// 搜索页面 — 搜索历史 + 热门搜索 + 关键词高亮 + 分类 Tab
//
// 通过 SearchBloc 驱动搜索状态：
// - 关键词输入 → SearchByKeyword event
// - 标签点击 → SearchByTag event
// - 心情选择 → SearchByMood event
// - Tab 切换 → SearchTabChanged event
// - 清除按钮 → SearchClear event
// 搜索结果由 BlocBuilder<SearchBloc, SearchState> 响应式渲染。

import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:go_router/go_router.dart';
import 'package:intl/intl.dart';

import '../../../core/theme/app_colors.dart';
import '../../../core/theme/app_radius.dart';
import '../../../core/utils/mood_utils.dart';
import '../../../data/models/journal_entry.dart';
import '../bloc/search_bloc.dart';

/// 搜索页面 — 搜索历史 + 热门搜索 + 结果分类
class SearchPage extends StatefulWidget {
  const SearchPage({super.key});

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

class _SearchPageState extends State<SearchPage> {
  final _searchController = TextEditingController();
  final _searchFocusNode = FocusNode();

  // 热门搜索占位数据
  final _hotSearches = ['日常', '学校', '旅行', '美食', '读书', '心情', '手账', '贴纸'];

  @override
  void initState() {
    super.initState();
    // 自动弹出键盘
    WidgetsBinding.instance.addPostFrameCallback((_) {
      _searchFocusNode.requestFocus();
    });
  }

  @override
  void dispose() {
    _searchController.dispose();
    _searchFocusNode.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final colorScheme = theme.colorScheme;
    final isDark = theme.brightness == Brightness.dark;

    return BlocBuilder<SearchBloc, SearchState>(
      builder: (context, state) {
        return Scaffold(
          body: SafeArea(
            child: Column(
              children: [
                // 6A: 搜索头部 — 返回 + 输入框 + 取消
                _buildSearchHeader(
                    context, theme, colorScheme, isDark),
                // 6C: 结果分类 Tab（有结果时显示）
                if (state case SearchLoaded(:final hasActiveFilter) when hasActiveFilter)
                  _buildResultTabs(context, state),
                // 主体内容
                Expanded(
                  child: _buildBody(
                      context, theme, colorScheme, isDark, state),
                ),
              ],
            ),
          ),
        );
      },
    );
  }

  // ===== 6A: 搜索头部 =====

  Widget _buildSearchHeader(
    BuildContext context,
    ThemeData theme,
    ColorScheme colorScheme,
    bool isDark,
  ) {
    final surfaceWarmColor = isDark
        ? AppColors.surfaceWarmDark
        : AppColors.surfaceWarmLight;

    return Padding(
      padding: const EdgeInsets.fromLTRB(8, 8, 8, 0),
      child: Row(
        children: [
          // 返回按钮
          SizedBox(
            width: 44,
            height: 44,
            child: IconButton(
              onPressed: () => Navigator.of(context).pop(),
              icon: Icon(
                Icons.arrow_back_ios_new,
                size: 18,
                color: isDark
                    ? AppColors.fgDark
                    : AppColors.fgLight,
              ),
              style: IconButton.styleFrom(
                shape: RoundedRectangleBorder(
                  borderRadius:
                      BorderRadius.circular(AppRadius.pill),
                ),
              ),
            ),
          ),
          const SizedBox(width: 4),
          // 搜索输入框
          Expanded(
            child: SizedBox(
              height: 44,
              child: TextField(
                controller: _searchController,
                focusNode: _searchFocusNode,
                decoration: InputDecoration(
                  hintText: '搜索日记...',
                  hintStyle: theme.textTheme.bodyLarge?.copyWith(
                    color: isDark
                        ? AppColors.mutedDark
                        : AppColors.mutedLight,
                  ),
                  prefixIcon: Icon(
                    Icons.search,
                    size: 20,
                    color: isDark
                        ? AppColors.mutedDark
                        : AppColors.mutedLight,
                  ),
                  suffixIcon: _searchController.text.isNotEmpty
                      ? IconButton(
                          icon: Icon(
                            Icons.clear,
                            size: 18,
                            color: isDark
                                ? AppColors.mutedDark
                                : AppColors.mutedLight,
                          ),
                          onPressed: () {
                            _searchController.clear();
                            _clearSearch();
                          },
                        )
                      : null,
                  filled: true,
                  fillColor: surfaceWarmColor,
                  border: OutlineInputBorder(
                    borderRadius:
                        BorderRadius.circular(AppRadius.pill),
                    borderSide: BorderSide.none,
                  ),
                  contentPadding:
                      const EdgeInsets.symmetric(horizontal: 16),
                  isDense: true,
                ),
                textInputAction: TextInputAction.search,
                onSubmitted: (value) {
                  if (value.trim().isNotEmpty) {
                    context
                        .read<SearchBloc>()
                        .add(SearchByKeyword(value.trim()));
                  }
                },
              ),
            ),
          ),
          const SizedBox(width: 4),
          // 取消按钮
          TextButton(
            onPressed: () => Navigator.of(context).pop(),
            child: Text(
              '取消',
              style: theme.textTheme.bodyMedium?.copyWith(
                color: AppColors.accent,
                fontWeight: FontWeight.w500,
              ),
            ),
          ),
        ],
      ),
    );
  }

