-- |
--   Module      :  Network.BitTorrent.Core.PeerAddr
--   Copyright   :  (c) Sam Truzjan 2013
--                  (c) Daniel Gröber 2013
--   License     :  BSD3
--   Maintainer  :  pxqr.sta@gmail.com
--   Stability   :  provisional
--   Portability :  portable
--
--   'PeerAddr' is used to represent peer address. Currently it's
--   just peer IP and peer port but this might change in future.
--
{-# LANGUAGE TemplateHaskell            #-}
{-# LANGUAGE StandaloneDeriving         #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE DeriveDataTypeable         #-}
{-# LANGUAGE FlexibleInstances          #-}
{-# LANGUAGE DeriveFunctor              #-}
{-# LANGUAGE ViewPatterns               #-}
{-# OPTIONS -fno-warn-orphans           #-} -- for PortNumber instances
module Network.BitTorrent.Core.PeerAddr
       ( -- * Peer address
         PeerAddr(..)
       , defaultPorts
       , peerSockAddr
       , peerSocket

         -- * Peer storage
       ) where

import Control.Applicative
import Control.Monad
import Data.BEncode   as BS
import Data.BEncode.BDict (BKey)
import Data.ByteString.Char8 as BS8
import Data.Char
import Data.Default
import Data.Hashable
import Data.IP
import Data.List      as L
import Data.List.Split
import Data.Monoid
import Data.Serialize as S
import Data.String
import Data.Typeable
import Data.Word
import Network.Socket
import Text.PrettyPrint as PP hiding ((<>))
import Text.PrettyPrint.Class
import Text.Read (readMaybe)
import qualified Text.ParserCombinators.ReadP as RP

--import Data.Torrent
import Network.BitTorrent.Core.PeerId


{-----------------------------------------------------------------------
--  Port number
-----------------------------------------------------------------------}

instance BEncode PortNumber where
  toBEncode   = toBEncode    .  fromEnum
  fromBEncode = fromBEncode >=> portNumber
    where
      portNumber :: Integer -> BS.Result PortNumber
      portNumber n
        | 0 <= n && n <= fromIntegral (maxBound :: Word16)
        = pure $ fromIntegral n
        | otherwise = decodingError $ "PortNumber: " ++ show n

instance Serialize PortNumber where
  get = fromIntegral <$> getWord16be
  {-# INLINE get #-}
  put = putWord16be . fromIntegral
  {-# INLINE put #-}

instance Hashable PortNumber where
  hashWithSalt s = hashWithSalt s . fromEnum
  {-# INLINE hashWithSalt #-}

instance Pretty PortNumber where
  pretty = PP.int . fromEnum
  {-# INLINE pretty #-}

{-----------------------------------------------------------------------
--  IP addr
-----------------------------------------------------------------------}

class IPAddress i where
  toHostAddr :: i -> Either HostAddress HostAddress6

instance IPAddress IPv4 where
  toHostAddr = Left . toHostAddress
  {-# INLINE toHostAddr #-}

instance IPAddress IPv6 where
  toHostAddr = Right . toHostAddress6
  {-# INLINE toHostAddr #-}

instance IPAddress IP where
  toHostAddr (IPv4 ip) = toHostAddr ip
  toHostAddr (IPv6 ip) = toHostAddr ip
  {-# INLINE toHostAddr #-}

deriving instance Typeable IP
deriving instance Typeable IPv4
deriving instance Typeable IPv6

ipToBEncode :: Show i => i -> BValue
ipToBEncode ip = BString $ BS8.pack $ show ip
{-# INLINE ipToBEncode #-}

ipFromBEncode :: Read a => BValue -> BS.Result a
ipFromBEncode (BString (BS8.unpack -> ipStr))
  | Just ip <- readMaybe (ipStr) = pure ip
  |         otherwise            = decodingError $ "IP: " ++ ipStr
ipFromBEncode _    = decodingError $ "IP: addr should be a bstring"

instance BEncode IP where
  toBEncode   = ipToBEncode
  {-# INLINE toBEncode #-}
  fromBEncode = ipFromBEncode
  {-# INLINE fromBEncode #-}

instance BEncode IPv4 where
  toBEncode   = ipToBEncode
  {-# INLINE toBEncode #-}
  fromBEncode = ipFromBEncode
  {-# INLINE fromBEncode #-}

instance BEncode IPv6 where
  toBEncode   = ipToBEncode
  {-# INLINE toBEncode #-}
  fromBEncode = ipFromBEncode
  {-# INLINE fromBEncode #-}

-- | When 'get'ing an IP it must be 'isolate'd to the appropriate
-- number of bytes since we have no other way of telling which
-- address type we are trying to parse
instance Serialize IP where
    put (IPv4 ip) = put ip
    put (IPv6 ip) = put ip

    get = do
      n <- remaining
      case n of
        4  -> IPv4 <$> get
        16 -> IPv6 <$> get
        _ -> fail "Wrong number of bytes remaining to parse IP"

instance Serialize IPv4 where
    put = putWord32host    .  toHostAddress
    get = fromHostAddress <$> getWord32host

instance Serialize IPv6 where
    put ip = put $ toHostAddress6 ip
    get = fromHostAddress6 <$> get

instance Pretty IPv4 where
  pretty = PP.text . show
  {-# INLINE pretty #-}

instance Pretty IPv6 where
  pretty = PP.text . show
  {-# INLINE pretty #-}

instance Pretty IP where
  pretty = PP.text . show
  {-# INLINE pretty #-}

instance Hashable IPv4 where
  hashWithSalt = hashUsing toHostAddress
  {-# INLINE hashWithSalt #-}

instance Hashable IPv6 where
  hashWithSalt s a = hashWithSalt s (toHostAddress6 a)

instance Hashable IP where
  hashWithSalt s (IPv4 h) = hashWithSalt s h
  hashWithSalt s (IPv6 h) = hashWithSalt s h

