- Example:
--
-- > {-# LANGUAGE OverloadedStrings #-}
-- > module Main where
-- > import Network.HTTP.Lucu
-- > 
-- > main :: IO ()
-- > main = let config    = defaultConfig
-- >            resources = mkResTree [ ([], helloWorld) ]
-- >        in
-- >          runHttpd config resourcees []
-- >
-- > helloWorld :: ResourceDef
-- > helloWorld = emptyResource {
-- >                resGet
-- >                  = Just $ do setContentType $ parseMIMEType "text/plain"
-- >                              putChunk "Hello, world!"
-- >              }
runHttpd ∷ Config → ResTree → [FallbackHandler] → IO ()
runHttpd cnf tree fbs
    = withSocketsDo $
      do let launchers
                 = catMaybes
                   [ do scnf ← cnfSSLConfig    cnf
                        addr ← cnfServerV4Addr cnf
                        return ( do so ← listenOn AF_INET addr (sslServerPort scnf)
                                    launchListener (sslContext scnf, so)
                               )
                   , do scnf ← cnfSSLConfig    cnf
                        addr ← cnfServerV6Addr cnf
                        return ( do so ← listenOn AF_INET6 addr (sslServerPort scnf)
                                    launchListener (sslContext scnf, so)
                               )
                   , do addr ← cnfServerV4Addr cnf
                        return ( launchListener =≪ listenOn AF_INET addr (cnfServerPort cnf)
                               )
                   , do addr ← cnfServerV6Addr cnf
                        return ( launchListener =≪ listenOn AF_INET6 addr (cnfServerPort cnf)
                               )
                   ]
         sequence_ launchers
         waitForever
    where
      launchListener ∷ SocketLike s ⇒ s → IO ()
      launchListener so
          = do p ← SL.socketPort so
               -- FIXME: Don't throw away the thread ID as we can't
               -- kill it later then. [1]
               void $ forkIO $ httpLoop p so

      listenOn ∷ Family → HostName → ServiceName → IO Socket
      listenOn fam host srv
          = do proto ← getProtocolNumber "tcp"
               let hints = defaultHints {
                             addrFlags      = [AI_PASSIVE]
                           , addrFamily     = fam
                           , addrSocketType = Stream
                           , addrProtocol   = proto
                           }
               addrs ← getAddrInfo (Just hints) (Just host) (Just srv)
               let addr = head addrs
               bracketOnError
                   (socket (addrFamily addr) (addrSocketType addr) (addrProtocol addr))
                   sClose
                   (\ sock →
                        do setSocketOption sock ReuseAddr 1
                           bindSocket sock (addrAddress addr)
                           listen sock maxListenQueue
                           return sock
                   )

      httpLoop ∷ SocketLike s ⇒ PortNumber → s → IO ()
      httpLoop port so
          = do (h, addr)  ← SL.accept so
               tQueue     ← mkInteractionQueue
               readerTID  ← forkIO $ requestReader cnf tree fbs h port addr tQueue
               _writerTID ← forkIO $ responseWriter cnf h tQueue readerTID
               httpLoop port so

      waitForever ∷ IO ()
      waitForever = forever (threadDelay 1000000)