import { Ionicons } from '@expo/vector-icons';
import { useRouter } from 'expo-router';
import { useState } from 'react';
import {
  ActivityIndicator,
  KeyboardAvoidingView,
  Platform,
  Pressable,
  ScrollView,
  StyleSheet,
  Text,
  TextInput,
  View,
} from 'react-native';
import { SafeAreaView } from 'react-native-safe-area-context';
import { useLegalData } from '../../src/hooks';
import { colors } from '../../src/theme';
import type { LegalMessage } from '../../src/types';

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

function Header({ onBack }: { 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}>阿布阿诺法律咨询</Text>
      <View style={styles.headerBtn} />
    </View>
  );
}

/* ===================== 子组件：消息气泡 ===================== */

function MessageBubble({ message }: { message: LegalMessage }) {
  const isUser = message.role === 'user';
  return (
    <View style={[styles.bubbleWrap, isUser ? styles.bubbleWrapRight : styles.bubbleWrapLeft]}>
      {!isUser && (
        <View style={styles.avatar}>
          <Text style={styles.avatarText}>诺</Text>
        </View>
      )}
      <View
        style={[
          styles.bubble,
          isUser ? styles.bubbleUser : styles.bubbleAssistant,
        ]}
      >
        <Text style={[styles.bubbleText, isUser ? styles.bubbleTextUser : styles.bubbleTextAssistant]}>
          {message.content}
        </Text>
      </View>
    </View>
  );
}

/* ===================== 页面 ===================== */

export default function LegalChatScreen() {
  const router = useRouter();
  const { conversation, loading, error, refresh, sendMessage } = useLegalData();
  const [input, setInput] = useState('');
  const [sending, setSending] = useState(false);

  const handleSend = async () => {
    const text = input.trim();
    if (!text || sending) return;
    setSending(true);
    setInput('');
    try {
      await sendMessage(text);
    } finally {
      setSending(false);
    }
  };

  return (
    <SafeAreaView style={styles.safeArea} edges={['top']}>
      <Header onBack={() => router.back()} />

      {loading ? (
        <View style={styles.stateBox}>
          <ActivityIndicator size="large" color={colors.primary} />
        </View>
      ) : error ? (
        <View style={styles.stateBox}>
          <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>
      ) : (
        <KeyboardAvoidingView
          style={styles.flex}
          behavior={Platform.OS === 'ios' ? 'padding' : undefined}
          keyboardVerticalOffset={Platform.OS === 'ios' ? 90 : 0}
        >
          <ScrollView
            style={styles.scroll}
            contentContainerStyle={styles.scrollContent}
            showsVerticalScrollIndicator={false}
          >
            <View style={styles.tipCard}>
              <Ionicons name="information-circle-outline" size={18} color={colors.info} />
              <Text style={styles.tipText}>
                阿布阿诺 AI 法律助手仅供参考，复杂问题建议升级到一对一律师咨询。
              </Text>
            </View>

            {conversation?.messages.map((message) => (
              <MessageBubble key={message.id} message={message} />
            ))}
          </ScrollView>

          <View style={styles.inputBar}>
            <TextInput
              style={styles.input}
              placeholder="描述你的法律问题…"
              placeholderTextColor={colors.textHint}
              value={input}
              onChangeText={setInput}
              multiline
              maxLength={500}
              editable={!sending}
            />
            <Pressable
              style={[styles.sendBtn, (!input.trim() || sending) && styles.sendBtnDisabled]}
              onPress={handleSend}
              disabled={!input.trim() || sending}
            >
              <Ionicons name="send" size={18} color={colors.white} />
            </Pressable>
          </View>
        </KeyboardAvoidingView>
      )}
    </SafeAreaView>
  );
}

const styles = StyleSheet.create({
  safeArea: {
    flex: 1,
    backgroundColor: colors.pageBg,
  },
  flex: {
    flex: 1,
  },
  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: {
    fontSize: 17,
    fontWeight: '700',
    color: colors.textPrimary,
  },
  scroll: {
    flex: 1,
  },
  scrollContent: {
    padding: 8,
    paddingBottom: 16,
  },
  tipCard: {
    flexDirection: 'row',
    alignItems: 'center',
    gap: 8,
    backgroundColor: colors.infoLight,
    borderRadius: 8,
    padding: 8,
    marginBottom: 8,
  },
  tipText: {
    flex: 1,
    fontSize: 12,
    lineHeight: 17,
    color: colors.infoText,
  },
  bubbleWrap: {
    flexDirection: 'row',
    alignItems: 'flex-end',
    marginBottom: 10,
  },
  bubbleWrapLeft: {
    justifyContent: 'flex-start',
  },
  bubbleWrapRight: {
    justifyContent: 'flex-end',
  },
  avatar: {
    width: 32,
    height: 32,
    borderRadius: 16,
    backgroundColor: colors.primary,
    alignItems: 'center',
    justifyContent: 'center',
    marginRight: 8,
  },
  avatarText: {
    fontSize: 13,
    fontWeight: '700',
    color: colors.white,
  },
  bubble: {
    maxWidth: '76%',
    paddingHorizontal: 12,
    paddingVertical: 10,
    borderRadius: 12,
  },
  bubbleUser: {
    backgroundColor: colors.primary,
    borderBottomRightRadius: 4,
  },
  bubbleAssistant: {
    backgroundColor: colors.white,
    borderBottomLeftRadius: 4,
  },
  bubbleText: {
    fontSize: 14,
    lineHeight: 20,
  },
  bubbleTextUser: {
    color: colors.white,
  },
  bubbleTextAssistant: {
    color: colors.textPrimary,
  },
  inputBar: {
    flexDirection: 'row',
    alignItems: 'center',
    gap: 8,
    paddingHorizontal: 8,
    paddingVertical: 10,
    backgroundColor: colors.white,
    borderTopWidth: 1,
    borderTopColor: colors.borderLight,
  },
  input: {
    flex: 1,
    maxHeight: 100,
    minHeight: 40,
    borderRadius: 20,
    borderWidth: 1,
    borderColor: colors.border,
    paddingHorizontal: 14,
    paddingVertical: 8,
    fontSize: 14,
    color: colors.textPrimary,
    backgroundColor: colors.pageBg,
  },
  sendBtn: {
    width: 40,
    height: 40,
    borderRadius: 20,
    alignItems: 'center',
    justifyContent: 'center',
    backgroundColor: colors.primaryBtn,
  },
  sendBtnDisabled: {
    opacity: 0.5,
  },
  stateBox: {
    flex: 1,
    alignItems: 'center',
    justifyContent: 'center',
  },
  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,
  },
});