const INTERVAL_TIME = 100

export class UrlController {
  constructor() {
    this._changeListeners = []
    this._interval = null
    this._url = window.location.href
  }

  onChange(cb) {
    this._changeListeners.push(cb)
    if (this._interval === null)
      this._createInterval()
  }

  removeEventListener(cb) {
    this._changeListeners = this._changeListeners.filter(item => item !== cb)
    if (this._changeListeners.length === 0)
      this._clearInterval()
  }

  _intervalTick() {
    const currentUrl = window.location.href
    if (currentUrl !== this.url) {
      this._broadcast(this.url, currentUrl)
      this.url = currentUrl
    }
  }

  _broadcast(oldUrl, newUrl) {
    this._changeListeners.forEach(cb => cb(oldUrl, newUrl))
  }

  _createInterval() {
    this.interval = setInterval(() => this._intervalTick(), INTERVAL_TIME)
  }

  _clearInterval() {
    clearInterval(this.interval)
    this.interval = null
  }
}