nimbus-eth2/beacon_chain/spec/eth2_apis/eth2_rest_serialization.nim

# Copyright (c) 2018-2022 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/typetraits
import stew/[assign2, results, base10, byteutils], presto/common,
       libp2p/peerid,
       serialization, json_serialization, json_serialization/std/[options, net, sets]
import ".."/[eth2_ssz_serialization, forks],
       ".."/datatypes/[phase0, altair, bellatrix],
       "."/[rest_types, rest_keymanager_types]

export
  eth2_ssz_serialization, results, peerid, common, serialization,
  json_serialization, options, net, sets, rest_types

from web3/ethtypes import BlockHash
export ethtypes.BlockHash

Json.createFlavor RestJson

const
  DecimalSet = {'0' .. '9'}
    # Base10 (decimal) set of chars
  ValidatorKeySize = RawPubKeySize * 2
    # Size of `ValidatorPubKey` hexadecimal value (without 0x)
  ValidatorSigSize = RawSigSize * 2
    # Size of `ValidatorSig` hexadecimal value (without 0x)
  RootHashSize = sizeof(Eth2Digest) * 2
    # Size of `xxx_root` hexadecimal value (without 0x)
  Phase0Version =
    [byte('p'), byte('h'), byte('a'), byte('s'), byte('e'), byte('0')]
  AltairVersion =
    [byte('a'), byte('l'), byte('t'), byte('a'), byte('i'), byte('r')]

type
  RestGenericError* = object
    code*: uint64
    message*: string
    stacktraces*: Option[seq[string]]

  RestAttestationError* = object
    code*: uint64
    message*: string
    failures*: seq[RestFailureItem]

  EncodeTypes* =
    AttesterSlashing |
    ProposerSlashing |
    phase0.SignedBeaconBlock |
    altair.SignedBeaconBlock |
    SignedVoluntaryExit |
    Web3SignerRequest |
    KeystoresAndSlashingProtection |
    DeleteKeystoresBody

  EncodeArrays* =
    seq[ValidatorIndex] |
    seq[Attestation] |
    seq[SignedAggregateAndProof] |
    seq[RestCommitteeSubscription] |
    seq[RestSyncCommitteeSubscription] |
    seq[RestSyncCommitteeMessage] |
    seq[RestSignedContributionAndProof]

  DecodeTypes* =
    DataEnclosedObject |
    DataMetaEnclosedObject |
    DataRootEnclosedObject |
    GetBlockV2Response |
    GetKeystoresResponse |
    GetStateV2Response |
    ProduceBlockResponseV2 |
    RestAttestationError |
    RestGenericError |
    Web3SignerErrorResponse |
    Web3SignerKeysResponse |
    Web3SignerSignatureResponse |
    Web3SignerStatusResponse

  # These types may be extended with additional fields in the future.
  # Locally unknown fields are silently ignored when decoding them.
  ExtensibleDecodeTypes* =
    GetSpecResponse |
    GetSpecVCResponse

  SszDecodeTypes* =
    GetPhase0StateSszResponse |
    GetPhase0BlockSszResponse

{.push raises: [Defect].}

proc prepareJsonResponse*(t: typedesc[RestApiResponse], d: auto): seq[byte] =
  let res =
    block:
      var default: seq[byte]
      try:
        var stream = memoryOutput()
        var writer = JsonWriter[RestJson].init(stream)
        writer.beginRecord()
        writer.writeField("data", d)
        writer.endRecord()
        stream.getOutput(seq[byte])
      except SerializationError:
        default
      except IOError:
        default
  res

proc prepareJsonStringResponse*(t: typedesc[RestApiResponse], d: auto): string =
  let res =
    block:
      var default: string
      try:
        var stream = memoryOutput()
        var writer = JsonWriter[RestJson].init(stream)
        writer.writeValue(d)
        stream.getOutput(string)
      except SerializationError:
        default
      except IOError:
        default
  res

proc jsonResponseWRoot*(t: typedesc[RestApiResponse], data: auto,
                        dependent_root: Eth2Digest): RestApiResponse =
  let res =
    block:
      var default: seq[byte]
      try:
        var stream = memoryOutput()
        var writer = JsonWriter[RestJson].init(stream)
        writer.beginRecord()
        writer.writeField("dependent_root", dependent_root)
        writer.writeField("data", data)
        writer.endRecord()
        stream.getOutput(seq[byte])
      except SerializationError:
        default
      except IOError:
        default
  RestApiResponse.response(res, Http200, "application/json")

proc jsonResponse*(t: typedesc[RestApiResponse], data: auto): RestApiResponse =
  let res =
    block:
      var default: seq[byte]
      try:
        var stream = memoryOutput()
        var writer = JsonWriter[RestJson].init(stream)
        writer.beginRecord()
        writer.writeField("data", data)
        writer.endRecord()
        stream.getOutput(seq[byte])
      except SerializationError:
        default
      except IOError:
        default
  RestApiResponse.response(res, Http200, "application/json")

proc jsonResponsePlain*(t: typedesc[RestApiResponse],
                        data: auto): RestApiResponse =
  let res =
    block:
      var default: seq[byte]
      try:
        var stream = memoryOutput()
        var writer = JsonWriter[RestJson].init(stream)
        writer.writeValue(data)
        stream.getOutput(seq[byte])
      except SerializationError:
        default
      except IOError:
        default
  RestApiResponse.response(res, Http200, "application/json")

proc jsonResponseWMeta*(t: typedesc[RestApiResponse],
                        data: auto, meta: auto): RestApiResponse =
  let res =
    block:
      var default: seq[byte]
      try:
        var stream = memoryOutput()
        var writer = JsonWriter[RestJson].init(stream)
        writer.beginRecord()
        writer.writeField("data", data)
        writer.writeField("meta", meta)
        writer.endRecord()
        stream.getOutput(seq[byte])
      except SerializationError:
        default
      except IOError:
        default
  RestApiResponse.response(res, Http200, "application/json")

proc jsonMsgResponse*(t: typedesc[RestApiResponse],
                      msg: string = ""): RestApiResponse =
  let data =
    block:
      var default: seq[byte]
      try:
        var defstrings: seq[string]
        var stream = memoryOutput()
        var writer = JsonWriter[RestJson].init(stream)
        writer.beginRecord()
        writer.writeField("code", "200")
        writer.writeField("message", msg)
        writer.writeField("stacktraces", defstrings)
        writer.endRecord()
        stream.getOutput(seq[byte])
      except SerializationError:
        default
      except IOError:
        default
  RestApiResponse.response(data, Http200, "application/json")

proc jsonError*(t: typedesc[RestApiResponse], status: HttpCode = Http200,
                msg: string = ""): RestApiResponse =
  let data =
    block:
      var default: string
      try:
        var defstrings: seq[string]
        var stream = memoryOutput()
        var writer = JsonWriter[RestJson].init(stream)
        writer.beginRecord()
        writer.writeField("code", Base10.toString(uint64(status.toInt())))
        writer.writeField("message", msg)
        writer.writeField("stacktraces", defstrings)
        writer.endRecord()
        stream.getOutput(string)
      except SerializationError:
        default
      except IOError:
        default
  RestApiResponse.error(status, data, "application/json")

proc jsonError*(t: typedesc[RestApiResponse], status: HttpCode = Http200,
                msg: string = "", stacktrace: string): RestApiResponse =
  let data =
    block:
      var default: string
      try:
        var defstrings: seq[string]
        var stream = memoryOutput()
        var writer = JsonWriter[RestJson].init(stream)
        writer.beginRecord()
        writer.writeField("code", Base10.toString(uint64(status.toInt())))
        writer.writeField("message", msg)
        if len(stacktrace) > 0:
          writer.writeField("stacktraces", [stacktrace])
        else:
          writer.writeField("stacktraces", defstrings)
        writer.endRecord()
        stream.getOutput(string)
      except SerializationError:
        default
      except IOError:
        default
  RestApiResponse.error(status, data, "application/json")

