# Nimbus
# Copyright (c) 2018-2019 Status Research & Development GmbH
# Licensed under either of
#  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
#  * MIT license ([LICENSE-MIT](LICENSE-MIT))
# at your option.
# This file may not be copied, modified, or distributed except according to
# those terms.

import
  parseopt, strutils, macros, os, times, json, tables, stew/[byteutils],
  chronos, eth/[keys, common, p2p, net/nat], chronicles, nimcrypto/hash,
  eth/p2p/bootnodes, eth/p2p/rlpx_protocols/whisper_protocol,
  ./db/select_backend, eth/keys, ./chain_config

from ./vm_types2 import Fork

const
  NimbusName* = "Nimbus"
  ## project name string

  NimbusMajor*: int = 0
  ## is the major number of Nimbus' version.

  NimbusMinor*: int = 0
  ## is the minor number of Nimbus' version.

  NimbusPatch*: int = 1
  ## is the patch number of Nimbus' version.

  NimbusVersion* = $NimbusMajor & "." & $NimbusMinor & "." & $NimbusPatch
  ## is the version of Nimbus as a string.

  NimbusIdent* = "$1/$2 ($3/$4)" % [NimbusName, NimbusVersion, hostCPU, hostOS]
  ## project ident name for networking services

  GitRevision = staticExec("git rev-parse --short HEAD").replace("\n") # remove CR

  NimVersion = staticExec("nim --version")

let
  NimbusCopyright* = "Copyright (c) 2018-" & $(now().utc.year) & " Status Research & Development GmbH"
  NimbusHeader* = "$# Version $# [$#: $#, $#, $#]\p$#\p\p$#\p" %
    [NimbusName, NimbusVersion, hostOS, hostCPU, nimbus_db_backend, GitRevision, NimbusCopyright, NimVersion]

type
  ConfigStatus* = enum
    ## Configuration status flags
    Success,                      ## Success
    EmptyOption,                  ## No options in category
    ErrorUnknownOption,           ## Unknown option in command line found
    ErrorParseOption,             ## Error in parsing command line option
    ErrorIncorrectOption,         ## Option has incorrect value
    Error                         ## Unspecified error

  RpcFlags* {.pure.} = enum
    ## RPC flags
    Enabled                       ## RPC enabled
    Eth                           ## enable eth_ set of RPC API
    Shh                           ## enable shh_ set of RPC API
    Debug                         ## enable debug_ set of RPC API

  ProtocolFlags* {.pure.} = enum
    ## Protocol flags
    Eth                           ## enable eth subprotocol
    Shh                           ## enable whisper subprotocol
    Les                           ## enable les subprotocol

  RpcConfiguration* = object
    ## JSON-RPC configuration object
    flags*: set[RpcFlags]         ## RPC flags
    binds*: seq[TransportAddress] ## RPC bind address

  GraphqlConfiguration* = object
    enabled*: bool
    address*: TransportAddress

  NetworkFlags* = enum
    ## Ethereum network flags
    NoDiscover                   ## Peer discovery disabled
    V5Discover                   ## Dicovery V5 enabled
    NetworkIdSet                 ## prevent CustomNetwork replacement

  DebugFlags* {.pure.} = enum
    ## Debug selection flags
    Enabled,                      ## Debugging enabled
    Test1,                        ## Test1 enabled
    Test2,                        ## Test2 enabled
    Test3                         ## Test3 enabled

  NetConfiguration* = object
    ## Network configuration object
    flags*: set[NetworkFlags]     ## Network flags
    bootNodes*: seq[ENode]        ## List of bootnodes
    staticNodes*: seq[ENode]      ## List of static nodes to connect to
    customBootNodes*: seq[ENode]
    bindPort*: uint16             ## Main TCP bind port
    discPort*: uint16             ## Discovery UDP bind port
    metricsServer*: bool          ## Enable metrics server
    metricsServerPort*: uint16    ## metrics HTTP server port
    maxPeers*: int                ## Maximum allowed number of peers
    maxPendingPeers*: int         ## Maximum allowed pending peers
    networkId*: NetworkId         ## Network ID as integer
    ident*: string                ## Server ident name string
    nodeKey*: PrivateKey          ## Server private key
    nat*: NatStrategy             ## NAT strategy
    externalIP*: string           ## user-provided external IP
    protocols*: set[ProtocolFlags]## Enabled subprotocols

