# Nim-LibP2P
# Copyright (c) 2023 Status Research & Development GmbH
# Licensed under either of
#  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
#  * MIT license ([LICENSE-MIT](LICENSE-MIT))
# at your option.
# This file may not be copied, modified, or distributed except according to
# those terms.

## `Identify <https://docs.libp2p.io/concepts/protocols/#identify>`_ and
## `Push Identify <https://docs.libp2p.io/concepts/protocols/#identify-push>`_ implementation

{.push raises: [].}

import std/[sequtils, options, strutils, sugar]
import stew/results
import chronos, chronicles
import ../protobuf/minprotobuf,
       ../peerinfo,
       ../stream/connection,
       ../peerid,
       ../crypto/crypto,
       ../multiaddress,
       ../multicodec,
       ../protocols/protocol,
       ../utility,
       ../errors,
       ../observedaddrmanager

export observedaddrmanager

logScope:
  topics = "libp2p identify"

const
  IdentifyCodec* = "/ipfs/id/1.0.0"
  IdentifyPushCodec* = "/ipfs/id/push/1.0.0"
  ProtoVersion* = "ipfs/0.1.0"
  AgentVersion* = "nim-libp2p/0.0.1"

type
  IdentifyError* = object of LPError
  IdentityNoMatchError* = object of IdentifyError
  IdentityInvalidMsgError* = object of IdentifyError
  IdentifyNoPubKeyError* = object of IdentifyError

  IdentifyInfo* {.public.} = object
    pubkey*: Option[PublicKey]
    peerId*: PeerId
    addrs*: seq[MultiAddress]
    observedAddr*: Option[MultiAddress]
    protoVersion*: Option[string]
    agentVersion*: Option[string]
    protos*: seq[string]
    signedPeerRecord*: Option[Envelope]

  Identify* = ref object of LPProtocol
    peerInfo*: PeerInfo
    sendSignedPeerRecord*: bool
    observedAddrManager*: ObservedAddrManager

  IdentifyPushHandler* = proc (
    peer: PeerId,
    newInfo: IdentifyInfo):
    Future[void]
    {.gcsafe, raises: [], public.}

  IdentifyPush* = ref object of LPProtocol
    identifyHandler: IdentifyPushHandler

chronicles.expandIt(IdentifyInfo):
  pubkey = ($it.pubkey).shortLog
  addresses = it.addrs.map(x => $x).join(",")
  protocols = it.protos.map(x => $x).join(",")
  observable_address = $it.observedAddr
  proto_version = it.protoVersion.get("None")
  agent_version = it.agentVersion.get("None")
  signedPeerRecord =
    # The SPR contains the same data as the identify message
    # would be cumbersome to log
    if iinfo.signedPeerRecord.isSome(): "Some"
    else: "None"

proc encodeMsg(peerInfo: PeerInfo, observedAddr: Opt[MultiAddress], sendSpr: bool): ProtoBuffer
  {.raises: [].} =
  result = initProtoBuffer()

  let pkey = peerInfo.publicKey

  result.write(1, pkey.getBytes().expect("valid key"))
  for ma in peerInfo.addrs:
    result.write(2, ma.data.buffer)
  for proto in peerInfo.protocols:
    result.write(3, proto)
  observedAddr.withValue(observed):
    result.write(4, observed.data.buffer)
  let protoVersion = ProtoVersion
  result.write(5, protoVersion)
  let agentVersion = if peerInfo.agentVersion.len <= 0:
    AgentVersion
  else:
    peerInfo.agentVersion
  result.write(6, agentVersion)

  ## Optionally populate signedPeerRecord field.
  ## See https://github.com/libp2p/go-libp2p/blob/ddf96ce1cfa9e19564feb9bd3e8269958bbc0aba/p2p/protocol/identify/pb/identify.proto for reference.
  if sendSpr:
    peerInfo.signedPeerRecord.envelope.encode().toOpt().withValue(sprBuff):
      result.write(8, sprBuff)

  result.finish()

proc decodeMsg*(buf: seq[byte]): Opt[IdentifyInfo] =
  var
    iinfo: IdentifyInfo
    pubkey: PublicKey
    oaddr: MultiAddress
    protoVersion: string
    agentVersion: string
    signedPeerRecord: SignedPeerRecord

