jenga.ts

import fetch from "node-fetch"

export interface PingData {
  total_rows: number
  offset: number
  rows: Row[]
}

type packageid = string
export interface Row {
  id: packageid
  key: string[]
  value: number
}

interface TreeArray extends Array<DependencyTree> { }
type DependencyTree = packageid | TreeArray

let requests = 0
let already_downloaded: packageid[] = []

async function get_dependents(package_name: packageid): Promise<packageid[]> {
  const url = `https://skimdb.npmjs.com/registry/_design/app/_view/dependedUpon?startkey=["${package_name}"]&endkey=["${package_name}",{}]&reduce=false`
  const encoded_url = encodeURI(url)

  const res = await fetch(encoded_url)
  const json: PingData = await res.json()
  console.log(`downloading package: ${package_name}, request number: ${requests++}`)

  return json.rows.map(row => row.id).filter(id => !id.startsWith("@"))
}

async function main() {
  async function count_dependents(
    package_name: packageid,
    level: number
  ): Promise<number> {
    if (already_downloaded.indexOf(package_name) > -1) {
      return 1
    }

    const deps = await get_dependents(package_name)
    already_downloaded.push(package_name)
    if (deps.length == 0) {
      return 1
    }
    return (await Promise.all(
      deps.map(package_name => count_dependents(package_name, level + 1))
    )).reduce((acc, n) => acc + n)
  }

  console.log(await count_dependents("is-odd", 0))
}

main()