import 'package:flutter_riverpod/flutter_riverpod.dart';

import '../core/storage/search_history_store.dart';
import '../models/video_item.dart';
import '../services/search_service.dart';

/// 搜索排序（《03-接口文档》5.10）
enum SearchSort {
  hot('hot', '热度'),
  latest('latest', '最新');

  const SearchSort(this.apiValue, this.label);

  final String apiValue;
  final String label;
}

/// 搜索页状态
class SearchState {
  const SearchState({
    this.keyword = '',
    this.sort = SearchSort.hot,
    this.items = const [],
    this.total = 0,
    this.page = 1,
    this.isSearching = false,
    this.isLoadingMore = false,
    this.searched = false,
    this.hotWords = const [],
    this.history = const [],
  });

  final String keyword;
  final SearchSort sort;
  final List<VideoItem> items;
  final int total;
  final int page;
  final bool isSearching;
  final bool isLoadingMore;

  /// 是否已执行过搜索（区分默认页与结果页）
  final bool searched;

  /// 热搜榜（进入页面时加载）
  final List<String> hotWords;

  /// 本地搜索历史（最新在前）
  final List<String> history;

  bool get hasMore => items.length < total;

  SearchState copyWith({
    String? keyword,
    SearchSort? sort,
    List<VideoItem>? items,
    int? total,
    int? page,
    bool? isSearching,
    bool? isLoadingMore,
    bool? searched,
    List<String>? hotWords,
    List<String>? history,
  }) =>
      SearchState(
        keyword: keyword ?? this.keyword,
        sort: sort ?? this.sort,
        items: items ?? this.items,
        total: total ?? this.total,
        page: page ?? this.page,
        isSearching: isSearching ?? this.isSearching,
        isLoadingMore: isLoadingMore ?? this.isLoadingMore,
        searched: searched ?? this.searched,
        hotWords: hotWords ?? this.hotWords,
        history: history ?? this.history,
      );
}

class SearchNotifier extends StateNotifier<SearchState> {
  SearchNotifier() : super(SearchState(history: SearchHistoryStore.I.history));

  /// 加载热搜榜（静默失败，空列表兜底）
  Future<void> loadHot() async {
    try {
      final words = await SearchService.hotWords();
      state = state.copyWith(hotWords: words);
    } catch (_) {}
  }

  /// 执行搜索（换关键词或排序时全量重来）
  Future<void> search(String keyword, {SearchSort? sort}) async {
    final word = keyword.trim();
    if (word.isEmpty) return;
    final nextSort = sort ?? state.sort;
    state = state.copyWith(
      keyword: word,
      sort: nextSort,
      isSearching: true,
      searched: true,
      items: const [],
      total: 0,
      page: 1,
    );
    // 写入本地历史（去重置顶，最多 10 条）
    await SearchHistoryStore.I.add(word);
    state = state.copyWith(history: SearchHistoryStore.I.history);
    try {
      final page =
          await SearchService.search(word, sort: nextSort.apiValue);
      state = state.copyWith(
        items: page.items,
        total: page.total,
        isSearching: false,
        page: 1,
      );
    } catch (_) {
      state = state.copyWith(isSearching: false);
    }
  }

  /// 触底加载更多
  Future<void> loadMore() async {
    if (!state.hasMore || state.isLoadingMore || state.isSearching) return;
    state = state.copyWith(isLoadingMore: true);
    try {
      final page = await SearchService.search(
        state.keyword,
        sort: state.sort.apiValue,
        page: state.page + 1,
      );
      state = state.copyWith(
        items: [...state.items, ...page.items],
        total: page.total,
        isLoadingMore: false,
        page: state.page + 1,
      );
    } catch (_) {
      state = state.copyWith(isLoadingMore: false);
    }
  }

  /// 删除单条历史
  Future<void> removeHistory(String word) async {
    await SearchHistoryStore.I.remove(word);
    state = state.copyWith(history: SearchHistoryStore.I.history);
  }

  /// 清空历史
  Future<void> clearHistory() async {
    await SearchHistoryStore.I.clear();
    state = state.copyWith(history: const []);
  }
}

final searchProvider =
    StateNotifierProvider<SearchNotifier, SearchState>((ref) => SearchNotifier());