# beacon_chain
# Copyright (c) 2018-2024 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: [].}
{.used.}

import
  # Status libraries
  stew/[byteutils, results], chronicles,
  taskpools,
  # Internals
  ../../beacon_chain/spec/[helpers, forks, state_transition_block],
  ../../beacon_chain/fork_choice/[fork_choice, fork_choice_types],
  ../../beacon_chain/[beacon_chain_db, beacon_clock],
  ../../beacon_chain/consensus_object_pools/[
    blockchain_dag, block_clearance, block_quarantine, spec_cache],
  # Third-party
  yaml,
  # Test
  ../testutil, ../testdbutil,
  ./fixtures_utils, ./os_ops

from std/json import
  JsonNode, getBool, getInt, getStr, hasKey, items, len, pairs, `$`, `[]`
from std/sequtils import mapIt, toSeq
from std/strutils import contains
from ../testbcutil import addHeadBlock

# Test format described at https://github.com/ethereum/consensus-specs/tree/v1.3.0/tests/formats/fork_choice
# Note that our implementation has been optimized with "ProtoArray"
# instead of following the spec (in particular the "store").

type
  OpKind = enum
    opOnTick
    opOnAttestation
    opOnBlock
    opOnMergeBlock
    opOnAttesterSlashing
    opInvalidateHash
    opChecks

  BlobData = object
    blobs: seq[KzgBlob]
    proofs: seq[KzgProof]

  Operation = object
    valid: bool
    # variant specific fields
    case kind: OpKind
    of opOnTick:
      tick: int
    of opOnAttestation:
      att: phase0.Attestation
    of opOnBlock:
      blck: ForkedSignedBeaconBlock
      blobData: Opt[BlobData]
    of opOnMergeBlock:
      powBlock: PowBlock
    of opOnAttesterSlashing:
      attesterSlashing: phase0.AttesterSlashing
    of opInvalidateHash:
      invalidatedHash: Eth2Digest
      latestValidHash: Eth2Digest
    of opChecks:
      checks: JsonNode

proc initialLoad(
    path: string, db: BeaconChainDB,
    StateType, BlockType: typedesc
): tuple[dag: ChainDAGRef, fkChoice: ref ForkChoice] {.raises: [
    IOError, UnconsumedInput].} =
  let
    forkedState = loadForkedState(
      path/"anchor_state.ssz_snappy",
      StateType.kind)

    blck = parseTest(
      path/"anchor_block.ssz_snappy",
      SSZ, BlockType)

  ChainDAGRef.preInit(db, forkedState[])

  let
    validatorMonitor = newClone(ValidatorMonitor.init())
    dag = ChainDAGRef.init(
      forkedState[].kind.genesisTestRuntimeConfig, db, validatorMonitor, {})
    fkChoice = newClone(ForkChoice.init(
      dag.getFinalizedEpochRef(), dag.finalizedHead.blck,
      ForkChoiceVersion.Pr3431))

  (dag, fkChoice)

proc loadOps(
    path: string,
    fork: ConsensusFork
): seq[Operation] {.raises: [
    IOError, KeyError, UnconsumedInput, ValueError,
    YamlConstructionError, YamlParserError].} =
  let stepsYAML = os_ops.readFile(path/"steps.yaml")
  let steps = yaml.loadToJson(stepsYAML)

  result = @[]
  for step in steps[0]:
    var numExtraFields = 0

    if step.hasKey"tick":
      result.add Operation(kind: opOnTick,
        tick: step["tick"].getInt())
    elif step.hasKey"attestation":
      let filename = step["attestation"].getStr()
      let att = parseTest(
          path/filename & ".ssz_snappy",
          SSZ, phase0.Attestation
      )
      result.add Operation(kind: opOnAttestation,
        att: att)
    elif step.hasKey"block":
      let filename = step["block"].getStr()
      doAssert step.hasKey"blobs" == step.hasKey"proofs"
      withConsensusFork(fork):
        when consensusFork != ConsensusFork.Electra:
          let
            blck = parseTest(
              path/filename & ".ssz_snappy",
              SSZ, consensusFork.SignedBeaconBlock)