  DebugConfiguration* = object
    ## Debug configuration object
    flags*: set[DebugFlags]       ## Debug flags
    logLevel*: LogLevel           ## Log level
    logFile*: string              ## Log file
    logMetrics*: bool             ## Enable metrics logging
    logMetricsInterval*: int      ## Metrics logging interval

  PruneMode* {.pure.} = enum
    Full
    Archive

  NimbusAccount* = object
    privateKey*: PrivateKey
    keystore*: JsonNode
    unlocked*: bool

  NimbusConfiguration* = ref object
    ## Main Nimbus configuration object
    dataDir*: string
    keyStore*: string
    prune*: PruneMode
    graphql*: GraphqlConfiguration
    rpc*: RpcConfiguration        ## JSON-RPC configuration
    net*: NetConfiguration        ## Network configuration
    debug*: DebugConfiguration    ## Debug configuration
    shh*: WhisperConfig           ## Whisper configuration
    customGenesis*: CustomGenesis ## Custom Genesis Configuration
    # You should only create one instance of the RNG per application / library
    # Ref is used so that it can be shared between components
    rng*: ref BrHmacDrbgContext
    accounts*: Table[EthAddress, NimbusAccount]
    importFile*: string

const
  # these are public network id
  CustomNet*  = 0.NetworkId
  MainNet*    = 1.NetworkId
  # No longer used: MordenNet = 2
  RopstenNet* = 3.NetworkId
  RinkebyNet* = 4.NetworkId
  GoerliNet*  = 5.NetworkId
  KovanNet*   = 42.NetworkId

const
  defaultRpcApi = {RpcFlags.Eth, RpcFlags.Shh}
  defaultProtocols = {ProtocolFlags.Eth, ProtocolFlags.Shh}
  defaultLogLevel = LogLevel.WARN
  defaultNetwork = MainNet

var nimbusConfig {.threadvar.}: NimbusConfiguration

proc getConfiguration*(): NimbusConfiguration {.gcsafe.}

proc `$`*(c: ChainId): string =
  $(c.int)

proc toFork*(c: ChainConfig, number: BlockNumber): Fork =
  if number >= c.berlinBlock: FkBerlin
  elif number >= c.istanbulBlock: FkIstanbul
  elif number >= c.petersburgBlock: FkPetersburg
  elif number >= c.constantinopleBlock: FkConstantinople
  elif number >= c.byzantiumBlock: FkByzantium
  elif number >= c.eip158Block: FkSpurious
  elif number >= c.eip150Block: FkTangerine
  elif number >= c.homesteadBlock: FkHomestead
  else: FkFrontier

proc chainConfig*(id: NetworkId): ChainConfig =
  # For some public networks, NetworkId and ChainId value are identical
  # but that is not always the case