  // ===== 6C: 结果分类 Tab =====

  Widget _buildResultTabs(
      BuildContext context, SearchLoaded state) {
    final theme = Theme.of(context);
    final isDark = theme.brightness == Brightness.dark;

    return Padding(
      padding: const EdgeInsets.fromLTRB(16, 8, 16, 0),
      child: Row(
        children: SearchResultTab.values.map((tab) {
          final isActive = state.activeTab == tab;
          return GestureDetector(
            onTap: () {
              context
                  .read<SearchBloc>()
                  .add(SearchTabChanged(tab));
            },
            child: Container(
              padding: const EdgeInsets.symmetric(
                horizontal: 16,
                vertical: 8,
              ),
              decoration: BoxDecoration(
                border: Border(
                  bottom: BorderSide(
                    color: isActive
                        ? AppColors.accent
                        : Colors.transparent,
                    width: 3,
                  ),
                ),
              ),
              child: Text(
                tab.label,
                style: theme.textTheme.bodySmall?.copyWith(
                  color: isActive
                      ? AppColors.accent
                      : (isDark
                          ? AppColors.mutedDark
                          : AppColors.mutedLight),
                  fontWeight: isActive
                      ? FontWeight.w600
                      : FontWeight.normal,
                ),
              ),
            ),
          );
        }).toList(),
      ),
    );
  }

  // ===== 主体内容 =====

  Widget _buildBody(
    BuildContext context,
    ThemeData theme,
    ColorScheme colorScheme,
    bool isDark,
    SearchState state,
  ) {
    return switch (state) {
      SearchInitial() => _buildSuggestions(
          context, theme, colorScheme, isDark, []),
      SearchLoading() =>
        const Center(child: CircularProgressIndicator()),
      SearchLoaded(
        :final results,
        :final activeMood,
        :final activeTag,
        :final activeKeyword,
        :final activeTab,
        :final searchHistory,
      ) =>
        hasActiveFilter(activeMood, activeTag, activeKeyword)
            ? _buildFilteredResults(
                context,
                theme,
                colorScheme,
                isDark,
                results,
                activeKeyword,
                activeTab,
              )
            : _buildSuggestions(
                context, theme, colorScheme, isDark, searchHistory),
      SearchError(:final message) =>
        _buildError(colorScheme, message),
    };
  }

  bool hasActiveFilter(String? mood, String? tag, String? keyword) =>
      mood != null || tag != null || keyword != null;

