import React, { useEffect, useMemo, useRef, useState } from 'react';
import { BackHandler, Platform, StatusBar, Modal, View, Image, StyleSheet, Button } from 'react-native';
import * as ScreenOrientation from 'expo-screen-orientation';
import * as SplashScreen from 'expo-splash-screen';
import { Accelerometer } from 'expo-sensors';
import { Audio } from 'expo-av';
import FocusScreen from './src/screens/FocusScreen';
import HomeScreen from './src/screens/HomeScreen';
import TimeUntilScreen from './src/screens/TimeUntilScreen';
import TimerScreen from './src/screens/TimerScreen';
import { createStyles } from './src/styles';
import { getTheme } from './src/theme';

// Keep the splash screen visible while we fetch resources
SplashScreen.preventAutoHideAsync().catch(() => {
  /* reloading the app might cause this to error in dev */
});

export default function App() {
  const styles = useMemo(() => createStyles(), []);

  const [screen, setScreen] = useState('home');
  const [focusMode, setFocusMode] = useState(false);
  const [darkMode, setDarkMode] = useState(true);
  const [pinkMode, setPinkMode] = useState(false);
  const [isFullscreen, setIsFullscreen] = useState(false);
  const [now, setNow] = useState(new Date());
  
  const [showMinion, setShowMinion] = useState(false);

  const [targetTime, setTargetTime] = useState(null);
  const [tuHour, setTuHour] = useState('');
  const [tuMinute, setTuMinute] = useState('');
  const [tuIsOver, setTuIsOver] = useState(false);

  const [timerRunning, setTimerRunning] = useState(false);
  const [timerDone, setTimerDone] = useState(false);
  const [timerRemaining, setTimerRemaining] = useState(0);
  const [timerHInput, setTimerHInput] = useState('');
  const [timerMInput, setTimerMInput] = useState('');
  const [timerSInput, setTimerSInput] = useState('');

  const timerRef = useRef(null);
  const theme = getTheme(darkMode, pinkMode);

  useEffect(() => {
    // Hide splash screen after initialization
    SplashScreen.hideAsync().catch(() => {});
  }, []);

  useEffect(() => {
    if (Platform.OS !== 'web') {
      ScreenOrientation.unlockAsync();
    }
  }, []);

  useEffect(() => {
    if (Platform.OS === 'android' || Platform.OS === 'ios') {
      Accelerometer.setUpdateInterval(500);
      const subscription = Accelerometer.addListener(({ x, y, z }) => {
        const acceleration = Math.sqrt(x * x + y * y + z * z);
        if (acceleration > 2.5) {
          setShowMinion(true);
          setTimeout(() => setShowMinion(false), 3000);
        }
      });
      return () => subscription.remove();
    }
  }, []);

  useEffect(() => {
    const interval = setInterval(() => setNow(new Date()), 1000);
    return () => clearInterval(interval);
  }, []);

  useEffect(() => {
    if (targetTime && now >= targetTime) {
      setTuIsOver(true);
    } else {
      setTuIsOver(false);
    }
  }, [now, targetTime]);

  useEffect(() => {
    if (timerRunning) {
      timerRef.current = setInterval(() => {
        setTimerRemaining((r) => {
          if (r <= 1) {
            clearInterval(timerRef.current);
            setTimerRunning(false);
            setTimerDone(true);
            return 0;
          }
          return r - 1;
        });
      }, 1000);
    }

    return () => clearInterval(timerRef.current);
  }, [timerRunning]);

  useEffect(() => {
    if (Platform.OS !== 'android') return undefined;

    const sub = BackHandler.addEventListener('hardwareBackPress', () => {
      if (focusMode) {
        setFocusMode(false);
        return true;
      }

      if (screen !== 'home') {
        setScreen('home');
        return true;
      }

      return false;
    });

    return () => sub.remove();
  }, [focusMode, screen]);

  const toggleFullscreen = () => {
    if (Platform.OS !== 'web') return;

    if (!document.fullscreenElement) {
      document.documentElement.requestFullscreen();
      setIsFullscreen(true);
    } else {
      document.exitFullscreen();
      setIsFullscreen(false);
    }
  };

  const setTuTimer = () => {
    const h = parseInt(tuHour, 10);
    const m = parseInt(tuMinute, 10);

    if (isNaN(h) || isNaN(m) || h < 0 || h > 23 || m < 0 || m > 59) return;

    const target = new Date();
    target.setHours(h, m, 0, 0);
    if (target <= new Date()) {
      target.setDate(target.getDate() + 1);
    }

    setTargetTime(target);
    setTuIsOver(false);
  };

  const resetTuTimer = () => {
    setTargetTime(null);
    setTuIsOver(false);
    setTuHour('');
    setTuMinute('');
  };

  const getTuCountdown = () => {
    if (!targetTime) return null;
    const diff = targetTime - now;
    if (diff <= 0) return null;

    const t = Math.floor(diff / 1000);
    return {
      hours: Math.floor(t / 3600),
      minutes: Math.floor((t % 3600) / 60),
      seconds: t % 60,
    };
  };

