import React, { useEffect, useMemo, useState } from 'react';
import { View, StyleSheet, TouchableOpacity, Alert, ScrollView } from 'react-native';
import { useNavigation, useRoute, RouteProp } from '@react-navigation/native';
import { NativeStackNavigationProp } from '@react-navigation/native-stack';
import { MaterialCommunityIcons } from '@expo/vector-icons';
import { SafeAreaView } from 'react-native-safe-area-context';

import { colors, spacing, borderRadius, shadows } from '../../theme';
import { Avatar, Text } from '../../components/common';
import { RootStackParamList } from '../../navigation/types';
import { groupService } from '../../services/groupService';
import { groupManager } from '../../stores/groupManager';
import { userManager } from '../../stores/userManager';
import { GroupInfoSummaryCard, DecisionFooter } from './components/GroupRequestShared';

type Route = RouteProp<RootStackParamList, 'GroupRequestDetail'>;
type Navigation = NativeStackNavigationProp<RootStackParamList>;

const GroupRequestDetailScreen: React.FC = () => {
  const route = useRoute<Route>();
  const navigation = useNavigation<Navigation>();
  const { message } = route.params;
  const { extra_data } = message;
  const [submitting, setSubmitting] = useState(false);
  const [memberCount, setMemberCount] = useState<number | null>(null);
  const [loadingGroup, setLoadingGroup] = useState(false);

  const requestType = extra_data?.request_type;
  const requestStatus = extra_data?.request_status;
  const reviewerName = extra_data?.actor_name || extra_data?.operator_name || '管理员';
  const canAction =
    requestStatus === 'pending' &&
    (message.system_type === 'group_join_apply' || message.system_type === 'group_invite');
  const processedText =
    requestStatus === 'accepted'
      ? `${reviewerName}已同意`
      : requestStatus === 'rejected'
        ? `${reviewerName}已拒绝`
        : '该请求已处理';

  const applicantName = useMemo(() => {
    if (requestType === 'invite') {
      return extra_data?.target_user_name || '被邀请用户';
    }
    return extra_data?.actor_name || '申请用户';
  }, [requestType, extra_data]);

  const applicantAvatar = useMemo(() => {
    if (requestType === 'invite') {
      return extra_data?.target_user_avatar || '';
    }
    return extra_data?.avatar_url || '';
  }, [requestType, extra_data]);

  const applicantId = useMemo(() => {
    if (requestType === 'invite') {
      return extra_data?.target_user_id;
    }
    return extra_data?.actor_id_str;
  }, [requestType, extra_data]);

  useEffect(() => {
    const loadGroupInfo = async () => {
      if (!extra_data?.group_id) return;
      setLoadingGroup(true);
      try {
        const group = await groupManager.getGroup(extra_data.group_id);
        setMemberCount(group.member_count ?? null);
      } catch {
        setMemberCount(null);
      } finally {
        setLoadingGroup(false);
      }
    };
    loadGroupInfo();
  }, [extra_data?.group_id]);

  const handleDecision = async (approve: boolean) => {
    const flag = extra_data?.flag;
    const groupId = extra_data?.group_id;
    if (!flag) {
      Alert.alert('提示', '缺少请求标识，无法处理');
      return;
    }
    if (!groupId) {
      Alert.alert('提示', '缺少群组标识，无法处理');
      return;
    }

    setSubmitting(true);
    try {
      if (message.system_type === 'group_invite') {
        await groupService.respondInvite(groupId, {
          flag,
          approve,
        });
      } else {
        await groupService.reviewJoinRequest(groupId, {
          flag,
          approve,
        });
      }
      Alert.alert('成功', approve ? '已同意申请' : '已拒绝申请', [
        { text: '确定', onPress: () => navigation.goBack() },
      ]);
    } catch (error) {
      Alert.alert('操作失败', '请稍后重试');
    } finally {
      setSubmitting(false);
    }
  };

  const handleOpenUser = async () => {
    if (!applicantId) return;
    const user = await userManager.getUserById(applicantId);
    if (user?.id) {
      navigation.navigate('UserProfile', { userId: String(user.id) });
    }
  };

  return (
    <SafeAreaView style={styles.container} edges={['bottom']}>
      <ScrollView style={styles.scrollView} contentContainerStyle={styles.scrollContent} showsVerticalScrollIndicator={false}>
        <GroupInfoSummaryCard
          groupName={extra_data?.group_name}
          groupAvatar={extra_data?.group_avatar}
          groupNo={extra_data?.group_id}
          groupDescription={extra_data?.group_description}
          memberCountText={loadingGroup ? '人数加载中...' : `${memberCount ?? '-'} 人`}
        />
        <View style={styles.card}>
          <Text variant="label" style={styles.sectionTitle}>用户信息</Text>
          <TouchableOpacity style={styles.row} activeOpacity={0.7} onPress={handleOpenUser} disabled={!applicantId}>
            <Avatar source={applicantAvatar} size={44} name={applicantName} />
            <View style={styles.meta}>
              <Text variant="body" style={styles.name}>{applicantName}</Text>
              <Text variant="caption" color={colors.text.secondary}>
                {requestType === 'invite' ? '被邀请加入' : '申请加入'}
              </Text>
            </View>
            {applicantId ? (
              <MaterialCommunityIcons name="chevron-right" size={20} color={colors.text.hint} />
            ) : null}
          </TouchableOpacity>
          {requestType === 'invite' && (
            <Text variant="caption" color={colors.text.secondary} style={styles.subDesc}>
              邀请人：{extra_data?.actor_name || '群成员'}
            </Text>
          )}
        </View>
      </ScrollView>

      <DecisionFooter
        canAction={canAction}
        submitting={submitting}
        onReject={() => handleDecision(false)}
        onApprove={() => handleDecision(true)}
        processedText={processedText}
      />
    </SafeAreaView>
  );
};

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: colors.background.default,
  },
  scrollView: {
    flex: 1,
  },
  scrollContent: {
    padding: spacing.lg,
    paddingBottom: spacing.xl,
  },
  card: {
    backgroundColor: colors.background.paper,
    borderRadius: borderRadius.lg,
    padding: spacing.lg,
    marginBottom: spacing.md,
    ...shadows.sm,
  },
  sectionTitle: {
    marginBottom: spacing.sm,
  },
  row: {
    flexDirection: 'row',
    alignItems: 'center',
  },
  meta: {
    marginLeft: spacing.md,
    flex: 1,
  },
  name: {
    marginBottom: 2,
  },
  subDesc: {
    marginTop: spacing.sm,
  },
});

export default GroupRequestDetailScreen;