App.js

import { useState } from "react";
import { StyleSheet, ImageBackground, SafeAreaView } from "react-native";
import { LinearGradient } from "expo-linear-gradient";
import { useFonts } from 'expo-font'
import AppLoading from 'expo-app-loading'

import StartGameScreen from "./screens/StartGameScreen";
import GameScreen from "./screens/GameScreen";
import GameOverScreen from "./screens/GameOverScreen"
import Colors from "./constants/colors";

export default function App() {
  const [userNumber, setUserNumber] = useState();
  const [gameIsOver, setGameIsOver] = useState(true);
  const [guessRounds, setGuessRounds] = useState(0);


  const [fontsLoaded] = useFonts({
    'open-sans': require('./assets/fonts/OpenSans-Regular.ttf'),
    'open-sans-bold': require('./assets/fonts/OpenSans-Bold.ttf') 
  });

  if (!fontsLoaded) {
    return <AppLoading />;
  }

  function pickedNumberHandler(pickedNumber) {
    setUserNumber(pickedNumber);
    setGameIsOver(false);
  }

  function gameOverHandler(numberOfRounds) {
    setGameIsOver(true);
    setGuessRounds(numberOfRounds);
  }

  function startNewGameHandler() {
    setUserNumber(null);
    setGuessRounds(0);
  }

  let screen = <StartGameScreen onPickNumber={pickedNumberHandler} />;

  if (userNumber) { 
    screen = <GameScreen userNumber={userNumber} onGameOver={gameOverHandler} />;
  }

  if (gameIsOver && userNumber) {
    screen = <GameOverScreen userNumber={userNumber} roundsNumber={guessRounds} onStartNewGame={startNewGameHandler}/>
  }

  return (
    <LinearGradient colors={[Colors.primary700, Colors.accent500]} style={styles.rootScreen}>
      <ImageBackground
        source={require("./assets/images/background.png")}
        resizeMode="cover"
        style={styles.rootScreen}
        imageStyle={styles.backgroundImage}
      >
        <SafeAreaView style={styles.rootScreen}>{screen}</SafeAreaView>
      </ImageBackground>
    </LinearGradient>
  );
}

const styles = StyleSheet.create({
  rootScreen: {
    flex: 1,
  },
  backgroundImage: {
    opacity: 0.15,
  },
});