/**
 * 搜索页 SearchScreen（响应式版本）
 * 胡萝卜BBS - 搜索帖子、用户
 * 支持响应式布局，宽屏下显示更大的搜索结果区域
 */

import React, { useState, useCallback, useEffect, useMemo } from 'react';
import {
  View,
  FlatList,
  StyleSheet,
  TouchableOpacity,
  ScrollView,
  RefreshControl,
} from 'react-native';
import { SafeAreaView, useSafeAreaInsets } from 'react-native-safe-area-context';
import { useRouter } from 'expo-router';
import { MaterialCommunityIcons } from '@expo/vector-icons';
import { spacing, fontSizes, borderRadius, useAppColors, type AppColors } from '../../theme';
import { Post, User } from '../../types';
import { useUserStore } from '../../stores';
import { postService, authService } from '../../services';
import { PostCard, TabBar, SearchBar } from '../../components/business';
import type { PostCardAction } from '../../components/business/PostCard';
import { Avatar, EmptyState, Text, ResponsiveGrid, Loading } from '../../components/common';
import * as hrefs from '../../navigation/hrefs';
import { useResponsive, useResponsiveSpacing, useResponsiveValue } from '../../hooks/useResponsive';
import { useCursorPagination } from '../../hooks/useCursorPagination';

const TABS = ['帖子', '用户'];
const DEFAULT_PAGE_SIZE = 20;

type SearchType = 'posts' | 'users';

interface SearchScreenProps {
  onBack?: () => void;
}

export const SearchScreen: React.FC<SearchScreenProps> = ({ onBack }) => {
  const colors = useAppColors();
  const styles = useMemo(() => createSearchScreenStyles(colors), [colors]);
  const router = useRouter();
  const insets = useSafeAreaInsets();
  const { searchHistory: history, addSearchHistory, clearSearchHistory } = useUserStore();
  
  // 使用响应式 hook
  const { 
    width, 
    isMobile, 
    isTablet, 
    isDesktop, 
    isWideScreen 
  } = useResponsive();
  
  // 响应式间距
  const responsivePadding = useResponsiveSpacing({ 
    xs: 12, sm: 14, md: 16, lg: 20, xl: 24, '2xl': 32, '3xl': 40, '4xl': 48 
  });
  
  const responsiveGap = useResponsiveSpacing({ 
    xs: 8, sm: 10, md: 12, lg: 16, xl: 20, '2xl': 24, '3xl': 28, '4xl': 32 
  });
  
  // 响应式搜索栏最大宽度（使用数字）
  const searchBarMaxWidth = useResponsiveValue({
    xs: 600,
    sm: 600,
    md: 600,
    lg: 700,
    xl: 800,
    '2xl': 900,
    '3xl': 1000,
    '4xl': 1200,
  });
  
  const [searchText, setSearchText] = useState('');
  const [activeIndex, setActiveIndex] = useState(0);
  const [hasSearched, setHasSearched] = useState(false);
  // 保存当前搜索关键词，用于Tab切换时重新搜索
  const [currentKeyword, setCurrentKeyword] = useState('');

  // 使用游标分页进行帖子搜索
  const {
    list: searchResults,
    isLoading,
    isRefreshing,
    hasMore,
    loadMore,
    refresh,
    reset,
  } = useCursorPagination<Post, { query: string }>(
    async ({ cursor, pageSize, extraParams }) => {
      if (!extraParams?.query) {
        return { list: [], next_cursor: null, prev_cursor: null, has_more: false };
      }
      const response = await postService.searchPostsCursor(extraParams.query, {
        cursor,
        page_size: pageSize,
      });
      return response;
    },
    { pageSize: DEFAULT_PAGE_SIZE },
    { query: '' }
  );

  // 用户搜索结果（保持原有分页方式）
  const [userResults, setUserResults] = useState<User[]>([]);
  const [userLoading, setUserLoading] = useState(false);

  // 当搜索词变化时重置
  useEffect(() => {
    if (currentKeyword) {
      refresh();
    } else {
      reset();
    }
  }, [currentKeyword]);

  // 执行搜索 - 根据当前Tab执行对应类型的搜索
  const performSearch = useCallback(async (keyword: string) => {
    if (!keyword.trim()) return;
    
    const trimmedKeyword = keyword.trim();
    
    // 保存当前搜索关键词
    setCurrentKeyword(trimmedKeyword);
    
    // 添加到搜索历史
    addSearchHistory(trimmedKeyword);
    
    try {
      const searchType = getSearchType();
      
      if (searchType === 'posts') {
        // 帖子搜索由 useCursorPagination 处理，这里只需触发刷新
        refresh();
      } else if (searchType === 'users') {
        // 用户搜索保持原有方式
        setUserLoading(true);
        const usersResponse = await authService.searchUsers(trimmedKeyword, 1, 20);
        setUserResults(usersResponse.list || []);
      }
    } catch (error) {
      console.error('搜索失败:', error);
    }
    
    setHasSearched(true);
  }, [addSearchHistory, activeIndex, refresh]);