            blobData =
              when consensusFork >= ConsensusFork.Deneb:
                if step.hasKey"blobs":
                  numExtraFields += 2
                  Opt.some BlobData(
                    blobs: distinctBase(parseTest(
                      path/(step["blobs"].getStr()) & ".ssz_snappy",
                      SSZ, List[KzgBlob, Limit MAX_BLOBS_PER_BLOCK])),
                    proofs: step["proofs"].mapIt(KzgProof.fromHex(it.getStr())))
                else:
                  Opt.none(BlobData)
              else:
                doAssert not step.hasKey"blobs"
                Opt.none(BlobData)

          result.add Operation(kind: opOnBlock,
            blck: ForkedSignedBeaconBlock.init(blck),
            blobData: blobData)
    elif step.hasKey"attester_slashing":
      let filename = step["attester_slashing"].getStr()
      let attesterSlashing = parseTest(
        path/filename & ".ssz_snappy",
        SSZ, phase0.AttesterSlashing
      )
      result.add Operation(kind: opOnAttesterSlashing,
        attesterSlashing: attesterSlashing)
    elif step.hasKey"payload_status":
      if step["payload_status"]["status"].getStr() == "INVALID":
        result.add Operation(kind: opInvalidateHash,
          valid: true,
          invalidatedHash: Eth2Digest.fromHex(step["block_hash"].getStr()),
          latestValidHash: Eth2Digest.fromHex(
            step["payload_status"]["latest_valid_hash"].getStr()))
    elif step.hasKey"checks":
      result.add Operation(kind: opChecks,
        checks: step["checks"])
    else:
      raiseAssert "Unknown test step: " & $step

    if step.hasKey"valid":
      doAssert step.len == 2 + numExtraFields
      result[^1].valid = step["valid"].getBool()
    elif not step.hasKey"checks" and not step.hasKey"payload_status":
      doAssert step.len == 1 + numExtraFields
      result[^1].valid = true

proc stepOnBlock(
       dag: ChainDAGRef,
       fkChoice: ref ForkChoice,
       verifier: var BatchVerifier,
       state: var ForkedHashedBeaconState,
       stateCache: var StateCache,
       signedBlock: ForkySignedBeaconBlock,
       blobData: Opt[BlobData],
       time: BeaconTime,
       invalidatedHashes: Table[Eth2Digest, Eth2Digest]):
       Result[BlockRef, VerifierError] =
  # 1. Validate blobs
  when typeof(signedBlock).kind >= ConsensusFork.Deneb:
    let kzgCommits = signedBlock.message.body.blob_kzg_commitments.asSeq
    if kzgCommits.len > 0 or blobData.isSome:
      if blobData.isNone or kzgCommits.validate_blobs(
          blobData.get.blobs, blobData.get.proofs).isErr:
        return err(VerifierError.Invalid)
  else:
    doAssert blobData.isNone, "Pre-Deneb test with specified blob data"

  # 2. Move state to proper slot
  doAssert dag.updateState(
    state,
    dag.getBlockIdAtSlot(time.slotOrZero).expect("block exists"),
    save = false,
    stateCache
  )

  # 3. Add block to DAG
  const consensusFork = typeof(signedBlock).kind

  # In normal Nimbus flow, for this (effectively) newPayload-based INVALID, it
  # is checked even before entering the DAG, by the block processor. Currently
  # the optimistic sync test(s) don't include a later-fcU-INVALID case. Whilst
  # this wouldn't be part of this check, presumably, their FC test vector step
  # would also have `true` validity because it'd not be known they weren't, so
  # adding this mock of the block processor is realistic and sufficient.
  when consensusFork >= ConsensusFork.Bellatrix:
    let executionBlockHash =
      signedBlock.message.body.execution_payload.block_hash
    if executionBlockHash in invalidatedHashes:
      # Mocks fork choice INVALID list application. These tests sequence this
      # in a way the block processor does not, specifying each payload_status
      # before the block itself, while Nimbus fork choice treats invalidating
      # a non-existent block root as a no-op and does not remember it for the
      # future.
      let lvh = invalidatedHashes.getOrDefault(
        executionBlockHash, static(default(Eth2Digest)))
      fkChoice[].mark_root_invalid(dag.getEarliestInvalidBlockRoot(
        signedBlock.message.parent_root, lvh, executionBlockHash))