  // ===== 6B: 搜索历史 + 热门搜索 =====

  Widget _buildSuggestions(
    BuildContext context,
    ThemeData theme,
    ColorScheme colorScheme,
    bool isDark,
    List<String> searchHistory,
  ) {
    return SingleChildScrollView(
      padding: const EdgeInsets.all(16),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          // 搜索历史
          if (searchHistory.isNotEmpty) ...[
            Row(
              mainAxisAlignment: MainAxisAlignment.spaceBetween,
              children: [
                Text(
                  '最近搜索',
                  style: theme.textTheme.titleSmall?.copyWith(
                    fontWeight: FontWeight.w600,
                  ),
                ),
                GestureDetector(
                  onTap: _clearSearch,
                  child: Text(
                    '清除',
                    style: theme.textTheme.bodySmall?.copyWith(
                      color: AppColors.accent,
                    ),
                  ),
                ),
              ],
            ),
            const SizedBox(height: 8),
            Wrap(
              spacing: 8,
              runSpacing: 8,
              children: searchHistory.map((keyword) {
                return ActionChip(
                  label: Text(keyword),
                  onPressed: () {
                    _searchController.text = keyword;
                    context
                        .read<SearchBloc>()
                        .add(SearchByKeyword(keyword));
                  },
                );
              }).toList(),
            ),
            const SizedBox(height: 24),
          ],

          // 热门搜索
          Text(
            '热门搜索',
            style: theme.textTheme.titleSmall?.copyWith(
              fontWeight: FontWeight.w600,
            ),
          ),
          const SizedBox(height: 8),
          Wrap(
            spacing: 8,
            runSpacing: 8,
            children: _hotSearches.map((keyword) {
              return ActionChip(
                label: Text(keyword),
                onPressed: () {
                  _searchController.text = keyword;
                  context
                      .read<SearchBloc>()
                      .add(SearchByKeyword(keyword));
                },
              );
            }).toList(),
          ),
          const SizedBox(height: 24),

          // 心情筛选
          Text(
            '按心情筛选',
            style: theme.textTheme.titleSmall?.copyWith(
              fontWeight: FontWeight.w600,
            ),
          ),
          const SizedBox(height: 12),
          Wrap(
            spacing: 12,
            runSpacing: 12,
            children: Mood.values.map((mood) {
              final color = AppColors.moodColors[mood.value] ??
                  colorScheme.primary;
              return GestureDetector(
                onTap: () {
                  _searchController.text = moodToLabel(mood);
                  context
                      .read<SearchBloc>()
                      .add(SearchByMood(mood));
                },
                child: Column(
                  children: [
                    Container(
                      width: 48,
                      height: 48,
                      decoration: BoxDecoration(
                        shape: BoxShape.circle,
                        color: color.withValues(alpha: 0.15),
                      ),
                      alignment: Alignment.center,
                      child: Text(moodToEmoji(mood),
                          style: const TextStyle(fontSize: 24)),
                    ),
                    const SizedBox(height: 4),
                    Text(moodToLabel(mood),
                        style: theme.textTheme.labelSmall),
                  ],
                ),
              );
            }).toList(),
          ),
        ],
      ),
    );
  }

  // ===== 按分类 Tab 过滤结果 =====

  Widget _buildFilteredResults(
    BuildContext context,
    ThemeData theme,
    ColorScheme colorScheme,
    bool isDark,
    List<JournalEntry> results,
    String? keyword,
    SearchResultTab activeTab,
  ) {
    if (results.isEmpty) {
      return Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            Icon(Icons.search_off_rounded,
                size: 48,
                color: colorScheme.onSurface.withValues(alpha: 0.2)),
            const SizedBox(height: 12),
            Text(
              '没有找到匹配的日记',
              style: theme.textTheme.bodyMedium?.copyWith(
                color:
                    colorScheme.onSurface.withValues(alpha: 0.5),
              ),
            ),
            const SizedBox(height: 16),
            FilledButton.tonal(
              onPressed: _clearSearch,
              child: const Text('清除筛选'),
            ),
          ],
        ),
      );
    }

    // 根据活跃 Tab 选择展示内容
    switch (activeTab) {
      case SearchResultTab.all:
      case SearchResultTab.journal:
        return _buildJournalResults(
            context, theme, colorScheme, isDark, results, keyword);
      case SearchResultTab.template:
        return _buildTemplateResults(theme, isDark);
      case SearchResultTab.tag:
        return _buildTagResults(theme, isDark, results);
    }
  }

