# beacon_chain
# Copyright (c) 2018-2021 Status Research & Development GmbH
# Licensed and distributed under either of
#   * MIT license (license terms in the root directory or at https://opensource.org/licenses/MIT).
#   * Apache v2 license (license terms in the root directory or at https://www.apache.org/licenses/LICENSE-2.0).
# at your option. This file may not be copied, modified, or distributed except according to those terms.

{.push raises: [Defect].}

import
  "."/[helpers, forks],
  "."/datatypes/base

export base

const
  # https://github.com/ethereum/consensus-specs/blob/v1.0.1/specs/phase0/p2p-interface.md#topics-and-messages
  topicBeaconBlocksSuffix* = "beacon_block/ssz"
  topicVoluntaryExitsSuffix* = "voluntary_exit/ssz"
  topicProposerSlashingsSuffix* = "proposer_slashing/ssz"
  topicAttesterSlashingsSuffix* = "attester_slashing/ssz"
  topicAggregateAndProofsSuffix* = "beacon_aggregate_and_proof/ssz"

  # https://github.com/ethereum/consensus-specs/blob/v1.0.1/specs/phase0/p2p-interface.md#eth2-network-interaction-domains
  MAX_CHUNK_SIZE* = 1 * 1024 * 1024 # bytes
  GOSSIP_MAX_SIZE* = 1 * 1024 * 1024 # bytes
  TTFB_TIMEOUT* = 5.seconds
  RESP_TIMEOUT* = 10.seconds

  defaultEth2TcpPort* = 9000

  # This is not part of the spec yet! Keep in sync with BASE_RPC_PORT
  defaultEth2RpcPort* = 9190

  # This is not part of the spec! But its port which uses Lighthouse
  DefaultEth2RestPort* = 5052

  enrAttestationSubnetsField* = "attnets"
  enrSyncSubnetsField* = "syncnets"
  enrForkIdField* = "eth2"

template eth2Prefix(forkDigest: ForkDigest): string =
  "/eth2/" & $forkDigest & "/"

func getBeaconBlocksTopic*(forkDigest: ForkDigest): string =
  eth2Prefix(forkDigest) & topicBeaconBlocksSuffix

func getVoluntaryExitsTopic*(forkDigest: ForkDigest): string =
  eth2Prefix(forkDigest) & topicVoluntaryExitsSuffix

func getProposerSlashingsTopic*(forkDigest: ForkDigest): string =
  eth2Prefix(forkDigest) & topicProposerSlashingsSuffix

func getAttesterSlashingsTopic*(forkDigest: ForkDigest): string =
  eth2Prefix(forkDigest) & topicAttesterSlashingsSuffix

func getAggregateAndProofsTopic*(forkDigest: ForkDigest): string =
  eth2Prefix(forkDigest) & topicAggregateAndProofsSuffix

# https://github.com/ethereum/consensus-specs/blob/v1.0.1/specs/phase0/validator.md#broadcast-attestation
func compute_subnet_for_attestation*(
    committees_per_slot: uint64, slot: Slot, committee_index: CommitteeIndex):
    SubnetId =
  # Compute the correct subnet for an attestation for Phase 0.
  # Note, this mimics expected Phase 1 behavior where attestations will be
  # mapped to their shard subnet.
  let
    slots_since_epoch_start = slot mod SLOTS_PER_EPOCH
    committees_since_epoch_start =
      committees_per_slot * slots_since_epoch_start

  SubnetId(
    (committees_since_epoch_start + committee_index.uint64) mod
    ATTESTATION_SUBNET_COUNT)

# https://github.com/ethereum/consensus-specs/blob/v1.0.1/specs/phase0/validator.md#broadcast-attestation
func getAttestationTopic*(forkDigest: ForkDigest,
                          subnetId: SubnetId): string =
  ## For subscribing and unsubscribing to/from a subnet.
  eth2Prefix(forkDigest) & "beacon_attestation_" & $(subnetId) & "/ssz"

# https://github.com/ethereum/consensus-specs/blob/v1.1.0-alpha.8/specs/altair/p2p-interface.md#topics-and-messages
func getSyncCommitteeTopic*(forkDigest: ForkDigest,
                            committeeIdx: SyncCommitteeIndex): string =
  ## For subscribing and unsubscribing to/from a subnet.
  eth2Prefix(forkDigest) & "sync_committee_" & $(committeeIdx.asUInt8) & "/ssz"

# https://github.com/ethereum/consensus-specs/blob/v1.1.0-beta.4/specs/altair/p2p-interface.md#topics-and-messages
func getSyncCommitteeContributionAndProofTopic*(forkDigest: ForkDigest): string =
  ## For subscribing and unsubscribing to/from a subnet.
  eth2Prefix(forkDigest) & "sync_committee_contribution_and_proof" & "/ssz"

func getENRForkID*(cfg: RuntimeConfig,
                   epoch: Epoch,
                   genesis_validators_root: Eth2Digest): ENRForkID =
  let
    current_fork_version = cfg.forkVersionAtEpoch(epoch)
    next_fork_version = if cfg.nextForkEpochAtEpoch(epoch) == FAR_FUTURE_EPOCH:
      current_fork_version
    else:
      cfg.forkVersionAtEpoch(cfg.nextForkEpochAtEpoch(epoch))
    fork_digest = compute_fork_digest(current_fork_version,
                                      genesis_validators_root)
  ENRForkID(
    fork_digest: fork_digest,
    next_fork_version: next_fork_version,
    next_fork_epoch: cfg.nextForkEpochAtEpoch(epoch))

func getDiscoveryForkID*(cfg: RuntimeConfig,
                   epoch: Epoch,
                   genesis_validators_root: Eth2Digest): ENRForkID =
  # Until 1 epoch from fork, returns pre-fork value
  if epoch + 1 >= cfg.ALTAIR_FORK_EPOCH:
    getENRForkID(cfg, epoch, genesis_validators_root)
  else:
    let
      current_fork_version = cfg.forkVersionAtEpoch(epoch)
      fork_digest = compute_fork_digest(current_fork_version,
                                        genesis_validators_root)
    ENRForkID(
      fork_digest: fork_digest,
      next_fork_version: current_fork_version,
      next_fork_epoch: FAR_FUTURE_EPOCH)