import { isCrawler } from './helpers'
import { UserConfig, TracktorConfig, Storage, Event } from './interfaces'
import {
  VISITOR_ID,
  SESSION_STAMP,
  DEVICE_ID,
  getCookieDomain,
  generateValueFor,
  getExpirationFor,
} from './storage'
import EventBuffer from './eventBuffer'

export class Tracktor {
  public userConfig: UserConfig
  private isCrawler: Boolean
  private storage: Storage
  private static eventBuffer: EventBuffer

  public static initializeEventBuffer(config: TracktorConfig) {
    if (!Tracktor.eventBuffer) {
      Tracktor.eventBuffer = new EventBuffer(config)
    }
  }

  constructor(config: UserConfig, storage: Storage) {
    if (!Tracktor.eventBuffer) {
      throw new Error(
        `The event buffer has not been configurated. Look for the initializeEventBuffer method in the documentation`
      )
    }

    this.storage = storage

    this.userConfig = config
    this.userConfig.visitorId = this.getTracktorConfig(VISITOR_ID, config.visitorId)
    this.userConfig.sessionStamp = Number(
      this.getTracktorConfig(SESSION_STAMP, config.sessionStamp)
    )
    this.userConfig.deviceId = this.getTracktorConfig(DEVICE_ID, config.deviceId)

    this.isCrawler = isCrawler(this.userConfig.userAgent)

    if (typeof window !== 'undefined') {
      window.addEventListener('beforeunload', () => {
        this.flush()
      })
    }
  }

  private getTracktorConfig(key, value) {
    let storageValue
    const expires = getExpirationFor(key)
    let options: { domain: string; expires?: Date } = {
      domain: getCookieDomain(this.userConfig.hostname),
      expires,
    }

    if (value) {
      storageValue = value
    } else if (this.storage.get(key)) {
      storageValue = this.storage.get(key)
    } else {
      storageValue = generateValueFor(key)
    }

    this.storage.set(key, storageValue, options)

    return storageValue
  }

  /**
   * Update userId in the config, after a login/logout/signup for instance.
   */
  public updateUserId(userId: string) {
    this.userConfig = { ...this.userConfig, userId }
  }

  public push({ name, version }: Partial<Event>, payload: object) {
    if (!this.isCrawler) {
      Tracktor.eventBuffer.push(name, version, payload, this.userConfig)
    }
  }

  public flush() {
    Tracktor.eventBuffer.flush(this.userConfig)
  }
}

export default Tracktor