  result = case id
  of MainNet:
    ChainConfig(
      poaEngine: false, # TODO: use real engine conf: PoW
      chainId:        MainNet.ChainId,
      homesteadBlock: 1_150_000.toBlockNumber, # 14/03/2016 20:49:53
      daoForkBlock:   1_920_000.toBlockNumber,
      daoForkSupport: true,
      eip150Block:    2_463_000.toBlockNumber, # 18/10/2016 17:19:31
      eip150Hash:     toDigest("2086799aeebeae135c246c65021c82b4e15a2c451340993aacfd2751886514f0"),
      eip155Block:    2_675_000.toBlockNumber, # 22/11/2016 18:15:44
      eip158Block:    2_675_000.toBlockNumber,
      byzantiumBlock: 4_370_000.toBlockNumber, # 16/10/2017 09:22:11
      constantinopleBlock: 7_280_000.toBlockNumber, # Never Occured in MainNet
      petersburgBlock:7_280_000.toBlockNumber, # 28/02/2019 07:52:04
      istanbulBlock:  9_069_000.toBlockNumber, # 08/12/2019 12:25:09
      muirGlacierBlock: 9_200_000.toBlockNumber, # 02/01/2020 08:30:49
      berlinBlock:      12_244_000.toBlockNumber # 15/04/2021 10:07:03
    )
  of RopstenNet:
    ChainConfig(
      poaEngine: false, # TODO: use real engine conf: PoW
      chainId:        RopstenNet.ChainId,
      homesteadBlock: 0.toBlockNumber,
      daoForkSupport: false,
      eip150Block:    0.toBlockNumber,
      eip150Hash:     toDigest("41941023680923e0fe4d74a34bdac8141f2540e3ae90623718e47d66d1ca4a2d"),
      eip155Block:    10.toBlockNumber,
      eip158Block:    10.toBlockNumber,
      byzantiumBlock: 1_700_000.toBlockNumber,
      constantinopleBlock: 4_230_000.toBlockNumber,
      petersburgBlock:4_939_394.toBlockNumber,
      istanbulBlock:  6_485_846.toBlockNumber,
      muirGlacierBlock: 7_117_117.toBlockNumber,
      berlinBlock:      9_812_189.toBlockNumber
    )
  of RinkebyNet:
    ChainConfig(
      poaEngine: true, # TODO: use real engine conf: PoA
      chainId:        RinkebyNet.ChainId,
      homesteadBlock: 1.toBlockNumber,
      daoForkSupport: false,
      eip150Block:    2.toBlockNumber,
      eip150Hash:     toDigest("9b095b36c15eaf13044373aef8ee0bd3a382a5abb92e402afa44b8249c3a90e9"),
      eip155Block:    3.toBlockNumber,
      eip158Block:    3.toBlockNumber,
      byzantiumBlock: 1_035_301.toBlockNumber,
      constantinopleBlock: 3_660_663.toBlockNumber,
      petersburgBlock:4_321_234.toBlockNumber,
      istanbulBlock:  5_435_345.toBlockNumber,
      muirGlacierBlock: 8_290_928.toBlockNumber, # never occured in rinkeby network
      berlinBlock:      8_290_928.toBlockNumber
    )
  of GoerliNet:
    ChainConfig(
      poaEngine: true, # TODO: use real engine conf: PoA
      chainId:        GoerliNet.ChainId,
      homesteadBlock: 0.toBlockNumber,
      daoForkSupport: false,
      eip150Block:    0.toBlockNumber,
      eip150Hash:     toDigest("0000000000000000000000000000000000000000000000000000000000000000"),
      eip155Block:    0.toBlockNumber,
      eip158Block:    0.toBlockNumber,
      byzantiumBlock: 0.toBlockNumber,
      constantinopleBlock: 0.toBlockNumber,
      petersburgBlock: 0.toBlockNumber,
      istanbulBlock:  1_561_651.toBlockNumber,
      muirGlacierBlock: 4_460_644.toBlockNumber, # never occured in goerli network
      berlinBlock:      4_460_644.toBlockNumber
    )
  else:
    # everything else will use CustomNet config
    let conf = getConfiguration()
    trace "Custom genesis block configuration loaded", conf=conf.customGenesis.config
    conf.customGenesis.config

proc processList(v: string, o: var seq[string]) =
  ## Process comma-separated list of strings.
  if len(v) > 0:
    for n in v.split({' ', ','}):
      if len(n) > 0:
        o.add(n)

proc processInteger*(v: string, o: var int): ConfigStatus =
  ## Convert string to integer.
  try:
    o  = parseInt(v)
    result = Success
  except ValueError:
    result = ErrorParseOption

