# Nimbus
# Copyright (c) 2018 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/accounts_cache,
  ../../transaction,
  ../../vm_state,
  ../../vm_types,
  ../clique,
  ../dao,
  ./calculate_reward,
  ./executor_helpers,
  ./process_transaction,
  chronicles,
  stew/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]): Result[void, string]
    {.gcsafe, raises: [CatchableError].} =
  vmState.receipts = newSeq[Receipt](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)
    vmState.receipts[txIndex] = vmState.makeReceipt(tx.txType)
  ok()

proc procBlkPreamble(vmState: BaseVMState;
                     header: BlockHeader; body: BlockBody): bool
    {.gcsafe, raises: [CatchableError].} =

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

  if body.transactions.calcTxRoot != header.txRoot:
    debug "Mismatched txRoot",
      blockNumber = header.blockNumber
    return false

  if header.txRoot != EMPTY_ROOT_HASH:
    if body.transactions.len == 0:
      debug "No transactions in body",
        blockNumber = header.blockNumber
      return false
    else:
      let r = processTransactions(vmState, header, body.transactions)
      if r.isErr:
        error("error in processing transactions", err=r.error)

  if vmState.determineFork >= FkShanghai:
    if header.withdrawalsRoot.isNone:
      raise ValidationError.newException("Post-Shanghai block header must have withdrawalsRoot")
    if body.withdrawals.isNone:
      raise ValidationError.newException("Post-Shanghai block body must have withdrawals")

    for withdrawal in body.withdrawals.get:
      vmState.stateDB.addBalance(withdrawal.address, withdrawal.amount.gwei)
  else:
    if header.withdrawalsRoot.isSome:
      raise ValidationError.newException("Pre-Shanghai block header must not have withdrawalsRoot")
    if body.withdrawals.isSome:
      raise ValidationError.newException("Pre-Shanghai block body must not have withdrawals")

  if vmState.cumulativeGasUsed != header.gasUsed:
    debug "gasUsed neq cumulativeGasUsed",
      gasUsed = header.gasUsed,
      cumulativeGasUsed = vmState.cumulativeGasUsed
    return false

  if header.ommersHash != EMPTY_UNCLE_HASH:
    let h = vmState.com.db.persistUncles(body.uncles)
    if h != header.ommersHash:
      debug "Uncle hash mismatch"
      return false

  true

proc procBlkEpilogue(vmState: BaseVMState;
                     header: BlockHeader; body: BlockBody): bool
    {.gcsafe, raises: [RlpError].} =
  # Reward beneficiary
  vmState.mutateStateDB:
    if vmState.generateWitness:
      db.collectWitnessData()
    let clearEmptyAccount = vmState.determineFork >= FkSpurious
    db.persist(clearEmptyAccount, ClearCache in vmState.flags)

  let stateDb = vmState.stateDB
  if header.stateRoot != stateDb.rootHash:
    debug "wrong state root in block",
      blockNumber = header.blockNumber,
      expected = header.stateRoot,
      actual = stateDb.rootHash,
      arrivedFrom = vmState.com.db.getCanonicalHead().stateRoot
    return false

  let bloom = createBloom(vmState.receipts)
  if header.bloom != bloom:
    debug "wrong bloom in block",
      blockNumber = header.blockNumber
    return false

  let receiptRoot = calcReceiptRoot(vmState.receipts)
  if header.receiptRoot != receiptRoot:
    debug "wrong receiptRoot in block",
      blockNumber = header.blockNumber,
      actual = receiptRoot,
      expected = header.receiptRoot
    return false

  true

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

proc processBlockNotPoA*(
    vmState: BaseVMState; ## Parent environment of header/body block
    header:  BlockHeader; ## Header/body block to add to the blockchain
    body:    BlockBody): ValidationResult
    {.gcsafe, raises: [CatchableError].} =
  ## Processes `(header,body)` pair for a non-PoA network, only. This function
  ## will fail when applied to a PoA network like `Goerli`.
  if vmState.com.consensus == ConsensusType.POA:
    # PoA consensus engine unsupported, see the other version of
    # processBlock() below
    debug "Unsupported PoA request"
    return ValidationResult.Error

  var dbTx = vmState.com.db.beginTransaction()
  defer: dbTx.dispose()

  if not vmState.procBlkPreamble(header, body):
    return ValidationResult.Error

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

  if not vmState.procBlkEpilogue(header, body):
    return ValidationResult.Error

  # `applyDeletes = false`
  # If the trie pruning activated, each of the block will have its own state
  # trie keep intact, rather than destroyed by trie pruning. But the current
  # block will still get a pruned trie. If trie pruning deactivated,
  # `applyDeletes` have no effects.
  dbTx.commit(applyDeletes = false)

  ValidationResult.OK


proc processBlock*(
    vmState: BaseVMState;  ## Parent environment of header/body block
    poa:     Clique;       ## PoA descriptor (if needed, at all)
    header:  BlockHeader;  ## Header/body block to add to the blockchain
    body:    BlockBody): ValidationResult
    {.gcsafe, raises: [CatchableError].} =
  ## Generalised function to processes `(header,body)` pair for any network,
  ## regardless of PoA or not. Currently there is no mining support so this
  ## function is mostly the same as `processBlockNotPoA()`.
  ##
  ## Rather than calculating the PoA state change here, it is done with the
  ## verification in the `chain/persist_blocks.persistBlocks()` method. So
  ## the `poa` descriptor is currently unused and only provided for later
  ## implementations (but can be savely removed, as well.)
  ## variant of `processBlock()` where the `header` argument is explicitely set.
  ##
  # # Process PoA state transition first so there is no need to re-wind on
  # # an error.
  # if vmState.chainDB.config.poaEngine and
  #    not poa.updatePoaState(header, body):
  #   debug "PoA update failed"
  #   return ValidationResult.Error

  var dbTx = vmState.com.db.beginTransaction()
  defer: dbTx.dispose()

  if not vmState.procBlkPreamble(header, body):
    return ValidationResult.Error

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

  if not vmState.procBlkEpilogue(header, body):
    return ValidationResult.Error

  dbTx.commit(applyDeletes = false)

  ValidationResult.OK

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