import { useCallback, useEffect, useRef, useState } from 'react'
import { describeCall, type CallEvent } from '../swyx/protocol'

type Permission = NotificationPermission | 'unsupported'

function currentPermission(): Permission {
  return typeof Notification === 'undefined' ? 'unsupported' : Notification.permission
}

/**
 * Zeigt bei einem eingehenden Anruf eine System-Benachrichtigung, damit der
 * Anruf auch bemerkt wird, wenn der Tab im Hintergrund liegt.
 */
export function useCallNotifications(ringingCall: CallEvent | null) {
  const [permission, setPermission] = useState<Permission>(currentPermission)
  // Pro klingelnder Leitung nur einmal benachrichtigen.
  const notifiedRef = useRef<number | null>(null)

  const requestPermission = useCallback(() => {
    if (typeof Notification === 'undefined') return
    void Notification.requestPermission().then(setPermission)
  }, [])

  useEffect(() => {
    if (!ringingCall) {
      notifiedRef.current = null
      return
    }
    if (permission !== 'granted' || notifiedRef.current === ringingCall.line) return

    notifiedRef.current = ringingCall.line
    const notification = new Notification(`Eingehender Anruf · Leitung ${ringingCall.line}`, {
      body: describeCall(ringingCall),
      tag: `swyx-line-${ringingCall.line}`,
    })
    notification.onclick = () => {
      window.focus()
      notification.close()
    }
    return () => notification.close()
  }, [ringingCall, permission])

  return { permission, requestPermission }
}