proc jsonError*(t: typedesc[RestApiResponse], status: HttpCode = Http200,
                msg: string = "",
                stacktraces: openarray[string]): RestApiResponse =
  let data =
    block:
      var default: string
      try:
        var stream = memoryOutput()
        var writer = JsonWriter[RestJson].init(stream)
        writer.beginRecord()
        writer.writeField("code", Base10.toString(uint64(status.toInt())))
        writer.writeField("message", msg)
        writer.writeField("stacktraces", stacktraces)
        writer.endRecord()
        stream.getOutput(string)
      except SerializationError:
        default
      except IOError:
        default
  RestApiResponse.error(status, data, "application/json")

proc jsonErrorList*(t: typedesc[RestApiResponse],
                    status: HttpCode = Http200,
                    msg: string = "", failures: auto): RestApiResponse =
  let data =
    block:
      var default: string
      try:
        var stream = memoryOutput()
        var writer = JsonWriter[RestJson].init(stream)
        writer.beginRecord()
        writer.writeField("code", Base10.toString(uint64(status.toInt())))
        writer.writeField("message", msg)
        writer.writeField("failures", failures)
        writer.endRecord()
        stream.getOutput(string)
      except SerializationError:
        default
      except IOError:
        default
  RestApiResponse.error(status, data, "application/json")

proc sszResponse*(t: typedesc[RestApiResponse], data: auto): RestApiResponse =
  let res =
    block:
      var default: seq[byte]
      try:
        var stream = memoryOutput()
        var writer = SszWriter.init(stream)
        writer.writeValue(data)
        stream.getOutput(seq[byte])
      except SerializationError:
        default
      except IOError:
        default
  RestApiResponse.response(res, Http200, "application/octet-stream")

template hexOriginal(data: openarray[byte]): string =
  to0xHex(data)

proc decodeJsonString*[T](t: typedesc[T],
                          data: JsonString,
                          requireAllFields = true): Result[T, cstring] =
  try:
    ok(RestJson.decode(string(data), T, requireAllFields = requireAllFields))
  except SerializationError:
    err("Unable to deserialize data")

## uint64
proc writeValue*(w: var JsonWriter[RestJson], value: uint64) {.
     raises: [IOError, Defect].} =
  writeValue(w, Base10.toString(value))

proc readValue*(reader: var JsonReader[RestJson], value: var uint64) {.
     raises: [IOError, SerializationError, Defect].} =
  let svalue = reader.readValue(string)
  let res = Base10.decode(uint64, svalue)
  if res.isOk():
    value = res.get()
  else:
    reader.raiseUnexpectedValue($res.error() & ": " & svalue)

proc writeValue*(w: var JsonWriter[RestJson], value: uint8) {.
     raises: [IOError, Defect].} =
  writeValue(w, Base10.toString(value))

proc readValue*(reader: var JsonReader[RestJson], value: var uint8) {.
     raises: [IOError, SerializationError, Defect].} =
  let svalue = reader.readValue(string)
  let res = Base10.decode(uint8, svalue)
  if res.isOk():
    value = res.get()
  else:
    reader.raiseUnexpectedValue($res.error() & ": " & svalue)

proc writeValue*(w: var JsonWriter[RestJson], value: JustificationBits) {.
    raises: [IOError, Defect].} =
  w.writeValue hexOriginal([uint8(value)])

proc readValue*(reader: var JsonReader[RestJson], value: var JustificationBits) {.
    raises: [IOError, SerializationError, Defect].} =
  let hex = reader.readValue(string)
  try:
    value = JustificationBits(hexToByteArray(hex, 1)[0])
  except ValueError:
    raiseUnexpectedValue(reader,
                        "The `justification_bits` value must be a hex string")

## UInt256
proc writeValue*(w: var JsonWriter[RestJson], value: UInt256) {.
     raises: [IOError, Defect].} =
  writeValue(w, toString(value))

proc readValue*(reader: var JsonReader[RestJson], value: var UInt256) {.
     raises: [IOError, SerializationError, Defect].} =
  let svalue = reader.readValue(string)
  try:
    value = parse(svalue, UInt256, 10)
  except ValueError:
    raiseUnexpectedValue(reader,
                         "UInt256 value should be a valid decimal string")

## Slot
proc writeValue*(writer: var JsonWriter[RestJson], value: Slot) {.
     raises: [IOError, Defect].} =
  writeValue(writer, Base10.toString(uint64(value)))

proc readValue*(reader: var JsonReader[RestJson], value: var Slot) {.
     raises: [IOError, SerializationError, Defect].} =
  let svalue = reader.readValue(string)
  let res = Base10.decode(uint64, svalue)
  if res.isOk():
    value = Slot(res.get())
  else:
    reader.raiseUnexpectedValue($res.error())

## Epoch
proc writeValue*(writer: var JsonWriter[RestJson], value: Epoch) {.
     raises: [IOError, Defect].} =
  writeValue(writer, Base10.toString(uint64(value)))

proc readValue*(reader: var JsonReader[RestJson], value: var Epoch) {.
     raises: [IOError, SerializationError, Defect].} =
  let svalue = reader.readValue(string)
  let res = Base10.decode(uint64, svalue)
  if res.isOk():
    value = Epoch(res.get())
  else:
    reader.raiseUnexpectedValue($res.error())

## ValidatorIndex
proc writeValue*(writer: var JsonWriter[RestJson], value: ValidatorIndex)
                {.raises: [IOError, Defect].} =
  writeValue(writer, Base10.toString(uint64(value)))

proc readValue*(reader: var JsonReader[RestJson], value: var ValidatorIndex)
               {.raises: [IOError, SerializationError, Defect].} =
  let svalue = reader.readValue(string)
  let res = Base10.decode(uint64, svalue)
  if res.isOk():
    let v = res.get()
    if v < VALIDATOR_REGISTRY_LIMIT:
      value = ValidatorIndex(v)
    else:
      reader.raiseUnexpectedValue(
        "Validator index is bigger then VALIDATOR_REGISTRY_LIMIT")
  else:
    reader.raiseUnexpectedValue($res.error())

proc writeValue*(writer: var JsonWriter[RestJson], value: IndexInSyncCommittee)
                {.raises: [IOError, Defect].} =
  writeValue(writer, Base10.toString(distinctBase(value)))

proc readValue*(reader: var JsonReader[RestJson], value: var IndexInSyncCommittee)
               {.raises: [IOError, SerializationError, Defect].} =
  let svalue = reader.readValue(string)
  let res = Base10.decode(uint64, svalue)
  if res.isOk():
    let v = res.get()
    if v < SYNC_COMMITTEE_SIZE:
      value = IndexInSyncCommittee(v)
    else:
      reader.raiseUnexpectedValue(
        "Index in committee is bigger than SYNC_COMMITTEE_SIZE")
  else:
    reader.raiseUnexpectedValue($res.error())

## RestValidatorIndex
proc writeValue*(writer: var JsonWriter[RestJson],
                 value: RestValidatorIndex) {.
     raises: [IOError, Defect].} =
  writeValue(writer, Base10.toString(uint64(value)))

proc readValue*(reader: var JsonReader[RestJson],
                value: var RestValidatorIndex) {.
     raises: [IOError, SerializationError, Defect].} =
  let svalue = reader.readValue(string)
  let res = Base10.decode(uint64, svalue)
  if res.isOk():
    let v = res.get()
    value = RestValidatorIndex(v)
  else:
    reader.raiseUnexpectedValue($res.error())

