'use strict'

const EventEmitter = require('bare-events')
const { APP_EVENT_CATEGORIES } = require('pearcord-app-events')
const { getWorkerTemplate } = require('pearcord-integration-worker')

/**
 * Headless integration worker wired to an active PearcordPlatform guild session.
 */
class PearcordIntegrationWorker extends EventEmitter {
  constructor (platform, opts = {}) {
    super()
    if (!platform) throw new Error('platform required')
    this.platform = platform
    this.templateId = null
    this._listener = null
    this._receiptUnwire = null
    this._platformEventUnwire = null
    this._recentEvents = []
    this._recentReceipts = []
    this.maxRecent = opts.maxRecent || 64
  }

  async start (opts = {}) {
    const templateId = opts.templateId || null
    const tpl = templateId ? getWorkerTemplate(templateId) : null
    this.templateId = templateId

    let categories = opts.categories
    if (categories == null && tpl) categories = tpl.categories
    if (categories == null) categories = APP_EVENT_CATEGORIES.MESSAGES

    if (!this.platform.guild?.guild) {
      throw new Error('join a guild first')
    }

    this._listener = this.platform.createAppListener(categories)
    const onEvent = (payload) => {
      if (tpl?.eventTypes?.length && !tpl.eventTypes.includes(payload.type)) return
      this._pushRecent(this._recentEvents, payload)
      this.emit('event', payload)
    }
    this._listener.on('event', onEvent)
    this.platform.on('app-event', onEvent)
    this._platformEventUnwire = () => this.platform.removeListener('app-event', onEvent)

    const traceReceipts = tpl?.listensReceipts || templateId === 'delivery-tracer'
    if (traceReceipts) {
      const onReceipt = (receipt) => {
        this._pushRecent(this._recentReceipts, receipt)
        this.emit('receipt', receipt)
      }
      this.platform.on('automation-delivery', onReceipt)
      this._receiptUnwire = () =>
        this.platform.removeListener('automation-delivery', onReceipt)
    }

    this.emit('started', {
      templateId,
      guildId: this.platform.guild.guild.id,
      categories
    })
    return this
  }

  _pushRecent (arr, row) {
    arr.push(row)
    if (arr.length > this.maxRecent) arr.splice(0, arr.length - this.maxRecent)
  }

  async stop () {
    this._listener?._unwire?.()
    this._listener = null
    if (this._platformEventUnwire) {
      this._platformEventUnwire()
      this._platformEventUnwire = null
    }
    if (this._receiptUnwire) {
      this._receiptUnwire()
      this._receiptUnwire = null
    }
    this.emit('stopped')
  }
}

module.exports = { PearcordIntegrationWorker }