proc processFloat*(v: string, o: var float): ConfigStatus =
  ## Convert string to float.
  try:
    o  = parseFloat(v)
    result = Success
  except ValueError:
    result = ErrorParseOption

proc processAddressPort(addrStr: string, ta: var TransportAddress): ConfigStatus =
  try:
    ta = initTAddress(addrStr)
    return Success
  except CatchableError:
    return ErrorParseOption

proc processAddressPortsList(v: string,
                             o: var seq[TransportAddress]): ConfigStatus =
  ## Convert <hostname:port>;...;<hostname:port> to list of `TransportAddress`.
  var list = newSeq[string]()
  processList(v, list)
  for item in list:
    var ta: TransportAddress
    if processAddressPort(item, ta) == Success:
      o.add ta
    else:
      return ErrorParseOption
  result = Success

proc processRpcApiList(v: string, flags: var set[RpcFlags]): ConfigStatus =
  var list = newSeq[string]()
  processList(v, list)
  result = Success
  for item in list:
    case item.toLowerAscii()
    of "eth": flags.incl RpcFlags.Eth
    of "shh": flags.incl RpcFlags.Shh
    of "debug": flags.incl RpcFlags.Debug
    else:
      warn "unknown rpc api", name = item
      result = ErrorIncorrectOption

proc processProtocolList(v: string, flags: var set[ProtocolFlags]): ConfigStatus =
  var list = newSeq[string]()
  processList(v, list)
  result = Success
  for item in list:
    case item.toLowerAscii()
    of "eth": flags.incl ProtocolFlags.Eth
    of "shh": flags.incl ProtocolFlags.Shh
    of "les": flags.incl ProtocolFlags.Les
    else:
      warn "unknown protocol", name = item
      result = ErrorIncorrectOption

proc processENode(v: string, o: var ENode): ConfigStatus =
  ## Convert string to ENode.
  let res = ENode.fromString(v)
  if res.isOk:
    o = res[]
    result = Success
  else:
    result = ErrorParseOption

proc processENodesList(v: string, o: var seq[ENode]): ConfigStatus =
  ## Convert comma-separated list of strings to list of ENode.
  var
    node: ENode
    list = newSeq[string]()
  processList(v, list)
  for item in list:
    result = processENode(item, node)
    if result == Success:
      o.add(node)
    else:
      break

proc processPrivateKey(v: string, o: var PrivateKey): ConfigStatus =
  ## Convert hexadecimal string to private key object.
  let seckey = PrivateKey.fromHex(v)
  if seckey.isOk():
    o = seckey[]
    return Success

  result = ErrorParseOption

proc processPruneList(v: string, flags: var PruneMode): ConfigStatus =
  var list = newSeq[string]()
  processList(v, list)
  result = Success
  for item in list:
    case item.toLowerAscii()
    of "full": flags = PruneMode.Full
    of "archive": flags = PruneMode.Archive
    else:
      warn "unknown prune flags", name = item
      result = ErrorIncorrectOption

proc processEthArguments(key, value: string): ConfigStatus =
  result = Success
  let config = getConfiguration()
  case key.toLowerAscii()
  of "keystore":
    config.keyStore = value
  of "datadir":
    config.dataDir = value
  of "prune":
    result = processPruneList(value, config.prune)
  of "import":
    config.importFile = value
  else:
    result = EmptyOption

proc processRpcArguments(key, value: string): ConfigStatus =
  ## Processes only `RPC` related command line options
  result = Success
  let config = getConfiguration()
  let skey = key.toLowerAscii()
  if skey == "rpc":
    if RpcFlags.Enabled notin config.rpc.flags:
      config.rpc.flags.incl(RpcFlags.Enabled)
      config.rpc.flags.incl(defaultRpcApi)
  elif skey == "rpcbind":
    config.rpc.binds.setLen(0)
    result = processAddressPortsList(value, config.rpc.binds)
  elif skey == "rpcapi":
    if RpcFlags.Enabled in config.rpc.flags:
      config.rpc.flags.excl(defaultRpcApi)
    else:
      config.rpc.flags.incl(RpcFlags.Enabled)
    result = processRpcApiList(value, config.rpc.flags)
  else:
    result = EmptyOption