## CommitteeIndex
proc writeValue*(writer: var JsonWriter[RestJson], value: CommitteeIndex) {.
     raises: [IOError, Defect].} =
  writeValue(writer, value.asUInt64)

proc readValue*(reader: var JsonReader[RestJson], value: var CommitteeIndex) {.
     raises: [IOError, SerializationError, Defect].} =
  var v: uint64
  reader.readValue(v)

  let res = CommitteeIndex.init(v)
  if res.isOk():
    value = res.get()
  else:
    reader.raiseUnexpectedValue($res.error())

## ValidatorSig
proc writeValue*(writer: var JsonWriter[RestJson], value: ValidatorSig) {.
     raises: [IOError, Defect].} =
  writeValue(writer, hexOriginal(toRaw(value)))

proc readValue*(reader: var JsonReader[RestJson], value: var ValidatorSig) {.
     raises: [IOError, SerializationError, Defect].} =
  let hexValue = reader.readValue(string)
  let res = ValidatorSig.fromHex(hexValue)
  if res.isOk():
    value = res.get()
  else:
    reader.raiseUnexpectedValue($res.error())

## TrustedSig
proc writeValue*(writer: var JsonWriter[RestJson], value: TrustedSig) {.
     raises: [IOError, Defect].} =
  writeValue(writer, hexOriginal(toRaw(value)))

proc readValue*(reader: var JsonReader[RestJson], value: var TrustedSig) {.
     raises: [IOError, SerializationError, Defect].} =
  let hexValue = reader.readValue(string)
  let res = ValidatorSig.fromHex(hexValue)
  if res.isOk():
    value = cast[TrustedSig](res.get())
  else:
    reader.raiseUnexpectedValue($res.error())

## ValidatorPubKey
proc writeValue*(writer: var JsonWriter[RestJson], value: ValidatorPubKey) {.
     raises: [IOError, Defect].} =
  writeValue(writer, hexOriginal(toRaw(value)))

proc readValue*(reader: var JsonReader[RestJson], value: var ValidatorPubKey) {.
     raises: [IOError, SerializationError, Defect].} =
  let hexValue = reader.readValue(string)
  let res = ValidatorPubKey.fromHex(hexValue)
  if res.isOk():
    value = res.get()
  else:
    reader.raiseUnexpectedValue($res.error())

## BitSeq
proc readValue*(reader: var JsonReader[RestJson], value: var BitSeq) {.
     raises: [IOError, SerializationError, Defect].} =
  try:
    value = BitSeq hexToSeqByte(reader.readValue(string))
  except ValueError:
    raiseUnexpectedValue(reader, "A BitSeq value should be a valid hex string")

proc writeValue*(writer: var JsonWriter[RestJson], value: BitSeq) {.
     raises: [IOError, Defect].} =
  writeValue(writer, hexOriginal(value.bytes()))

## BitList
proc readValue*(reader: var JsonReader[RestJson], value: var BitList) {.
     raises: [IOError, SerializationError, Defect].} =
  type T = type(value)
  value = T readValue(reader, BitSeq)

proc writeValue*(writer: var JsonWriter[RestJson], value: BitList) {.
     raises: [IOError, Defect].} =
  writeValue(writer, BitSeq value)

## BitArray
proc readValue*(reader: var JsonReader[RestJson], value: var BitArray) {.
     raises: [IOError, SerializationError, Defect].} =
  try:
    hexToByteArray(readValue(reader, string), value.bytes)
  except ValueError:
    raiseUnexpectedValue(reader,
                         "A BitArray value should be a valid hex string")

proc writeValue*(writer: var JsonWriter[RestJson], value: BitArray) {.
     raises: [IOError, Defect].} =
  writeValue(writer, hexOriginal(value.bytes))

## BlockHash
proc readValue*(reader: var JsonReader[RestJson], value: var BlockHash) {.
     raises: [IOError, SerializationError, Defect].} =
  try:
    hexToByteArray(reader.readValue(string), distinctBase(value))
  except ValueError:
    raiseUnexpectedValue(reader,
                         "BlockHash value should be a valid hex string")

proc writeValue*(writer: var JsonWriter[RestJson], value: BlockHash) {.
     raises: [IOError, Defect].} =
  writeValue(writer, hexOriginal(distinctBase(value)))

## Eth2Digest
proc readValue*(reader: var JsonReader[RestJson], value: var Eth2Digest) {.
     raises: [IOError, SerializationError, Defect].} =
  try:
    hexToByteArray(reader.readValue(string), value.data)
  except ValueError:
    raiseUnexpectedValue(reader,
                         "Eth2Digest value should be a valid hex string")

proc writeValue*(writer: var JsonWriter[RestJson], value: Eth2Digest) {.
     raises: [IOError, Defect].} =
  writeValue(writer, hexOriginal(value.data))

## BloomLogs
proc readValue*(reader: var JsonReader[RestJson], value: var BloomLogs) {.
     raises: [IOError, SerializationError, Defect].} =
  try:
    hexToByteArray(reader.readValue(string), value.data)
  except ValueError:
    raiseUnexpectedValue(reader,
                         "BloomLogs value should be a valid hex string")

proc writeValue*(writer: var JsonWriter[RestJson], value: BloomLogs) {.
     raises: [IOError, Defect].} =
  writeValue(writer, hexOriginal(value.data))

## HashArray
proc readValue*(reader: var JsonReader[RestJson], value: var HashArray) {.
     raises: [IOError, SerializationError, Defect].} =
  readValue(reader, value.data)

proc writeValue*(writer: var JsonWriter[RestJson], value: HashArray) {.
     raises: [IOError, Defect].} =
  writeValue(writer, value.data)

## HashList
proc readValue*(reader: var JsonReader[RestJson], value: var HashList) {.
     raises: [IOError, SerializationError, Defect].} =
  readValue(reader, value.data)
  value.resetCache()

proc writeValue*(writer: var JsonWriter[RestJson], value: HashList) {.
     raises: [IOError, Defect].} =
  writeValue(writer, value.data)

## Eth1Address
proc readValue*(reader: var JsonReader[RestJson], value: var Eth1Address) {.
     raises: [IOError, SerializationError, Defect].} =
  try:
    hexToByteArray(reader.readValue(string), distinctBase(value))
  except ValueError:
    raiseUnexpectedValue(reader,
                         "Eth1Address value should be a valid hex string")

proc writeValue*(writer: var JsonWriter[RestJson], value: Eth1Address) {.
     raises: [IOError, Defect].} =
  writeValue(writer, hexOriginal(distinctBase(value)))

proc writeValue*(writer: var JsonWriter[RestJson], value: GraffitiBytes)
                {.raises: [IOError, Defect].} =
  writeValue(writer, hexOriginal(distinctBase(value)))

proc readValue*(reader: var JsonReader[RestJson], T: type GraffitiBytes): T
               {.raises: [IOError, SerializationError, Defect].} =
  try:
    init(GraffitiBytes, reader.readValue(string))
  except ValueError as err:
    reader.raiseUnexpectedValue err.msg

## Version
proc readValue*(
    reader: var JsonReader[RestJson],
    value: var (Version | ForkDigest | DomainType | GraffitiBytes)) {.
     raises: [IOError, SerializationError, Defect].} =
  try:
    hexToByteArray(reader.readValue(string), distinctBase(value))
  except ValueError:
    raiseUnexpectedValue(
      reader, "Expected a valid hex string with " & $value.len() & " bytes")

