import
  tables, strutils, os, options,
  stew/shims/macros, nimcrypto/hash,
  web3/[ethtypes, conversions],
  spec/presets

# ATTENTION! This file will produce a large C file, because we are inlining
# genesis states as C literals in the generated code (and blobs in the final
# binary). It makes sense to keep the file small and separated from the rest
# of the module in order go gain maximum efficiency in incremental compilation.
#
# TODO:
# We can compress the embedded states with snappy before embedding them here.

{.push raises: [Defect].}

export
  ethtypes, conversions, RuntimePreset

type
  Eth1Address* = ethtypes.Address
  Eth1BlockHash* = ethtypes.BlockHash

  Eth1Network* = enum
    mainnet
    rinkeby
    goerli

  PresetIncompatible* = object of CatchableError

  Eth2NetworkMetadata* = object
    case incompatible*: bool
    of false:
      eth1Network*: Option[Eth1Network]
      runtimePreset*: RuntimePreset

      # Parsing `enr.Records` is still not possible at compile-time
      bootstrapNodes*: seq[string]

      depositContractAddress*: Eth1Address
      depositContractDeployedAt*: Eth1BlockHash

      # Please note that we are using `string` here because SSZ.decode
      # is not currently usable at compile time and we want to load the
      # network metadata into a constant.
      #
      # We could have also used `seq[byte]`, but this results in a lot
      # more generated code that slows down compilation. The impact on
      # compilation times of embedding the genesis as a string is roughly
      # 0.1s on my machine (you can test this by choosing an invalid name
      # for the genesis file below).
      #
      # `genesisData` will have `len == 0` for networks with a still
      # unknown genesis state.
      genesisData*: string
    else:
      incompatibilityDesc*: string

const presetValueLoaders = genExpr(nnkBracket):
  for constName in PresetValue:
    let
      constNameIdent = ident $constName
      constType = ident getType(constName)

    yield quote do:
      (
        proc (preset: var RuntimePreset, presetValue: string): bool
             {.gcsafe, noSideEffect, raises: [Defect].} =
          try:
            when PresetValue.`constNameIdent` in runtimeValues:
              preset.`constNameIdent` = parse(`constType`, presetValue)
              true
            elif PresetValue.`constNameIdent` in ignoredValues:
              true
            else:
              `constType`(`constNameIdent`) == parse(`constType`, presetValue)
          except CatchableError as err:
            false
      )

proc extractRuntimePreset*(configPath: string, configData: PresetFile): RuntimePreset
                          {.raises: [PresetIncompatible, Defect].} =
  result = RuntimePreset()

  for name, value in configData.values:
    if name notin runtimeValues:
      if not presetValueLoaders[name.int](result, value):
        let errMsg = "The preset '" & configPath & "'is not compatible with " &
                     "the current build due to an incompatible value " &
                     $name & " = " & value.string
        raise newException(PresetIncompatible, errMsg)

proc loadEth2NetworkMetadata*(path: string): Eth2NetworkMetadata
                             {.raises: [CatchableError, Defect].} =
  try:
    let
      genesisPath = path / "genesis.ssz"
      configPath = path / "config.yaml"
      runtimePreset = extractRuntimePreset(configPath, readPresetFile(configPath))

    Eth2NetworkMetadata(
      incompatible: false,
      eth1Network: some goerli,
      runtimePreset: runtimePreset,
      bootstrapNodes: readFile(path / "bootstrap_nodes.txt").split("\n"),
      depositContractAddress: Eth1Address.fromHex readFile(path / "deposit_contract.txt").strip,
      depositContractDeployedAt: Eth1BlockHash.fromHex readFile(path / "deposit_contract_block.txt").strip,
      genesisData: if fileExists(genesisPath): readFile(genesisPath) else: "")
  except PresetIncompatible as err:
    Eth2NetworkMetadata(incompatible: true,
                        incompatibilityDesc: err.msg)

when const_preset == "mainnet":
  const
    mainnetMetadata* = Eth2NetworkMetadata(
      incompatible: false, # TODO: This can be more accurate if we verify
                           # that there are no constant overrides
      eth1Network: some mainnet,
      runtimePreset: mainnetRuntimePreset,
      # TODO The values below are just placeholders for now
      bootstrapNodes: @[],
      depositContractAddress: Eth1Address.fromHex "0x1234567890123456789012345678901234567890",
      depositContractDeployedAt: Eth1BlockHash.fromHex "0x73056f16a59bf70abad5b4365438e8a7d646aa0d7f56d22c3d9e4c6000d8e176",
      genesisData: "")

    altonaMetadata* = loadEth2NetworkMetadata(
      currentSourcePath.parentDir / ".." / "vendor" / "eth2-testnets" / "shared" / "altona")