# Copyright (c) 2018-2020 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.

import
  std/[parseutils, sequtils, strutils, deques, sets],
  stew/results,
  json_rpc/[rpcserver, jsonmarshal],
  chronicles,
  nimcrypto/utils as ncrutils,
  ../beacon_node_common, ../eth2_json_rpc_serialization, ../eth2_network,
  ../validator_duties,
  ../block_pools/chain_dag, ../exit_pool,
  ../spec/[crypto, digest, datatypes, validator, network],
  ../spec/eth2_apis/callsigs_types,
  ../ssz/merkleization,
  ./rpc_utils

logScope: topics = "beaconapi"

type
  RpcServer = RpcHttpServer

  ValidatorQuery = object
    keyset: HashSet[ValidatorPubKey]
    ids: seq[uint64]

template unimplemented() =
  raise (ref CatchableError)(msg: "Unimplemented")

proc parsePubkey(str: string): ValidatorPubKey =
  const expectedLen = RawPubKeySize * 2 + 2
  if str.len != expectedLen: # +2 because of the `0x` prefix
    raise newException(ValueError,
      "A hex public key should be exactly " & $expectedLen & " characters. " &
      $str.len & " provided")
  let pubkeyRes = fromHex(ValidatorPubKey, str)
  if pubkeyRes.isErr:
    raise newException(CatchableError, "Not a valid public key")
  return pubkeyRes[]

proc createQuery(ids: seq[string]): Result[ValidatorQuery, string] =
  # validatorIds array should have maximum 30 items, and all items should be
  # unique.
  if len(ids) > 30:
    return err("The number of ids exceeds the limit")

  # All ids in validatorIds must be unique.
  if len(ids) != len(toHashSet(ids)):
    return err("ids array must have unique item")

  var res = ValidatorQuery(
    keyset: initHashSet[ValidatorPubKey](),
    ids: newSeq[uint64]()
  )

  for item in ids:
    if item.startsWith("0x"):
      if len(item) != RawPubKeySize * 2 + 2:
        return err("Incorrect hexadecimal key")
      let pubkeyRes = ValidatorPubKey.fromHex(item)
      if pubkeyRes.isErr:
        return err("Incorrect public key")
      res.keyset.incl(pubkeyRes.get())
    else:
      var tmp: uint64
      if parseBiggestUInt(item, tmp) != len(item):
        return err("Incorrect index value")
      res.ids.add(tmp)
  ok(res)

proc getValidatorInfoFromValidatorId(
    state: BeaconState,
    current_epoch: Epoch,
    validatorId: string,
    status = ""):
    Option[BeaconStatesValidatorsTuple] =
  const allowedStatuses = ["", "pending", "pending_initialized", "pending_queued",
    "active", "active_ongoing", "active_exiting", "active_slashed", "exited",
    "exited_unslashed", "exited_slashed", "withdrawal", "withdrawal_possible",
    "withdrawal_done"]
  if status notin allowedStatuses:
    raise newException(CatchableError, "Invalid status requested")

  var validatorIdx: uint64
  let validator = if validatorId.startsWith("0x"):
    let pubkey = parsePubkey(validatorId)
    let idx = state.validators.asSeq.findIt(it.pubKey == pubkey)
    if idx == -1:
      raise newException(CatchableError, "Could not find validator")
    validatorIdx = idx.uint64
    state.validators[idx]
  else:
    if parseBiggestUInt(validatorId, validatorIdx) != validatorId.len:
      raise newException(CatchableError, "Not a valid index")
    if validatorIdx > state.validators.lenu64:
      raise newException(CatchableError, "Index out of bounds")
    state.validators[validatorIdx]