## ForkedBeaconBlock
proc readValue*(reader: var JsonReader[RestJson],
                value: var ForkedBeaconBlock) {.
     raises: [IOError, SerializationError, Defect].} =
  var
    version: Option[BeaconBlockFork]
    data: Option[JsonString]

  for fieldName in readObjectFields(reader):
    case fieldName
    of "version":
      if version.isSome():
        reader.raiseUnexpectedField("Multiple version fields found",
                                    "ForkedBeaconBlock")
      let vres = reader.readValue(string)
      case vres
      of "phase0":
        version = some(BeaconBlockFork.Phase0)
      of "altair":
        version = some(BeaconBlockFork.Altair)
      of "merge":
        version = some(BeaconBlockFork.Bellatrix)
      else:
        reader.raiseUnexpectedValue("Incorrect version field value")
    of "data":
      if data.isSome():
        reader.raiseUnexpectedField("Multiple data fields found",
                                    "ForkedBeaconBlock")
      data = some(reader.readValue(JsonString))
    else:
      reader.raiseUnexpectedField(fieldName, "ForkedBeaconBlock")

  if version.isNone():
    reader.raiseUnexpectedValue("Field version is missing")
  if data.isNone():
    reader.raiseUnexpectedValue("Field data is missing")

  case version.get():
  of BeaconBlockFork.Phase0:
    let res =
      try:
        some(RestJson.decode(string(data.get()), phase0.BeaconBlock,
                             requireAllFields = true))
      except SerializationError:
        none[phase0.BeaconBlock]()
    if res.isNone():
      reader.raiseUnexpectedValue("Incorrect phase0 block format")
    value = ForkedBeaconBlock.init(res.get())
  of BeaconBlockFork.Altair:
    let res =
      try:
        some(RestJson.decode(string(data.get()), altair.BeaconBlock,
                             requireAllFields = true))
      except SerializationError:
        none[altair.BeaconBlock]()
    if res.isNone():
      reader.raiseUnexpectedValue("Incorrect altair block format")
    value = ForkedBeaconBlock.init(res.get())
  of BeaconBlockFork.Bellatrix:
    let res =
      try:
        some(RestJson.decode(string(data.get()), bellatrix.BeaconBlock,
                             requireAllFields = true))
      except SerializationError:
        none[bellatrix.BeaconBlock]()
    if res.isNone():
      reader.raiseUnexpectedValue("Incorrect merge block format")
    value = ForkedBeaconBlock.init(res.get())

proc writeValue*(writer: var JsonWriter[RestJson], value: ForkedBeaconBlock) {.
     raises: [IOError, Defect].} =
  writer.beginRecord()
  case value.kind
  of BeaconBlockFork.Phase0:
    writer.writeField("version", "phase0")
    writer.writeField("data", value.phase0Data)
  of BeaconBlockFork.Altair:
    writer.writeField("version", "altair")
    writer.writeField("data", value.altairData)
  of BeaconBlockFork.Bellatrix:
    writer.writeField("version", "merge")
    when false:
      # TODO SerializationError
      writer.writeField("data", value.mergeData)
  writer.endRecord()

## ForkedSignedBeaconBlock
proc readValue*(reader: var JsonReader[RestJson],
                value: var ForkedSignedBeaconBlock) {.
     raises: [IOError, SerializationError, Defect].} =
  var
    version: Option[BeaconBlockFork]
    data: Option[JsonString]

  for fieldName in readObjectFields(reader):
    case fieldName
    of "version":
      if version.isSome():
        reader.raiseUnexpectedField("Multiple version fields found",
                                    "ForkedSignedBeaconBlock")
      let vres = reader.readValue(string)
      case vres
      of "phase0":
        version = some(BeaconBlockFork.Phase0)
      of "altair":
        version = some(BeaconBlockFork.Altair)
      of "merge":
        version = some(BeaconBlockFork.Bellatrix)
      else:
        reader.raiseUnexpectedValue("Incorrect version field value")
    of "data":
      if data.isSome():
        reader.raiseUnexpectedField("Multiple data fields found",
                                    "ForkedSignedBeaconBlock")
      data = some(reader.readValue(JsonString))
    else:
      reader.raiseUnexpectedField(fieldName, "ForkedSignedBeaconBlock")

  if version.isNone():
    reader.raiseUnexpectedValue("Field version is missing")
  if data.isNone():
    reader.raiseUnexpectedValue("Field data is missing")

  case version.get():
  of BeaconBlockFork.Phase0:
    let res =
      try:
        some(RestJson.decode(string(data.get()), phase0.SignedBeaconBlock,
                             requireAllFields = true))
      except SerializationError:
        none[phase0.SignedBeaconBlock]()
    if res.isNone():
      reader.raiseUnexpectedValue("Incorrect phase0 block format")
    value = ForkedSignedBeaconBlock.init(res.get())
  of BeaconBlockFork.Altair:
    let res =
      try:
        some(RestJson.decode(string(data.get()), altair.SignedBeaconBlock,
                             requireAllFields = true))
      except SerializationError:
        none[altair.SignedBeaconBlock]()
    if res.isNone():
      reader.raiseUnexpectedValue("Incorrect altair block format")
    value = ForkedSignedBeaconBlock.init(res.get())
  of BeaconBlockFork.Bellatrix:
    let res =
      try:
        some(RestJson.decode(string(data.get()), bellatrix.SignedBeaconBlock,
                             requireAllFields = true))
      except SerializationError:
        none[bellatrix.SignedBeaconBlock]()
    if res.isNone():
      reader.raiseUnexpectedValue("Incorrect merge block format")
    value = ForkedSignedBeaconBlock.init(res.get())
  withBlck(value):
    blck.root = hash_tree_root(blck.message)

proc writeValue*(writer: var JsonWriter[RestJson],
                 value: ForkedSignedBeaconBlock) {.
     raises: [IOError, Defect].} =
  writer.beginRecord()
  case value.kind
  of BeaconBlockFork.Phase0:
    writer.writeField("version", "phase0")
    writer.writeField("data", value.phase0Data)
  of BeaconBlockFork.Altair:
    writer.writeField("version", "altair")
    writer.writeField("data", value.altairData)
  of BeaconBlockFork.Bellatrix:
    writer.writeField("version", "merge")
    when false:
      # TODO SerializationError
      writer.writeField("data", value.mergeData)
  writer.endRecord()

# ForkedHashedBeaconState is used where a `ForkedBeaconState` normally would
# be used, mainly because caching the hash early on is easier to do
proc readValue*(reader: var JsonReader[RestJson],
                value: var ForkedHashedBeaconState) {.
     raises: [IOError, SerializationError, Defect].} =
  var
    version: Option[BeaconStateFork]
    data: Option[JsonString]

  for fieldName in readObjectFields(reader):
    case fieldName
    of "version":
      if version.isSome():
        reader.raiseUnexpectedField("Multiple version fields found",
                                    "ForkedBeaconState")
      let vres = reader.readValue(string)
      version = case vres
      of "phase0": some(BeaconStateFork.Phase0)
      of "altair": some(BeaconStateFork.Altair)
      of "merge": some(BeaconStateFork.Bellatrix)
      else: reader.raiseUnexpectedValue("Incorrect version field value")
    of "data":
      if data.isSome():
        reader.raiseUnexpectedField("Multiple data fields found",
                                    "ForkedBeaconState")
      data = some(reader.readValue(JsonString))
    else:
      reader.raiseUnexpectedField(fieldName, "ForkedBeaconState")

  if version.isNone():
    reader.raiseUnexpectedValue("Field version is missing")
  if data.isNone():
    reader.raiseUnexpectedValue("Field data is missing")