  const startTimer = () => {
    const h = parseInt(timerHInput, 10) || 0;
    const m = parseInt(timerMInput, 10) || 0;
    const s = parseInt(timerSInput, 10) || 0;
    const total = h * 3600 + m * 60 + s;

    if (total <= 0) return;

    setTimerRemaining(total);
    setTimerDone(false);
    setTimerRunning(true);
  };

  const resetTimerState = () => {
    clearInterval(timerRef.current);
    setTimerRunning(false);
    setTimerDone(false);
    setTimerRemaining(0);
    setTimerHInput('');
    setTimerMInput('');
    setTimerSInput('');
  };

  const timerHr = Math.floor(timerRemaining / 3600);
  const timerMin = Math.floor((timerRemaining % 3600) / 60);
  const timerSec = timerRemaining % 60;
  const tuCountdown = getTuCountdown();

  const playSound = async () => {
    try {
      const { sound } = await Audio.Sound.createAsync(
        require('./assets/alert.mp3'),
        { shouldPlay: true, volume: 1.0 }
      );
      
      sound.setOnPlaybackStatusUpdate((status) => {
        if (status.didJustFinish) {
          sound.unloadAsync();
        }
      });
    } catch (error) {
      console.log('Error playing sound:', error);
    }
  };

  useEffect(() => {
    if (timerDone || tuIsOver) {
      playSound();
    }
  }, [timerDone, tuIsOver]);

  if (focusMode) {
    return (
      <FocusScreen
        styles={styles}
        theme={theme}
        screen={screen}
        pinkMode={pinkMode}
        tuIsOver={tuIsOver}
        tuCountdown={tuCountdown}
        targetTime={targetTime}
        timerDone={timerDone}
        timerHr={timerHr}
        timerMin={timerMin}
        timerSec={timerSec}
        onShowUI={() => setFocusMode(false)}
      />
    );
  }

  const barStyle = darkMode ? 'light-content' : 'dark-content';

  if (screen === 'home') {
    return (
      <>
        <StatusBar barStyle={barStyle} backgroundColor={theme.bg} />
        <HomeScreen
          styles={styles}
          theme={theme}
          now={now}
          darkMode={darkMode}
          pinkMode={pinkMode}
          isFullscreen={isFullscreen}
          onToggleDark={() => setDarkMode((d) => !d)}
          onTogglePink={() => setPinkMode((p) => !p)}
          onToggleFullscreen={toggleFullscreen}
          onSelectTimeUntil={() => setScreen('timeuntil')}
          onSelectTimer={() => setScreen('timer')}
        />
      </>
    );
  }

  if (screen === 'timeuntil') {
    return (
      <>
        <StatusBar barStyle={barStyle} backgroundColor={theme.bg} />
        <TimeUntilScreen
          styles={styles}
          theme={theme}
          now={now}
          darkMode={darkMode}
          pinkMode={pinkMode}
          isFullscreen={isFullscreen}
          targetTime={targetTime}
          tuHour={tuHour}
          tuMinute={tuMinute}
          tuIsOver={tuIsOver}
          tuCountdown={tuCountdown}
          onChangeHour={setTuHour}
          onChangeMinute={setTuMinute}
          onSetTimer={setTuTimer}
          onResetTimer={resetTuTimer}
          onBackToMenu={() => setScreen('home')}
          onToggleDark={() => setDarkMode((d) => !d)}
          onTogglePink={() => setPinkMode((p) => !p)}
          onToggleFullscreen={toggleFullscreen}
          onFocus={() => setFocusMode(true)}
        />
      </>
    );
  }

  return (
    <>
      <Modal visible={showMinion} transparent={true} animationType="fade">
        <View style={StyleSheet.absoluteFill}>
          <Image
            source={{ uri: 'https://shx.reversed.dev/u/XHuDcA.jpg' }}
            style={{ flex: 1 }}
            resizeMode="contain"
          />
          <View style={{ position: 'absolute', top: 50, right: 20 }}>
            <Button title="Dismiss" onPress={() => setShowMinion(false)} />
          </View>
        </View>
      </Modal>
      <StatusBar barStyle={barStyle} backgroundColor={theme.bg} />
      <TimerScreen
        styles={styles}
        theme={theme}
        now={now}
        darkMode={darkMode}
        pinkMode={pinkMode}
        isFullscreen={isFullscreen}
        timerRunning={timerRunning}
        timerDone={timerDone}
        timerRemaining={timerRemaining}
        timerHInput={timerHInput}
        timerMInput={timerMInput}
        timerSInput={timerSInput}
        timerHr={timerHr}
        timerMin={timerMin}
        timerSec={timerSec}
        onChangeH={setTimerHInput}
        onChangeM={setTimerMInput}
        onChangeS={setTimerSInput}
        onStart={startTimer}
        onPause={() => setTimerRunning(false)}
        onResume={() => {
          if (timerRemaining > 0) {
            setTimerRunning(true);
          }
        }}
        onReset={resetTimerState}
        onBackToMenu={() => setScreen('home')}
        onToggleDark={() => setDarkMode((d) => !d)}
        onTogglePink={() => setPinkMode((p) => !p)}
        onToggleFullscreen={toggleFullscreen}
        onFocus={() => setFocusMode(true)}
      />
    </>
  );
}