import { Ionicons } from '@expo/vector-icons';
import { useRouter } from 'expo-router';
import {
  ActivityIndicator,
  Pressable,
  ScrollView,
  StyleSheet,
  Text,
  View,
} from 'react-native';
import { SafeAreaView } from 'react-native-safe-area-context';
import { useLegalDocument } from '../hooks';
import { colors } from '../theme';

/* ===================== 子组件：顶部导航 ===================== */

function Header({ title, onBack }: { title: string; onBack: () => void }) {
  return (
    <View style={styles.header}>
      <Pressable style={styles.headerBtn} onPress={onBack} hitSlop={8}>
        <Ionicons name="chevron-back" size={24} color={colors.textPrimary} />
      </Pressable>
      <Text style={styles.headerTitle} numberOfLines={1}>
        {title}
      </Text>
      <View style={styles.headerBtn} />
    </View>
  );
}

/* ===================== 共享页面：法律文档（隐私政策 / 用户协议） ===================== */

export function LegalDocScreen({
  docId,
  fallbackTitle,
}: {
  docId: string;
  fallbackTitle: string;
}) {
  const router = useRouter();
  const { doc, loading, error, refresh } = useLegalDocument(docId);

  if (loading) {
    return (
      <SafeAreaView style={styles.safeArea} edges={['top']}>
        <Header title={fallbackTitle} onBack={() => router.back()} />
        <View style={styles.stateBox}>
          <ActivityIndicator size="large" color={colors.primary} />
        </View>
      </SafeAreaView>
    );
  }

  if (error || !doc) {
    return (
      <SafeAreaView style={styles.safeArea} edges={['top']}>
        <Header title={fallbackTitle} onBack={() => router.back()} />
        <View style={styles.stateBox}>
          <Ionicons name="alert-circle-outline" size={40} color={colors.danger} />
          <Text style={styles.stateText}>加载失败，请重试</Text>
          <Pressable style={styles.retryBtn} onPress={refresh}>
            <Text style={styles.retryText}>重试</Text>
          </Pressable>
        </View>
      </SafeAreaView>
    );
  }

  return (
    <SafeAreaView style={styles.safeArea} edges={['top', 'bottom']}>
      <Header title={doc.title} onBack={() => router.back()} />
      <ScrollView
        style={styles.scroll}
        contentContainerStyle={styles.content}
        showsVerticalScrollIndicator={false}
      >
        <View style={styles.metaRow}>
          <Text style={styles.metaText}>版本 {doc.version}</Text>
          <Text style={styles.metaText}>更新于 {doc.updatedAt}</Text>
        </View>

        <View style={styles.preambleCard}>
          <Text style={styles.preambleText}>{doc.preamble}</Text>
        </View>

        {doc.sections.map((section, index) => (
          <View key={index} style={styles.section}>
            <Text style={styles.sectionHeading}>{section.heading}</Text>
            {section.paragraphs.map((p, pIndex) => (
              <Text key={pIndex} style={styles.paragraph}>
                {p}
              </Text>
            ))}
          </View>
        ))}

        <Text style={styles.footNote}>
          本文件含【待确认】占位项，正式发布前需由法务复核并替换公司全称、联系方式、管辖法院等信息。
        </Text>
      </ScrollView>
    </SafeAreaView>
  );
}

const styles = StyleSheet.create({
  safeArea: {
    flex: 1,
    backgroundColor: colors.pageBg,
  },
  header: {
    flexDirection: 'row',
    alignItems: 'center',
    justifyContent: 'space-between',
    paddingHorizontal: 8,
    height: 48,
    backgroundColor: colors.white,
    borderBottomWidth: 1,
    borderBottomColor: colors.borderLight,
  },
  headerBtn: {
    width: 40,
    height: 40,
    alignItems: 'center',
    justifyContent: 'center',
  },
  headerTitle: {
    flex: 1,
    textAlign: 'center',
    fontSize: 17,
    fontWeight: '700',
    color: colors.textPrimary,
  },
  scroll: {
    flex: 1,
  },
  content: {
    padding: 16,
    paddingBottom: 32,
  },
  stateBox: {
    flex: 1,
    alignItems: 'center',
    justifyContent: 'center',
    gap: 12,
  },
  stateText: {
    marginTop: 12,
    fontSize: 14,
    color: colors.textSecondary,
  },
  retryBtn: {
    marginTop: 16,
    paddingHorizontal: 24,
    paddingVertical: 8,
    borderRadius: 18,
    backgroundColor: colors.primaryBtn,
  },
  retryText: {
    fontSize: 13,
    fontWeight: '600',
    color: colors.white,
  },
  metaRow: {
    flexDirection: 'row',
    justifyContent: 'space-between',
    marginBottom: 12,
  },
  metaText: {
    fontSize: 12,
    color: colors.textHint,
  },
  preambleCard: {
    backgroundColor: colors.infoLight,
    borderRadius: 8,
    padding: 14,
    marginBottom: 16,
  },
  preambleText: {
    fontSize: 13,
    lineHeight: 20,
    color: colors.textSecondary,
  },
  section: {
    marginBottom: 16,
  },
  sectionHeading: {
    fontSize: 15,
    fontWeight: '700',
    color: colors.textPrimary,
    marginBottom: 8,
  },
  paragraph: {
    fontSize: 13,
    lineHeight: 21,
    color: colors.textSecondary,
    marginBottom: 8,
  },
  footNote: {
    fontSize: 11,
    lineHeight: 16,
    color: colors.textHint,
    marginTop: 8,
  },
});