  // ===== 日记结果列表 =====

  Widget _buildJournalResults(
    BuildContext context,
    ThemeData theme,
    ColorScheme colorScheme,
    bool isDark,
    List<JournalEntry> results,
    String? keyword,
  ) {
    return ListView.separated(
      padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
      itemCount: results.length,
      separatorBuilder: (_, _) => const SizedBox(height: 8),
      itemBuilder: (context, index) {
        final entry = results[index];
        return _JournalCard(
          entry: entry,
          keyword: keyword,
        );
      },
    );
  }

  // ===== 6E: 模板结果（占位） =====

  Widget _buildTemplateResults(ThemeData theme, bool isDark) {
    // Phase 1 占位 — 模板功能未实现
    return GridView.builder(
      padding: const EdgeInsets.all(16),
      gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(
        crossAxisCount: 2,
        mainAxisSpacing: 12,
        crossAxisSpacing: 12,
        childAspectRatio: 0.75,
      ),
      itemCount: 4,
      itemBuilder: (context, index) {
        final gradients = [
          const [AppColors.accent, AppColors.tertiary],
          const [AppColors.secondary, AppColors.tertiary],
          const [AppColors.rose, AppColors.accent],
          const [AppColors.tertiary, AppColors.secondary],
        ];
        final labels = ['每日心情', '旅行手账', '读书笔记', '日常记录'];
        return Container(
          decoration: BoxDecoration(
            borderRadius: BorderRadius.circular(AppRadius.md),
            gradient: LinearGradient(
              begin: Alignment.topLeft,
              end: Alignment.bottomRight,
              colors: gradients[index],
            ),
          ),
          child: Stack(
            children: [
              // 装饰圆
              Positioned(
                right: -10,
                bottom: -10,
                child: Container(
                  width: 60,
                  height: 60,
                  decoration: BoxDecoration(
                    shape: BoxShape.circle,
                    color: Colors.white.withValues(alpha: 0.12),
                  ),
                ),
              ),
              Padding(
                padding: const EdgeInsets.all(16),
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  mainAxisAlignment: MainAxisAlignment.end,
                  children: [
                    Text(
                      labels[index],
                      style: theme.textTheme.titleSmall?.copyWith(
                        color: Colors.white,
                        fontWeight: FontWeight.w600,
                      ),
                    ),
                    const SizedBox(height: 4),
                    Text(
                      '即将上线',
                      style: theme.textTheme.bodySmall?.copyWith(
                        color: Colors.white.withValues(alpha: 0.7),
                      ),
                    ),
                  ],
                ),
              ),
            ],
          ),
        );
      },
    );
  }

  // ===== 6E: 标签结果 =====

  Widget _buildTagResults(
    ThemeData theme, bool isDark, List<JournalEntry> results) {
    // 从搜索结果中提取所有标签及其频次
    final tagFreq = <String, int>{};
    for (final entry in results) {
      for (final tag in entry.tags) {
        tagFreq[tag] = (tagFreq[tag] ?? 0) + 1;
      }
    }

    final sortedTags = tagFreq.keys.toList()
      ..sort((a, b) => tagFreq[b]!.compareTo(tagFreq[a]!));

    if (sortedTags.isEmpty) {
      return Center(
        child: Text(
          '没有找到相关标签',
          style: theme.textTheme.bodyMedium?.copyWith(
            color: isDark ? AppColors.mutedDark : AppColors.mutedLight,
          ),
        ),
      );
    }

    return Wrap(
      spacing: 10,
      runSpacing: 10,
      children: sortedTags.map((tag) {
        return Container(
          padding: const EdgeInsets.symmetric(
            horizontal: 20,
            vertical: 10,
          ),
          decoration: BoxDecoration(
            color: isDark
                ? AppColors.surfaceDark
                : AppColors.surfaceLight,
            borderRadius: BorderRadius.circular(AppRadius.pill),
            border: Border.all(
              color: isDark
                  ? AppColors.borderDark
                  : AppColors.borderLight,
            ),
          ),
          child: Text(
            '$tag (${tagFreq[tag]})',
            style: theme.textTheme.bodyMedium,
          ),
        );
      }).toList(),
    ).padAll(16);
  }

