readful/lib/pages/search_page.dart

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import '../providers/search_provider.dart';
import '../models/book.dart';

/// 搜索页面
///
/// 提供实时搜索功能，支持书名和作者的模糊搜索
/// 使用StatefulWidget管理输入框状态和焦点控制
class SearchPage extends StatefulWidget {
  const SearchPage({super.key});

  @override
  State<SearchPage> createState() => _SearchPageState();
}

class _SearchPageState extends State<SearchPage> {
  late TextEditingController _textController;
  late FocusNode _focusNode;

  @override
  void initState() {
    super.initState();
    _textController = TextEditingController();
    _focusNode = FocusNode();

    // 页面初始化时重置搜索状态
    WidgetsBinding.instance.addPostFrameCallback((_) {
      final searchProvider = Provider.of<SearchProvider>(context, listen: false);
      searchProvider.clearSearch();
    });

    // 监听文本变化，同步到Provider
    _textController.addListener(_onTextChanged);
  }

  @override
  void dispose() {
    _textController.removeListener(_onTextChanged);
    _textController.dispose();
    _focusNode.dispose();
    super.dispose();
  }

  /// 文本变化处理
  ///
  /// 同步TextField文本到SearchProvider，避免循环更新
  void _onTextChanged() {
    final currentQuery = Provider.of<SearchProvider>(context, listen: false).searchQuery;
    if (_textController.text != currentQuery) {
      Provider.of<SearchProvider>(context, listen: false).updateQuery(_textController.text);
    }
  }

  /// 清空搜索
  ///
  /// 同时清空Provider状态、TextField文本，并重新获取焦点
  void _clearSearch() {
    final searchProvider = Provider.of<SearchProvider>(context, listen: false);
    searchProvider.clearSearch();
    _textController.clear();
    _focusNode.requestFocus();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Column(
        children: [
          SafeArea(
            bottom: false,
            child: Padding(
              padding: const EdgeInsets.all(16.0),
              child: _buildSearchInput(context),
            ),
          ),
          Expanded(
            child: _buildSearchResults(context),
          ),
        ],
      ),
    );
  }

  /// 构建搜索输入框
  ///
  /// 使用TextEditingController控制文本状态
  /// 使用Consumer响应搜索状态变化，动态显示清空按钮
  Widget _buildSearchInput(BuildContext context) {
    return Consumer<SearchProvider>(
      builder: (context, searchProvider, child) {
        return TextField(
          controller: _textController,
          focusNode: _focusNode,
          autofocus: true,
          decoration: InputDecoration(
            hintText: '输入书名、作者或关键词...',
            prefixIcon: const Icon(Icons.search),
            suffixIcon: searchProvider.hasQuery
                ? IconButton(
                    icon: const Icon(Icons.clear),
                    onPressed: _clearSearch,
                  )
                : null,
          ),
        );
      },
    );
  }

  /// 构建搜索结果区域
///
/// 根据搜索状态显示不同的UI：
/// - 搜索中：显示加载指示器
/// - 无搜索词：显示空状态提示
/// - 无结果：显示未找到提示
/// - 有结果：显示书籍列表
Widget _buildSearchResults(BuildContext context) {
  return Consumer<SearchProvider>(
    builder: (context, searchProvider, child) {
      if (searchProvider.isSearching) {
        return const Center(
          child: CircularProgressIndicator(),
        );
      }

      if (!searchProvider.hasQuery) {
        return _buildEmptyState();
      }

      if (!searchProvider.hasResults) {
        return _buildNoResults();
      }

      return _buildBookList(searchProvider.searchResults);
    },
  );
}

/// 构建空状态界面
///
/// 当用户未输入搜索词时显示的引导界面
Widget _buildEmptyState() {
  return const Center(
    child: Column(
      mainAxisAlignment: MainAxisAlignment.center,
      children: [
        Icon(Icons.search, size: 64, color: Colors.grey),
        SizedBox(height: 16),
        Text(
          '输入关键词开始搜索',
          style: TextStyle(fontSize: 16, color: Colors.grey),
        ),
      ],
    ),
  );
}

  /// 构建无结果界面
///
/// 当搜索没有找到匹配书籍时显示的提示界面
Widget _buildNoResults() {
  return const Center(
    child: Column(
      mainAxisAlignment: MainAxisAlignment.center,
      children: [
        Icon(Icons.search_off, size: 64, color: Colors.grey),
        SizedBox(height: 16),
        Text(
          '没有找到相关书籍',
          style: TextStyle(fontSize: 16, color: Colors.grey),
        ),
      ],
    ),
  );
}

/// 构建书籍列表
///
/// [books] 搜索结果书籍列表
/// 使用ListView.builder实现高效的滚动性能
Widget _buildBookList(List<Book> books) {
  return ListView.builder(
    itemCount: books.length,
    cacheExtent: 500,
    itemBuilder: (context, index) {
      final book = books[index];
      return ListTile(
        leading: Container(
          width: 50,
          height: 70,
          decoration: BoxDecoration(
            color: Colors.grey[300],
            borderRadius: BorderRadius.circular(8),
          ),
          child: const Icon(Icons.book, color: Colors.grey),
        ),
        title: Text(book.title),
        subtitle: Text(book.author ?? '未知作者'),
        trailing: const Icon(Icons.chevron_right),
        onTap: () {
          // TODO: 实现跳转到书籍详情页面的功能
          print('点击了书籍: ${book.title}');
        },
      );
    },
  );
}
}