import
  std/[os, strutils, stats],
  confutils, chronicles, json_serialization,
  stew/[byteutils, io2],
  snappy,
  ../research/simutils,
  ../beacon_chain/spec/eth2_apis/eth2_rest_serialization,
  ../beacon_chain/spec/datatypes/[phase0, altair, bellatrix],
  ../beacon_chain/spec/[
    eth2_ssz_serialization, forks, helpers, state_transition],
  ../beacon_chain/networking/network_metadata

type
  Cmd* = enum
    hashTreeRoot = "Compute hash tree root of SSZ object"
    pretty = "Pretty-print SSZ object"
    transition = "Run state transition function"
    slots = "Apply empty slots"

  NcliConf* = object
    eth2Network* {.
      desc: "The Eth2 network preset to use"
      name: "network" }: Option[string]

    # TODO confutils argument pragma doesn't seem to do much; also, the cases
    # are largely equivalent, but this helps create command line usage text
    case cmd* {.command}: Cmd
    of hashTreeRoot:
      htrKind* {.
        argument
        desc: "kind of SSZ object: attester_slashing, attestation, signed_block, block, block_body, block_header, deposit, deposit_data, eth1_data, state, proposer_slashing, or voluntary_exit"}: string

      htrFile* {.
        argument
        desc: "filename of SSZ or JSON-encoded object of which to compute hash tree root"}: string

    of pretty:
      prettyKind* {.
        argument
        desc: "kind of SSZ object: attester_slashing, attestation, signed_block, block, block_body, block_header, deposit, deposit_data, eth1_data, state, proposer_slashing, or voluntary_exit"}: string

      prettyFile* {.
        argument
        desc: "filename of SSZ or JSON-encoded object to pretty-print"}: string

    of transition:
      preState* {.
        argument
        desc: "State to which to apply specified block"}: string

      blck* {.
        argument
        desc: "Block to apply to preState"}: string

      postState* {.
        argument
        desc: "Filename of state resulting from applying blck to preState"}: string

      verifyStateRoot* {.
        argument
        desc: "Verify state root (default true)"
        defaultValue: true}: bool

    of slots:
      preState2* {.
        argument
        desc: "State to which to apply specified block"}: string

      slot* {.
        argument
        desc: "Block to apply to preState"}: uint64

      postState2* {.
        argument
        desc: "Filename of state resulting from applying blck to preState"}: string

template saveSSZFile(filename: string, value: ForkedHashedBeaconState) =
  case value.kind:
  of BeaconStateFork.Phase0:    SSZ.saveFile(filename, value.phase0Data.data)
  of BeaconStateFork.Altair:    SSZ.saveFile(filename, value.altairData.data)
  of BeaconStateFork.Bellatrix: SSZ.saveFile(filename, value.bellatrixData.data)

proc loadFile(filename: string, T: type): T =
  let
    ext = splitFile(filename).ext
    bytes = readAllBytes(filename).expect("file exists")
  if cmpIgnoreCase(ext, ".ssz") == 0:
    SSZ.decode(bytes, T)
  elif cmpIgnoreCase(ext, ".ssz_snappy") == 0:
    SSZ.decode(snappy.decode(bytes), T)
  elif cmpIgnoreCase(ext, ".json") == 0:
    # JSON.loadFile(file, t)
    echo "TODO needs porting to RestJson"
    quit 1
  else:
    echo "Unknown file type: ", ext
    quit 1

proc doTransition(conf: NcliConf) =
  let
    cfg = getRuntimeConfig(conf.eth2Network)
    stateY = newClone(readSszForkedHashedBeaconState(
      cfg, readAllBytes(conf.preState).tryGet()))
    blckX = readSszForkedSignedBeaconBlock(
      cfg, readAllBytes(conf.blck).tryGet())
    flags = if not conf.verifyStateRoot: {skipStateRootValidation} else: {}

  var
    cache = StateCache()
    info = ForkedEpochInfo()
  let res = withBlck(blckX):
    state_transition(
      cfg, stateY[], blck, cache, info, flags, noRollback)
  if res.isErr():
    error "State transition failed", error = res.error()
    quit 1
  else:
    saveSSZFile(conf.postState, stateY[])

proc doSlots(conf: NcliConf) =
  type
    Timers = enum
      tLoadState = "Load state from file"
      tApplySlot = "Apply slot"
      tApplyEpochSlot = "Apply epoch slot"
      tSaveState = "Save state to file"

  var timers: array[Timers, RunningStat]
  let
    cfg = getRuntimeConfig(conf.eth2Network)
    stateY = withTimerRet(timers[tLoadState]):
      newClone(readSszForkedHashedBeaconState(
        cfg, readAllBytes(conf.preState2).tryGet()))
  var
    cache = StateCache()
    info = ForkedEpochInfo()
  for i in 0'u64..<conf.slot:
    let isEpoch = (getStateField(stateY[], slot) + 1).is_epoch
    withTimer(timers[if isEpoch: tApplyEpochSlot else: tApplySlot]):
      process_slots(
        cfg, stateY[], getStateField(stateY[], slot) + 1,
        cache, info, {}).expect("should be able to advance slot")

  withTimer(timers[tSaveState]):
    saveSSZFile(conf.postState2, stateY[])

  printTimers(false, timers)

proc doSSZ(conf: NcliConf) =
  let (kind, file) =
    case conf.cmd:
    of hashTreeRoot: (conf.htrKind, conf.htrFile)
    of pretty: (conf.prettyKind, conf.prettyFile)
    else:
      raiseAssert "doSSZ() only implements hashTreeRoot and pretty commands"

  template printit(t: untyped) {.dirty.} =
    let v = newClone(loadFile(file, t))

    case conf.cmd:
    of hashTreeRoot:
      when t is ForkySignedBeaconBlock:
        echo hash_tree_root(v.message).data.toHex()
      else:
        echo hash_tree_root(v[]).data.toHex()
    of pretty:
      echo RestJson.encode(v[], pretty = true)
    else:
      raiseAssert "doSSZ() only implements hashTreeRoot and pretty commands"


  case kind
  of "attester_slashing": printit(AttesterSlashing)
  of "attestation": printit(Attestation)
  of "phase0_signed_block": printit(phase0.SignedBeaconBlock)
  of "altair_signed_block": printit(altair.SignedBeaconBlock)
  of "bellatrix_signed_block": printit(bellatrix.SignedBeaconBlock)
  of "phase0_block": printit(phase0.BeaconBlock)
  of "altair_block": printit(altair.BeaconBlock)
  of "bellatrix_block": printit(bellatrix.BeaconBlock)
  of "phase0_block_body": printit(phase0.BeaconBlockBody)
  of "altair_block_body": printit(altair.BeaconBlockBody)
  of "bellatrix_block_body": printit(bellatrix.BeaconBlockBody)
  of "block_header": printit(BeaconBlockHeader)
  of "deposit": printit(Deposit)
  of "deposit_data": printit(DepositData)
  of "eth1_data": printit(Eth1Data)
  of "phase0_state": printit(phase0.BeaconState)
  of "altiar_state": printit(altair.BeaconState)
  of "bellatrix_state": printit(bellatrix.BeaconState)
  of "proposer_slashing": printit(ProposerSlashing)
  of "voluntary_exit": printit(VoluntaryExit)

when isMainModule:
  let
    conf = NcliConf.load()

  case conf.cmd:
  of hashTreeRoot: doSSZ(conf)
  of pretty: doSSZ(conf)
  of transition: doTransition(conf)
  of slots: doSlots(conf)