  var pb = initProtoBuffer(buf)
  if ? pb.getField(1, pubkey).toOpt():
    iinfo.pubkey = some(pubkey)
    if ? pb.getField(8, signedPeerRecord).toOpt() and
      pubkey == signedPeerRecord.envelope.publicKey:
      iinfo.signedPeerRecord = some(signedPeerRecord.envelope)
  discard ? pb.getRepeatedField(2, iinfo.addrs).toOpt()
  discard ? pb.getRepeatedField(3, iinfo.protos).toOpt()
  if ? pb.getField(4, oaddr).toOpt():
    iinfo.observedAddr = some(oaddr)
  if ? pb.getField(5, protoVersion).toOpt():
    iinfo.protoVersion = some(protoVersion)
  if ? pb.getField(6, agentVersion).toOpt():
    iinfo.agentVersion = some(agentVersion)

  debug "decodeMsg: decoded identify", iinfo
  Opt.some(iinfo)

proc new*(
  T: typedesc[Identify],
  peerInfo: PeerInfo,
  sendSignedPeerRecord = false,
  observedAddrManager = ObservedAddrManager.new(),
  ): T =
  let identify = T(
    peerInfo: peerInfo,
    sendSignedPeerRecord: sendSignedPeerRecord,
    observedAddrManager: observedAddrManager,
  )
  identify.init()
  identify

method init*(p: Identify) =
  proc handle(conn: Connection, proto: string) {.async, gcsafe, closure.} =
    try:
      trace "handling identify request", conn
      var pb = encodeMsg(p.peerInfo, conn.observedAddr, p.sendSignedPeerRecord)
      await conn.writeLp(pb.buffer)
    except CancelledError as exc:
      raise exc
    except CatchableError as exc:
      trace "exception in identify handler", exc = exc.msg, conn
    finally:
      trace "exiting identify handler", conn
      await conn.closeWithEOF()

  p.handler = handle
  p.codec = IdentifyCodec

proc identify*(self: Identify,
               conn: Connection,
               remotePeerId: PeerId): Future[IdentifyInfo] {.async, gcsafe.} =
  trace "initiating identify", conn
  var message = await conn.readLp(64*1024)
  if len(message) == 0:
    trace "identify: Empty message received!", conn
    raise newException(IdentityInvalidMsgError, "Empty message received!")

  var info = decodeMsg(message).valueOr: raise newException(IdentityInvalidMsgError, "Incorrect message received!")
  let
    pubkey = info.pubkey.valueOr: raise newException(IdentityInvalidMsgError, "No pubkey in identify")
    peer = PeerId.init(pubkey).valueOr: raise newException(IdentityInvalidMsgError, $error)

  if peer != remotePeerId:
    trace "Peer ids don't match", remote = peer, local = remotePeerId
    raise newException(IdentityNoMatchError, "Peer ids don't match")
  info.peerId = peer

  info.observedAddr.withValue(observed):
    # Currently, we use the ObservedAddrManager only to find our dialable external NAT address. Therefore, addresses
    # like "...\p2p-circuit\p2p\..." and "\p2p\..." are not useful to us.
    if observed.contains(multiCodec("p2p-circuit")).get(false) or P2PPattern.matchPartial(observed):
      trace "Not adding address to ObservedAddrManager.", observed
    elif not self.observedAddrManager.addObservation(observed):
      trace "Observed address is not valid.", observedAddr = observed
  return info

proc new*(T: typedesc[IdentifyPush], handler: IdentifyPushHandler = nil): T {.public.} =
  ## Create a IdentifyPush protocol. `handler` will be called every time
  ## a peer sends us new `PeerInfo`
  let identifypush = T(identifyHandler: handler)
  identifypush.init()
  identifypush

proc init*(p: IdentifyPush) =
  proc handle(conn: Connection, proto: string) {.async, gcsafe, closure.} =
    trace "handling identify push", conn
    try:
      var message = await conn.readLp(64*1024)

      var identInfo = decodeMsg(message).valueOr:
        raise newException(IdentityInvalidMsgError, "Incorrect message received!")

      identInfo.pubkey.withValue(pubkey):
        let receivedPeerId = PeerId.init(pubkey).tryGet()
        if receivedPeerId != conn.peerId:
          raise newException(IdentityNoMatchError, "Peer ids don't match")
        identInfo.peerId = receivedPeerId

      trace "triggering peer event", peerInfo = conn.peerId
      if not isNil(p.identifyHandler):
        await p.identifyHandler(conn.peerId, identInfo)
    except CancelledError as exc:
      raise exc
    except CatchableError as exc:
      info "exception in identify push handler", exc = exc.msg, conn
    finally:
      trace "exiting identify push handler", conn
      await conn.closeWithEOF()

  p.handler = handle
  p.codec = IdentifyPushCodec

proc push*(p: IdentifyPush, peerInfo: PeerInfo, conn: Connection) {.async, public.} =
  ## Send new `peerInfo`s to a connection
  var pb = encodeMsg(peerInfo, conn.observedAddr, true)
  await conn.writeLp(pb.buffer)