import 'package:flutter_riverpod/flutter_riverpod.dart';

import '../services/wallet_service.dart';

/// 钱包状态：钱包信息 + 积分明细（biz_type 筛选 + 触底分页）
class WalletState {
  const WalletState({
    this.wallet,
    this.records = const [],
    this.recordsTotal = 0,
    this.bizType,
    this.isLoading = false,
    this.loadFailed = false,
    this.loadingMore = false,
  });

  final WalletInfo? wallet;
  final List<PointsRecord> records;
  final int recordsTotal;

  /// null = 全部
  final int? bizType;
  final bool isLoading;
  final bool loadFailed;
  final bool loadingMore;

  bool get hasMore => records.length < recordsTotal;

  WalletState copyWith({
    WalletInfo? wallet,
    List<PointsRecord>? records,
    int? recordsTotal,
    int? Function()? bizType,
    bool? isLoading,
    bool? loadFailed,
    bool? loadingMore,
  }) =>
      WalletState(
        wallet: wallet ?? this.wallet,
        records: records ?? this.records,
        recordsTotal: recordsTotal ?? this.recordsTotal,
        bizType: bizType != null ? bizType() : this.bizType,
        isLoading: isLoading ?? this.isLoading,
        loadFailed: loadFailed ?? this.loadFailed,
        loadingMore: loadingMore ?? this.loadingMore,
      );
}

class WalletNotifier extends StateNotifier<WalletState> {
  WalletNotifier() : super(const WalletState()) {
    load();
  }

  static const _pageSize = 20;

  Future<void> load() async {
    state = state.copyWith(isLoading: true, loadFailed: false);
    try {
      final wallet = await WalletService.fetchWallet();
      final page = await WalletService.fetchPointsRecords(
        page: 1,
        pageSize: _pageSize,
        bizType: state.bizType,
      );
      state = state.copyWith(
        wallet: wallet,
        records: page.items,
        recordsTotal: page.total,
        isLoading: false,
      );
    } catch (_) {
      state = state.copyWith(isLoading: false, loadFailed: true);
    }
  }

  /// 切换 biz_type 筛选并重载明细
  Future<void> setBizType(int? bizType) async {
    if (bizType == state.bizType) return;
    state = state.copyWith(bizType: () => bizType);
    await load();
  }

  /// 触底加载下一页
  Future<void> loadMore() async {
    if (state.loadingMore || !state.hasMore || state.isLoading) return;
    state = state.copyWith(loadingMore: true);
    try {
      final page = await WalletService.fetchPointsRecords(
        page: state.records.length ~/ _pageSize + 1,
        pageSize: _pageSize,
        bizType: state.bizType,
      );
      state = state.copyWith(
        records: [...state.records, ...page.items],
        recordsTotal: page.total,
        loadingMore: false,
      );
    } catch (_) {
      state = state.copyWith(loadingMore: false);
    }
  }
}

/// autoDispose：进入钱包页时创建并加载，离开即销毁；
/// 避免登录态切换（登录/会员变更/充值后）仍展示上一次的旧数据
final walletProvider = StateNotifierProvider.autoDispose<WalletNotifier, WalletState>(
  (_) => WalletNotifier(),
);