proc processGraphqlArguments(key, value: string): ConfigStatus =
  ## Processes only `Graphql` related command line options
  result = Success
  let conf = getConfiguration()
  case key.toLowerAscii()
  of "graphql":
    conf.graphql.enabled = true
  of "graphqlbind":
    result = processAddressPort(value, conf.graphql.address)
  else:
    result = EmptyOption

proc setBootnodes(onodes: var seq[ENode], nodeUris: openarray[string]) =
  var node: ENode
  onodes = newSeqOfCap[ENode](nodeUris.len)
  for item in nodeUris:
    doAssert(processENode(item, node) == Success)
    onodes.add(node)


proc setNetwork(conf: var NetConfiguration, id: NetworkId) =
  ## Set network id and default network bootnodes
  conf.networkId = id
  case id
  of MainNet:
    conf.bootNodes.setBootnodes(MainnetBootnodes)
  of RopstenNet:
    conf.bootNodes.setBootnodes(RopstenBootnodes)
  of RinkebyNet:
    conf.bootNodes.setBootnodes(RinkebyBootnodes)
  of GoerliNet:
    conf.bootNodes.setBootnodes(GoerliBootnodes)
  of KovanNet:
    conf.bootNodes.setBootnodes(KovanBootnodes)
  else:
    # everything else will use bootnodes
    # from --bootnodes switch
    discard

proc processNetArguments(key, value: string): ConfigStatus =
  ## Processes only `Networking` related command line options
  result = Success
  let config = getConfiguration()
  let skey = key.toLowerAscii()
  if skey == "bootnodes":
    result = processENodesList(value, config.net.customBootNodes)
  elif skey == "bootnodesv4":
    result = processENodesList(value, config.net.customBootNodes)
  elif skey == "bootnodesv5":
    result = processENodesList(value, config.net.customBootNodes)
  elif skey == "staticnodes":
    result = processENodesList(value, config.net.staticNodes)
  elif skey == "testnet":
    config.net.setNetwork(RopstenNet)
  elif skey == "mainnet":
    config.net.setNetwork(MainNet)
  elif skey == "ropsten":
    config.net.setNetwork(RopstenNet)
  elif skey == "rinkeby":
    config.net.setNetwork(RinkebyNet)
  elif skey == "goerli":
    config.net.setNetwork(GoerliNet)
  elif skey == "kovan":
    config.net.setNetwork(KovanNet)
  elif skey == "customnetwork":
    if not loadCustomGenesis(value, config.customGenesis):
      result = Error
    if NetworkIdSet notin config.net.flags:
      # prevent clash with --networkid if it already set
      # because any --networkid value that is not
      # in the public network will also translated as
      # CustomNetwork
      config.net.networkId = CustomNet
  elif skey == "networkid":
    var res = 0
    result = processInteger(value, res)
    if result == Success:
      config.net.setNetwork(NetworkId(result))
      config.net.flags.incl NetworkIdSet
  elif skey == "nodiscover":
    config.net.flags.incl(NoDiscover)
  elif skey == "v5discover":
    config.net.flags.incl(V5Discover)
    config.net.customBootNodes.setBootnodes(DiscoveryV5Bootnodes)
  elif skey == "port":
    var res = 0
    result = processInteger(value, res)
    if result == Success:
      config.net.bindPort = uint16(res and 0xFFFF)
  elif skey == "discport":
    var res = 0
    result = processInteger(value, res)
    if result == Success:
      config.net.discPort = uint16(res and 0xFFFF)
  elif skey == "metrics":
    config.net.metricsServer = true
  elif skey == "metricsport":
    var res = 0
    result = processInteger(value, res)
    if result == Success:
      config.net.metricsServerPort = uint16(res and 0xFFFF)
  elif skey == "maxpeers":
    var res = 0
    result = processInteger(value, res)
    if result == Success:
      config.net.maxPeers = res
  elif skey == "maxpendpeers":
    var res = 0
    result = processInteger(value, res)
    if result == Success:
      config.net.maxPendingPeers = res
  elif skey == "nodekey":
    var res: PrivateKey
    result = processPrivateKey(value, res)
    if result == Success:
      config.net.nodeKey = res
  elif skey == "ident":
    config.net.ident = value
  elif skey == "nat":
    case value.toLowerAscii:
      of "any":
        config.net.nat = NatAny
      of "upnp":
        config.net.nat = NatUpnp
      of "pmp":
        config.net.nat = NatPmp
      of "none":
        config.net.nat = NatNone
      else:
        if isIpAddress(value):
          config.net.externalIP = value
          config.net.nat = NatNone
        else:
          error "not a valid NAT mechanism, nor a valid IP address", value
          result = ErrorParseOption
  elif skey == "protocols":
    config.net.protocols = {}
    result = processProtocolList(value, config.net.protocols)
  else:
    result = EmptyOption

