# 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.

## Transaction Pool Item Container & Wrapper
## =========================================
##

import
  std/[hashes, sequtils, strutils, times],
  ../../utils/ec_recover,
  ./tx_info,
  eth/[common, keys],
  stew/results

{.push raises: [].}

type
  GasPrice* = ##|
    ## Handy definition distinct from `GasInt` which is a commodity unit while
    ## the `GasPrice` is the commodity valuation per unit of gas, similar to a
    ## kind of currency.
    distinct uint64

  GasPriceEx* = ##\
    ## Similar to `GasPrice` but is allowed to be negative.
    distinct int64

  TxItemStatus* = enum ##\
    ## Current status of a transaction as seen by the pool.
    txItemPending = 0
    txItemStaged
    txItemPacked

  TxItemRef* = ref object of RootObj ##\
    ## Data container with transaction and meta data. Entries are *read-only*\
    ## by default, for some there is a setter available.
    tx:        Transaction           ## Transaction data
    itemID:    Hash256               ## Transaction hash
    timeStamp: Time                  ## Time when added
    sender:    EthAddress            ## Sender account address
    info:      string                ## Whatever
    status:    TxItemStatus          ## Transaction status (setter available)
    reject:    TxInfo                ## Reason for moving to waste basket

# ------------------------------------------------------------------------------
# Private, helpers for debugging and pretty printing
# ------------------------------------------------------------------------------

proc utcTime: Time =
  getTime().utc.toTime

# ------------------------------------------------------------------------------
# Public helpers supporting distinct types
# ------------------------------------------------------------------------------

proc `$`*(a: GasPrice): string {.borrow.}
proc `<`*(a, b: GasPrice): bool {.borrow.}
proc `<=`*(a, b: GasPrice): bool {.borrow.}
proc `==`*(a, b: GasPrice): bool {.borrow.}
proc `+`*(a, b: GasPrice): GasPrice {.borrow.}
proc `-`*(a, b: GasPrice): GasPrice {.borrow.}

proc `$`*(a: GasPriceEx): string {.borrow.}
proc `<`*(a, b: GasPriceEx): bool {.borrow.}
proc `<=`*(a, b: GasPriceEx): bool {.borrow.}
proc `==`*(a, b: GasPriceEx): bool {.borrow.}
proc `+`*(a, b: GasPriceEx): GasPriceEx {.borrow.}
proc `-`*(a, b: GasPriceEx): GasPriceEx {.borrow.}
proc `+=`*(a: var GasPriceEx; b: GasPriceEx) {.borrow.}
proc `-=`*(a: var GasPriceEx; b: GasPriceEx) {.borrow.}

# Multiplication/division of *price* and *commodity unit*

proc `*`*(a: GasPrice; b: SomeUnsignedInt): GasPrice {.borrow.}
proc `*`*(a: SomeUnsignedInt; b: GasPrice): GasPrice {.borrow.}

proc `div`*(a: GasPrice; b: SomeUnsignedInt): GasPrice =
  (a.uint64 div b).GasPrice # beware of zero denominator

proc `*`*(a: SomeInteger; b: GasPriceEx): GasPriceEx =
  (a * b.int64).GasPriceEx # beware of under/overflow

# Mixed stuff, convenience ops

proc `-`*(a: GasPrice; b: SomeUnsignedInt): GasPrice {.borrow.}

proc `<`*(a: GasPriceEx; b: SomeSignedInt): bool =
  a.int64 < b

proc `<`*(a: GasPriceEx|SomeSignedInt; b: GasPrice): bool =
  if a.int64 < 0: true else: a.GasPrice < b

proc `<=`*(a: SomeSignedInt; b: GasPriceEx): bool =
  a < b.int64

# ------------------------------------------------------------------------------
# Public functions, Constructor
# ------------------------------------------------------------------------------

proc init*(item: TxItemRef; status: TxItemStatus; info: string) =
  ## Update item descriptor.
  item.info = info
  item.status = status
  item.timeStamp = utcTime()
  item.reject = txInfoOk

