# Nimbus
# Copyright (c) 2018-2024 Status Research & Development GmbH
# Licensed under either of
#  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
#    http://www.apache.org/licenses/LICENSE-2.0)
#  * MIT license ([LICENSE-MIT](LICENSE-MIT) or
#    http://opensource.org/licenses/MIT)
# at your option. This file may not be copied, modified, or distributed except
# according to those terms.

import
  ../../utils/utils,
  ../../common/common,
  ../../constants,
  ../../db/ledger,
  ../../transaction,
  ../../evm/state,
  ../../evm/types,
  ../dao,
  ./calculate_reward,
  ./executor_helpers,
  ./process_transaction,
  chronicles,
  results

{.push raises: [].}

# Factored this out of procBlkPreamble so that it can be used directly for
# stateless execution of specific transactions.
proc processTransactions*(
    vmState: BaseVMState,
    header: BlockHeader,
    transactions: seq[Transaction],
    skipReceipts = false,
): Result[void, string] =
  vmState.receipts.setLen(if skipReceipts: 0 else: transactions.len)
  vmState.cumulativeGasUsed = 0

  for txIndex, tx in transactions:
    var sender: EthAddress
    if not tx.getSender(sender):
      return err("Could not get sender for tx with index " & $(txIndex))
    let rc = vmState.processTransaction(tx, sender, header)
    if rc.isErr:
      return err("Error processing tx with index " & $(txIndex) & ":" & rc.error)
    if skipReceipts:
      # TODO don't generate logs at all if we're not going to put them in
      #      receipts
      discard vmState.getAndClearLogEntries()
    else:
      vmState.receipts[txIndex] = vmState.makeReceipt(tx.txType)
  ok()

proc procBlkPreamble(
    vmState: BaseVMState, blk: EthBlock, skipValidation, skipReceipts, skipUncles: bool
): Result[void, string] =
  template header(): BlockHeader =
    blk.header

  let com = vmState.com
  if com.daoForkSupport and com.daoForkBlock.get == header.number:
    vmState.mutateStateDB:
      db.applyDAOHardFork()

  if not skipValidation: # Expensive!
    if blk.transactions.calcTxRoot != header.txRoot:
      return err("Mismatched txRoot")

  if com.isCancunOrLater(header.timestamp):
    if header.parentBeaconBlockRoot.isNone:
      return err("Post-Cancun block header must have parentBeaconBlockRoot")

    ?vmState.processBeaconBlockRoot(header.parentBeaconBlockRoot.get)
  else:
    if header.parentBeaconBlockRoot.isSome:
      return err("Pre-Cancun block header must not have parentBeaconBlockRoot")

  if header.txRoot != EMPTY_ROOT_HASH:
    if blk.transactions.len == 0:
      return err("Transactions missing from body")

    ?processTransactions(vmState, header, blk.transactions, skipReceipts)
  elif blk.transactions.len > 0:
    return err("Transactions in block with empty txRoot")

  if com.isShanghaiOrLater(header.timestamp):
    if header.withdrawalsRoot.isNone:
      return err("Post-Shanghai block header must have withdrawalsRoot")
    if blk.withdrawals.isNone:
      return err("Post-Shanghai block body must have withdrawals")

    for withdrawal in blk.withdrawals.get:
      vmState.stateDB.addBalance(withdrawal.address, withdrawal.weiAmount)
  else:
    if header.withdrawalsRoot.isSome:
      return err("Pre-Shanghai block header must not have withdrawalsRoot")
    if blk.withdrawals.isSome:
      return err("Pre-Shanghai block body must not have withdrawals")

  if vmState.cumulativeGasUsed != header.gasUsed:
    # TODO replace logging with better error
    debug "gasUsed neq cumulativeGasUsed",
      gasUsed = header.gasUsed, cumulativeGasUsed = vmState.cumulativeGasUsed
    return err("gasUsed mismatch")

  if header.ommersHash != EMPTY_UNCLE_HASH:
    # TODO It's strange that we persist uncles before processing block but the
    #      rest after...
    if not skipUncles:
      let h = vmState.com.db.persistUncles(blk.uncles)
      if h != header.ommersHash:
        return err("ommersHash mismatch")
    elif not skipValidation and rlpHash(blk.uncles) != header.ommersHash:
      return err("ommersHash mismatch")
  elif blk.uncles.len > 0:
    return err("Uncles in block with empty uncle hash")

  ok()

proc procBlkEpilogue(
    vmState: BaseVMState, header: BlockHeader, skipValidation: bool, skipReceipts: bool
): Result[void, string] =
  # Reward beneficiary
  vmState.mutateStateDB:
    if vmState.collectWitnessData:
      db.collectWitnessData()

    # Clearing the account cache here helps manage its size when replaying
    # large ranges of blocks, implicitly limiting its size using the gas limit
    db.persist(
      clearEmptyAccount = vmState.com.isSpuriousOrLater(header.number),
      clearCache = true)

  if not skipValidation:
    let stateDB = vmState.stateDB
    if header.stateRoot != stateDB.rootHash:
      # TODO replace logging with better error
      debug "wrong state root in block",
        blockNumber = header.number,
        expected = header.stateRoot,
        actual = stateDB.rootHash,
        arrivedFrom = vmState.com.db.getCanonicalHead().stateRoot
      return err("stateRoot mismatch")

    if not skipReceipts:
      let bloom = createBloom(vmState.receipts)
  
      if header.logsBloom != bloom:
        return err("bloom mismatch")
  
      let receiptsRoot = calcReceiptsRoot(vmState.receipts)
      if header.receiptsRoot != receiptsRoot:
        # TODO replace logging with better error
        debug "wrong receiptRoot in block",
          blockNumber = header.number,
          actual = receiptsRoot,
          expected = header.receiptsRoot
        return err("receiptRoot mismatch")

  ok()

# ------------------------------------------------------------------------------
# Public functions
# ------------------------------------------------------------------------------

proc processBlock*(
    vmState: BaseVMState, ## Parent environment of header/body block
    blk: EthBlock, ## Header/body block to add to the blockchain
    skipValidation: bool = false,
    skipReceipts: bool = false,
    skipUncles: bool = false,
): Result[void, string] =
  ## Generalised function to processes `blk` for any network.
  ?vmState.procBlkPreamble(blk, skipValidation, skipReceipts, skipUncles)

  # EIP-3675: no reward for miner in POA/POS
  if vmState.com.consensus == ConsensusType.POW:
    vmState.calculateReward(blk.header, blk.uncles)

  ?vmState.procBlkEpilogue(blk.header, skipValidation, skipReceipts)

  ok()

# ------------------------------------------------------------------------------
# End
# ------------------------------------------------------------------------------