import std/json
import std/macros
import std/sequtils
import pkg/chronicles
import pkg/chronos
import pkg/contractabi
import ./basics
import ./provider
import ./signer
import ./events
import ./fields

export basics
export provider
export events

logScope:
  topics = "ethers contract"

type
  Contract* = ref object of RootObj
    provider: Provider
    signer: ?Signer
    address: Address
  TransactionOverrides* = ref object of RootObj
    nonce*: ?UInt256
    chainId*: ?UInt256
    gasPrice*: ?UInt256
    maxFee*: ?UInt256
    maxPriorityFee*: ?UInt256
    gasLimit*: ?UInt256
  CallOverrides* = ref object of TransactionOverrides
    blockTag*: ?BlockTag

  ContractError* = object of EthersError
  Confirmable* = ?TransactionResponse
  EventHandler*[E: Event] = proc(event: E) {.gcsafe, upraises:[].}

func new*(ContractType: type Contract,
          address: Address,
          provider: Provider): ContractType =
  ContractType(provider: provider, address: address)

func new*(ContractType: type Contract,
          address: Address,
          signer: Signer): ContractType =
  ContractType(signer: some signer, provider: signer.provider, address: address)

func connect*[T: Contract](contract: T, provider: Provider | Signer): T =
  T.new(contract.address, provider)

func provider*(contract: Contract): Provider =
  contract.provider

func signer*(contract: Contract): ?Signer =
  contract.signer

func address*(contract: Contract): Address =
  contract.address

template raiseContractError(message: string) =
  raise newException(ContractError, message)

proc createTransaction(contract: Contract,
                       function: string,
                       parameters: tuple,
                       overrides = TransactionOverrides()): Transaction =
  let selector = selector(function, typeof parameters).toArray
  let data = @selector & AbiEncoder.encode(parameters)
  Transaction(
    to: contract.address,
    data: data,
    nonce: overrides.nonce,
    chainId: overrides.chainId,
    gasPrice: overrides.gasPrice,
    maxFee: overrides.maxFee,
    maxPriorityFee: overrides.maxPriorityFee,
    gasLimit: overrides.gasLimit,
  )

proc decodeResponse(T: type, multiple: static bool, bytes: seq[byte]): T =
  when multiple:
    without decoded =? AbiDecoder.decode(bytes, T):
      raiseContractError "unable to decode return value as " & $T
    return decoded
  else:
    return decodeResponse((T,), true, bytes)[0]

proc call(provider: Provider,
          transaction: Transaction,
          overrides: TransactionOverrides): Future[seq[byte]] =
  if overrides of CallOverrides and
     blockTag =? CallOverrides(overrides).blockTag:
    provider.call(transaction, blockTag)
  else:
    provider.call(transaction)

proc call(contract: Contract,
          function: string,
          parameters: tuple,
          overrides = TransactionOverrides()) {.async.} =
  var transaction = createTransaction(contract, function, parameters, overrides)

  if signer =? contract.signer and transaction.sender.isNone:
    transaction.sender = some(await signer.getAddress())

  discard await contract.provider.call(transaction, overrides)

proc call(contract: Contract,
          function: string,
          parameters: tuple,
          ReturnType: type,
          returnMultiple: static bool,
          overrides = TransactionOverrides()): Future[ReturnType] {.async.} =
  var transaction = createTransaction(contract, function, parameters, overrides)

  if signer =? contract.signer and transaction.sender.isNone:
    transaction.sender = some(await signer.getAddress())

  let response = await contract.provider.call(transaction, overrides)
  return decodeResponse(ReturnType, returnMultiple, response)

proc send(contract: Contract,
          function: string,
          parameters: tuple,
          overrides = TransactionOverrides()):
         Future[?TransactionResponse] {.async.} =
  if signer =? contract.signer:
    let transaction = createTransaction(contract, function, parameters, overrides)
    let populated = await signer.populateTransaction(transaction)
    let txResp = await signer.sendTransaction(populated)
    return txResp.some
  else:
    await call(contract, function, parameters)
    return TransactionResponse.none

func getParameterTuple(procedure: NimNode): NimNode =
  let parameters = procedure[3]
  var tupl = newNimNode(nnkTupleConstr, parameters)
  for parameter in parameters[2..^1]:
    for name in parameter[0..^3]:
      tupl.add name
  return tupl

func isConstant(procedure: NimNode): bool =
  let pragmas = procedure[4]
  for pragma in pragmas:
    if pragma.eqIdent "view":
      return true
    elif pragma.eqIdent "pure":
      return true
  false

func isMultipleReturn(returnType: NimNode): bool =
  (returnType.kind == nnkPar and returnType.len > 1) or
  (returnType.kind == nnkTupleConstr) or
  (returnType.kind == nnkTupleTy)

func addOverrides(procedure: var NimNode) =
  procedure[3].add(
    newIdentDefs(
      ident("overrides"),
      newEmptyNode(),
      quote do: TransactionOverrides()
    )
  )

func addContractCall(procedure: var NimNode) =
  let contract = procedure[3][1][0]
  let function = $basename(procedure[0])
  let parameters = getParameterTuple(procedure)
  let returnType = procedure[3][0]
  let returnMultiple = returnType.isMultipleReturn.newLit

