import React, { useEffect, useRef } from 'react';
import {
  View,
  Text,
  StyleSheet,
  TouchableOpacity,
  Animated,
  Dimensions,
  Image,
} from 'react-native';
import { Ionicons } from '@expo/vector-icons';
import { router } from 'expo-router';
import { useApp } from '../context/AppContext';
import { useColors } from '../constants/Colors';
import { ThemeBackdrop } from '../components/ThemeBackdrop';

const { height: SCREEN_H, width: SCREEN_W } = Dimensions.get('window');

export default function OnboardingScreen() {
  const { isDarkMode, colorPalette, t } = useApp();
  const colors = useColors(isDarkMode, colorPalette);

  const FEATURES = [
    { icon: 'camera-outline' as const, label: t.onboardingFeatureScan },
    { icon: 'notifications-outline' as const, label: t.onboardingFeatureReminder },
    { icon: 'book-outline' as const, label: t.onboardingFeatureLexicon },
  ];

  // Entrance animations
  const logoAnim = useRef(new Animated.Value(0)).current;
  const logoScale = useRef(new Animated.Value(0.85)).current;
  const featuresAnim = useRef(new Animated.Value(0)).current;
  const buttonsAnim = useRef(new Animated.Value(0)).current;
  const featureAnims = useRef(FEATURES.map(() => new Animated.Value(0))).current;

  useEffect(() => {
    Animated.sequence([
      Animated.parallel([
        Animated.timing(logoAnim, { toValue: 1, duration: 700, useNativeDriver: true }),
        Animated.spring(logoScale, { toValue: 1, tension: 50, friction: 8, useNativeDriver: true }),
      ]),
      Animated.stagger(100, featureAnims.map(anim =>
        Animated.timing(anim, { toValue: 1, duration: 400, useNativeDriver: true })
      )),
      Animated.timing(buttonsAnim, { toValue: 1, duration: 400, useNativeDriver: true }),
    ]).start();
  }, []);

  return (
    <View style={[styles.container, { backgroundColor: colors.background }]}>
      <ThemeBackdrop colors={colors} />

      {/* Logo-Bereich */}
      <Animated.View
        style={[
          styles.heroSection,
          { opacity: logoAnim, transform: [{ scale: logoScale }] },
        ]}
      >
        <View style={[styles.iconContainer, { shadowColor: colors.primary }]}>
          <Image 
            source={require('../assets/icon.png')} 
            style={styles.appIcon}
            resizeMode="cover"
          />
        </View>

        <Text style={[styles.appName, { color: colors.text }]}>GreenLens</Text>
        <Text style={[styles.tagline, { color: colors.textSecondary }]}>
          {t.onboardingTagline}
        </Text>
      </Animated.View>

      {/* Feature-Liste */}
      <View style={styles.featuresSection}>
        {FEATURES.map((feat, i) => (
          <Animated.View
            key={feat.label}
            style={[
              styles.featureRow,
              {
                backgroundColor: colors.surface + '88', // Semi-transparent for backdrop effect
                borderColor: colors.border,
                opacity: featureAnims[i],
                transform: [{
                  translateY: featureAnims[i].interpolate({
                    inputRange: [0, 1],
                    outputRange: [20, 0],
                  }),
                }],
              },
            ]}
          >
            <View style={[styles.featureIcon, { backgroundColor: colors.primary + '15' }]}>
              <Ionicons name={feat.icon} size={22} color={colors.primary} />
            </View>
            <Text style={[styles.featureText, { color: colors.text }]}>{feat.label}</Text>
          </Animated.View>
        ))}
      </View>

      {/* Buttons */}
      <Animated.View style={[styles.buttonsSection, { opacity: buttonsAnim }]}>
        <TouchableOpacity
          style={[styles.primaryBtn, { backgroundColor: colors.primary }]}
          onPress={() => router.push('/scanner')}
          activeOpacity={0.85}
        >
          <Ionicons name="scan" size={20} color={colors.onPrimary} />
          <Text style={[styles.primaryBtnText, { color: colors.onPrimary }]}>
            {t.onboardingScanBtn}
          </Text>
        </TouchableOpacity>

        <View style={styles.authActions}>
          <TouchableOpacity
            style={[styles.secondaryBtn, { borderColor: colors.primary, backgroundColor: colors.surface }]}
            onPress={() => router.push('/auth/signup')}
            activeOpacity={0.82}
          >
            <Text style={[styles.secondaryBtnText, { color: colors.primary }]}>
              {t.onboardingRegister}
            </Text>
          </TouchableOpacity>

          <TouchableOpacity
            style={[styles.secondaryBtn, { borderColor: colors.borderStrong, backgroundColor: colors.surface }]}
            onPress={() => router.push('/auth/login')}
            activeOpacity={0.82}
          >
            <Text style={[styles.secondaryBtnText, { color: colors.text }]}>
              {t.onboardingLogin}
            </Text>
          </TouchableOpacity>
        </View>

        <Text style={[styles.disclaimer, { color: colors.textMuted }]}>
          {t.onboardingDisclaimer}
        </Text>
      </Animated.View>
    </View>
  );
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    paddingHorizontal: 32,
    paddingTop: SCREEN_H * 0.12,
    paddingBottom: 40,
  },
  heroSection: {
    alignItems: 'center',
    marginBottom: 40,
  },
  iconContainer: {
    width: 120,
    height: 120,
    borderRadius: 28,
    backgroundColor: '#fff',
    elevation: 8,
    shadowOffset: { width: 0, height: 4 },
    shadowOpacity: 0.15,
    shadowRadius: 12,
    marginBottom: 24,
    overflow: 'hidden',
  },
  appIcon: {
    width: '100%',
    height: '100%',
  },
  appName: {
    fontSize: 40,
    fontWeight: '900',
    letterSpacing: -1.5,
    marginBottom: 4,
  },
  tagline: {
    fontSize: 17,
    fontWeight: '500',
    opacity: 0.8,
  },
  featuresSection: {
    gap: 12,
    flex: 1,
    justifyContent: 'center',
  },
  featureRow: {
    flexDirection: 'row',
    alignItems: 'center',
    gap: 16,
    paddingHorizontal: 20,
    paddingVertical: 16,
    borderRadius: 20,
    borderWidth: 1,
  },
  featureIcon: {
    width: 44,
    height: 44,
    borderRadius: 14,
    justifyContent: 'center',
    alignItems: 'center',
  },
  featureText: {
    flex: 1,
    fontSize: 15,
    fontWeight: '600',
    letterSpacing: 0.1,
  },
  buttonsSection: {
    gap: 16,
    marginTop: 20,
  },
  primaryBtn: {
    height: 58,
    borderRadius: 20,
    flexDirection: 'row',
    justifyContent: 'center',
    alignItems: 'center',
    gap: 12,
    elevation: 4,
    shadowColor: '#000',
    shadowOffset: { width: 0, height: 2 },
    shadowOpacity: 0.1,
    shadowRadius: 4,
  },
  primaryBtnText: {
    fontSize: 17,
    fontWeight: '700',
  },
  authActions: {
    flexDirection: 'row',
    gap: 12,
  },
  secondaryBtn: {
    flex: 1,
    height: 54,
    borderRadius: 20,
    borderWidth: 1.5,
    justifyContent: 'center',
    alignItems: 'center',
  },
  secondaryBtnText: {
    fontSize: 15,
    fontWeight: '600',
  },
  disclaimer: {
    fontSize: 12,
    textAlign: 'center',
    opacity: 0.6,
    marginTop: 8,
  },
});