  /// 错误提示
  Widget _buildError(ColorScheme colorScheme, String message) {
    return Center(
      child: Column(
        mainAxisSize: MainAxisSize.min,
        children: [
          Icon(Icons.error_outline_rounded,
              size: 48,
              color: colorScheme.error.withValues(alpha: 0.6)),
          const SizedBox(height: 12),
          Text(
            message,
            style: TextStyle(
              color: colorScheme.error,
              fontSize: 14,
            ),
          ),
          const SizedBox(height: 16),
          FilledButton.tonal(
            onPressed: _clearSearch,
            child: const Text('重试'),
          ),
        ],
      ),
    );
  }

  void _clearSearch() {
    _searchController.clear();
    context.read<SearchBloc>().add(const SearchClear());
  }
}

// ===== 6D: 关键词高亮辅助函数 =====

/// 将文本中的关键词部分用高亮样式包裹
Widget _highlightText(String text, String? keyword) {
  if (keyword == null || keyword.isEmpty || !text.toLowerCase().contains(keyword.toLowerCase())) {
    return Text(text);
  }

  final lowerText = text.toLowerCase();
  final lowerKeyword = keyword.toLowerCase();
  final spans = <TextSpan>[];
  int start = 0;

  while (start < text.length) {
    final index = lowerText.indexOf(lowerKeyword, start);
    if (index == -1) {
      spans.add(TextSpan(text: text.substring(start)));
      break;
    }
    if (index > start) {
      spans.add(TextSpan(text: text.substring(start, index)));
    }
    spans.add(TextSpan(
      text: text.substring(index, index + keyword.length),
      style: const TextStyle(
        color: AppColors.accent,
        backgroundColor: AppColors.tertiarySoftLight,
        fontWeight: FontWeight.w600,
      ),
    ));
    start = index + keyword.length;
  }

  return RichText(text: TextSpan(style: const TextStyle(), children: spans));
}

/// 日记卡片 — 在搜索结果中展示单条日记摘要（支持关键词高亮）
class _JournalCard extends StatelessWidget {
  final JournalEntry entry;
  final String? keyword;

  const _JournalCard({required this.entry, this.keyword});

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final colorScheme = theme.colorScheme;
    final moodColor =
        AppColors.moodColors[entry.mood.value] ?? colorScheme.primary;

    return Card(
      elevation: 0,
      shape: RoundedRectangleBorder(
        borderRadius: BorderRadius.circular(16),
        side: BorderSide(color: colorScheme.outlineVariant),
      ),
      child: InkWell(
        borderRadius: BorderRadius.circular(16),
        onTap: () {
          context.push('/editor?id=${entry.id}');
        },
        child: Padding(
          padding: const EdgeInsets.all(16),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              // 第一行：心情 emoji + 标题（高亮）+ 日期
              Row(
                children: [
                  Text(
                    moodToEmoji(entry.mood),
                    style: const TextStyle(fontSize: 20),
                  ),
                  const SizedBox(width: 8),
                  Expanded(
                    child: _highlightText(entry.title, keyword),
                  ),
                  Text(
                    DateFormat('MM/dd').format(entry.date),
                    style: theme.textTheme.labelSmall?.copyWith(
                      color: colorScheme.onSurfaceVariant,
                    ),
                  ),
                ],
              ),
              // 第二行：标签
              if (entry.tags.isNotEmpty) ...[
                const SizedBox(height: 8),
                Wrap(
                  spacing: 6,
                  runSpacing: 4,
                  children: entry.tags.take(4).map((tag) {
                    return Container(
                      padding: const EdgeInsets.symmetric(
                        horizontal: 8,
                        vertical: 2,
                      ),
                      decoration: BoxDecoration(
                        color: moodColor.withValues(alpha: 0.1),
                        borderRadius: BorderRadius.circular(8),
                      ),
                      child: Text(
                        tag,
                        style: theme.textTheme.labelSmall?.copyWith(
                          color: moodColor,
                          fontSize: 11,
                        ),
                      ),
                    );
                  }).toList(),
                ),
              ],
            ],
          ),
        ),
      ),
    );
  }

}

/// Padding 扩展 — 简化 Wrap 的 padding
extension _PadAll on Widget {
  Widget padAll(double value) => Padding(
        padding: EdgeInsets.all(value),
        child: this,
      );
}