# Nimbus
# Copyright (c) 2021 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
  std/[tables, strutils, options, times],
  eth/[common, rlp], stint, stew/[byteutils],
  nimcrypto/hash,
  json_serialization, chronicles,
  json_serialization/std/options as jsoptions,
  json_serialization/std/tables as jstable,
  json_serialization/lexer

type
  ChainOptions = object
    chainId            : ChainId
    homesteadBlock     : Option[BlockNumber]
    daoForkBlock       : Option[BlockNumber]
    daoForkSupport     : bool
    eip150Block        : Option[BlockNumber]
    eip150Hash         : Hash256
    eip155Block        : Option[BlockNumber]
    eip158Block        : Option[BlockNumber]
    byzantiumBlock     : Option[BlockNumber]
    constantinopleBlock: Option[BlockNumber]
    petersburgBlock    : Option[BlockNumber]
    istanbulBlock      : Option[BlockNumber]
    muirGlacierBlock   : Option[BlockNumber]
    berlinBlock        : Option[BlockNumber]

  ChainConfig* = object
    chainId*            : ChainId
    homesteadBlock*     : BlockNumber
    daoForkBlock*       : BlockNumber
    daoForkSupport*     : bool

    # EIP150 implements the Gas price changes (https://github.com/ethereum/EIPs/issues/150)
    eip150Block*        : BlockNumber
    eip150Hash*         : Hash256

    eip155Block*        : BlockNumber
    eip158Block*        : BlockNumber

    byzantiumBlock*     : BlockNumber
    constantinopleBlock*: BlockNumber
    petersburgBlock*    : BlockNumber
    istanbulBlock*      : BlockNumber
    muirGlacierBlock*   : BlockNumber
    berlinBlock*        : BlockNumber

    # TODO: this need to be fixed somehow
    # using `real` engine configuration
    poaEngine*          : bool

  Genesis* = object
    nonce*      : BlockNonce
    timestamp*  : EthTime
    extraData*  : seq[byte]
    gasLimit*   : GasInt
    difficulty* : DifficultyInt
    mixHash*    : Hash256
    coinbase*   : EthAddress
    alloc*      : GenesisAlloc

  GenesisAlloc* = Table[EthAddress, GenesisAccount]
  GenesisAccount* = object
    code*   : seq[byte]
    storage*: Table[UInt256, UInt256]
    balance*: UInt256
    nonce*  : AccountNonce

  CustomGenesis* = object
    config* : ChainConfig
    genesis*: Genesis

  AddressBalance = object
    address {.rlpCustomSerialization.}: EthAddress
    account {.rlpCustomSerialization.}: GenesisAccount

  CustomChain = object
    config : ChainOptions
    genesis: Genesis

proc read(rlp: var Rlp, x: var AddressBalance, _: type EthAddress): EthAddress {.inline.} =
  let val = rlp.read(UInt256).toByteArrayBE()
  result[0 .. ^1] = val.toOpenArray(12, val.high)

proc read(rlp: var Rlp, x: var AddressBalance, _: type GenesisAccount): GenesisAccount {.inline.} =
  GenesisAccount(balance: rlp.read(UInt256))

func decodePrealloc*(data: seq[byte]): GenesisAlloc =
  for tup in rlp.decode(data, seq[AddressBalance]):
    result[tup.address] = tup.account

proc readValue(reader: var JsonReader, value: var BlockNumber) =
  let tok = reader.lexer.tok
  if tok == tkInt:
    value = toBlockNumber(reader.lexer.absintVal)
    reader.lexer.next()
  elif tok == tkString:
    value = UInt256.fromHex(reader.lexer.strVal)
    reader.lexer.next()
  else:
    reader.raiseUnexpectedValue("expect int or hex string")

proc readValue(reader: var JsonReader, value: var ChainId) =
  value = reader.readValue(int).ChainId

proc readValue(reader: var JsonReader, value: var Hash256) =
  value = Hash256.fromHex(reader.readValue(string))

proc readValue(reader: var JsonReader, value: var BlockNonce) =
  value = fromHex[uint64](reader.readValue(string)).toBlockNonce

proc readValue(reader: var JsonReader, value: var EthTime) =
  value = fromHex[int64](reader.readValue(string)).fromUnix

proc readValue(reader: var JsonReader, value: var seq[byte]) =
  value = hexToSeqByte(reader.readValue(string))

proc readValue(reader: var JsonReader, value: var GasInt) =
  value = fromHex[GasInt](reader.readValue(string))

proc readValue(reader: var JsonReader, value: var EthAddress) =
  value = parseAddress(reader.readValue(string))

proc readValue(reader: var JsonReader, value: var AccountNonce) =
  value = fromHex[uint64](reader.readValue(string))

template to(a: string, b: type EthAddress): EthAddress =
  # json_serialization decode table stuff
  parseAddress(a)

template to(a: string, b: type UInt256): UInt256 =
  # json_serialization decode table stuff
  UInt256.fromHex(a)

proc loadCustomGenesis*(fileName: string, cg: var CustomGenesis): bool =
  var cc: CustomChain
  try:
    cc = Json.loadFile(fileName, CustomChain, allowUnknownFields = true)
  except IOError as e:
    error "Genesis config file error", fileName, msg=e.msg
    return false
  except JsonReaderError as e:
    error "Invalid genesis config file format", fileName, msg=e.formatMsg("")
    return false
  except:
    var msg = getCurrentExceptionMsg()
    error "Error loading genesis block config file", fileName, msg
    return false

  cg.genesis               = cc.genesis
  cg.config.chainId        = cc.config.chainId
  cg.config.daoForkSupport = cc.config.daoForkSupport
  cg.config.eip150Hash     = cc.config.eip150Hash

  # TODO: this need to be fixed somehow
  # using `real` engine configuration
  cg.config.poaEngine      = false

  template validateFork(forkName: untyped, nextBlock: BlockNumber) =
    let fork = astToStr(forkName)
    if cc.config.forkName.isSome:
      cg.config.forkName = cc.config.forkName.get()
    else:
      cg.config.forkName = nextBlock
    if cg.config.forkName > nextBlock:
      error "Forks can't be assigned out of order", fork=fork
      return false

  validateFork(berlinBlock,         high(BlockNumber).toBlockNumber)
  validateFork(muirGlacierBlock,    cg.config.berlinBlock)
  validateFork(istanbulBlock,       cg.config.muirGlacierBlock)
  validateFork(petersburgBlock,     cg.config.istanbulBlock)
  validateFork(constantinopleBlock, cg.config.petersburgBlock)
  validateFork(byzantiumBlock,      cg.config.constantinopleBlock)
  validateFork(eip158Block,         cg.config.byzantiumBlock)
  validateFork(eip155Block,         cg.config.eip158Block)
  validateFork(eip150Block,         cg.config.eip155Block)
  validateFork(daoForkBlock,        cg.config.eip150Block)
  validateFork(homesteadBlock,      cg.config.daoForkBlock)

  return true

proc parseGenesisAlloc*(data: string, ga: var GenesisAlloc): bool =
  try:
    ga = Json.decode(data, GenesisAlloc, allowUnknownFields = true)
  except JsonReaderError as e:
    error "Invalid genesis config file format", msg=e.formatMsg("")
    return false

  return true