const Service = require('./Service')
const discord = require('discord.js')
const superagent = require('superagent')

class DiscordService extends Service {
  constructor (ctx) {
    super(ctx)

    this.botToken = process.env.DISCORD_BOT_TOKEN
    this.clientId = process.env.DISCORD_CLIENT_ID
    this.clientSecret = process.env.DISCORD_CLIENT_SECRET
    this.oauthCallback = process.env.OAUTH_AUTH_CALLBACK
    this.botCallback = `${ctx.config.appUrl}/oauth/bot/callback`

    this.startBot()
  }

  async startBot () {
    await discord.login(this.botToken)
  }

  // oauth step 2 flow, grab the auth token via code
  async getAuthToken (code) {
    const url = 'https://discordapp.com/api/oauth2/token'
    try {
      const rsp =
        await superagent
          .post(url)
          .send({
            client_id: this.clientId,
            client_secret: this.clientSecret,
            grant_type: 'authorization_code',
            code: code,
            redirect_uri: this.oauthCallback
          })

      return rsp.body
    } catch (e) {
      this.log.error('getAuthToken failed', e)
      throw e
    }
  }

  // on sign out, we revoke the token we had.
  async revokeAuthToken (code, state) {
    const url = 'https://discordapp.com/api/oauth2/revoke'
    try {
      const rsp =
        await superagent
          .post(url)
          .send({
            client_id: this.clientId,
            client_secret: this.clientSecret,
            grant_type: 'authorization_code',
            code: code,
            redirect_uri: this.oauthCallback
          })

      return rsp.body
    } catch (e) {
      this.log.error('getAuthToken failed', e)
      throw e
    }
  }

  // returns oauth authorize url with IDENTIFY permission
  // we only need IDENTIFY because we only use it for matching IDs from the bot
  getAuthUrl (state) {
    return `https://discordapp.com/oauth2/authorize?client_id=${this.clientId}&redirect_uri=${this.oauthCallback}&response_type=code&scope=identify`
  }

  // returns the bot join url with MANAGE_ROLES permission
  // MANAGE_ROLES is the only permission we really need.
  getBotJoinUrl () {
    return `https://discordapp.com/oauth2/authorize?client_id=${this.clientId}&scope=bot&permissions=268435456&redirect_uri=${this.botCallback}`
  }

}

module.exports = DiscordService