proc new*(T: type TxItemRef; tx: Transaction; itemID: Hash256;
          status: TxItemStatus; info: string): Result[T,void] {.gcsafe,raises: [].} =
  ## Create item descriptor.
  let rc = tx.ecRecover
  if rc.isErr:
    return err()
  ok(T(itemID:    itemID,
       tx:        tx,
       sender:    rc.value,
       timeStamp: utcTime(),
       info:      info,
       status:    status))

proc new*(T: type TxItemRef; tx: Transaction;
          reject: TxInfo; status: TxItemStatus; info: string): T {.gcsafe,raises: [].} =
  ## Create incomplete item descriptor, so meta-data can be stored (e.g.
  ## for holding in the waste basket to be investigated later.)
  T(tx:        tx,
    timeStamp: utcTime(),
    info:      info,
    status:    status)

# ------------------------------------------------------------------------------
#  Public functions, Table ID helper
# ------------------------------------------------------------------------------

proc hash*(item: TxItemRef): Hash =
  ## Needed if `TxItemRef` is used as hash-`Table` index.
  cast[pointer](item).hash

# ------------------------------------------------------------------------------
# Public functions, transaction getters
# ------------------------------------------------------------------------------

proc itemID*(tx: Transaction): Hash256 =
  ## Getter, transaction ID
  tx.rlpHash

# core/types/transaction.go(297): func (tx *Transaction) Cost() *big.Int {
proc cost*(tx: Transaction): UInt256 =
  ## Getter (go/ref compat): gas * gasPrice + value.
  (tx.gasPrice * tx.gasLimit).u256 + tx.value

# core/types/transaction.go(332): .. *Transaction) EffectiveGasTip(baseFee ..
# core/types/transaction.go(346): .. EffectiveGasTipValue(baseFee ..
proc effectiveGasTip*(tx: Transaction; baseFee: GasPrice): GasPriceEx =
  ## The effective miner gas tip for the globally argument `baseFee`. The
  ## result (which is a price per gas) might well be negative.
  if tx.txType < TxEip1559:
    (tx.gasPrice - baseFee.int64).GasPriceEx
  else:
    # London, EIP1559
    min(tx.maxPriorityFee, tx.maxFee - baseFee.int64).GasPriceEx

proc effectiveGasTip*(tx: Transaction; baseFee: UInt256): GasPriceEx =
  ## Variant of `effectiveGasTip()`
  tx.effectiveGasTip(baseFee.truncate(uint64).GasPrice)

# ------------------------------------------------------------------------------
# Public functions, item getters
# ------------------------------------------------------------------------------

proc dup*(item: TxItemRef): TxItemRef =
  ## Getter, provide contents copy
  item.deepCopy

proc info*(item: TxItemRef): string =
  ## Getter
  item.info

proc itemID*(item: TxItemRef): Hash256 =
  ## Getter
  item.itemID

proc reject*(item: TxItemRef): TxInfo =
  ## Getter
  item.reject

proc sender*(item: TxItemRef): EthAddress =
  ## Getter
  item.sender

proc status*(item: TxItemRef): TxItemStatus =
  ## Getter
  item.status

proc timeStamp*(item: TxItemRef): Time =
  ## Getter
  item.timeStamp

proc tx*(item: TxItemRef): Transaction =
  ## Getter
  item.tx

func rejectInfo*(item: TxItemRef): string =
  ## Getter
  result = $item.reject
  if item.info.len > 0:
    result.add ": "
    result.add item.info

# ------------------------------------------------------------------------------
# Public functions, setters
# ------------------------------------------------------------------------------

proc `status=`*(item: TxItemRef; val: TxItemStatus) =
  ## Setter
  item.status = val

proc `reject=`*(item: TxItemRef; val: TxInfo) =
  ## Setter
  item.reject = val

proc `info=`*(item: TxItemRef; val: string) =
  ## Setter
  item.info = val

# ------------------------------------------------------------------------------
# Public functions, pretty printing and debugging
# ------------------------------------------------------------------------------

proc `$`*(w: TxItemRef): string =
  ## Visualise item ID (use for debugging)
  "<" & w.itemID.data.mapIt(it.toHex(2)).join[24 .. 31].toLowerAscii & ">"

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