      return err VerifierError.Invalid

  let blockAdded = dag.addHeadBlock(verifier, signedBlock) do (
      blckRef: BlockRef, signedBlock: consensusFork.TrustedSignedBeaconBlock,
      epochRef: EpochRef, unrealized: FinalityCheckpoints):

    # 4. Update fork choice if valid
    let status = fkChoice[].process_block(
      dag, epochRef, blckRef, unrealized, signedBlock.message, time)
    doAssert status.isOk()

    # 5. Update DAG with new head
    var quarantine = Quarantine.init()
    let newHead = fkChoice[].get_head(dag, time).get()
    dag.updateHead(dag.getBlockRef(newHead).get(), quarantine, [])
    if dag.needStateCachesAndForkChoicePruning():
      dag.pruneStateCachesDAG()
      let pruneRes = fkChoice[].prune()
      doAssert pruneRes.isOk()

  blockAdded

proc stepChecks(
    checks: JsonNode,
    dag: ChainDAGRef,
    fkChoice: ref ForkChoice,
    time: BeaconTime) {.raises: [KeyError].} =
  doAssert checks.len >= 1, "No checks found"
  for check, val in checks:
    if check == "time":
      doAssert time.ns_since_genesis == val.getInt().seconds.nanoseconds()
      doAssert fkChoice.checkpoints.time.slotOrZero == time.slotOrZero
    elif check == "head":
      let headRoot = fkChoice[].get_head(dag, time).get()
      let headRef = dag.getBlockRef(headRoot).get()
      doAssert headRef.slot == Slot(val["slot"].getInt())
      doAssert headRef.root == Eth2Digest.fromHex(val["root"].getStr())
    elif check == "justified_checkpoint":
      let checkpointRoot = fkChoice.checkpoints.justified.checkpoint.root
      let checkpointEpoch = fkChoice.checkpoints.justified.checkpoint.epoch
      doAssert checkpointEpoch == Epoch(val["epoch"].getInt())
      doAssert checkpointRoot == Eth2Digest.fromHex(val["root"].getStr())
    elif check == "justified_checkpoint_root": # undocumented check
      let checkpointRoot = fkChoice.checkpoints.justified.checkpoint.root
      doAssert checkpointRoot == Eth2Digest.fromHex(val.getStr())
    elif check == "finalized_checkpoint":
      let checkpointRoot = fkChoice.checkpoints.finalized.root
      let checkpointEpoch = fkChoice.checkpoints.finalized.epoch
      doAssert checkpointEpoch == Epoch(val["epoch"].getInt())
      doAssert checkpointRoot == Eth2Digest.fromHex(val["root"].getStr())
    elif check == "best_justified_checkpoint":
      let checkpointRoot = fkChoice.checkpoints.best_justified.root
      let checkpointEpoch = fkChoice.checkpoints.best_justified.epoch
      doAssert checkpointEpoch == Epoch(val["epoch"].getInt())
      doAssert checkpointRoot == Eth2Digest.fromHex(val["root"].getStr())
    elif check == "proposer_boost_root":
      doAssert fkChoice.checkpoints.proposer_boost_root ==
        Eth2Digest.fromHex(val.getStr())
    elif check == "genesis_time":
      # We do not store genesis in fork choice..
      discard
    else:
      raiseAssert "Unsupported check '" & $check & "'"

proc doRunTest(
    path: string,
    fork: ConsensusFork
) {.raises: [
    IOError, KeyError, UnconsumedInput, ValueError,
    YamlConstructionError, YamlParserError].} =
  let db = BeaconChainDB.new("", inMemory = true)
  defer:
    db.close()

  let
    stores = withConsensusFork(fork):
      initialLoad(
        path, db, consensusFork.BeaconState, consensusFork.BeaconBlock)

