## Nim-Codex
## Copyright (c) 2022 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.

{.push raises: [].}

import std/algorithm
import std/net
import std/sequtils

import pkg/chronos
import pkg/libp2p/[cid, multicodec, routing_record, signed_envelope]
import pkg/questionable
import pkg/questionable/results
import pkg/contractabi/address as ca
import pkg/codexdht/discv5/[routing_table, protocol as discv5]
from pkg/nimcrypto import keccak256

import ./rng
import ./errors
import ./logutils

export discv5

# TODO: If generics in methods had not been
# deprecated, this could have been implemented
# much more elegantly.

logScope:
  topics = "codex discovery"

type Discovery* = ref object of RootObj
  protocol*: discv5.Protocol # dht protocol
  key: PrivateKey # private key
  peerId: PeerId # the peer id of the local node
  announceAddrs*: seq[MultiAddress] # addresses announced as part of the provider records
  providerRecord*: ?SignedPeerRecord
    # record to advertice node connection information, this carry any
    # address that the node can be connected on
  dhtRecord*: ?SignedPeerRecord # record to advertice DHT connection information
  isStarted: bool

proc toNodeId*(cid: Cid): NodeId =
  ## Cid to discovery id
  ##

  readUintBE[256](keccak256.digest(cid.data.buffer).data)

proc toNodeId*(host: ca.Address): NodeId =
  ## Eth address to discovery id
  ##

  readUintBE[256](keccak256.digest(host.toArray).data)

proc findPeer*(
    d: Discovery, peerId: PeerId
): Future[?PeerRecord] {.async: (raises: [CancelledError]).} =
  trace "protocol.resolve..."
  ## Find peer using the given Discovery object
  ##

  try:
    let node = await d.protocol.resolve(toNodeId(peerId))

    return
      if node.isSome():
        node.get().record.data.some
      else:
        PeerRecord.none
  except CancelledError as exc:
    warn "Error finding peer", peerId = peerId, exc = exc.msg
    raise exc
  except CatchableError as exc:
    warn "Error finding peer", peerId = peerId, exc = exc.msg

  return PeerRecord.none

method find*(
    d: Discovery, cid: Cid
): Future[seq[SignedPeerRecord]] {.async: (raises: [CancelledError]), base.} =
  ## Find block providers
  ##

  try:
    without providers =? (await d.protocol.getProviders(cid.toNodeId())).mapFailure,
      error:
      warn "Error finding providers for block", cid, error = error.msg

    return providers.filterIt(not (it.data.peerId == d.peerId))
  except CancelledError as exc:
    warn "Error finding providers for block", cid, exc = exc.msg
    raise exc
  except CatchableError as exc:
    warn "Error finding providers for block", cid, exc = exc.msg

method provide*(d: Discovery, cid: Cid) {.async: (raises: [CancelledError]), base.} =
  ## Provide a block Cid
  ##
  try:
    let nodes = await d.protocol.addProvider(cid.toNodeId(), d.providerRecord.get)

    if nodes.len <= 0:
      warn "Couldn't provide to any nodes!"
  except CancelledError as exc:
    warn "Error providing block", cid, exc = exc.msg
    raise exc
  except CatchableError as exc:
    warn "Error providing block", cid, exc = exc.msg

method find*(
    d: Discovery, host: ca.Address
): Future[seq[SignedPeerRecord]] {.async: (raises: [CancelledError]), base.} =
  ## Find host providers
  ##

  try:
    trace "Finding providers for host", host = $host
    without var providers =? (await d.protocol.getProviders(host.toNodeId())).mapFailure,
      error:
      trace "Error finding providers for host", host = $host, exc = error.msg
      return

    if providers.len <= 0:
      trace "No providers found", host = $host
      return

    providers.sort do(a, b: SignedPeerRecord) -> int:
      system.cmp[uint64](a.data.seqNo, b.data.seqNo)

    return providers
  except CancelledError as exc:
    warn "Error finding providers for host", host = $host, exc = exc.msg
    raise exc
  except CatchableError as exc:
    warn "Error finding providers for host", host = $host, exc = exc.msg

