Find the genesis of an IPNI chain given it is stored in an S3 bucket you have access to.

find-ipni-genesis.js

import { GetObjectCommand, ListObjectsV2Command, S3Client } from '@aws-sdk/client-s3'
import Ora from 'ora'
import * as dagJSON from '@ipld/dag-json'

const spinner = Ora()
const client = new S3Client({ region: 'us-west-2' })
const bucket = 'ipfs-advertisement'

let oldest
let cursor
let total = 0

spinner.start()

while (cursor || !oldest) {
  const cmd = new ListObjectsV2Command({ Bucket: bucket, ContinuationToken: cursor })
  const res = await client.send(cmd)
  total += res.Contents.length

  for (const item of res.Contents) {
    if (item.Key === 'head') continue

    if (!oldest || item.LastModified.getTime() < oldest.LastModified.getTime()) {
      oldest = item

      const cmd = new GetObjectCommand({ Bucket: bucket, Key: item.Key })
      const res = await client.send(cmd)
      const data = await res.Body.transformToString()
      const adOrEntries = dagJSON.parse(data)
      if (adOrEntries.ContextID && !adOrEntries.PreviousID) {
        spinner.succeed(`genesis: ${item.Key} ${item.LastModified.toISOString()}`)
        break
      }

      spinner.fail(`not genesis: ${item.Key} ${item.LastModified.toISOString()}`)
      spinner.start()
    }

    spinner.text = `oldest of ${total.toLocaleString()}: ${oldest.Key} ${oldest.LastModified.toISOString()}`
  }

  cursor = res.NextContinuationToken
}