sdk-monorepo/src/lib/chain.ts

// Types
import { MarkOptional } from 'ts-essentials'
import * as Types from 'types/sdk/chain'

// Our local types
import {
  ERC20Tornado__factory,
  ETHTornado__factory,
  TornadoInstance,
  TornadoInstance__factory,
  TornadoProxy__factory,
  TornadoProxy,
  ERC20__factory,
  ERC20,
  Multicall3Contract__factory
} from 'types/deth'
import { Multicall3 } from 'types/deth/Multicall3Contract'

// External imports
import { TransactionRequest } from '@ethersproject/abstract-provider'
import { BaseContract, BigNumber, ContractTransaction, providers, Signer, VoidSigner } from 'ethers'
import { randomBytes } from 'crypto'

// Local modules
import { Onchain } from 'lib/data'
import { ErrorUtils, HexUtils } from 'lib/utils'

// We use a vanilla provider here, but in reality we will probably
// add a censorship-checking custom derivative of it
type Provider = providers.Provider

/**
 * The Chain class stores Tornado-agnostic chain data and also
 * handles such interactions.
 */
export class Chain {
  public signer?: Signer
  public provider: Provider
  private _emptySigner: VoidSigner
  public chainId?: number
  public symbol?: string

  constructor(provider: Provider, signer?: Signer) {
    this.provider = provider
    this.signer = signer
    this._emptySigner = new VoidSigner('0x' + randomBytes(20).toString('hex'), provider)
  }

  async getChainId(): Promise<number> {
    if (!this.chainId) this.chainId = (await this.provider.getNetwork()).chainId
    return this.chainId
  }

  async getChainSymbol(): Promise<string> {
    if (!this.symbol) this.symbol = await Onchain.getNetworkSymbol(String(await this.getChainId()))
    return this.symbol
  }

  latestBlockNum(): Promise<number> {
    return this.provider.getBlockNumber()
  }

  getAccountBalance(account: string): Promise<BigNumber> {
    return this.provider.getBalance(account)
  }

  getGasPrice(): Promise<BigNumber> {
    return this.provider.getGasPrice()
  }

  getTokenContract(tokenAddress: string): ERC20 {
    return Contracts.getToken(tokenAddress, this.signer ?? this.provider)
  }

  async getTokenDecimals(token: string): Promise<BigNumber> {
    let treq = {
      to: token,
      data: '0x313ce567'
    }
    return BigNumber.from(await this._emptySigner.call(treq))
  }

  async getTokenBalance(account: string, token: string, normalized: boolean = false): Promise<BigNumber> {
    let treq = {
      to: token,
      data: '0x70a08231000000000000000000000000' + HexUtils.prepareAddress(account)
    }
    let divisor = normalized ? BigNumber.from(10).pow(await this.getTokenDecimals(token)) : 1
    return BigNumber.from(await this._emptySigner.call(treq)).div(divisor)
  }

  async populateBatchCall(
    callStruct: Array<MarkOptional<Multicall3.Call3ValueStruct, 'value'>>
  ): Promise<TransactionRequest> {
    if (callStruct[0].value)
      return await Multicall3Contract__factory.connect(
        await Onchain.getMulticall3Address(String(this.chainId)),
        this.provider
      ).populateTransaction.aggregate3Value(callStruct as Array<Multicall3.Call3ValueStruct>)

    return await Multicall3Contract__factory.connect(
      await Onchain.getMulticall3Address(String(this.chainId)),
      this.provider
    ).populateTransaction.aggregate3(callStruct)
  }

  async batchCall(
    callStruct: Array<MarkOptional<Multicall3.Call3ValueStruct, 'value'>>
  ): Promise<ContractTransaction> {
    if (this.signer)
      if (callStruct[0].value)
        return await Multicall3Contract__factory.connect(
          await Onchain.getMulticall3Address(String(this.chainId)),
          this.signer
        ).aggregate3Value(callStruct as Array<Multicall3.Call3ValueStruct>)
      else {
        return await Multicall3Contract__factory.connect(
          await Onchain.getMulticall3Address(String(this.chainId)),
          this.provider
        ).aggregate3(callStruct)
      }
    else throw ErrorUtils.getError('Chain.batchCall: no signer provided.')
  }
}

/**
 * This is Tornado-specific.
 */
export namespace Contracts {
  function _getContract<C extends Types.Contracts.TornadoContracts>(
    name: string,
    address: string,
    signerOrProvider: Signer | Provider
  ): C {
    if (name == 'TornadoInstance') {
      return TornadoInstance__factory.connect(address, signerOrProvider) as C
    } else if (name == 'TornadoProxy') {
      return TornadoProxy__factory.connect(address, signerOrProvider) as C
    } else if (name == 'ETHTornado') {
      return ETHTornado__factory.connect(address, signerOrProvider) as C
    } else if (name == 'ERC20Tornado') {
      return ERC20Tornado__factory.connect(address, signerOrProvider) as C
    } else {
      return ERC20__factory.connect(address, signerOrProvider) as C
    }
  }

  type Path = string
  const contractMap: Map<Path, BaseContract> = new Map<Path, BaseContract>()

  export async function getProxy(
    network: string,
    signerOrProvider: Signer | Provider
  ): Promise<TornadoProxy> {
    const key = `TornadoProxy${network}`
    if (!contractMap.has(key)) {
      contractMap.set(
        key,
        _getContract<TornadoProxy>('TornadoProxy', await Onchain.getProxyAddress(network), signerOrProvider)
      )
    }
    return contractMap.get(`TornadoProxy${network}`) as TornadoProxy
  }

  export async function getInstance(
    network: string,
    token: string,
    denomination: string,
    signerOrProvider: Signer | Provider
  ): Promise<TornadoInstance> {
    const key = `TornadoInstance${network}${token}${denomination}`
    if (!contractMap.has(key)) {
      contractMap.set(
        key,
        _getContract<TornadoInstance>(
          'TornadoInstance',
          await Onchain.getInstanceAddress(network, token, denomination),
          signerOrProvider
        )
      )
    }
    return contractMap.get(key) as TornadoInstance
  }

  export function getToken(tokenAddress: string, signerOrProvider: Signer | Provider): ERC20 {
    if (!contractMap.has(tokenAddress))
      contractMap.set(tokenAddress, _getContract<ERC20>('ERC20', tokenAddress, signerOrProvider))
    return contractMap.get(tokenAddress) as ERC20
  }

  export function getTornToken(signerOrProvider: Signer | Provider): ERC20 {
    const key = '$TORN'
    if (!contractMap.has(key)) {
      contractMap.set(
        key,
        _getContract<ERC20>('ERC20', '0x77777feddddffc19ff86db637967013e6c6a116c', signerOrProvider)
      )
    }
    return contractMap.get(key) as ERC20
  }
}