Puedo guardar el push token en la DB

package.json

@@ -26,7 +26,9 @@
     "react-redux": "^7.2.5",
     "redux": "^4.1.1",
     "redux-thunk": "^2.3.0",
-    "react-native-safe-area-context": "3.2.0"
+    "react-native-safe-area-context": "3.2.0",
+    "expo-notifications": "~0.12.3",
+    "expo-constants": "~11.0.1"
   },
   "devDependencies": {
     "@babel/core": "^7.9.0"

screens/main/Home_page.js

@@ -1,4 +1,4 @@
-import React, {useState, useEffect} from 'react'
+import React, {useState, useEffect, useRef} from 'react'
 import { Button, Text, View, StyleSheet} from 'react-native'
 import {FlatList, ListViewBase } from 'react-native'
 import {TouchableOpacity} from 'react-native-gesture-handler'
@@ -12,13 +12,41 @@ import { connect } from 'react-redux'
 import { bindActionCreators } from 'redux' 
 import { fetchUser } from '../../redux/actions/index'
 
+import Constants from 'expo-constants';
+import * as Notifications from 'expo-notifications';
+
+Notifications.setNotificationHandler({
+  handleNotification: async () => ({
+    shouldShowAlert: true,
+    shouldPlaySound: true,
+    shouldSetBadge: false,
+  }),
+});
+
+
 export function Home_page({navigation}) {
   const [threads, setThreads] = useState([]);  
   const [loading, setLoading] = useState(true);
   
   const [roomName, setRoomName] = useState('');
 
+
+
+  const [expoPushToken, setExpoPushToken] = useState('');
+  const [notification, setNotification] = useState(false);
+  const notificationListener = useRef();
+  const responseListener = useRef();
+
+
   useEffect(() => {
+    registerForPushNotificationsAsync().then(token => setExpoPushToken(token));
+    notificationListener.current = Notifications.addNotificationReceivedListener(notification => {
+      setNotification(notification);
+    });
+
+    responseListener.current = Notifications.addNotificationResponseReceivedListener(response => {
+      console.log(response);
+    });
 
     const fire = firebase.firestore()
     .collection('THREADS')
@@ -41,14 +69,37 @@ export function Home_page({navigation}) {
 
     });
 
-    return () => fire();
+    //return () => fire();
+    return () => {
+      Notifications.removeNotificationSubscription(notificationListener.current);
+      Notifications.removeNotificationSubscription(responseListener.current);
+      fire();
+    }
   }, []);
   
   if (loading) {
     return <Loading />;
   }
 
+  const sendMessage = (token) => {
+    fetch('https://exp.host/--/api/v2/push/send', {
+      method: 'POST',
+      headers: {
+        Accept: 'application/json',
+        'Accept-encoding': 'gzip, deflate',
+        'Content-type': 'application/json',
+      },
+      body: JSON.stringify({
+        to: token,
+        title: 'Ernesto',
+        body: 'Freehand message',
+        data: { data: 'goes here' },
+        _displayInForeground: true,
+      }),
+    });
+  }
 
+  
   function handleButtonPress() {
       firebase.firestore()
         .collection('THREADS')
@@ -84,7 +135,18 @@ export function Home_page({navigation}) {
           </TouchableOpacity>
         )}
         />
-        
+      <Text>Your expo push token: {expoPushToken}</Text>
+      <View style={{ alignItems: 'center', justifyContent: 'center' }}>
+        <Text>Title: {notification && notification.request.content.title} </Text>
+        <Text>Body: {notification && notification.request.content.body}</Text>
+        <Text>Data: {notification && JSON.stringify(notification.request.content.data)}</Text>
+      </View>
+      <Button
+        title="Press to Send Notification"
+        onPress={async () => {
+          await sendPushNotification(expoPushToken);
+        }}
+      /> 
       <Button
         title='CrearChat'
         onPress={() => handleButtonPress()}
@@ -93,13 +155,74 @@ export function Home_page({navigation}) {
         title ='Hacer Busqueda'
         onPress= {() => navigation.navigate('Search')}
       />
+      <Button
+        title ='Logout'
+        onPress= {() => firebase.auth().signOut()}
+      />
+      <Button
+        title ='SendMessage'
+        onPress= {() => sendMessage(expoPushToken)}
+      />
         </ImageBackground>
     );
   }
+// Can use this function below, OR use Expo's Push Notification Tool-> https://expo.dev/notifications
+async function sendPushNotification(expoPushToken) {
+  const message = {
+    to: expoPushToken,
+    sound: 'default',
+    title: 'Original Title',
+    body: 'And here is the body!',
+    data: { someData: 'goes here' },
+  };
+
+  await fetch('https://exp.host/--/api/v2/push/send', {
+    method: 'POST',
+    headers: {
+      Accept: 'application/json',
+      'Accept-encoding': 'gzip, deflate',
+      'Content-Type': 'application/json',
+    },
+    body: JSON.stringify(message),
+  });
+}
+
+async function registerForPushNotificationsAsync() {
+  let token;
+  if (Constants.isDevice) {
+    const { status: existingStatus } = await Notifications.getPermissionsAsync();
+    let finalStatus = existingStatus;
+    if (existingStatus !== 'granted') {
+      const { status } = await Notifications.requestPermissionsAsync();
+      finalStatus = status;
+    }
+    if (finalStatus !== 'granted') {
+      alert('Failed to get push token for push notification!');
+      return;
+    }
+    token = (await Notifications.getExpoPushTokenAsync()).data;
+    console.log(token);
+  } else {
+    alert('Must use physical device for Push Notifications');
+  }
+
+  if (Platform.OS === 'android') {
+    Notifications.setNotificationChannelAsync('default', {
+      name: 'default',
+      importance: Notifications.AndroidImportance.MAX,
+      vibrationPattern: [0, 250, 250, 250],
+      lightColor: '#FF231F7C',
+    });
+  }
+
+  firebase.firestore().collection('Users').doc(firebase.auth().currentUser.uid).update({'push_token': token})
+  return token;
+}
+
 
 const mapStateToProps = (store) => ({
   currentUser: store.userState.currentUser
 })
 const mapDispatchProps = (dispatch) => bindActionCreators({fetchUser}, dispatch);
 
-export default connect(mapStateToProps, mapDispatchProps)(Home_page);
+export default connect(mapStateToProps, mapDispatchProps)(Home_page);