  procedure.addOverrides()

  func call: NimNode =
    if returnType.kind == nnkEmpty:
      quote:
        await call(`contract`, `function`, `parameters`, overrides)
    else:
      quote:
        return await call(
          `contract`, `function`, `parameters`, `returnType`, `returnMultiple`, overrides)

  func send: NimNode =
    if returnType.kind == nnkEmpty:
      quote:
        discard await send(`contract`, `function`, `parameters`, overrides)
    else:
      quote:
        when typeof(result) isnot Confirmable:
          {.error: "unexpected return type, missing {.view.} or {.pure.} ?".}
        return await send(`contract`, `function`, `parameters`, overrides)

  procedure[6] =
    if procedure.isConstant:
      call()
    else:
      send()

func addFuture(procedure: var NimNode) =
  let returntype = procedure[3][0]
  if returntype.kind != nnkEmpty:
    procedure[3][0] = quote: Future[`returntype`]

func addAsyncPragma(procedure: var NimNode) =
  let pragmas = procedure[4]
  if pragmas.kind == nnkEmpty:
    procedure[4] = newNimNode(nnkPragma)
  procedure[4].add ident("async")

macro contract*(procedure: untyped{nkProcDef|nkMethodDef}): untyped =

  let parameters = procedure[3]
  let body = procedure[6]

  parameters.expectMinLen(2) # at least return type and contract instance
  body.expectKind(nnkEmpty)

  var contractcall = copyNimTree(procedure)
  contractcall.addContractCall()
  contractcall.addFuture()
  contractcall.addAsyncPragma()
  contractcall

template view* {.pragma.}
template pure* {.pragma.}

proc subscribe*[E: Event](contract: Contract,
                          _: type E,
                          handler: EventHandler[E]):
                         Future[Subscription] =

  let topic = topic($E, E.fieldTypes).toArray
  let filter = EventFilter(address: contract.address, topics: @[topic])

  proc logHandler(log: Log) {.upraises: [].} =
    if event =? E.decode(log.data, log.topics):
      handler(event)

  contract.provider.subscribe(filter, logHandler)

proc confirm*(tx: Future[?TransactionResponse],
              confirmations: int = EthersDefaultConfirmations,
              timeout: int = EthersReceiptTimeoutBlks):
             Future[TransactionReceipt] {.async.} =
  ## Convenience method that allows confirm to be chained to a contract
  ## transaction, eg:
  ## `await token.connect(signer0)
  ##          .mint(accounts[1], 100.u256)
  ##          .confirm(3)`
  without response =? (await tx):
    raise newException(
      EthersError,
      "Transaction hash required. Possibly was a call instead of a send?"
    )

  let receipt = await response.confirm(confirmations, timeout)

  if receipt.status != TransactionStatus.Success:
    logScope:
      transactionHash = receipt.transactionHash
    echo "[ethers contract] transaction failed, status: ", receipt.status
    trace "transaction failed", status = receipt.status
    without blockNumber =? receipt.blockNumber:
      raiseContractError "Transaction reverted with unknown reason"

    let provider = response.provider
    without transaction =? await provider.getTransaction(receipt.transactionHash):
      raiseContractError "Transaction reverted with unknown reason"

    try:
      echo "[ethers contract] replaying transaction to get revert reason"
      trace "replaying transaction to get revert reason"
      await provider.replay(transaction, blockNumber)
      echo "transaction replay completed, no revert reason obtained"
      trace "transaction replay completed, no revert reason obtained"
    except ProviderError as e:
      echo "transaction revert reason obtained, reason: ", e.msg
      trace "transaction revert reason obtained", reason = e.msg
      # should contain the revert reason
      raiseContractError e.msg

  return receipt

proc queryFilter[E: Event](contract: Contract,
                            _: type E,
                            filter: EventFilter):
                           Future[seq[E]] {.async.} =

  var logs = await contract.provider.getLogs(filter)
  logs.keepItIf(not it.removed)

  var events: seq[E] = @[]
  for log in logs:
    if event =? E.decode(log.data, log.topics):
      events.add event

  return events

proc queryFilter*[E: Event](contract: Contract,
                            _: type E):
                           Future[seq[E]] =

  let topic = topic($E, E.fieldTypes).toArray
  let filter = EventFilter(address: contract.address,
                           topics: @[topic])

  contract.queryFilter(E, filter)

proc queryFilter*[E: Event](contract: Contract,
                            _: type E,
                            blockHash: BlockHash):
                           Future[seq[E]] =

  let topic = topic($E, E.fieldTypes).toArray
  let filter = FilterByBlockHash(address: contract.address,
                                 topics: @[topic],
                                 blockHash: blockHash)

  contract.queryFilter(E, filter)

proc queryFilter*[E: Event](contract: Contract,
                            _: type E,
                            fromBlock: BlockTag,
                            toBlock: BlockTag):
                           Future[seq[E]] =

  let topic = topic($E, E.fieldTypes).toArray
  let filter = Filter(address: contract.address,
                      topics: @[topic],
                      fromBlock: fromBlock,
                      toBlock: toBlock)

  contract.queryFilter(E, filter)