proc processShhArguments(key, value: string): ConfigStatus =
  ## Processes only `Shh` related command line options
  result = Success
  let config = getConfiguration()
  let skey = key.toLowerAscii()
  if skey == "shh-maxsize":
    var res = 0
    result = processInteger(value, res)
    if result == Success:
      config.shh.maxMsgSize = res.uint32
  elif skey == "shh-pow":
    var res = 0.0
    result = processFloat(value, res)
    if result == Success:
      config.shh.powRequirement = res
  elif skey == "shh-light":
    config.shh.isLightNode = true
  else:
    result = EmptyOption

proc processDebugArguments(key, value: string): ConfigStatus =
  ## Processes only `Debug` related command line options
  let config = getConfiguration()
  result = Success
  let skey = key.toLowerAscii()
  if skey == "debug":
    config.debug.flags.incl(DebugFlags.Enabled)
  elif skey == "test":
    var res = newSeq[string]()
    processList(value, res)
    for item in res:
      if item == "test1":
        config.debug.flags.incl(DebugFlags.Test1)
      elif item == "test2":
        config.debug.flags.incl(DebugFlags.Test2)
      elif item == "test3":
        config.debug.flags.incl(DebugFlags.Test3)
  elif skey == "log-level":
    try:
      let logLevel = parseEnum[LogLevel](value)
      if logLevel >= enabledLogLevel:
        config.debug.logLevel = logLevel
      else:
        result = ErrorIncorrectOption
    except ValueError:
      result = ErrorIncorrectOption
  elif skey == "log-file":
    if len(value) == 0:
      result = ErrorIncorrectOption
    else:
      config.debug.logFile = value
  elif skey == "logmetrics":
    config.debug.logMetrics = true
  elif skey == "logmetricsinterval":
    var res = 0
    result = processInteger(value, res)
    if result == Success:
      config.debug.logMetricsInterval = res
  else:
    result = EmptyOption

proc dumpConfiguration*(): string =
  ## Dumps current configuration as string
  let config = getConfiguration()
  result = repr config

template processArgument(processor, key, value, msg: untyped) =
  ## Checks if arguments got processed successfully
  var res = processor(string(key), string(value))
  if res == Success:
    result = res
    continue
  elif res == ErrorParseOption:
    msg = "Error processing option '" & key & "' with value '" & value & "'."
    result = res
    break
  elif res == ErrorIncorrectOption:
    msg = "Incorrect value for option '" & key & "': '" & value & "'."
    result = res
    break

proc getDefaultDataDir*(): string =
  when defined(windows):
    "AppData" / "Roaming" / "Nimbus"
  elif defined(macosx):
    "Library" / "Application Support" / "Nimbus"
  else:
    ".cache" / "nimbus"

proc getDefaultKeystoreDir*(): string =
  getDefaultDataDir() / "keystore"

proc initConfiguration(): NimbusConfiguration =
  ## Allocates and initializes `NimbusConfiguration` with default values
  result = new NimbusConfiguration
  result.rng = newRng()
  result.accounts = initTable[EthAddress, NimbusAccount]()