  # time to determine the status of the validator - the code mimics
  # whatever is detailed here: https://hackmd.io/ofFJ5gOmQpu1jjHilHbdQQ
  let actual_status = if validator.activation_epoch > current_epoch:
    # pending
    if validator.activation_eligibility_epoch == FAR_FUTURE_EPOCH:
      "pending_initialized"
    else:
      # validator.activation_eligibility_epoch < FAR_FUTURE_EPOCH:
      "pending_queued"
  elif validator.activation_epoch <= current_epoch and
      current_epoch < validator.exit_epoch:
    # active
    if validator.exit_epoch == FAR_FUTURE_EPOCH:
      "active_ongoing"
    elif not validator.slashed:
      # validator.exit_epoch < FAR_FUTURE_EPOCH
      "active_exiting"
    else:
      # validator.exit_epoch < FAR_FUTURE_EPOCH and validator.slashed:
      "active_slashed"
  elif validator.exit_epoch <= current_epoch and
      current_epoch < validator.withdrawable_epoch:
    # exited
    if not validator.slashed:
      "exited_unslashed"
    else:
      # validator.slashed
      "exited_slashed"
  elif validator.withdrawable_epoch <= current_epoch:
    # withdrawal
    if validator.effective_balance != 0:
      "withdrawal_possible"
    else:
      # validator.effective_balance == 0
      "withdrawal_done"
  else:
    raise newException(CatchableError, "Invalid validator status")

  # if the requested status doesn't match the actual status
  if status != "" and status notin actual_status:
    return none(BeaconStatesValidatorsTuple)

  return some((validator: validator,
               index: validatorIdx,
               status: actual_status,
               balance: validator.effective_balance))

proc getBlockDataFromBlockId(node: BeaconNode, blockId: string): BlockData =
  result = case blockId:
    of "head":
      node.chainDag.get(node.chainDag.head)
    of "genesis":
      node.chainDag.getGenesisBlockData()
    of "finalized":
      node.chainDag.get(node.chainDag.finalizedHead.blck)
    else:
      if blockId.startsWith("0x"):
        let blckRoot = parseRoot(blockId)
        let blockData = node.chainDag.get(blckRoot)
        if blockData.isNone:
          raise newException(CatchableError, "Block not found")
        blockData.get()
      else:
        let blockSlot = node.getBlockSlotFromString(blockId)
        if blockSlot.blck.isNil:
          raise newException(CatchableError, "Block not found")
        node.chainDag.get(blockSlot.blck)

proc installBeaconApiHandlers*(rpcServer: RpcServer, node: BeaconNode) =
  rpcServer.rpc("get_v1_beacon_genesis") do () -> BeaconGenesisTuple:
    return (
      genesis_time: node.chainDag.headState.data.data.genesis_time,
      genesis_validators_root:
        node.chainDag.headState.data.data.genesis_validators_root,
      genesis_fork_version: node.config.runtimePreset.GENESIS_FORK_VERSION
    )

  rpcServer.rpc("get_v1_beacon_states_root") do (stateId: string) -> Eth2Digest:
    withStateForStateId(stateId):
      return hashedState.root

  rpcServer.rpc("get_v1_beacon_states_fork") do (stateId: string) -> Fork:
    withStateForStateId(stateId):
      return state.fork

  rpcServer.rpc("get_v1_beacon_states_finality_checkpoints") do (
      stateId: string) -> BeaconStatesFinalityCheckpointsTuple:
    withStateForStateId(stateId):
      return (previous_justified: state.previous_justified_checkpoint,
              current_justified: state.current_justified_checkpoint,
              finalized: state.finalized_checkpoint)

  rpcServer.rpc("get_v1_beacon_states_stateId_validators") do (
      stateId: string, validatorIds: seq[string],
      status: string) -> seq[BeaconStatesValidatorsTuple]:
    let current_epoch = get_current_epoch(node.chainDag.headState.data.data)
    withStateForStateId(stateId):
      for validatorId in validatorIds:
        let res = state.getValidatorInfoFromValidatorId(
          current_epoch, validatorId, status)
        if res.isSome():
          result.add(res.get())

  rpcServer.rpc("get_v1_beacon_states_stateId_validators_validatorId") do (
      stateId: string, validatorId: string) -> BeaconStatesValidatorsTuple:
    let current_epoch = get_current_epoch(node.chainDag.headState.data.data)
    withStateForStateId(stateId):
      let res = state.getValidatorInfoFromValidatorId(current_epoch, validatorId)
      if res.isNone:
        # TODO should we raise here? Maybe this is different from the array case...
        raise newException(CatchableError, "Validator status differs")
      return res.get()

  rpcServer.rpc("get_v1_beacon_states_stateId_validator_balances") do (
      stateId: string, validatorsId: Option[seq[string]]) -> seq[BalanceTuple]:

