@architect/functions/src/events/publish.js

Runtime utility library for Functional Web Apps (FWAs) built with Architect (https://arc.codes)

let http = require('http')
let { getAwsClient, getPorts, useAWS } = require('../lib')
let ledger = { events: {}, queues: {} }
let client, port

/**
 * Invoke
 * - `@events` Lambdas by EventBridge topic name
 * - `@queues` Lambdas by SQS queue name
 */
module.exports = function publishFactory (arc, type) {
  let factory = type === 'events' ? eventFactory : queueFactory
  return function publish (params, callback) {
    if (!params.name) {
      throw ReferenceError('missing params.name')
    }
    if (!params.payload) {
      throw ReferenceError('missing params.payload')
    }

    let promise
    if (!callback) {
      promise = new Promise((resolve, reject) => {
        callback = function errback (err, result) {
          err ? reject(err) : resolve(result)
        }
      })
    }

    let local = !useAWS()
    if (local && port) {
      _publishSandbox(type, params, callback)
    }
    else if (local) {
      getPorts((err, ports) => {
        if (err) callback(err)
        else {
          port = ports.events
          if (!port) {
            return callback(ReferenceError('Sandbox events port not found'))
          }
          _publishSandbox(type, params, callback)
        }
      })
    }
    else if (client) {
      let publishAWS = factory(arc)
      publishAWS(params, callback)
    }
    else {
      getAwsClient({
        plugins: [ import('@aws-lite/sns'), import('@aws-lite/sqs') ],
      }, (err, _client) => {
        if (err) callback(err)
        else {
          client = _client
          let publishAWS = factory(arc)
          publishAWS(params, callback)
        }
      })
    }

    return promise
  }
}

function _publishSandbox (type, params, callback) {
  let req = http.request({
    method: 'POST',
    port,
    path: '/' + type,
  },
  function done (res) {
    let data = []
    res.resume()
    res.on('data', chunk => data.push(chunk))
    res.on('end', () => {
      let body = Buffer.concat(data).toString()
      let code = `${res.statusCode}`
      if (!code.startsWith(2)) callback(Error(`${body} (${code})`))
      else callback(null, body)
    })
  })
  req.write(JSON.stringify(params))
  req.end('\n')
}

function eventFactory (arc) {
  return function live ({ name, payload }, callback) {

    function publish (arn, payload, callback) {
      client.sns.Publish({
        TopicArn: arn,
        Message: JSON.stringify(payload),
      })
        .then(result => callback(null, result))
        .catch(callback)
    }

    function cacheLedgerAndPublish (serviceMap) {
      ledger.events = serviceMap.events
      arn = ledger.events[name]
      if (!arn) callback(ReferenceError(`${name} event not found`))
      else publish(arn, payload, callback)
    }

    let arn = ledger.events[name]
    if (arn) {
      publish(arn, payload, callback)
    }
    else {
      arc.services().then(cacheLedgerAndPublish).catch(callback)
    }
  }
}

function queueFactory (arc) {
  return function live ({ name, payload, delaySeconds, groupID }, callback) {

    function publish (url, payload, callback) {
      let params = {
        QueueUrl: url,
        DelaySeconds: delaySeconds || 0,
        MessageBody: JSON.stringify(payload),
      }
      if (url.endsWith('.fifo')) {
        params.MessageGroupId = groupID || name
      }
      client.sqs.SendMessage(params)
        .then(result => callback(null, result))
        .catch(callback)
    }

    function cacheLedgerAndPublish (serviceMap) {
      ledger.queues = serviceMap.queues
      url = ledger.queues[name]
      if (!url) callback(ReferenceError(`${name} queue not found`))
      else publish(url, payload, callback)
    }

    let url = ledger.queues[name]
    if (url) {
      publish(url, payload, callback)
    }
    else {
      arc.services().then(cacheLedgerAndPublish).catch(callback)
    }
  }
}