Farcaster bot that responds to mentions (supports V2)

bot.js

import got from 'got'
import 'dotenv/config'
import cron from 'node-cron'
import { publishCast } from './utils/farcaster.js'
import { Farcaster } from '@standard-crypto/farcaster-js' // version 2.0.2

const lastNotifs = []
const farcaster = new Farcaster()

let firstRun = true
const pKey = process.env.FARCASTER_PRIVATE_KEY
const farcasterAddress = process.env.FARCASTER_ADDRESS
const notificationsApi = `https://api.farcaster.xyz/v1/notifications?address=${farcasterAddress}&per_page=10`

// Check for notifications every 10 seconds
cron.schedule('*/10 * * * * *', async () => {
  const res = await got(notificationsApi).then((res) => JSON.parse(res.body))

  const notifs = Object.keys(res.result.notifications).map(
    (key) => res.result.notifications[key]
  )

  const newNotifs = notifs.filter(
    (notif) =>
      !lastNotifs.some((lastNotif) => lastNotif.timestamp === notif.timestamp)
  )
  lastNotifs.push(...newNotifs)

  if (firstRun) {
    firstRun = false
    console.log(`Watching ${notificationsApi}`)
    return
  }

  const mentions = newNotifs.filter(
    (notif) =>
      notif.type === 'cast-mention' ||
      (notif.type === 'cast-reply' &&
        notif.replyCast.text.includes(`@${process.env.USERNAME}`))
  )

  if (mentions.length === 0) return

  // Handle new mentions
  for (let i = 0; i < mentions.length; i++) {
    const mention = mentions[i]
    const user = mention.user.username
    const merkleRoot = mention.cast.merkleRoot
    let castToReply

    // Get the full cast
    for await (const activity of farcaster.getAllActivityForUser(user)) {
      if (activity.merkleRoot === merkleRoot) {
        castToReply = activity
        break
      }
    }

    // Reply to the cast
    await publishCast(pKey, 'yooooo', castToReply).then(() =>
      console.log(`Replied to @${user}`)
    )
  }
})

farcaster.js

import {
  Farcaster,
  FarcasterGuardianContentHost,
} from '@standard-crypto/farcaster-js'
import { Wallet } from 'ethers'

/**
 * MODIFIED FROM STANDARD-CRYPTO LIBRARY
 * Signs and publishes a simple text string.
 * The cast will be attributed to the username currently registered
 * to the given private key's address.
 */
const _defaultFarcaster = new Farcaster()
export async function publishCast(privateKey, text, replyTo) {
  const contentHost = new FarcasterGuardianContentHost(privateKey)
  const signer = new Wallet(privateKey)
  const unsignedCast = await _defaultFarcaster.prepareCast({
    fromUsername: process.env.USERNAME,
    text,
    replyTo,
  })
  const signedCast = await Farcaster.signCast(unsignedCast, signer)
  await contentHost.publishCast(signedCast)
  return signedCast
}

mnemonic-to-pkey.js

import { Wallet } from 'ethers'

/*
  Enter your Farcaster mnemonic here to get the private key
  associated with your account
*/
getPkeyFromMnemonic('')

function getPkeyFromMnemonic(mnemonic) {
  const wallet = Wallet.fromMnemonic(mnemonic)

  console.log({
    address: wallet.address,
    pkey: wallet._signingKey().privateKey,
  })
}