  # Use a temporary to avoid stack instances and `value` mutation in case of
  # exception
  let
    tmp = (ref ForkedHashedBeaconState)(kind: version.get())

  template toValue(field: untyped) =
    if tmp[].kind == value.kind:
      assign(value.field, tmp[].field)
    else:
      value = tmp[] # slow, but rare (hopefully)
    value.field.root = hash_tree_root(value.field.data)

  case version.get():
  of BeaconStateFork.Phase0:
    try:
      tmp[].phase0Data.data = RestJson.decode(
        string(data.get()), phase0.BeaconState, requireAllFields = true)
    except SerializationError:
      reader.raiseUnexpectedValue("Incorrect phase0 beacon state format")

    toValue(phase0Data)
  of BeaconStateFork.Altair:
    try:
      tmp[].altairData.data = RestJson.decode(
        string(data.get()), altair.BeaconState, requireAllFields = true)
    except SerializationError:
      reader.raiseUnexpectedValue("Incorrect altair beacon state format")

    toValue(altairData)
  of BeaconStateFork.Bellatrix:
    try:
      tmp[].mergeData.data = RestJson.decode(
        string(data.get()), bellatrix.BeaconState, requireAllFields = true)
    except SerializationError:
      reader.raiseUnexpectedValue("Incorrect altair beacon state format")
    toValue(mergeData)

proc writeValue*(writer: var JsonWriter[RestJson], value: ForkedHashedBeaconState) {.
     raises: [IOError, Defect].} =
  writer.beginRecord()
  case value.kind
  of BeaconStateFork.Phase0:
    writer.writeField("version", "phase0")
    writer.writeField("data", value.phase0Data.data)
  of BeaconStateFork.Altair:
    writer.writeField("version", "altair")
    writer.writeField("data", value.altairData.data)
  of BeaconStateFork.Bellatrix:
    writer.writeField("version", "merge")
    when false:
      # TODO SerializationError
      writer.writeField("data", value.mergeData.data)
  writer.endRecord()

# Web3SignerRequest
proc writeValue*(writer: var JsonWriter[RestJson],
                 value: Web3SignerRequest) {.
     raises: [IOError, Defect].} =
  case value.kind
  of Web3SignerRequestKind.AggregationSlot:
    doAssert(value.forkInfo.isSome(),
             "forkInfo should be set for this type of request")
    writer.writeField("type", "AGGREGATION_SLOT")
    writer.writeField("fork_info", value.forkInfo.get())
    if isSome(value.signingRoot):
      writer.writeField("signingRoot", value.signingRoot)
    writer.writeField("aggregation_slot", value.aggregationSlot)
  of Web3SignerRequestKind.AggregateAndProof:
    doAssert(value.forkInfo.isSome(),
             "forkInfo should be set for this type of request")
    writer.writeField("type", "AGGREGATE_AND_PROOF")
    writer.writeField("fork_info", value.forkInfo.get())
    if isSome(value.signingRoot):
      writer.writeField("signingRoot", value.signingRoot)
    writer.writeField("aggregate_and_proof", value.aggregateAndProof)
  of Web3SignerRequestKind.Attestation:
    doAssert(value.forkInfo.isSome(),
             "forkInfo should be set for this type of request")
    writer.writeField("type", "ATTESTATION")
    writer.writeField("fork_info", value.forkInfo.get())
    if isSome(value.signingRoot):
      writer.writeField("signingRoot", value.signingRoot)
    writer.writeField("attestation", value.attestation)
  of Web3SignerRequestKind.Block:
    doAssert(value.forkInfo.isSome(),
             "forkInfo should be set for this type of request")
    writer.writeField("type", "BLOCK")
    writer.writeField("fork_info", value.forkInfo.get())
    if isSome(value.signingRoot):
      writer.writeField("signingRoot", value.signingRoot)
    writer.writeField("block", value.blck)
  of Web3SignerRequestKind.BlockV2:
    doAssert(value.forkInfo.isSome(),
             "forkInfo should be set for this type of request")
    writer.writeField("type", "BLOCK_V2")
    writer.writeField("fork_info", value.forkInfo.get())
    if isSome(value.signingRoot):
      writer.writeField("signingRoot", value.signingRoot)
    writer.writeField("beacon_block", value.beaconBlock)
  of Web3SignerRequestKind.Deposit:
    writer.writeField("type", "DEPOSIT")
    if isSome(value.signingRoot):
      writer.writeField("signingRoot", value.signingRoot)
    writer.writeField("deposit", value.deposit)
  of Web3SignerRequestKind.RandaoReveal:
    doAssert(value.forkInfo.isSome(),
             "forkInfo should be set for this type of request")
    writer.writeField("type", "RANDAO_REVEAL")
    writer.writeField("fork_info", value.forkInfo.get())
    if isSome(value.signingRoot):
      writer.writeField("signingRoot", value.signingRoot)
    writer.writeField("randao_reveal", value.randaoReveal)
  of Web3SignerRequestKind.VoluntaryExit:
    doAssert(value.forkInfo.isSome(),
             "forkInfo should be set for this type of request")
    writer.writeField("type", "VOLUNTARY_EXIT")
    writer.writeField("fork_info", value.forkInfo.get())
    if isSome(value.signingRoot):
      writer.writeField("signingRoot", value.signingRoot)
    writer.writeField("voluntary_exit", value.voluntaryExit)
  of Web3SignerRequestKind.SyncCommitteeMessage:
    doAssert(value.forkInfo.isSome(),
             "forkInfo should be set for this type of request")
    writer.writeField("type", "SYNC_COMMITTEE_MESSAGE")
    writer.writeField("fork_info", value.forkInfo.get())
    if isSome(value.signingRoot):
      writer.writeField("signingRoot", value.signingRoot)
    writer.writeField("sync_committee_message", value.syncCommitteeMessage)
  of Web3SignerRequestKind.SyncCommitteeSelectionProof:
    doAssert(value.forkInfo.isSome(),
             "forkInfo should be set for this type of request")
    writer.writeField("type", "SYNC_COMMITTEE_SELECTION_PROOF")
    writer.writeField("fork_info", value.forkInfo.get())
    if isSome(value.signingRoot):
      writer.writeField("signingRoot", value.signingRoot)
    writer.writeField("sync_aggregator_selection_data",
                      value.syncAggregatorSelectionData)
  of Web3SignerRequestKind.SyncCommitteeContributionAndProof:
    doAssert(value.forkInfo.isSome(),
             "forkInfo should be set for this type of request")
    writer.writeField("type", "SYNC_COMMITTEE_CONTRIBUTION_AND_PROOF")
    writer.writeField("fork_info", value.forkInfo.get())
    if isSome(value.signingRoot):
      writer.writeField("signingRoot", value.signingRoot)
    writer.writeField("contribution_and_proof",
                      value.syncCommitteeContributionAndProof)

proc readValue*(reader: var JsonReader[RestJson],
                value: var Web3SignerRequest) {.
     raises: [IOError, SerializationError, Defect].} =
  var
    requestKind: Option[Web3SignerRequestKind]
    forkInfo: Option[Web3SignerForkInfo]
    signingRoot: Option[Eth2Digest]
    data: Option[JsonString]
    dataName: string