    rng = HmacDrbgContext.new()
    taskpool =
      try:
        Taskpool.new()
      except Exception as exc:
        fatal "Failed to initialize Taskpool", exc = exc.msg
        fail()
        return
  var verifier = BatchVerifier.init(rng, taskpool)

  let steps = loadOps(path, fork)
  var time = stores.fkChoice.checkpoints.time
  var invalidatedHashes: Table[Eth2Digest, Eth2Digest]

  let state = newClone(stores.dag.headState)
  var stateCache = StateCache()

  for step in steps:
    case step.kind
    of opOnTick:
      time = BeaconTime(ns_since_genesis: step.tick.seconds.nanoseconds)
      let status = stores.fkChoice[].update_time(stores.dag, time)
      doAssert status.isOk == step.valid
    of opOnAttestation:
      let status = stores.fkChoice[].on_attestation(
        stores.dag, step.att.data.slot, step.att.data.beacon_block_root,
        toSeq(stores.dag.get_attesting_indices(step.att.asTrusted)), time)
      doAssert status.isOk == step.valid
    of opOnBlock:
      withBlck(step.blck):
        let status = stepOnBlock(
          stores.dag, stores.fkChoice,
          verifier, state[], stateCache,
          forkyBlck, step.blobData, time, invalidatedHashes)
        doAssert status.isOk == step.valid
    of opOnAttesterSlashing:
      let indices =
        check_attester_slashing(state[], step.attesterSlashing, flags = {})
      if indices.isOk:
        for idx in indices.get:
          stores.fkChoice[].process_equivocation(idx)
      doAssert indices.isOk == step.valid
    of opInvalidateHash:
      invalidatedHashes[step.invalidatedHash] = step.latestValidHash
    of opChecks:
      stepChecks(step.checks, stores.dag, stores.fkChoice, time)
    else:
      raiseAssert "Unsupported"

proc runTest(suiteName: static[string], path: string, fork: ConsensusFork) =
  const SKIP = [
    # protoArray can handle blocks in the future gracefully
    # spec: https://github.com/ethereum/consensus-specs/blame/v1.1.3/specs/phase0/fork-choice.md#L349
    # test: tests/fork_choice/scenarios/no_votes.nim
    #       "Ensure the head is still 4 whilst the justified epoch is 0."
    "on_block_future_block",

    # TODO on_merge_block
    "too_early_for_merge",
    "too_late_for_merge",
    "block_lookup_failed",
    "all_valid",

    # TODO intentional reorgs
    "should_override_forkchoice_update__false",
    "should_override_forkchoice_update__true",
    "basic_is_parent_root",
    "basic_is_head_root",
  ]

  test suiteName & " - " & path.relativeTestPathComponent():
    when defined(windows):
      # Some test files have very long paths
      skip()
    else:
      if os_ops.splitPath(path).tail in SKIP:
        skip()
      else:
        doRunTest(path, fork)

template fcSuite(suiteName: static[string], testPathElem: static[string]) =
  suite "EF - " & suiteName & preset():
    const presetPath = SszTestsDir/const_preset
    for kind, path in walkDir(presetPath, relative = true, checkDir = true):
      let testsPath = presetPath/path/testPathElem
      if kind != pcDir or not os_ops.dirExists(testsPath):
        continue
      if testsPath.contains("/electra/") or testsPath.contains("\\electra\\"):
        continue
      let fork = forkForPathComponent(path).valueOr:
        raiseAssert "Unknown test fork: " & testsPath
      for kind, path in walkDir(testsPath, relative = true, checkDir = true):
        let basePath = testsPath/path/"pyspec_tests"
        if kind != pcDir:
          continue
        for kind, path in walkDir(basePath, relative = true, checkDir = true):
          runTest(suiteName, basePath/path, fork)

from ../../beacon_chain/conf import loadKzgTrustedSetup
discard loadKzgTrustedSetup()  # Required for Deneb tests

fcSuite("ForkChoice", "fork_choice")
fcSuite("Sync", "sync")