import yaml from 'js-yaml'
import fs from 'fs'
import jsonata from 'jsonata'
import fetch from 'node-fetch'

const outputFn = 'build/spec.json'

const strategies = {
  async default (conf, all) {
    const req = await fetch(conf.url)
    const resp = await req.json()
    return jsonata(conf.query).evaluate(resp)
  },
  async github (conf, all) {
    const req = await fetch('https://api.github.com/repos/@@/releases/latest'.replace(/@@/, all.repo))
    const resp = await req.json()
    return jsonata('$match(tag_name,/^v(.+)/)[0].groups[0]').evaluate(resp)
  },
  async html (conf, all) {
    const req = await fetch(conf.url)
    const resp = await req.text()
    return resp.match(conf.query)[1]
  }
}

async function getVersions (config, all) {
  const local = await strategies[config.from.strategy ? config.from.strategy : 'default'](config.from, all)
  const latest = await strategies[config.to.strategy ? config.to.strategy : 'default'](config.to, all)
  return { local, latest }
}

async function build () {
  const spec = yaml.load(fs.readFileSync('./spec/services.yaml'))

  for (const item of spec.services) {

    item.url = item.host ? `https://${item.host}` : item.url
    if (item.version_conf) {
      item.versions = await getVersions(item.version_conf, item)
    }
    delete item.version_conf
  } 

  spec.time = new Date

  fs.writeFileSync(outputFn, JSON.stringify(spec, null, 2))
  console.log(`saved: ${outputFn}`)
  console.log('build done')
}

build()