  // 处理搜索提交
  const handleSearch = () => {
    performSearch(searchText);
  };

  // 处理搜索历史点击
  const handleHistoryPress = (keyword: string) => {
    setSearchText(keyword);
    performSearch(keyword);
  };

  // 清除搜索历史
  const handleClearHistory = () => {
    clearSearchHistory();
  };

  // 跳转到帖子详情
  const handlePostPress = (postId: string, scrollToComments: boolean = false) => {
    router.push(hrefs.hrefPostDetail(postId, scrollToComments));
  };

  // 跳转到用户主页
  const handleUserPress = (userId: string) => {
    router.push(hrefs.hrefUserProfile(userId));
  };

  // 统一处理 PostCard 的操作（搜索页不支持删除）
  const handlePostAction = (post: Post, action: PostCardAction) => {
    switch (action.type) {
      case 'press':
        handlePostPress(post.id);
        break;
      case 'userPress':
        if (post.author?.id) {
          handleUserPress(post.author.id);
        }
        break;
      case 'like':
        postService.likePost(post.id);
        break;
      case 'unlike':
        postService.unlikePost(post.id);
        break;
      case 'comment':
        handlePostPress(post.id, true);
        break;
      case 'bookmark':
        postService.favoritePost(post.id);
        break;
      case 'unbookmark':
        postService.unfavoritePost(post.id);
        break;
      case 'share':
        // 搜索页暂不处理分享
        break;
      case 'imagePress':
      case 'delete':
        break;
    }
  };

  // 获取当前搜索类型
  const getSearchType = (): SearchType => {
    switch (activeIndex) {
      case 0: return 'posts';
      case 1: return 'users';
      default: return 'posts';
    }
  };

  // 渲染帖子搜索结果（使用响应式网格）
  const renderPostResults = () => {
    const posts = searchResults;
    
    if (posts.length === 0 && !isLoading) {
      return (
        <EmptyState
          title="未找到相关帖子"
          description="试试其他关键词吧"
          icon="file-search-outline"
        />
      );
    }
    
    // 平板/桌面端使用网格布局
    if (isTablet || isDesktop || isWideScreen) {
      return (
        <ScrollView 
          showsVerticalScrollIndicator={false}
          contentContainerStyle={{ paddingBottom: responsivePadding }}
          refreshControl={
            <RefreshControl
              refreshing={isRefreshing}
              onRefresh={refresh}
              colors={[colors.primary.main]}
              tintColor={colors.primary.main}
            />
          }
        >
          <ResponsiveGrid
            columns={{ xs: 1, sm: 2, md: 2, lg: 3, xl: 3, '2xl': 4, '3xl': 4, '4xl': 5 }}
            gap={{ xs: 12, sm: 14, md: 16, lg: 20, xl: 24 }}
            containerStyle={{ paddingHorizontal: responsivePadding }}
          >
            {posts.map(post => (
              <PostCard
                key={post.id}
                post={post}
                onAction={(action) => handlePostAction(post, action)}
                variant="list"
                features={isMobile ? 'compact' : 'full'}
              />
            ))}
          </ResponsiveGrid>
          {isLoading && (
            <View style={styles.loadingMore}>
              <Loading size="sm" />
            </View>
          )}
        </ScrollView>
      );
    }
    
    // 移动端使用列表布局
    return (
      <FlatList
        data={posts}
        renderItem={({ item }) => (
          <PostCard
            post={item}
            onAction={(action) => handlePostAction(item, action)}
            variant="list"
            features="compact"
          />
        )}
        keyExtractor={item => item.id}
        contentContainerStyle={{ paddingBottom: responsivePadding }}
        showsVerticalScrollIndicator={false}
        refreshControl={
          <RefreshControl
            refreshing={isRefreshing}
            onRefresh={refresh}
            colors={[colors.primary.main]}
            tintColor={colors.primary.main}
          />
        }
        onEndReached={loadMore}
        onEndReachedThreshold={0.3}
        ListFooterComponent={isLoading ? <Loading size="sm" /> : null}
      />
    );
  };
  
  // 渲染用户搜索结果
  const renderUserResults = () => {
    const users = userResults;
    
    if (users.length === 0 && !userLoading) {
      return (
        <EmptyState
          title="未找到相关用户"
          description="试试其他关键词吧"
          icon="account-search-outline"
        />
      );
    }
    
