import
  math, strutils, eth/common, nimcrypto/hash

proc default(t: typedesc): t = discard

# constants
const
  UINT_256_MAX*: UInt256 =                  high(UInt256)
  INT_256_MAX_AS_UINT256* =                 high(Uint256) shr 1
  UINT160CEILING*: UInt256 =                2.u256.pow(160)
  ZERO_ADDRESS* =                           default(EthAddress)
  # TODO: use Option[EthAddress]?
  # create contract address cannot be ZERO_ADDRESS
  # because actual zero address exists
  CREATE_CONTRACT_ADDRESS* =                ZERO_ADDRESS
  ZERO_HASH32* =                            Hash256()

  GAS_LIMIT_EMA_DENOMINATOR* =              1_024
  GAS_LIMIT_ADJUSTMENT_FACTOR* =            1_024
  GAS_LIMIT_USAGE_ADJUSTMENT_NUMERATOR* =   3
  GAS_LIMIT_USAGE_ADJUSTMENT_DENOMINATOR* = 2

  DIFFICULTY_ADJUSTMENT_DENOMINATOR* =      2_048.u256
  DIFFICULTY_MINIMUM* =                     131_072.u256
  BYZANTIUM_DIFFICULTY_ADJUSTMENT_CUTOFF* = 9

  BOMB_EXPONENTIAL_PERIOD* =                100_000.u256
  BOMB_EXPONENTIAL_FREE_PERIODS* =          2.u256

  BLOCK_REWARD* =                           5.u256 * 2.u256 # denoms.ether

  UNCLE_DEPTH_PENALTY_FACTOR* =             8.u256

  MAX_UNCLE_DEPTH* =                        6.u256
  MAX_UNCLES* =                             2

  EMPTY_UNCLE_HASH* =                       "1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347".toDigest

  GENESIS_BLOCK_NUMBER* =                   0.toBlockNumber
  GENESIS_DIFFICULTY* =                     131_072.u256
  GENESIS_GAS_LIMIT* =                      3_141_592
  GENESIS_PARENT_HASH* =                    ZERO_HASH32
  GENESIS_COINBASE* =                       ZERO_ADDRESS
  GENESIS_NONCE* =                          "\x00\x00\x00\x00\x00\x00\x00B"
  GENESIS_MIX_HASH* =                       ZERO_HASH32
  GENESIS_EXTRA_DATA* =                     ""
  GAS_LIMIT_MINIMUM* =                      5000

  BLANK_ROOT_HASH* =                        "56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421".toDigest
  EMPTY_SHA3* =                             "c5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470".toDigest

  GAS_MOD_EXP_QUADRATIC_DENOMINATOR* =      20.u256

  MAX_PREV_HEADER_DEPTH* =                  256.toBlockNumber
  MaxCallDepth* =                           1024

  SECPK1_N* =                               Uint256.fromHex("fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141")

  ## Fork specific constants

  # See: https://github.com/ethereum/EIPs/blob/master/EIPS/eip-170.md
  # and: https://github.com/ethereum/EIPs/issues/170
  EIP170_CODE_SIZE_LIMIT* =                 24577