    var res: seq[BalanceTuple]
    withStateForStateId(stateId):
      if validatorsId.isNone():
        for index, value in state.balances.pairs():
          let balance = (index: uint64(index), balance: value)
          res.add(balance)
      else:
        let qres = createQuery(validatorsId.get())
        if qres.isErr:
          raise newException(CatchableError, qres.error)

        var query = qres.get()
        for index in query.ids:
          if index < lenu64(state.validators):
            let validator = state.validators[index]
            query.keyset.excl(validator.pubkey)
            let balance = (index: uint64(index),
                           balance: validator.effective_balance)
            res.add(balance)

        for index, validator in state.validators.pairs():
          if validator.pubkey in query.keyset:
            let balance = (index: uint64(index),
                           balance: validator.effective_balance)
            res.add(balance)
    return res

  rpcServer.rpc("get_v1_beacon_states_stateId_committees_epoch") do (
      stateId: string, epoch: uint64, index: uint64, slot: uint64) ->
      seq[BeaconStatesCommitteesTuple]:
    checkEpochToSlotOverflow(epoch.Epoch)
    withStateForStateId(stateId):
      proc getCommittee(slot: Slot, index: CommitteeIndex): BeaconStatesCommitteesTuple =
        let vals = get_beacon_committee(state, slot, index, cache).mapIt(it.uint64)
        return (index: index.uint64, slot: slot.uint64, validators: vals)

      proc forSlot(slot: Slot, res: var seq[BeaconStatesCommitteesTuple]) =
        let committees_per_slot =
          get_committee_count_per_slot(state, slot.epoch, cache)
        if index == 0: # parameter is missing (it's optional)
          for committee_index in 0'u64..<committees_per_slot:
            res.add(getCommittee(slot, committee_index.CommitteeIndex))
        else:
          if index >= committees_per_slot:
            raise newException(ValueError, "Committee index out of bounds")
          res.add(getCommittee(slot, index.CommitteeIndex))

      if slot == 0: # parameter is missing (it's optional)
        for i in 0 ..< SLOTS_PER_EPOCH:
          forSlot(compute_start_slot_at_epoch(epoch.Epoch) + i, result)
      else:
        forSlot(slot.Slot, result)

  rpcServer.rpc("get_v1_beacon_headers") do (
      slot: Option[string], parent_root: Option[string]) ->
      seq[BeaconHeadersTuple]:
    unimplemented()

  rpcServer.rpc("get_v1_beacon_headers_blockId") do (
      blockId: string) ->
      tuple[canonical: bool, header: SignedBeaconBlockHeader]:
    let bd = node.getBlockDataFromBlockId(blockId)
    let tsbb = bd.data
    result.header.signature = ValidatorSig.init tsbb.signature.data

    result.header.message.slot = tsbb.message.slot
    result.header.message.proposer_index = tsbb.message.proposer_index
    result.header.message.parent_root = tsbb.message.parent_root
    result.header.message.state_root = tsbb.message.state_root
    result.header.message.body_root = tsbb.message.body.hash_tree_root()

    result.canonical = bd.refs.isAncestorOf(node.chainDag.head)

  rpcServer.rpc("post_v1_beacon_blocks") do (blck: SignedBeaconBlock) -> int:
    if not(node.syncManager.inProgress):
      raise newException(CatchableError,
                         "Beacon node is currently syncing, try again later.")
    let head = node.chainDag.head
    if head.slot >= blck.message.slot:
      node.network.broadcast(getBeaconBlocksTopic(node.forkDigest), blck)
      # The block failed validation, but was successfully broadcast anyway.
      # It was not integrated into the beacon node''s database.
      return 202
    else:
      let res = await proposeSignedBlock(node, head, AttachedValidator(), blck)
      if res == head:
        node.network.broadcast(getBeaconBlocksTopic(node.forkDigest), blck)
        # The block failed validation, but was successfully broadcast anyway.
        # It was not integrated into the beacon node''s database.
        return 202
      else:
        # The block was validated successfully and has been broadcast.
        # It has also been integrated into the beacon node's database.
        return 200

  rpcServer.rpc("get_v1_beacon_blocks_blockId") do (
      blockId: string) -> TrustedSignedBeaconBlock:
    return node.getBlockDataFromBlockId(blockId).data

