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@m1guelpf
Created March 1, 2022 11:00
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An Ethers.js-compatible Multicall implementation
import { ethers } from 'ethers'
import { ChainId } from '@/types/utils'
import { namehash } from 'ethers/lib/utils'
import { multicallAddresses, ZERO_ADDRESS } from '../consts'
import { Multicall as MulticallInterface, Multicall__factory } from '@/contracts'
export type Call = {
contract: {
address: string
}
name: string
inputs: ethers.utils.ParamType[]
outputs: ethers.utils.ParamType[]
params: any[]
}
class Multicall {
#contract: MulticallInterface
#abiCoder: ethers.utils.AbiCoder
#provider: ethers.providers.Provider
#ensRegistry: string
constructor(chainId: ChainId, provider: ethers.providers.Provider) {
this.#provider = provider
this.#abiCoder = new ethers.utils.AbiCoder()
this.#contract = Multicall__factory.connect(multicallAddresses[chainId], provider)
}
async execute<T extends any = any>(calls: Call[]): Promise<T[]> {
const callReqs = calls.map(call => ({
target: call.contract.address,
callData: this.#encodeCall(call.name, call.inputs, call.params),
}))
const response = await this.#contract.callStatic.aggregate(callReqs)
return calls.map(({ outputs }, i) => {
const params = this.#abiCoder.decode(outputs, response.returnData[i])
return outputs.length === 1 ? params[0] : params
})
}
async resolveNames(addresses: string[]): Promise<Record<string, string | null>> {
const dict = {}
if (!this.#ensRegistry) this.#ensRegistry = (await this.#provider.getNetwork()).ensAddress
const resolvers = await this.execute<string>(
addresses.map(address => ({
contract: {
address: this.#ensRegistry,
},
name: 'resolver',
inputs: [ethers.utils.ParamType.fromString('bytes32')],
outputs: [ethers.utils.ParamType.fromString('address')],
params: [namehash(`${address.toLowerCase().substring(2)}.addr.reverse`)],
}))
)
const addrLeft = addresses
.map((address, i) => [address, resolvers[i]])
.filter(([address, resolver]) => {
if (resolver !== ZERO_ADDRESS) return true
dict[address] = null
return false
})
const names = await this.execute<string>(
addrLeft.map(([address, resolver]) => ({
contract: {
address: resolver,
},
name: 'name',
inputs: [ethers.utils.ParamType.fromString('bytes32')],
outputs: [ethers.utils.ParamType.fromString('string')],
params: [namehash(`${address.toLowerCase().substring(2)}.addr.reverse`)],
}))
)
addrLeft.forEach(([address], i) => (dict[address] = names[i]))
return dict
}
#getFnSig(name: string, inputs: ethers.utils.ParamType[]): string {
return `${name}(${inputs
.map(input => {
if (input.type === 'tuple') return this.#getFnSig('', input.components)
if (input.type === 'tuple[]') return `${this.#getFnSig('', input.components)}[]`
return input.type
})
.join(',')})`
}
#encodeCall(name: string, inputs: ethers.utils.ParamType[], params: any[]): string {
return `0x${ethers.utils
.keccak256(ethers.utils.toUtf8Bytes(this.#getFnSig(name, inputs)))
.substring(2, 10)}${this.#abiCoder.encode(inputs, params).substring(2)}`
}
}
export default Multicall
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