{-
Module:  Net.Mptcp.PathManager
Description :
Maintainer  : matt
Portability : Linux

Userspace abstractions for MPTCP path management

-}


module Net.Mptcp.PathManager (
    PathManager (..)
    , NetworkInterface(..)
    , ExistingInterfaces
    , PathManagerConfig
    -- , loadConnectionsFromFile
    , mapIPtoInterfaceIdx
    , defaultPathManagerConfig
    -- TODO don't export / move to its own file
    , handleAddr
    , globalInterfaces
) where

import Prelude hiding (concat, init)

import Control.Concurrent
import qualified Data.Map as Map
import Data.Word (Word32)
import Debug.Trace
import Net.IP
import Net.Mptcp
-- import Net.Tcp
import Net.Mptcp.Netlink
import Net.IPAddress

-- hackage
import System.Linux.Netlink as NL
import qualified System.Linux.Netlink.Route as NLR
-- import System.Linux.Netlink.Constants (eRTM_NEWADDR)
import System.Linux.Netlink.Constants as NLC
-- import qualified System.Linux.Netlink.Simple as NLS
import Data.ByteString (ByteString, empty)
import Data.ByteString.Char8 (init, unpack)
import Data.Maybe (fromMaybe)
import System.IO.Unsafe
-- import Data.Aeson

{-# NOINLINE globalInterfaces #-}
globalInterfaces :: MVar ExistingInterfaces
globalInterfaces = unsafePerformIO newEmptyMVar


data PathManagerConfig = PathManagerConfig {
  pmcIgnoreInterfaces :: [String]
}

defaultPathManagerConfig :: PathManagerConfig
defaultPathManagerConfig = PathManagerConfig {
  pmcIgnoreInterfaces = interfacesToIgnore
}

interfacesToIgnore :: [String]
interfacesToIgnore = [
    "virbr0"
  , "virbr1"
  , "docker0"
  , "nlmon0"
  -- , "ppp0"
  -- , "lo"
  ]

-- basically a retranscription of NLR.NAddrMsg
data NetworkInterface = NetworkInterface {
  ipAddress     :: IP,   -- ^ Should be a list or a set
  interfaceName :: String,  -- ^ eth0 / ppp0
  interfaceId   :: Word32  -- ^ refers to addrInterfaceIndex
} deriving Show


-- [NetworkInterface]
type ExistingInterfaces = Map.Map IP NetworkInterface



-- |
mapIPtoInterfaceIdx :: ExistingInterfaces -> IP -> Maybe Word32
mapIPtoInterfaceIdx paths ip =
    interfaceId <$> Map.lookup ip paths

-- class AvailableIPsContainer a where

-- | Load a list of connections from a json file
-- loadConnectionsFromFile :: FilePath -> IO [TcpConnection]
-- loadConnectionsFromFile filename = do
--   -- Log.info ("Loading connections whitelist from " <> tshow filename <> "...")
--   filteredConnectionsStr <- BL.readFile filename
--   case Data.Aeson.eitherDecode filteredConnectionsStr of
--     Left errMsg -> error ("Failed loading " ++ filename ++ ":\n" ++ errMsg)
--     Right list  -> return list


-- |Reimplements
-- TODO we should not need the socket
-- onMasterEstablishement
data PathManager = PathManager {
    name                     :: String
    -- interfacesToIgnore :: [String]
  , onMasterEstablishement :: MptcpSocket -> MptcpConnection -> ExistingInterfaces -> [MptcpPacket]
  -- , idManager ::
  -- ^ to keep track of advertised/present ids/generate new ones
}

-- } deriving PathManager


handleInterfaceNotification
  :: AddressFamily -> Attributes -> Word32 -> Maybe NetworkInterface
handleInterfaceNotification addrFamily attrs addrIntf =

  -- filter on flags too (UP), should be != LOOPBACK
  -- lo: <LOOPBACK,UP,LOWER_UP> and
  -- eno1: <BROADCAST,MULTICAST,UP,LOWER_UP
  case ifNameM of
    Nothing -> Nothing
    Just ifName -> case (elem ifName interfacesToIgnore) of
        True  -> Nothing
        False -> Just $ NetworkInterface ip ifName addrIntf
  where
    -- gets the bytestring / assume it always work
    ipBstr = fromMaybe empty (NLR.getIFAddr attrs)
    ifNameBstr = (Map.lookup NLC.eIFLA_IFNAME attrs)
    ifNameM = getString <$> ifNameBstr
    -- ip = getIPFromByteString addrFamily ipBstr
    ip = case (getIPFromByteString addrFamily ipBstr) of
      Right val -> val
      Left err  -> undefined

-- taken from netlink
getString :: ByteString -> String
getString b = unpack (init b)


-- TODO handle remove/new event move to PathManager
-- todo should be pure and let daemon
handleAddr :: [String] -> Either String NLR.RoutePacket -> IO ()
handleAddr _ (Left errStr) = putStrLn $ "Error decoding packet: " ++ errStr
handleAddr _ (Right (DoneMsg hdr)) = putStrLn $ "Error decoding packet: " ++ show hdr
handleAddr _ (Right (ErrorMsg hdr errorInt errorBstr)) = putStrLn $ "Error decoding packet: " ++ show hdr
-- TODO need handleMessage pkt
-- family maskLen flags scope addrIntf
handleAddr cfg (Right (Packet hdr pkt attrs)) = do
  (putStrLn $ "received packet" ++ show pkt)
  oldIntfs <- trace "taking MVAR" (takeMVar globalInterfaces)

  let toto = (case pkt of
        arg@NLR.NAddrMsg{} ->
          let resIntf = handleInterfaceNotification (NLR.addrFamily arg) attrs (NLR.addrInterfaceIndex arg)
          in case resIntf of
            Nothing -> oldIntfs
            Just newIntf -> let
              ip = ipAddress newIntf
              -- todo use cae ?
              in if msgType == eRTM_NEWADDR
                    then trace "adding ip" (Map.insert ip newIntf oldIntfs)
                    -- >> putStrLn "Added interface"
                    else if msgType == eRTM_GETADDR
                    then trace "GET_ADDR" oldIntfs

                    else if msgType == eRTM_DELADDR
                    then
                    trace "deleting ip" (Map.delete ip oldIntfs)
                    -- >> putStrLn "Removed interface"
                    else trace "other type" oldIntfs

        -- _ -> error "can't be anything else"
        arg@NLR.NNeighMsg{} -> trace "neighbor msg" oldIntfs
        arg@NLR.NLinkMsg{} -> trace "link msg" oldIntfs
        )

  trace ("putting mvar") (putMVar globalInterfaces $! (toto))

 where
    -- gets the bytestring
    msgType = messageType hdr

-- (arg@DiagTcpInfo{})


---- Updates the list of interfaces
---- should run in background
----
--trackSystemInterfaces :: IO()
--trackSystemInterfaces = do
--  -- check routing information
--  routingSock <- NLS.makeNLHandle (const $ pure ()) =<< NL.makeSocket
--  let cb = NLS.NLCallback (pure ()) (handleAddr . runGet getGenPacket)
--  NLS.nlPostMessage routingSock queryAddrs cb
--  NLS.nlWaitCurrent routingSock
--  dumpSystemInterfaces



-- fullmesh / ndiffports
    -- []

  -- where
  --   -- genPkt NetworkInterface
  --   -- let newSfPkt = newSubflowPkt mptcpSock newSubflowAttrs
  --   newSubflowAttrs = [
  --         MptcpAttrToken $ connectionToken con
  --       ]
  -- ++ (subflowAttrs $ masterSf { srcPort = 0 })