  for fieldName in readObjectFields(reader):
    case fieldName
    of "type":
      if requestKind.isSome():
        reader.raiseUnexpectedField("Multiple `type` fields found",
                                    "Web3SignerRequest")
      let vres = reader.readValue(string)
      requestKind = some(
        case vres
        of "AGGREGATION_SLOT":
          Web3SignerRequestKind.AggregationSlot
        of "AGGREGATE_AND_PROOF":
          Web3SignerRequestKind.AggregateAndProof
        of "ATTESTATION":
          Web3SignerRequestKind.Attestation
        of "BLOCK":
          Web3SignerRequestKind.Block
        of "BLOCK_V2":
          Web3SignerRequestKind.BlockV2
        of "DEPOSIT":
          Web3SignerRequestKind.Deposit
        of "RANDAO_REVEAL":
          Web3SignerRequestKind.RandaoReveal
        of "VOLUNTARY_EXIT":
          Web3SignerRequestKind.VoluntaryExit
        of "SYNC_COMMITTEE_MESSAGE":
          Web3SignerRequestKind.SyncCommitteeMessage
        of "SYNC_COMMITTEE_SELECTION_PROOF":
          Web3SignerRequestKind.SyncCommitteeSelectionProof
        of "SYNC_COMMITTEE_CONTRIBUTION_AND_PROOF":
          Web3SignerRequestKind.SyncCommitteeContributionAndProof
        else:
          reader.raiseUnexpectedValue("Unexpected `type` value")
      )
    of "fork_info":
      if forkInfo.isSome():
        reader.raiseUnexpectedField("Multiple `fork_info` fields found",
                                    "Web3SignerRequest")
      forkInfo = some(reader.readValue(Web3SignerForkInfo))
    of "signingRoot":
      if signingRoot.isSome():
        reader.raiseUnexpectedField("Multiple `signingRoot` fields found",
                                    "Web3SignerRequest")
      signingRoot = some(reader.readValue(Eth2Digest))
    of "aggregation_slot", "aggregate_and_proof", "block", "beacon_block",
       "randao_reveal", "voluntary_exit", "sync_committee_message",
       "sync_aggregator_selection_data", "contribution_and_proof":
      if data.isSome():
        reader.raiseUnexpectedField("Multiple data fields found",
                                    "Web3SignerRequest")
      dataName = fieldName
      data = some(reader.readValue(JsonString))
    else:
      # We ignore all unknown fields.
      discard

  if requestKind.isNone():
    reader.raiseUnexpectedValue("Field `type` is missing")

  value =
    case requestKind.get()
    of Web3SignerRequestKind.AggregationSlot:
      if dataName != "aggregation_slot":
        reader.raiseUnexpectedValue("Field `aggregation_slot` is missing")
      if forkInfo.isNone():
        reader.raiseUnexpectedValue("Field `fork_info` is missing")
      let data =
        block:
          let res = decodeJsonString(Web3SignerAggregationSlotData,
                                     data.get(), true)
          if res.isErr():
            reader.raiseUnexpectedValue(
              "Incorrect field `aggregation_slot` format")
          res.get()
      Web3SignerRequest(kind: Web3SignerRequestKind.AggregationSlot,
        forkInfo: forkInfo, signingRoot: signingRoot, aggregationSlot: data
      )
    of Web3SignerRequestKind.AggregateAndProof:
      if dataName != "aggregate_and_proof":
        reader.raiseUnexpectedValue("Field `aggregate_and_proof` is missing")
      if forkInfo.isNone():
        reader.raiseUnexpectedValue("Field `fork_info` is missing")
      let data =
        block:
          let res = decodeJsonString(AggregateAndProof, data.get(), true)
          if res.isErr():
            reader.raiseUnexpectedValue(
              "Incorrect field `aggregate_and_proof` format")
          res.get()
      Web3SignerRequest(
        kind: Web3SignerRequestKind.AggregateAndProof,
        forkInfo: forkInfo, signingRoot: signingRoot, aggregateAndProof: data
      )
    of Web3SignerRequestKind.Attestation:
      if dataName != "attestation":
        reader.raiseUnexpectedValue("Field `attestation` is missing")
      if forkInfo.isNone():
        reader.raiseUnexpectedValue("Field `fork_info` is missing")
      let data =
        block:
          let res = decodeJsonString(AttestationData, data.get(), true)
          if res.isErr():
            reader.raiseUnexpectedValue(
              "Incorrect field `attestation` format")
          res.get()
      Web3SignerRequest(
        kind: Web3SignerRequestKind.Attestation,
        forkInfo: forkInfo, signingRoot: signingRoot, attestation: data
      )
    of Web3SignerRequestKind.Block:
      if dataName != "block":
        reader.raiseUnexpectedValue("Field `block` is missing")
      if forkInfo.isNone():
        reader.raiseUnexpectedValue("Field `fork_info` is missing")
      let data =
        block:
          let res = decodeJsonString(phase0.BeaconBlock, data.get(), true)
          if res.isErr():
            reader.raiseUnexpectedValue(
              "Incorrect field `block` format")
          res.get()
      Web3SignerRequest(
        kind: Web3SignerRequestKind.Block,
        forkInfo: forkInfo, signingRoot: signingRoot, blck: data
      )
    of Web3SignerRequestKind.BlockV2:
      if dataName != "beacon_block":
        reader.raiseUnexpectedValue("Field `beacon_block` is missing")
      if forkInfo.isNone():
        reader.raiseUnexpectedValue("Field `fork_info` is missing")
      let data =
        block:
          let res = decodeJsonString(ForkedBeaconBlock, data.get(), true)
          if res.isErr():
            reader.raiseUnexpectedValue(
              "Incorrect field `beacon_block` format")
          res.get()
      Web3SignerRequest(
        kind: Web3SignerRequestKind.BlockV2,
        forkInfo: forkInfo, signingRoot: signingRoot, beaconBlock: data
      )
    of Web3SignerRequestKind.Deposit:
      if dataName != "deposit":
        reader.raiseUnexpectedValue("Field `deposit` is missing")
      let data =
        block:
          let res = decodeJsonString(Web3SignerDepositData, data.get(), true)
          if res.isErr():
            reader.raiseUnexpectedValue(
              "Incorrect field `deposit` format")
          res.get()
      Web3SignerRequest(
        kind: Web3SignerRequestKind.Deposit,
        signingRoot: signingRoot, deposit: data
      )
    of Web3SignerRequestKind.RandaoReveal:
      if dataName != "randao_reveal":
        reader.raiseUnexpectedValue("Field `randao_reveal` is missing")
      if forkInfo.isNone():
        reader.raiseUnexpectedValue("Field `fork_info` is missing")
      let data =
        block:
          let res = decodeJsonString(Web3SignerRandaoRevealData, data.get(),
                                     true)
          if res.isErr():
            reader.raiseUnexpectedValue(
              "Incorrect field `randao_reveal` format")
          res.get()
      Web3SignerRequest(
        kind: Web3SignerRequestKind.RandaoReveal,
        forkInfo: forkInfo, signingRoot: signingRoot, randaoReveal: data
      )
    of Web3SignerRequestKind.VoluntaryExit:
      if dataName != "voluntary_exit":
        reader.raiseUnexpectedValue("Field `voluntary_exit` is missing")
      if forkInfo.isNone():
        reader.raiseUnexpectedValue("Field `fork_info` is missing")
      let data =
        block:
          let res = decodeJsonString(VoluntaryExit, data.get(), true)
          if res.isErr():
            reader.raiseUnexpectedValue(
              "Incorrect field `voluntary_exit` format")
          res.get()
      Web3SignerRequest(
        kind: Web3SignerRequestKind.VoluntaryExit,
        forkInfo: forkInfo, signingRoot: signingRoot, voluntaryExit: data
      )
    of Web3SignerRequestKind.SyncCommitteeMessage:
      if dataName != "sync_committee_message":
        reader.raiseUnexpectedValue(
          "Field `sync_committee_message` is missing")
      if forkInfo.isNone():
        reader.raiseUnexpectedValue("Field `fork_info` is missing")
      let data =
        block:
          let res = decodeJsonString(Web3SignerSyncCommitteeMessageData,
                                     data.get(), true)
          if res.isErr():
            reader.raiseUnexpectedValue(
              "Incorrect field `sync_committee_message` format")
          res.get()
      Web3SignerRequest(
        kind: Web3SignerRequestKind.SyncCommitteeMessage,
        forkInfo: forkInfo, signingRoot: signingRoot,
        syncCommitteeMessage: data
      )
    of Web3SignerRequestKind.SyncCommitteeSelectionProof:
      if dataName != "sync_aggregator_selection_data":
        reader.raiseUnexpectedValue(
          "Field `sync_aggregator_selection_data` is missing")
      if forkInfo.isNone():
        reader.raiseUnexpectedValue("Field `fork_info` is missing")
      let data =
        block:
          let res = decodeJsonString(SyncAggregatorSelectionData,
                                     data.get(), true)
          if res.isErr():
            reader.raiseUnexpectedValue(
              "Incorrect field `sync_aggregator_selection_data` format")
          res.get()
      Web3SignerRequest(
        kind: Web3SignerRequestKind.SyncCommitteeSelectionProof,
        forkInfo: forkInfo, signingRoot: signingRoot,
        syncAggregatorSelectionData: data
      )
    of Web3SignerRequestKind.SyncCommitteeContributionAndProof:
      if dataName != "contribution_and_proof":
        reader.raiseUnexpectedValue(
          "Field `contribution_and_proof` is missing")
      if forkInfo.isNone():
        reader.raiseUnexpectedValue("Field `fork_info` is missing")
      let data =
        block:
          let res = decodeJsonString(ContributionAndProof,
                                     data.get(), true)
          if res.isErr():
            reader.raiseUnexpectedValue(
              "Incorrect field `contribution_and_proof` format")
          res.get()
      Web3SignerRequest(
        kind: Web3SignerRequestKind.SyncCommitteeContributionAndProof,
        forkInfo: forkInfo, signingRoot: signingRoot,
        syncCommitteeContributionAndProof: data
      )

