LoginScreen

import {TextInput,Button} from "react-native-paper";
import firebase from "../database/firebaseConfig";
import {View,StyleSheet,Text} from "react-native";
import {useEffect} from "react";
import React, { useState } from "react";


const Login = (props) => {
    const [email,setEmail] = useState('');
    const [password,setPassword] = useState('');

   function loginFirebase(){
    firebase.auth().signInWithEmailAndPassword(email, password).catch(function(error) {
      var errorCode = error.code;
      var errorMessage = error.message;
      alert(errorCode, errorMessage);
    });
  }


  useEffect(()=>{
    firebase.auth().onAuthStateChanged(function(user) {
      if (user) {
       console.log("Logado"+user.uid);
       props.navigation.navigate('Task')
      } else {
        console.log('não logado!')
      }
    });
  },[])


    return (
        <View style={styles.container}>
        <Text style= {styles.title}>Faça login para continuar</Text>
            <TextInput
                mode = "flat"
                style={styles.input}
                placeholder="E-mail"
                value={email}
                onChangeText={email => setEmail(email)}
            />

            <TextInput
                mode = "flat"
                style={styles.input}
                placeholder="Senha"
                // defaultValue={}
                onChangeText={password => setPassword(password)}
                value={password}
                secureTextEntry={true}
            />

            <Button style={styles.loginBtn} mode="contained" onPress={()=>{ loginFirebase()}}>
                Entrar
            </Button>

        </View>
    );
};

const styles = StyleSheet.create({
    container:{
      width:'94%',
      marginRight:'2%',
      marginLeft:'2%',
      paddingTop:100
    },
    title: {
        fontSize: 30,
        fontWeight: 'bold',
        color:'#7159C1',
        marginTop: 50,
        marginBottom: 40,
        borderRadius: 10,
        paddingLeft:20,
    },
    input:{
      marginTop:20,
      paddingLeft:10,
      backgroundColor:'whitesmoke',
    },
    loginBtn:{
        marginTop:30,
        width:150,
        alignSelf: 'flex-end'
    }
  });

export default Login;