import * as BackgroundFetch from 'expo-background-fetch'
import * as TaskManager from 'expo-task-manager'
import { Platform } from 'react-native'
import { useEffect } from 'react'

const BACKGROUND_FETCH_TASK = "background-fetch"
const BACKGROUND_FETCH_INTERVAL = 60

async function backgroundUpdate() {
  const now = Date.now()
  console.log(`Got background fetch call at date: ${new Date(now).toISOString()}`)
  // Be sure to return the successful result type!
  return BackgroundFetch.BackgroundFetchResult.NewData
}

TaskManager.defineTask(BACKGROUND_FETCH_TASK, backgroundUpdate)
  
export async function startBackgroundFetchService(): Promise<void | (() => void)> {
  if (Platform.OS === "web") {
    const interval = setInterval(backgroundUpdate, BACKGROUND_FETCH_INTERVAL)
    return () => clearInterval(interval)
  }

  if (await TaskManager.isTaskRegisteredAsync(BACKGROUND_FETCH_TASK))
    return async () => await BackgroundFetch.unregisterTaskAsync(BACKGROUND_FETCH_TASK)

  await BackgroundFetch.registerTaskAsync(BACKGROUND_FETCH_TASK, {
    minimumInterval: BACKGROUND_FETCH_INTERVAL,
    stopOnTerminate: false,
    startOnBoot: true,
  })

  return async () => await BackgroundFetch.unregisterTaskAsync(BACKGROUND_FETCH_TASK)
}

export const useStartBackgroundFetchServiceEffect = () => useEffect(() => {
  let cleanup: void | (() => void) = () => {}
  startBackgroundFetchService().then(result => cleanup = result)
  return cleanup
}, [])