  ## Graphql defaults
  result.graphql.enabled = false
  result.graphql.address = initTAddress("127.0.0.1:8547")

  ## RPC defaults
  result.rpc.flags = {}
  result.rpc.binds = @[initTAddress("127.0.0.1:8545")]

  ## Network defaults
  result.net.setNetwork(defaultNetwork)
  result.net.maxPeers = 25
  result.net.maxPendingPeers = 0
  result.net.bindPort = 30303'u16
  result.net.discPort = 30303'u16
  result.net.metricsServer = false
  result.net.metricsServerPort = 9093'u16
  result.net.ident = NimbusIdent
  result.net.nat = NatAny
  result.net.protocols = defaultProtocols
  result.net.nodekey = random(PrivateKey, result.rng[])

  const
    dataDir = getDefaultDataDir()
    keystore = getDefaultKeystoreDir()

  result.dataDir = getHomeDir() / dataDir
  result.keystore = getHomeDir() / keystore
  result.prune = PruneMode.Full

  ## Whisper defaults
  result.shh.maxMsgSize = defaultMaxMsgSize
  result.shh.powRequirement = defaultMinPow
  result.shh.isLightNode = false
  result.shh.bloom = fullBloom()

  ## Debug defaults
  result.debug.flags = {}
  result.debug.logLevel = defaultLogLevel
  result.debug.logMetrics = false
  result.debug.logMetricsInterval = 10

proc getConfiguration*(): NimbusConfiguration =
  ## Retreive current configuration object `NimbusConfiguration`.
  if isNil(nimbusConfig):
    nimbusConfig = initConfiguration()
  result = nimbusConfig

proc getHelpString*(): string =
  var logLevels: seq[string]
  for level in LogLevel:
    if level < enabledLogLevel:
      continue
    logLevels.add($level)

  result = """

USAGE:
  nimbus [options]

ETHEREUM OPTIONS:
  --datadir:<value>       Base directory for all blockchain-related data
  --keystore:<value>      Directory for the keystore (default: inside datadir)
  --prune:<value>         Blockchain prune mode (full or archive, default: full)
  --import:<path>         Import RLP encoded block(s), validate, write to database and quit

NETWORKING OPTIONS:
  --bootnodes:<value>     Comma separated enode URLs for P2P discovery bootstrap (set v4+v5 instead for light servers)
  --bootnodesv4:<value>   Comma separated enode URLs for P2P v4 discovery bootstrap (light server, full nodes)
  --bootnodesv5:<value>   Comma separated enode URLs for P2P v5 discovery bootstrap (light server, light nodes)
  --staticnodes:<value>   Comma separated enode URLs to connect with
  --port:<value>          Network listening TCP port (default: 30303)
  --discport:<value>      Network listening UDP port (defaults to --port argument)
  --maxpeers:<value>      Maximum number of network peers (default: 25)
  --maxpendpeers:<value>  Maximum number of pending connection attempts (default: 0)
  --nat:<value>           NAT port mapping mechanism (any|none|upnp|pmp|<external IP>) (default: "any")
  --nodiscover            Disables the peer discovery mechanism (manual peer addition)
  --v5discover            Enables the experimental RLPx V5 (topic discovery) mechanism
  --nodekey:<value>       P2P node private key (as hexadecimal string)
  --ident:<value>         Client identifier (default is '$1')
  --protocols:<value>     Enable specific set of protocols (default: $4)