proc parseRoot(value: string): Result[Eth2Digest, cstring] =
  try:
    ok(Eth2Digest(data: hexToByteArray[32](value)))
  except ValueError:
    err("Unable to decode root value")

proc decodeBody*[T](t: typedesc[T],
                    body: ContentBody): Result[T, cstring] =
  if body.contentType != "application/json":
    return err("Unsupported content type")
  let data =
    try:
      RestJson.decode(cast[string](body.data), T)
    except SerializationError:
      return err("Unable to deserialize data")
    except CatchableError:
      return err("Unexpected deserialization error")
  ok(data)

proc encodeBytes*[T: EncodeTypes](value: T,
                                  contentType: string): RestResult[seq[byte]] =
  case contentType
  of "application/json":
    let data =
      block:
        try:
          var stream = memoryOutput()
          var writer = JsonWriter[RestJson].init(stream)
          writer.writeValue(value)
          stream.getOutput(seq[byte])
        except IOError:
          return err("Input/output error")
        except SerializationError:
          return err("Serialization error")
    ok(data)
  else:
    err("Content-Type not supported")

proc encodeBytes*[T: EncodeArrays](value: T,
                                   contentType: string): RestResult[seq[byte]] =
  case contentType
  of "application/json":
    let data =
      block:
        try:
          var stream = memoryOutput()
          var writer = JsonWriter[RestJson].init(stream)
          writer.writeArray(value)
          stream.getOutput(seq[byte])
        except IOError:
          return err("Input/output error")
        except SerializationError:
          return err("Serialization error")
    ok(data)
  else:
    err("Content-Type not supported")

proc decodeBytes*[T: DecodeTypes](t: typedesc[T], value: openarray[byte],
                                  contentType: string): RestResult[T] =
  const isExtensibleType = t is ExtensibleDecodeTypes
  case contentType
  of "application/json":
    try:
      ok RestJson.decode(value, T, allowUnknownFields = isExtensibleType)
    except SerializationError:
      err("Serialization error")
  else:
    err("Content-Type not supported")

proc decodeBytes*[T: SszDecodeTypes](t: typedesc[T], value: openarray[byte],
                                     contentType: string, updateRoot = true): RestResult[T] =
  case contentType
  of "application/octet-stream":
    try:
      var v: RestResult[T]
      v.ok(T()) # This optimistically avoids an expensive genericAssign
      readSszBytes(value, v.get(), updateRoot)
      v
    except SerializationError as exc:
      err("Serialization error")
  else:
    err("Content-Type not supported")

proc encodeString*(value: string): RestResult[string] =
  ok(value)

proc encodeString*(value: Epoch|Slot|CommitteeIndex|SyncSubcommitteeIndex): RestResult[string] =
  ok(Base10.toString(uint64(value)))

proc encodeString*(value: ValidatorSig): RestResult[string] =
  ok(hexOriginal(toRaw(value)))

proc encodeString*(value: GraffitiBytes): RestResult[string] =
  ok(hexOriginal(distinctBase(value)))

proc encodeString*(value: Eth2Digest): RestResult[string] =
  ok(hexOriginal(value.data))

proc encodeString*(value: ValidatorIdent): RestResult[string] =
  case value.kind
  of ValidatorQueryKind.Index:
    ok(Base10.toString(uint64(value.index)))
  of ValidatorQueryKind.Key:
    ok(hexOriginal(toRaw(value.key)))

proc encodeString*(value: ValidatorPubKey): RestResult[string] =
  ok(hexOriginal(toRaw(value)))

proc encodeString*(value: StateIdent): RestResult[string] =
  case value.kind
  of StateQueryKind.Slot:
    ok(Base10.toString(uint64(value.slot)))
  of StateQueryKind.Root:
    ok(hexOriginal(value.root.data))
  of StateQueryKind.Named:
    case value.value
    of StateIdentType.Head:
      ok("head")
    of StateIdentType.Genesis:
      ok("genesis")
    of StateIdentType.Finalized:
      ok("finalized")
    of StateIdentType.Justified:
      ok("justified")

proc encodeString*(value: BlockIdent): RestResult[string] =
  case value.kind
  of BlockQueryKind.Slot:
    ok(Base10.toString(uint64(value.slot)))
  of BlockQueryKind.Root:
    ok(hexOriginal(value.root.data))
  of BlockQueryKind.Named:
    case value.value
    of BlockIdentType.Head:
      ok("head")
    of BlockIdentType.Genesis:
      ok("genesis")
    of BlockIdentType.Finalized:
      ok("finalized")

proc decodeString*(t: typedesc[PeerStateKind],
                   value: string): Result[PeerStateKind, cstring] =
  case value
  of "disconnected":
    ok(PeerStateKind.Disconnected)
  of "connecting":
    ok(PeerStateKind.Connecting)
  of "connected":
    ok(PeerStateKind.Connected)
  of "disconnecting":
    ok(PeerStateKind.Disconnecting)
  else:
    err("Incorrect peer's state value")

proc encodeString*(value: PeerStateKind): Result[string, cstring] =
  case value
  of PeerStateKind.Disconnected:
    ok("disconnected")
  of PeerStateKind.Connecting:
    ok("connecting")
  of PeerStateKind.Connected:
    ok("connected")
  of PeerStateKind.Disconnecting:
    ok("disconnecting")

proc decodeString*(t: typedesc[PeerDirectKind],
                   value: string): Result[PeerDirectKind, cstring] =
  case value
  of "inbound":
    ok(PeerDirectKind.Inbound)
  of "outbound":
    ok(PeerDirectKind.Outbound)
  else:
    err("Incorrect peer's direction value")

proc encodeString*(value: PeerDirectKind): Result[string, cstring] =
  case value
  of PeerDirectKind.Inbound:
    ok("inbound")
  of PeerDirectKind.Outbound:
    ok("outbound")

proc encodeString*(peerid: PeerID): Result[string, cstring] =
  ok($peerid)

proc decodeString*(t: typedesc[EventTopic],
                   value: string): Result[EventTopic, cstring] =
  case value
  of "head":
    ok(EventTopic.Head)
  of "block":
    ok(EventTopic.Block)
  of "attestation":
    ok(EventTopic.Attestation)
  of "voluntary_exit":
    ok(EventTopic.VoluntaryExit)
  of "finalized_checkpoint":
    ok(EventTopic.FinalizedCheckpoint)
  of "chain_reorg":
    ok(EventTopic.ChainReorg)
  of "contribution_and_proof":
    ok(EventTopic.ContributionAndProof)
  else:
    err("Incorrect event's topic value")