method provide*(
    d: Discovery, host: ca.Address
) {.async: (raises: [CancelledError]), base.} =
  ## Provide hosts
  ##

  try:
    trace "Providing host", host = $host
    let nodes = await d.protocol.addProvider(host.toNodeId(), d.providerRecord.get)
    if nodes.len > 0:
      trace "Provided to nodes", nodes = nodes.len
  except CancelledError as exc:
    warn "Error providing host", host = $host, exc = exc.msg
    raise exc
  except CatchableError as exc:
    warn "Error providing host", host = $host, exc = exc.msg

method removeProvider*(
    d: Discovery, peerId: PeerId
): Future[void] {.base, async: (raises: [CancelledError]).} =
  ## Remove provider from providers table
  ##

  trace "Removing provider", peerId
  try:
    await d.protocol.removeProvidersLocal(peerId)
  except CancelledError as exc:
    warn "Error removing provider", peerId = peerId, exc = exc.msg
    raise exc
  except CatchableError as exc:
    warn "Error removing provider", peerId = peerId, exc = exc.msg
  except Exception as exc: # Something in discv5 is raising Exception
    warn "Error removing provider", peerId = peerId, exc = exc.msg
    raiseAssert("Unexpected Exception in removeProvider")

proc updateAnnounceRecord*(d: Discovery, addrs: openArray[MultiAddress]) =
  ## Update providers record
  ##

  d.announceAddrs = @addrs

  info "Updating announce record", addrs = d.announceAddrs
  d.providerRecord = SignedPeerRecord
    .init(d.key, PeerRecord.init(d.peerId, d.announceAddrs))
    .expect("Should construct signed record").some

  if not d.protocol.isNil:
    d.protocol.updateRecord(d.providerRecord).expect("Should update SPR")

proc updateDhtRecord*(d: Discovery, addrs: openArray[MultiAddress]) =
  ## Update providers record
  ##

  info "Updating Dht record", addrs = addrs
  d.dhtRecord = SignedPeerRecord
    .init(d.key, PeerRecord.init(d.peerId, @addrs))
    .expect("Should construct signed record").some

  if not d.protocol.isNil:
    d.protocol.updateRecord(d.dhtRecord).expect("Should update SPR")

proc start*(d: Discovery) {.async: (raises: []).} =
  try:
    d.protocol.open()
    await d.protocol.start()
    d.isStarted = true
  except CatchableError as exc:
    error "Error starting discovery", exc = exc.msg

proc stop*(d: Discovery) {.async: (raises: []).} =
  if not d.isStarted:
    warn "Discovery not started, skipping stop"
    return

  try:
    await noCancel d.protocol.closeWait()
  except CatchableError as exc:
    error "Error stopping discovery", exc = exc.msg

proc new*(
    T: type Discovery,
    key: PrivateKey,
    bindIp = IPv4_any(),
    bindPort = 0.Port,
    announceAddrs: openArray[MultiAddress],
    bootstrapNodes: openArray[SignedPeerRecord] = [],
    store: Datastore = SQLiteDatastore.new(Memory).expect("Should not fail!"),
): Discovery =
  ## Create a new Discovery node instance for the given key and datastore
  ##

  var self =
    Discovery(key: key, peerId: PeerId.init(key).expect("Should construct PeerId"))

  self.updateAnnounceRecord(announceAddrs)

  # --------------------------------------------------------------------------
  # FIXME disable IP limits temporarily so we can run our workshop. Re-enable
  #   and figure out proper solution.
  let discoveryConfig = DiscoveryConfig(
    tableIpLimits: TableIpLimits(tableIpLimit: high(uint), bucketIpLimit: high(uint)),
    bitsPerHop: DefaultBitsPerHop,
  )
  # --------------------------------------------------------------------------

  self.protocol = newProtocol(
    key,
    bindIp = bindIp,
    bindPort = bindPort,
    record = self.providerRecord.get,
    bootstrapRecords = bootstrapNodes,
    rng = Rng.instance(),
    providers = ProvidersManager.new(store),
    config = discoveryConfig,
  )

  self