import options,
  eth/[common, bloom], ranges, chronicles, nimcrypto,
  ../db/[db_chain, state_db],
  ../utils, ../constants, ../transaction,
  ../vm_state, ../vm_types, ../vm_state_transactions,
  ../vm/[computation, interpreter_dispatch, message],
  ../vm/interpreter/vm_forks

proc processTransaction*(tx: Transaction, sender: EthAddress, vmState: BaseVMState, forkOverride=none(Fork)): GasInt =
  ## Process the transaction, write the results to db.
  ## Returns amount of ETH to be rewarded to miner
  trace "Sender", sender
  trace "txHash", rlpHash = tx.rlpHash

  # TODO: we have identical `fork` code in setupComputation.
  # at later stage, we need to get rid of it
  # and apply changes in eth_*, debug_* RPC,
  # macro assembler and premix tool set.
  # at every place where setupComputation and
  # processTransaction are used.
  let fork =
    if forkOverride.isSome:
      forkOverride.get
    else:
      vmState.blockNumber.toFork

  let upfrontGasCost = tx.gasLimit.u256 * tx.gasPrice.u256
  var balance = vmState.readOnlyStateDb().getBalance(sender)
  if balance < upfrontGasCost:
    return tx.gasLimit

  let recipient = tx.getRecipient()
  let isCollision = vmState.readOnlyStateDb().hasCodeOrNonce(recipient)

  var computation = setupComputation(vmState, tx, sender, recipient, forkOverride)
  if computation.isNil:
    return 0

  vmState.mutateStateDB:
    db.incNonce(sender)
    db.subBalance(sender, upfrontGasCost)

  if tx.isContractCreation and isCollision:
    return tx.gasLimit

  var snapshot = vmState.snapshot()
  defer: snapshot.dispose()

  var contractOK = true
  result = tx.gasLimit

  if execComputation(computation):
    if tx.isContractCreation:
      contractOK = computation.writeContract(fork)
    result = computation.refundGas(tx, sender)

  if not contractOK and fork == FkHomestead:
    snapshot.revert()
    # consume all gas
    result = tx.gasLimit
  else:
    snapshot.commit()
  
  if computation.isSuicided(vmState.blockHeader.coinbase):
    return 0

type
  # TODO: these types need to be removed
  # once eth/bloom and eth/common sync'ed
  Bloom = common.BloomFilter
  LogsBloom = bloom.BloomFilter

# TODO: move these three receipt procs below somewhere else more appropriate
func logsBloom(logs: openArray[Log]): LogsBloom =
  for log in logs:
    result.incl log.address
    for topic in log.topics:
      result.incl topic

func createBloom*(receipts: openArray[Receipt]): Bloom =
  var bloom: LogsBloom
  for receipt in receipts:
    bloom.value = bloom.value or logsBloom(receipt.logs).value
  result = bloom.value.toByteArrayBE

proc makeReceipt(vmState: BaseVMState, cumulativeGasUsed: GasInt, fork = FkFrontier): Receipt =
  if fork < FkByzantium:
    result.stateRootOrStatus = hashOrStatus(vmState.accountDb.rootHash)
  else:
    # TODO: post byzantium fork use status instead of rootHash
    let vmStatus = true # success or failure
    result.stateRootOrStatus = hashOrStatus(vmStatus)

  result.cumulativeGasUsed = cumulativeGasUsed
  result.logs = vmState.getAndClearLogEntries()
  result.bloom = logsBloom(result.logs).value.toByteArrayBE

proc processBlock*(chainDB: BaseChainDB, head, header: BlockHeader, body: BlockBody, vmState: BaseVMState): ValidationResult =
  let blockReward = 5.u256 * pow(10.u256, 18) # 5 ETH

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

  if header.txRoot != BLANK_ROOT_HASH:
    if body.transactions.len == 0:
      debug "No transactions in body", blockNumber=header.blockNumber
      return ValidationResult.Error
    else:
      trace "Has transactions", blockNumber = header.blockNumber, blockHash = header.blockHash

      vmState.receipts = newSeq[Receipt](body.transactions.len)
      var cumulativeGasUsed = GasInt(0)
      for txIndex, tx in body.transactions:
        if cumulativeGasUsed + tx.gasLimit > header.gasLimit:
          vmState.mutateStateDB:
            db.addBalance(header.coinbase, 0.u256)
          # TODO: do we need to break or continue execution?
        else:
          var sender: EthAddress
          if tx.getSender(sender):
            let gasUsed = processTransaction(tx, sender, vmState)
            cumulativeGasUsed += gasUsed

            # miner fee
            let txFee = gasUsed.u256 * tx.gasPrice.u256
            vmState.mutateStateDB:
              db.addBalance(header.coinbase, txFee)
          else:
            debug "Could not get sender", txIndex, tx
            return ValidationResult.Error
          vmState.receipts[txIndex] = makeReceipt(vmState, cumulativeGasUsed)

  var mainReward = blockReward
  if header.ommersHash != EMPTY_UNCLE_HASH:
    let h = chainDB.persistUncles(body.uncles)
    if h != header.ommersHash:
      debug "Uncle hash mismatch"
      return ValidationResult.Error
    for uncle in body.uncles:
      var uncleReward = uncle.blockNumber + 8.u256
      uncleReward -= header.blockNumber
      uncleReward = uncleReward * blockReward
      uncleReward = uncleReward div 8.u256
      vmState.mutateStateDB:
        db.addBalance(uncle.coinbase, uncleReward)
      mainReward += blockReward div 32.u256

  # Reward beneficiary
  vmState.mutateStateDB:
    db.addBalance(header.coinbase, mainReward)

  let stateDb = vmState.accountDb
  if header.stateRoot != stateDb.rootHash:
    error "Wrong state root in block", blockNumber=header.blockNumber, expected=header.stateRoot, actual=stateDb.rootHash, arrivedFrom=chainDB.getCanonicalHead().stateRoot
    # this one is a show stopper until we are confident in our VM's
    # compatibility with the main chain
    return ValidationResult.Error

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

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