import { IconSymbol } from '@/components/ui/IconSymbol';
import { Colors } from '@/constants/Colors';
import { useAppSelector } from '@/hooks/redux';
import { useColorScheme } from '@/hooks/useColorScheme';
import { selectChallengeCards, type ChallengeViewModel } from '@/store/challengesSlice';
import { LinearGradient } from 'expo-linear-gradient';
import { useRouter } from 'expo-router';
import React from 'react';
import { Image, ScrollView, StatusBar, StyleSheet, Text, TouchableOpacity, View } from 'react-native';
import { SafeAreaView } from 'react-native-safe-area-context';

const AVATAR_SIZE = 36;
const CARD_IMAGE_WIDTH = 132;
const CARD_IMAGE_HEIGHT = 96;

export default function ChallengesScreen() {
  const theme = (useColorScheme() ?? 'light') as 'light' | 'dark';
  const colorTokens = Colors[theme];
  const router = useRouter();
  const challenges = useAppSelector(selectChallengeCards);

  const gradientColors: [string, string] =
    theme === 'dark'
      ? ['#1f2230', '#10131e']
      : [colorTokens.backgroundGradientStart, colorTokens.backgroundGradientEnd];

  return (
    <View style={[styles.screen, { backgroundColor: colorTokens.pageBackgroundEmphasis }]}>
      <StatusBar barStyle={theme === 'dark' ? 'light-content' : 'dark-content'} />
      <LinearGradient colors={gradientColors} style={StyleSheet.absoluteFillObject} />
      <SafeAreaView style={styles.safeArea} edges={['top']}>
        <ScrollView
          contentContainerStyle={styles.scrollContent}
          showsVerticalScrollIndicator={false}
          bounces
        >
          <View style={styles.headerRow}>
            <View>
              <Text style={[styles.title, { color: colorTokens.text }]}>挑战</Text>
              <Text style={[styles.subtitle, { color: colorTokens.textSecondary }]}>参与精选活动，保持每日动力</Text>
            </View>
            <TouchableOpacity activeOpacity={0.9} style={styles.giftShadow}>
              <LinearGradient
                colors={[colorTokens.primary, colorTokens.accentPurple]}
                start={{ x: 0, y: 0 }}
                end={{ x: 1, y: 1 }}
                style={styles.giftButton}
              >
                <IconSymbol name="gift.fill" size={22} color={colorTokens.onPrimary} />
              </LinearGradient>
            </TouchableOpacity>
          </View>

          <View style={styles.cardsContainer}>
            {challenges.map((challenge) => (
              <ChallengeCard
                key={challenge.id}
                challenge={challenge}
                surfaceColor={colorTokens.surface}
                textColor={colorTokens.text}
                mutedColor={colorTokens.textSecondary}
                onPress={() =>
                  router.push({ pathname: '/challenges/[id]', params: { id: challenge.id } })
                }
              />
            ))}
          </View>
        </ScrollView>
      </SafeAreaView>
    </View>
  );
}

type ChallengeCardProps = {
  challenge: ChallengeViewModel;
  surfaceColor: string;
  textColor: string;
  mutedColor: string;
  onPress: () => void;
};

function ChallengeCard({ challenge, surfaceColor, textColor, mutedColor, onPress }: ChallengeCardProps) {
  return (
    <TouchableOpacity
      activeOpacity={0.92}
      onPress={onPress}
      style={[
        styles.card,
        {
          backgroundColor: surfaceColor,
          shadowColor: 'rgba(15, 23, 42, 0.18)',
        },
      ]}
    >
      <Image
        source={{ uri: challenge.image }}
        style={styles.cardImage}
        resizeMode="cover"
      />

      <View style={styles.cardContent}>
        <Text style={[styles.cardTitle, { color: textColor }]} numberOfLines={1}>
          {challenge.title}
        </Text>
        <Text style={[styles.cardDate, { color: mutedColor }]}>{challenge.dateRange}</Text>
        <Text style={[styles.cardParticipants, { color: mutedColor }]}>{challenge.participantsLabel}</Text>
        <AvatarStack avatars={challenge.avatars} borderColor={surfaceColor} />
      </View>
    </TouchableOpacity>
  );
}

type AvatarStackProps = {
  avatars: string[];
  borderColor: string;
};

function AvatarStack({ avatars, borderColor }: AvatarStackProps) {
  return (
    <View style={styles.avatarRow}>
      {avatars.map((avatar, index) => (
        <Image
          key={`${avatar}-${index}`}
          source={{ uri: avatar }}
          style={[
            styles.avatar,
            { borderColor },
            index === 0 ? null : styles.avatarOffset,
          ]}
        />
      ))}
    </View>
  );
}

const styles = StyleSheet.create({
  screen: {
    flex: 1,
  },
  safeArea: {
    flex: 1,
  },
  scrollContent: {
    paddingHorizontal: 20,
    paddingBottom: 32,
  },
  headerRow: {
    flexDirection: 'row',
    justifyContent: 'space-between',
    alignItems: 'center',
    marginTop: 8,
    marginBottom: 26,
  },
  title: {
    fontSize: 32,
    fontWeight: '700',
    letterSpacing: 1,
  },
  subtitle: {
    marginTop: 6,
    fontSize: 14,
    fontWeight: '500',
    opacity: 0.8,
  },
  giftShadow: {
    shadowColor: 'rgba(94, 62, 199, 0.45)',
    shadowOffset: { width: 0, height: 8 },
    shadowOpacity: 0.35,
    shadowRadius: 12,
    elevation: 8,
    borderRadius: 26,
  },
  giftButton: {
    width: 52,
    height: 52,
    borderRadius: 26,
    alignItems: 'center',
    justifyContent: 'center',
  },
  cardsContainer: {
    gap: 18,
  },
  card: {
    flexDirection: 'row',
    borderRadius: 28,
    padding: 18,
    alignItems: 'center',
    shadowOffset: { width: 0, height: 16 },
    shadowOpacity: 0.18,
    shadowRadius: 24,
    elevation: 6,
  },
  cardImage: {
    width: CARD_IMAGE_WIDTH,
    height: CARD_IMAGE_HEIGHT,
    borderRadius: 22,
  },
  cardContent: {
    flex: 1,
    marginLeft: 16,
  },
  cardTitle: {
    fontSize: 18,
    fontWeight: '700',
    marginBottom: 4,
  },
  cardDate: {
    fontSize: 13,
    fontWeight: '500',
    marginBottom: 4,
  },
  cardParticipants: {
    fontSize: 13,
    fontWeight: '500',
  },
  avatarRow: {
    flexDirection: 'row',
    marginTop: 16,
    alignItems: 'center',
  },
  avatar: {
    width: AVATAR_SIZE,
    height: AVATAR_SIZE,
    borderRadius: AVATAR_SIZE / 2,
    borderWidth: 2,
  },
  avatarOffset: {
    marginLeft: -12,
  },
});