    // 平板/桌面端使用网格布局
    if (isTablet || isDesktop || isWideScreen) {
      return (
        <ScrollView 
          showsVerticalScrollIndicator={false}
          contentContainerStyle={{ paddingBottom: responsivePadding }}
        >
          <ResponsiveGrid
            columns={{ xs: 1, sm: 2, md: 2, lg: 3, xl: 3, '2xl': 4, '3xl': 4, '4xl': 5 }}
            gap={{ xs: 12, sm: 14, md: 16, lg: 20, xl: 24 }}
            containerStyle={{ paddingHorizontal: responsivePadding }}
          >
            {users.map(item => (
              <TouchableOpacity 
                key={item.id}
                style={[
                  styles.userCard,
                  { padding: responsiveGap }
                ]}
                onPress={() => handleUserPress(item.id)}
              >
                <Avatar
                  source={item.avatar}
                  size={isDesktop ? 70 : isTablet ? 60 : 50}
                  name={item.nickname}
                />
                <View style={styles.userCardInfo}>
                  <Text 
                    variant="body" 
                    style={[
                      styles.userCardName,
                      { fontSize: isDesktop ? fontSizes.lg : fontSizes.md }
                    ]}
                  >
                    {item.nickname}
                  </Text>
                  <Text 
                    variant="caption" 
                    color={colors.text.secondary}
                    style={{ fontSize: isDesktop ? fontSizes.md : fontSizes.sm }}
                  >
                    {item.bio || '@' + item.username}
                  </Text>
                </View>
                {item.is_following && (
                  <View style={styles.followingBadge}>
                    <MaterialCommunityIcons name="check" size={14} color={colors.primary.main} />
                  </View>
                )}
              </TouchableOpacity>
            ))}
          </ResponsiveGrid>
          {userLoading && (
            <View style={styles.loadingMore}>
              <Loading size="sm" />
            </View>
          )}
        </ScrollView>
      );
    }
    
    // 移动端使用列表布局
    return (
      <FlatList
        data={users}
        renderItem={({ item }) => (
          <TouchableOpacity 
            style={[
              styles.userItem,
              { 
                marginHorizontal: responsivePadding,
                marginVertical: responsiveGap / 2,
                padding: responsiveGap
              }
            ]}
            onPress={() => handleUserPress(item.id)}
          >
            <Avatar
              source={item.avatar}
              size={50}
              name={item.nickname}
            />
            <View style={styles.userInfo}>
              <Text variant="body" style={styles.userName}>{item.nickname}</Text>
              <Text variant="caption" color={colors.text.secondary}>{item.bio || '@' + item.username}</Text>
            </View>
            {item.is_following && (
              <View style={styles.followingBadge}>
                <MaterialCommunityIcons name="check" size={14} color={colors.primary.main} />
              </View>
            )}
          </TouchableOpacity>
        )}
        keyExtractor={item => item.id}
        contentContainerStyle={{ paddingVertical: responsiveGap }}
        showsVerticalScrollIndicator={false}
        ListFooterComponent={userLoading ? <Loading size="sm" /> : null}
      />
    );
  };

  // 渲染搜索结果
  const renderSearchResults = () => {
    const searchType = getSearchType();
    
    if (searchType === 'posts') {
      return renderPostResults();
    }
    
    if (searchType === 'users') {
      return renderUserResults();
    }
    
    return null;
  };

  // 渲染搜索历史和热门搜索
  const renderSearchSuggestions = () => {
    if (hasSearched) return null;
    
    return (
      <View style={[styles.suggestionsContainer, { paddingHorizontal: responsivePadding }]}>
        {/* 搜索历史 */}
        {history.length > 0 && (
          <View style={[styles.section, { marginTop: responsiveGap }]}>
            <View style={styles.sectionHeader}>
              <Text 
                variant="body" 
                style={[
                  styles.sectionTitle,
                  { fontSize: isDesktop ? fontSizes.lg : fontSizes.md }
                ]}
              >
                搜索历史
              </Text>
              <TouchableOpacity onPress={handleClearHistory}>
                <MaterialCommunityIcons name="delete-outline" size={isDesktop ? 22 : 18} color={colors.text.secondary} />
              </TouchableOpacity>
            </View>
            <View style={styles.tagContainer}>
              {history.map((keyword, index) => (
                <TouchableOpacity
                  key={index}
                  style={[
                    styles.tag,
                    { 
                      paddingHorizontal: responsiveGap,
                      paddingVertical: responsiveGap / 2,
                      marginRight: responsiveGap / 2,
                      marginBottom: responsiveGap / 2
                    }
                  ]}
                  onPress={() => handleHistoryPress(keyword)}
                >
                  <MaterialCommunityIcons name="history" size={isDesktop ? 16 : 14} color={colors.text.secondary} />
                  <Text 
                    variant="caption" 
                    color={colors.text.secondary} 
                    style={[
                      styles.tagText,
                      { fontSize: isDesktop ? fontSizes.md : fontSizes.sm }
                    ]}
                  >
                    {keyword}
                  </Text>
                </TouchableOpacity>
              ))}
            </View>
          </View>
        )}
      </View>
    );
  };