ETHEREUM NETWORK OPTIONS:
  --mainnet               Use Ethereum main network (default)
  --testnet               Use Ropsten test network
  --ropsten               Use Ropsten test network (proof-of-work, the one most like Ethereum mainnet)
  --goerli                Use Görli test network (proof-of-authority, works across all clients)
  --rinkeby               Use Rinkeby test network (proof-of-authority, for those running Geth clients)
  --kovan                 Use Kovan test network (proof-of-authority, for those running OpenEthereum clients)
  --networkid:<value>     Network id (0=custom, 1=mainnet, 3=ropsten, 4=rinkeby, 5=goerli, 42=kovan, other...)
  --customnetwork:<path>  Use custom genesis block for private Ethereum Network (as /path/to/genesis.json)

WHISPER OPTIONS:
  --shh-maxsize:<value>   Max message size accepted (default: $5)
  --shh-pow:<value>       Minimum POW accepted (default: $6)
  --shh-light             Run as Whisper light client (no outgoing messages)

LOCAL SERVICE OPTIONS:
  --metrics               Enable the metrics HTTP server
  --metricsport:<value>   Set port (always on localhost) metrics HTTP server will bind to (default: 9093)
  --rpc                   Enable the HTTP-RPC server
  --rpcbind:<value>       Set address:port pair(s) (comma-separated) HTTP-RPC server will bind to (default: localhost:8545)
  --rpcapi:<value>        Enable specific set of RPC API from list (comma-separated) (available: eth, shh, debug)
  --graphql               Enable the HTTP-GraphQL server
  --graphqlbind:<value>   Set address:port pair GraphQL server will bind (default: localhost:8547)

LOGGING AND DEBUGGING OPTIONS:
  --log-level:<value>     One of: $2 (default: $3)
  --log-file:<value>      Optional log file, replacing stdout
  --logmetrics            Enable metrics logging
  --logmetricsinterval:<value> Interval at which to log metrics, in seconds (default: 10)
  --debug                 Enable debug mode
  --test:<value>          Perform specified test
""" % [
    NimbusIdent,
    join(logLevels, ", "),
    $defaultLogLevel,
    strip($defaultProtocols, chars = {'{','}'}),
    $defaultMaxMsgSize,
    $defaultMinPow,
    $ord(defaultNetwork)
  ]

when declared(os.paramCount): # not available with `--app:lib`
  proc processArguments*(msg: var string, opt: var OptParser): ConfigStatus =
    ## Process command line argument and update `NimbusConfiguration`.
    let config = getConfiguration()

    # At this point `config.net.discPort` is likely populated with network default
    # discPort. We want to override those if it is specified on the command line.
    config.net.discPort = 0

    var length = 0
    for kind, key, value in opt.getopt():
      result = Error
      case kind
      of cmdArgument:
        discard
      of cmdLongOption, cmdShortOption:
        inc(length)
        case key.toLowerAscii()
          of "help", "h":
            msg = getHelpString()
            result = Success
            break
          of "version", "ver", "v":
            msg = NimbusVersion
            result = Success
            break
          else:
            processArgument processEthArguments, key, value, msg
            processArgument processRpcArguments, key, value, msg
            processArgument processNetArguments, key, value, msg
            processArgument processShhArguments, key, value, msg
            processArgument processDebugArguments, key, value, msg
            processArgument processGraphqlArguments, key, value, msg
            if result != Success:
              msg = "Unknown option: '" & key & "'."
              break
      of cmdEnd:
        doAssert(false) # we're never getting this kind here

    if config.net.discPort == 0:
      config.net.discPort = config.net.bindPort

  proc processArguments*(msg: var string): ConfigStatus =
    var opt = initOptParser()
    processArguments(msg, opt)

proc processConfiguration*(pathname: string): ConfigStatus =
  ## Process configuration file `pathname` and update `NimbusConfiguration`.
  result = Success