proc decodeString*(t: typedesc[ValidatorSig],
                   value: string): Result[ValidatorSig, cstring] =
  if len(value) != ValidatorSigSize + 2:
    return err("Incorrect validator signature value length")
  if value[0] != '0' and value[1] != 'x':
    return err("Incorrect validator signature encoding")
  ValidatorSig.fromHex(value)

proc decodeString*(t: typedesc[ValidatorPubKey],
                   value: string): Result[ValidatorPubKey, cstring] =
  if len(value) != ValidatorKeySize + 2:
    return err("Incorrect validator's key value length")
  if value[0] != '0' and value[1] != 'x':
    err("Incorrect validator's key encoding")
  else:
    ValidatorPubKey.fromHex(value)

proc decodeString*(t: typedesc[GraffitiBytes],
                   value: string): Result[GraffitiBytes, cstring] =
  try:
    ok(GraffitiBytes.init(value))
  except ValueError:
    err("Unable to decode graffiti value")

proc decodeString*(t: typedesc[string],
                   value: string): Result[string, cstring] =
  ok(value)

proc decodeString*(t: typedesc[Slot], value: string): Result[Slot, cstring] =
  let res = ? Base10.decode(uint64, value)
  ok(Slot(res))

proc decodeString*(t: typedesc[Epoch], value: string): Result[Epoch, cstring] =
  let res = ? Base10.decode(uint64, value)
  ok(Epoch(res))

proc decodeString*(t: typedesc[uint64],
                   value: string): Result[uint64, cstring] =
  Base10.decode(uint64, value)

proc decodeString*(t: typedesc[StateIdent],
                   value: string): Result[StateIdent, cstring] =
  if len(value) > 2:
    if (value[0] == '0') and (value[1] == 'x'):
      if len(value) != RootHashSize + 2:
        err("Incorrect state root value length")
      else:
        let res = ? parseRoot(value)
        ok(StateIdent(kind: StateQueryKind.Root, root: res))
    elif (value[0] in DecimalSet) and (value[1] in DecimalSet):
      let res = ? Base10.decode(uint64, value)
      ok(StateIdent(kind: StateQueryKind.Slot, slot: Slot(res)))
    else:
      case value
      of "head":
        ok(StateIdent(kind: StateQueryKind.Named,
                      value: StateIdentType.Head))
      of "genesis":
        ok(StateIdent(kind: StateQueryKind.Named,
                      value: StateIdentType.Genesis))
      of "finalized":
        ok(StateIdent(kind: StateQueryKind.Named,
                      value: StateIdentType.Finalized))
      of "justified":
        ok(StateIdent(kind: StateQueryKind.Named,
                      value: StateIdentType.Justified))
      else:
        err("Incorrect state identifier value")
  else:
    let res = ? Base10.decode(uint64, value)
    ok(StateIdent(kind: StateQueryKind.Slot, slot: Slot(res)))

proc decodeString*(t: typedesc[BlockIdent],
                   value: string): Result[BlockIdent, cstring] =
  if len(value) > 2:
    if (value[0] == '0') and (value[1] == 'x'):
      if len(value) != RootHashSize + 2:
        err("Incorrect block root value length")
      else:
        let res = ? parseRoot(value)
        ok(BlockIdent(kind: BlockQueryKind.Root, root: res))
    elif (value[0] in DecimalSet) and (value[1] in DecimalSet):
      let res = ? Base10.decode(uint64, value)
      ok(BlockIdent(kind: BlockQueryKind.Slot, slot: Slot(res)))
    else:
      case value
        of "head":
          ok(BlockIdent(kind: BlockQueryKind.Named,
                        value: BlockIdentType.Head))
        of "genesis":
          ok(BlockIdent(kind: BlockQueryKind.Named,
                        value: BlockIdentType.Genesis))
        of "finalized":
          ok(BlockIdent(kind: BlockQueryKind.Named,
                        value: BlockIdentType.Finalized))
        else:
          err("Incorrect block identifier value")
  else:
    let res = ? Base10.decode(uint64, value)
    ok(BlockIdent(kind: BlockQueryKind.Slot, slot: Slot(res)))

proc decodeString*(t: typedesc[ValidatorIdent],
                   value: string): Result[ValidatorIdent, cstring] =
  if len(value) > 2:
    if (value[0] == '0') and (value[1] == 'x'):
      if len(value) != ValidatorKeySize + 2:
        err("Incorrect validator's key value length")
      else:
        let res = ? ValidatorPubKey.fromHex(value)
        ok(ValidatorIdent(kind: ValidatorQueryKind.Key,
                          key: res))
    elif (value[0] in DecimalSet) and (value[1] in DecimalSet):
      let res = ? Base10.decode(uint64, value)
      ok(ValidatorIdent(kind: ValidatorQueryKind.Index,
                        index: RestValidatorIndex(res)))
    else:
      err("Incorrect validator identifier value")
  else:
    let res = ? Base10.decode(uint64, value)
    ok(ValidatorIdent(kind: ValidatorQueryKind.Index,
                      index: RestValidatorIndex(res)))

proc decodeString*(t: typedesc[PeerID],
                   value: string): Result[PeerID, cstring] =
  PeerID.init(value)

proc decodeString*(t: typedesc[CommitteeIndex],
                   value: string): Result[CommitteeIndex, cstring] =
  let res = ? Base10.decode(uint64, value)
  CommitteeIndex.init(res)

proc decodeString*(t: typedesc[SyncSubcommitteeIndex],
                   value: string): Result[SyncSubcommitteeIndex, cstring] =
  let res = ? Base10.decode(uint64, value)
  SyncSubcommitteeIndex.init(res)

proc decodeString*(t: typedesc[Eth2Digest],
                   value: string): Result[Eth2Digest, cstring] =
  if len(value) != RootHashSize + 2:
    return err("Incorrect root value length")
  if value[0] != '0' and value[1] != 'x':
    return err("Incorrect root value encoding")
  parseRoot(value)

proc decodeString*(t: typedesc[ValidatorFilter],
                   value: string): Result[ValidatorFilter, cstring] =
  case value
  of "pending_initialized":
    ok({ValidatorFilterKind.PendingInitialized})
  of "pending_queued":
    ok({ValidatorFilterKind.PendingQueued})
  of "active_ongoing":
    ok({ValidatorFilterKind.ActiveOngoing})
  of "active_exiting":
    ok({ValidatorFilterKind.ActiveExiting})
  of "active_slashed":
    ok({ValidatorFilterKind.ActiveSlashed})
  of "exited_unslashed":
    ok({ValidatorFilterKind.ExitedUnslashed})
  of "exited_slashed":
    ok({ValidatorFilterKind.ExitedSlashed})
  of "withdrawal_possible":
    ok({ValidatorFilterKind.WithdrawalPossible})
  of "withdrawal_done":
    ok({ValidatorFilterKind.WithdrawalDone})
  of "pending":
    ok({
      ValidatorFilterKind.PendingInitialized,
      ValidatorFilterKind.PendingQueued
    })
  of "active":
    ok({
      ValidatorFilterKind.ActiveOngoing,
      ValidatorFilterKind.ActiveExiting,
      ValidatorFilterKind.ActiveSlashed
    })
  of "exited":
    ok({
      ValidatorFilterKind.ExitedUnslashed,
      ValidatorFilterKind.ExitedSlashed
    })
  of "withdrawal":
    ok({
      ValidatorFilterKind.WithdrawalPossible,
      ValidatorFilterKind.WithdrawalDone
    })
  else:
    err("Incorrect validator state identifier value")