  rpcServer.rpc("get_v1_beacon_blocks_blockId_root") do (
      blockId: string) -> Eth2Digest:
    return node.getBlockDataFromBlockId(blockId).data.message.state_root

  rpcServer.rpc("get_v1_beacon_blocks_blockId_attestations") do (
      blockId: string) -> seq[TrustedAttestation]:
    return node.getBlockDataFromBlockId(blockId).data.message.body.attestations.asSeq

  rpcServer.rpc("get_v1_beacon_pool_attestations") do (
      slot: Option[string], committee_index: Option[string]) ->
      seq[AttestationTuple]:

    var res: seq[AttestationTuple]

    let qslot =
      if slot.isSome():
        var tmp: uint64
        let sslot = slot.get()
        if parseBiggestUInt(sslot, tmp) != len(sslot):
          raise newException(CatchableError, "Incorrect slot number")
        some(Slot(tmp))
      else:
        none[Slot]()

    let qindex =
      if committee_index.isSome():
        var tmp: uint64
        let scommittee_index = committee_index.get()
        if parseBiggestUInt(scommittee_index, tmp) != len(scommittee_index):
          raise newException(CatchableError, "Incorrect committee_index number")
        some(CommitteeIndex(tmp))
      else:
        none[CommitteeIndex]()

    for item in node.attestationPool[].attestations(qslot, qindex):
      let atuple = (
        aggregation_bits: "0x" & ncrutils.toHex(item.aggregation_bits.bytes),
        data: item.data,
        signature: item.signature
      )
      res.add(atuple)

    return res

  rpcServer.rpc("post_v1_beacon_pool_attestations") do (
      attestation: Attestation) -> bool:
    node.sendAttestation(attestation)
    return true

  rpcServer.rpc("get_v1_beacon_pool_attester_slashings") do (
      ) -> seq[AttesterSlashing]:
    var res: seq[AttesterSlashing]
    if isNil(node.exitPool):
      return res
    let length = len(node.exitPool.attester_slashings)
    res = newSeqOfCap[AttesterSlashing](length)
    for item in node.exitPool.attester_slashings.items():
      res.add(item)
    return res

  rpcServer.rpc("post_v1_beacon_pool_attester_slashings") do (
      slashing: AttesterSlashing) -> bool:
    if isNil(node.exitPool):
      raise newException(CatchableError, "Exit pool is not yet available!")
    let validity = node.exitPool[].validateAttesterSlashing(slashing)
    if validity.isOk:
      node.sendAttesterSlashing(slashing)
    else:
      raise newException(CatchableError, $(validity.error[1]))
    return true

  rpcServer.rpc("get_v1_beacon_pool_proposer_slashings") do (
      ) -> seq[ProposerSlashing]:
    var res: seq[ProposerSlashing]
    if isNil(node.exitPool):
      return res
    let length = len(node.exitPool.proposer_slashings)
    res = newSeqOfCap[ProposerSlashing](length)
    for item in node.exitPool.proposer_slashings.items():
      res.add(item)
    return res

  rpcServer.rpc("post_v1_beacon_pool_proposer_slashings") do (
      slashing: ProposerSlashing) -> bool:
    if isNil(node.exitPool):
      raise newException(CatchableError, "Exit pool is not yet available!")
    let validity = node.exitPool[].validateProposerSlashing(slashing)
    if validity.isOk:
      node.sendProposerSlashing(slashing)
    else:
      raise newException(CatchableError, $(validity.error[1]))
    return true

  rpcServer.rpc("get_v1_beacon_pool_voluntary_exits") do (
      ) -> seq[SignedVoluntaryExit]:
    var res: seq[SignedVoluntaryExit]
    if isNil(node.exitPool):
      return res
    let length = len(node.exitPool.voluntary_exits)
    res = newSeqOfCap[SignedVoluntaryExit](length)
    for item in node.exitPool.voluntary_exits.items():
      res.add(item)
    return res

  rpcServer.rpc("post_v1_beacon_pool_voluntary_exits") do (
      exit: SignedVoluntaryExit) -> bool:
    if isNil(node.exitPool):
      raise newException(CatchableError, "Exit pool is not yet available!")
    let validity = node.exitPool[].validateVoluntaryExit(exit)
    if validity.isOk:
      node.sendVoluntaryExit(exit)
    else:
      raise newException(CatchableError, $(validity.error[1]))
    return true