Automated refunds

The goal here is to integrate a backend to send refunds through Mimic Protocol.

Function

import { BigInt, ERC20Token, log, TokenAmount, Transfer } from '@mimicprotocol/lib-ts'

import { inputs } from './types'

export default function main(): void {
  const token = ERC20Token.fromString(inputs.token, inputs.chainId)
  const tokenAmount = TokenAmount.fromStringDecimal(token, inputs.amount)
  const maxFee = BigInt.fromStringDecimal(inputs.maxFee, token.decimals)

  Transfer.create(token, tokenAmount.amount, inputs.recipient, maxFee).send()
  log.info(`Created transfer intent of ${tokenAmount}`)
}

Github link

Manifest

version: 1.0.0
name: Client refunds
description: Refunds clients based on past orders
inputs:
  - chainId: uint32
  - token: string
  - amount: string       # e.g., '1.5' = 1.5 of the given token
  - recipient: address
  - maxFee: string       # e.g., '0.01' = 0.01 of the given token

Github link

Backend

import { config } from 'dotenv'
config()

import { Client, EthersSigner, getNextCronDate, HOUR, randomEvmAddress, Sort, TriggerType } from '@mimicprotocol/sdk'
import { inc } from 'semver'

/* eslint-disable @typescript-eslint/explicit-function-return-type */

async function main() {
  // Create client with signer
  if (!process.env.PRIVATE_KEY) throw new Error('Missing PRIVATE_KEY in .env file')
  const signer = EthersSigner.fromPrivateKey(process.env.PRIVATE_KEY)
  const client = new Client({ signer })

  // Get function manifest from deployed function
  if (!process.env.FUNCTION_CID) throw new Error('Missing FUNCTION_CID in .env file')
  const functionCid = process.env.FUNCTION_CID
  const manifest = await client.functions.getManifest(functionCid)

  // Increment trigger version
  const latestTrigger = await client.triggers.get({ functionCid, sort: Sort.desc, limit: 1 })
  const version = latestTrigger.length ? inc(latestTrigger[0].version, 'patch') : '0.0.1'
  if (!version) throw new Error('Invalid trigger version')

  // Get inputs and calculate trigger values
  const { chainId, token, amount, recipient, maxFee } = getRefundData()
  const schedule = '0 0 * * *' // At midnight UTC
  const deltaMs = HOUR * 1000
  const endDate = getNextCronDate(schedule).getTime() + deltaMs + 1 // 1 AM UTC

  // Submit the signed function trigger to Mimic Protocol for one-time execution
  await client.triggers.signAndCreate({
    description: `Refund execution - ${Date.now()}`,
    functionCid,
    version,
    manifest,
    config: {
      type: TriggerType.Cron,
      schedule,
      delta: '1h',
      endDate,
    },
    input: { chainId, token, amount, recipient, maxFee },
    executionFeeLimit: '0',
    minValidations: 1,
  })
}

function getRefundData() {
  // TODO: Fetch the refund info from an external service
  return {
    chainId: 8453,
    token: randomEvmAddress(),
    amount: '100',
    recipient: randomEvmAddress(),
    maxFee: '0.3',
  }
}

main().catch((err) => {
  console.error(err)
  process.exit(1)
})

Github link