ReelShort/lib/pages/discover/discover_logic.dart

// Author: fruit.com.cn

import 'dart:async';

import 'package:flutter/material.dart';

import '../../core/data/models/drama.dart';
import '../../core/data/remote/api_exception.dart';
import '../../core/data/repositories/search_repository.dart';
import 'discover_types.dart';

/// 剧场页搜索状态：服务端检索、防抖与错误态。
class DiscoverLogic extends ChangeNotifier {
  DiscoverLogic({this.searchRepository});

  final SearchRepository? searchRepository;
  final TextEditingController search = TextEditingController();
  final FocusNode searchFocus = FocusNode();
  final ScrollController scroll = ScrollController();

  /// 搜索防抖与分页口径：与后端 `/app/search` 一致。
  Duration searchDebounce = const Duration(milliseconds: 350);
  static const int searchPageSize = 20;
  List<Drama> searchResults = const [];
  bool searchLoading = false;
  String? searchError;
  Timer? _searchTimer;
  String _lastRequestedQuery = '';
  int _searchRequest = 0;
  bool _disposed = false;
  String? selectedCategoryId;

  bool get hasSearchQuery => search.text.trim().isNotEmpty;

  void notify() {
    if (!_disposed) notifyListeners();
  }

  void onSearchChanged() {
    final query = search.text.trim();
    if (query.isEmpty) {
      _resetSearch();
      notify();
      return;
    }
    notify();
    _scheduleSearch(query);
  }

  void openSearch() => searchFocus.requestFocus();

  /// 选择分类；空值表示全部。
  void selectCategory(String? categoryId) {
    if (selectedCategoryId == categoryId) return;
    selectedCategoryId = categoryId;
    notify();
  }

  void retrySearch() {
    final query = search.text.trim();
    if (query.isNotEmpty) unawaited(_runSearch(query));
  }

  /// 用当前关键词重新请求第一页；刷新期间保留旧结果。
  Future<void> refreshSearch() async {
    final query = search.text.trim();
    if (query.isEmpty) return;
    _searchTimer?.cancel();
    await _runSearch(query, preserveResults: true);
  }

  void _resetSearch() {
    _searchTimer?.cancel();
    _searchRequest++;
    searchResults = const [];
    searchLoading = false;
    searchError = null;
    _lastRequestedQuery = '';
  }

  void _scheduleSearch(String query) {
    final alreadyRequested = query == _lastRequestedQuery;
    if (alreadyRequested &&
        (searchLoading || searchResults.isNotEmpty || searchError != null)) {
      return;
    }
    _lastRequestedQuery = query;
    _searchTimer?.cancel();
    if (searchDebounce == Duration.zero) {
      unawaited(_runSearch(query));
      return;
    }
    _searchTimer = Timer(searchDebounce, () => unawaited(_runSearch(query)));
  }

  Future<void> _runSearch(String query, {bool preserveResults = false}) async {
    final repository = searchRepository;
    if (repository == null) return;
    final request = ++_searchRequest;
    searchLoading = true;
    searchError = null;
    notify();
    try {
      final result = await repository.search(
        query,
        pageIndex: 1,
        pageSize: searchPageSize,
      );
      if (request != _searchRequest) return;
      searchResults = result.list;
    } on ApiException catch (exception) {
      _applySearchError(
        request,
        exception.message,
        preserveResults: preserveResults,
      );
    } catch (_) {
      _applySearchError(
        request,
        'searchFailed',
        preserveResults: preserveResults,
      );
    } finally {
      if (request == _searchRequest) {
        searchLoading = false;
        notify();
      }
    }
  }

  void _applySearchError(
    int request,
    String message, {
    bool preserveResults = false,
  }) {
    if (request != _searchRequest) return;
    if (preserveResults && searchResults.isNotEmpty) return;
    searchError = message;
    searchResults = const [];
  }

  void act(
    BuildContext context,
    DiscoverPageAction action, {
    required bool embedded,
    ValueChanged<DiscoverPageAction>? onAction,
  }) {
    if (embedded) {
      onAction?.call(action);
    } else {
      Navigator.pop(context, action);
    }
  }

  @override
  void dispose() {
    _disposed = true;
    _searchTimer?.cancel();
    search.dispose();
    searchFocus.dispose();
    scroll.dispose();
    super.dispose();
  }
}