{-----------------------------------------------------------------------
--  Peer addr
-----------------------------------------------------------------------}
-- TODO check semantic of ord and eq instances

-- | Peer address info normally extracted from peer list or peer
-- compact list encoding.
data PeerAddr a = PeerAddr
  { peerId   :: !(Maybe PeerId)

    -- | This is usually 'IPv4', 'IPv6', 'IP' or unresolved
    -- 'HostName'.
  , peerHost :: !a

    -- | The port the peer listenning for incoming P2P sessions.
  , peerPort :: {-# UNPACK #-} !PortNumber
  } deriving (Show, Eq, Ord, Typeable, Functor)

peer_ip_key, peer_id_key, peer_port_key :: BKey
peer_ip_key   = "ip"
peer_id_key   = "peer id"
peer_port_key = "port"

-- | The tracker's 'announce response' compatible encoding.
instance (Typeable a, BEncode a) => BEncode (PeerAddr a) where
  toBEncode PeerAddr {..} = toDict $
       peer_ip_key   .=! peerHost
    .: peer_id_key   .=? peerId
    .: peer_port_key .=! peerPort
    .: endDict

  fromBEncode = fromDict $ do
    peerAddr <$>! peer_ip_key
             <*>? peer_id_key
             <*>! peer_port_key
    where
      peerAddr = flip PeerAddr

-- | The tracker's 'compact peer list' compatible encoding. The
-- 'peerId' is always 'Nothing'.
--
--   For more info see: <http://www.bittorrent.org/beps/bep_0023.html>
--
-- TODO: test byte order
instance (Serialize a) => Serialize (PeerAddr a) where
  put PeerAddr {..} = put peerHost >> put peerPort
  get = PeerAddr Nothing <$> get <*> get

-- | @127.0.0.1:6881@
instance Default (PeerAddr IPv4) where
  def = "127.0.0.1:6881"

-- | @127.0.0.1:6881@
instance Default (PeerAddr IP) where
  def = IPv4 <$> def

-- | Example:
--
--   @peerPort \"127.0.0.1:6881\" == 6881@
--
instance IsString (PeerAddr IPv4) where
  fromString str
    | [hostAddrStr, portStr] <- splitWhen (== ':') str
    , Just hostAddr <- readMaybe hostAddrStr
    , Just portNum  <- toEnum <$> readMaybe portStr
                = PeerAddr Nothing hostAddr portNum
    | otherwise = error $ "fromString: unable to parse (PeerAddr IPv4): " ++ str

instance Read (PeerAddr IPv4) where
  readsPrec i = RP.readP_to_S $ do
    ipv4 <- RP.readS_to_P (readsPrec i)
    _    <- RP.char ':'
    port <- toEnum <$> RP.readS_to_P (readsPrec i)
    return $ PeerAddr Nothing ipv4 port

readsIPv6_port :: String -> [((IPv6, PortNumber), String)]
readsIPv6_port = RP.readP_to_S $ do
  ip <- RP.char '[' *> (RP.readS_to_P reads) <* RP.char ']'
  _ <- RP.char ':'
  port <- toEnum <$> read <$> (RP.many1 $ RP.satisfy isDigit) <* RP.eof
  return (ip,port)

instance IsString (PeerAddr IPv6) where
  fromString str
    | [((ip,port),"")] <- readsIPv6_port str =
        PeerAddr Nothing ip port
    | otherwise = error $ "fromString: unable to parse (PeerAddr IPv6): " ++ str

instance IsString (PeerAddr IP) where
  fromString str
    | '[' `L.elem` str = IPv6 <$> fromString str
    |      otherwise   = IPv4 <$> fromString str

-- | fingerprint + "at" + dotted.host.inet.addr:port
-- TODO: instances for IPv6, HostName
instance Pretty a => Pretty (PeerAddr a) where
  pretty PeerAddr {..}
    | Just pid <- peerId = pretty (fingerprint pid) <+> "at" <+> paddr
    |     otherwise      = paddr
    where
      paddr = pretty peerHost <> ":" <> text (show peerPort)

instance Hashable a => Hashable (PeerAddr a) where
  hashWithSalt s PeerAddr {..} =
    s `hashWithSalt` peerId `hashWithSalt` peerHost `hashWithSalt` peerPort

-- | Ports typically reserved for bittorrent P2P listener.
defaultPorts :: [PortNumber]
defaultPorts =  [6881..6889]

_resolvePeerAddr :: (IPAddress i) => PeerAddr HostName -> PeerAddr i
_resolvePeerAddr = undefined

_peerSockAddr :: PeerAddr IP -> (Family, SockAddr)
_peerSockAddr PeerAddr {..} =
    case peerHost of
          IPv4 ipv4 ->
              (AF_INET, SockAddrInet peerPort (toHostAddress  ipv4))
          IPv6 ipv6 ->
              (AF_INET6, SockAddrInet6 peerPort 0 (toHostAddress6 ipv6) 0)

peerSockAddr :: PeerAddr IP -> SockAddr
peerSockAddr = snd . _peerSockAddr

-- | Create a socket connected to the address specified in a peerAddr
peerSocket :: SocketType -> PeerAddr IP -> IO Socket
peerSocket socketType pa = do
    let (family, addr) = _peerSockAddr pa
    sock <- socket family socketType defaultProtocol
    connect sock addr
    return sock