  return (
    <SafeAreaView style={styles.container} edges={['bottom']}>
      {/* 搜索输入框 */}
      <View
        style={[
          styles.searchHeader,
          {
            paddingTop: Math.max(spacing.sm, insets.top + spacing.xs),
            paddingHorizontal: responsivePadding,
            paddingBottom: spacing.xs,
          },
        ]}
      >
        <View style={[styles.searchShell, { maxWidth: searchBarMaxWidth }]}>
          <SearchBar
            value={searchText}
            onChangeText={setSearchText}
            onSubmit={handleSearch}
            placeholder="搜索帖子、用户"
            autoFocus
          />
        </View>
        <TouchableOpacity
          style={[styles.cancelButton, { marginLeft: responsiveGap }]}
          onPress={() => (onBack ? onBack() : router.back())}
          activeOpacity={0.85}
        >
          <Text 
            variant="body" 
            color={colors.primary.main}
            style={styles.cancelText}
          >
            取消
          </Text>
        </TouchableOpacity>
      </View>

      {/* Tab切换 */}
      <View style={styles.tabWrapper}>
        <TabBar
          tabs={TABS}
          activeIndex={activeIndex}
          onTabChange={(index) => {
            setActiveIndex(index);
            // 如果已经搜索过，切换Tab时重新搜索
            if (currentKeyword && hasSearched) {
              performSearch(currentKeyword);
            }
          }}
        />
      </View>

      {/* 内容区域 */}
      {hasSearched ? renderSearchResults() : renderSearchSuggestions()}
    </SafeAreaView>
  );
};

function createSearchScreenStyles(colors: AppColors) {
  return StyleSheet.create({
    container: {
      flex: 1,
      backgroundColor: colors.background.default,
    },
    searchHeader: {
      flexDirection: 'row',
      alignItems: 'center',
      backgroundColor: colors.background.paper,
      borderBottomWidth: 1,
      borderBottomColor: `${colors.divider}70`,
    },
    searchShell: {
      flex: 1,
      borderRadius: borderRadius.xl,
      backgroundColor: `${colors.primary.main}08`,
      paddingHorizontal: spacing.xs,
      paddingVertical: spacing.xs,
      // 移除阴影效果
      shadowColor: 'transparent',
      shadowOffset: { width: 0, height: 0 },
      shadowOpacity: 0,
      shadowRadius: 0,
      elevation: 0,
    },
    cancelButton: {
      backgroundColor: `${colors.primary.main}14`,
      borderRadius: borderRadius.full,
      paddingHorizontal: spacing.md,
      paddingVertical: spacing.xs,
    },
    cancelText: {
      fontSize: fontSizes.md,
      fontWeight: '600',
    },
    tabWrapper: {
      backgroundColor: colors.background.paper,
      borderBottomWidth: 1,
      borderBottomColor: `${colors.divider}50`,
    },
    suggestionsContainer: {
      flex: 1,
    },
    section: {
      marginTop: spacing.md,
    },
    sectionHeader: {
      flexDirection: 'row',
      justifyContent: 'space-between',
      alignItems: 'center',
      marginBottom: spacing.sm,
    },
    sectionTitle: {
      fontWeight: '600',
      color: colors.text.primary,
    },
    tagContainer: {
      flexDirection: 'row',
      flexWrap: 'wrap',
    },
    tag: {
      flexDirection: 'row',
      alignItems: 'center',
      backgroundColor: colors.background.paper,
      borderRadius: borderRadius.lg,
      borderWidth: 1,
      borderColor: colors.divider,
    },
    tagText: {
      marginLeft: spacing.xs,
    },
    userCard: {
      backgroundColor: colors.background.paper,
      borderRadius: borderRadius.lg,
      flexDirection: 'row',
      alignItems: 'center',
    },
    userCardInfo: {
      flex: 1,
      marginLeft: spacing.md,
    },
    userCardName: {
      fontWeight: '600',
      color: colors.text.primary,
    },
    userItem: {
      flexDirection: 'row',
      alignItems: 'center',
      backgroundColor: colors.background.paper,
      borderRadius: borderRadius.lg,
    },
    userInfo: {
      flex: 1,
      marginLeft: spacing.md,
    },
    userName: {
      fontWeight: '600',
      color: colors.text.primary,
    },
    followingBadge: {
      width: 20,
      height: 20,
      borderRadius: 10,
      backgroundColor: `${colors.primary.main}14`,
      alignItems: 'center',
      justifyContent: 'center',
    },
    loadingMore: {
      paddingVertical: spacing.md,
      alignItems: 'center',
    },
  });
}
