import React from 'react';
import { StyleSheet, Text, View, Button } from 'react-native';
import * as BackgroundFetch from 'expo-background-fetch';
import * as TaskManager from 'expo-task-manager';

const BACKGROUND_FETCH_TASK = 'background-fetch';

// 1. Define the task by providing a name and the function that should be executed
// Note: This needs to be called in the global scope (e.g outside of your React components)
TaskManager.defineTask(BACKGROUND_FETCH_TASK, async () => {
  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.Result.NewData;
});

// 2. Register the task at some point in your app by providing the same name, and some configuration options for how the background fetch should behave
// Note: This does NOT need to be in the global scope and CAN be used in your React components!
async function registerBackgroundFetchAsync() {
  return BackgroundFetch.registerTaskAsync(BACKGROUND_FETCH_TASK, {
    minimumInterval: 60 * 15, // 15 minutes
    stopOnTerminate: false, // android only,
    startOnBoot: true, // android only
  });
}

// 3. (Optional) Unregister tasks by specifying the task name
// This will cancel any future background fetch calls that match the given name
// Note: This does NOT need to be in the global scope and CAN be used in your React components!
async function unregisterBackgroundFetchAsync() {
  return BackgroundFetch.unregisterTaskAsync(BACKGROUND_FETCH_TASK);
}

export default function BackgroundFetchScreen() {
  const [isRegistered, setIsRegistered] = React.useState<boolean>(false);
  const [status, setStatus] = React.useState<BackgroundFetch.Status | null>(null);

  React.useEffect(() => {
    checkStatusAsync();
  }, []);

  const checkStatusAsync = async () => {
    const status = await BackgroundFetch.getStatusAsync();
    const isRegistered = await TaskManager.isTaskRegisteredAsync(BACKGROUND_FETCH_TASK);
    setStatus(status);
    setIsRegistered(isRegistered);
  };

  const toggleFetchTask = async () => {
    if (isRegistered) {
      await unregisterBackgroundFetchAsync();
    } else {
      await registerBackgroundFetchAsync();
    }

    checkStatusAsync();
  };

  return (
    <View style={styles.screen}>
      <View style={styles.textContainer}>
        <Text>
          Background fetch status:{' '}
          <Text style={styles.boldText}>{status ? BackgroundFetch.Status[status] : null}</Text>
        </Text>
        <Text>
          Background fetch task name:{' '}
          <Text style={styles.boldText}>
            {isRegistered ? BACKGROUND_FETCH_TASK : 'Not registered yet!'}
          </Text>
        </Text>
      </View>
      <View style={styles.textContainer}></View>
      <Button
        title={isRegistered ? 'Unregister BackgroundFetch task' : 'Register BackgroundFetch task'}
        onPress={toggleFetchTask}
      />
    </View>
  );
}

%%placeholder-start%%%%placeholder-end%%const styles = StyleSheet.create({
  screen: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
  },

  textContainer: {
    margin: 10,
  },
  boldText: {
    fontWeight: 'bold',
  },
});

Returns

• Promise<BackgroundFetchStatus | null>

Returns a promise which fulfils with one of BackgroundFetchStatus enum values.

Returns

• Promise<void>

Returns

• Promise<void>

A promise which fulfils once the minimum interval is set.

Returns

• Promise<void>

A promise which fulfils when the task is fully unregistered.