module IRE.Server
  ( server
  ) where

import Control.Exception.Base (bracket, catch, throwIO)
import Data.Bits ((.|.))
import Data.Yaml.Include (decodeFileEither)
import Network.Socket
       (Family(AF_INET, AF_UNIX), SockAddr(..), Socket,
        SocketOption(ReuseAddr), SocketType(Stream), bind, close,
        getSocketName, inet_addr, listen, maxListenQueue, setSocketOption,
        socket)
import Network.Wai.Handler.Warp
       (Port, defaultSettings, runSettingsSocket)
import System.Exit (exitFailure)
import System.IO (hPutStrLn, stderr)
import System.IO.Error (isDoesNotExistError)
import System.Posix.Files
       (fileExist, groupReadMode, groupWriteMode, ownerReadMode,
        ownerWriteMode, removeLink, setFileMode, socketMode)

import IRE.Application (app)
import IRE.Config (ConfigFile(..), defaultConfig)
import qualified IRE.Logging as Log
import IRE.YOLO (newDetector)

type Listen = Either Port FilePath

server :: FilePath -> FilePath -> IO ()
server rootDir configFile = do
  cf <- readConfigFile configFile
  net <- newDetector (cfYOLO cf)
  Log.start Log.Debug
  let socketSpec =
        case cfSocket cf of
          Just p -> Right p
          Nothing -> Left $ cfPort cf
  bracket
    (createSocket socketSpec)
    closeSocket
    (\sock -> do
       listen sock maxListenQueue
       runSettingsSocket defaultSettings sock =<< app rootDir net)

readConfigFile :: FilePath -> IO ConfigFile
readConfigFile f = do
  e <- fileExist f
  if e
    then do
      r <- decodeFileEither f
      case r of
        Left ex -> do
          hPutStrLn stderr $ "FATAL: " ++ f ++ ": " ++ show ex
          exitFailure
        Right cf -> return cf
    else return defaultConfig

createSocket :: Listen -> IO Socket
createSocket (Right path) = do
  removeIfExists path
  sock <- socket AF_UNIX Stream 0
  bind sock $ SockAddrUnix path
  setFileMode path $
    socketMode .|. ownerWriteMode .|. ownerReadMode .|. groupWriteMode .|.
    groupReadMode
  Log.info $ "Listening on UNIX socket `" ++ path ++ "'"
  return sock
createSocket (Left port) = do
  sock <- socket AF_INET Stream 0
  setSocketOption sock ReuseAddr 1
  addr <- inet_addr "127.0.0.1"
  bind sock $ SockAddrInet (fromIntegral port) addr
  Log.info $ "Listening on localhost:" ++ show port
  return sock

closeSocket :: Socket -> IO ()
closeSocket sock = do
  name <- getSocketName sock
  close sock
  case name of
    SockAddrUnix path -> removeIfExists path
    _ -> return ()

removeIfExists :: FilePath -> IO ()
removeIfExists fileName = removeLink fileName `catch` handleExists
  where
    handleExists e
      | isDoesNotExistError e = return ()
      | otherwise = throwIO e