import 'package:flutter_riverpod/flutter_riverpod.dart';

import '../api/bill_api.dart';
import '../core/network/api_exception.dart';
import '../models/bill_request.dart';
import '../utils/date_util.dart';
import 'bill_refresh.dart';

/// 账单编辑页的表单状态
class BillEditState {
  final bool loading; // 详情加载中
  final String? loadError; // 详情加载失败提示
  final int type; // 1=支出 2=收入
  final int? categoryId;
  final double? amount;
  final String billDate; // yyyy-MM-dd
  final String description;
  final bool submitting;
  final int revision; // 服务端数据回填时 +1，供页面同步非受控输入框

  const BillEditState({
    this.loading = false,
    this.loadError,
    this.type = 1,
    this.categoryId,
    this.amount,
    required this.billDate,
    this.description = '',
    this.submitting = false,
    this.revision = 0,
  });

  BillEditState copyWith({
    bool? loading,
    Object? loadError = _sentinel,
    int? type,
    int? categoryId,
    Object? amount = _sentinel,
    String? billDate,
    String? description,
    bool? submitting,
    int? revision,
  }) {
    return BillEditState(
      loading: loading ?? this.loading,
      loadError: loadError == _sentinel ? this.loadError : loadError as String?,
      type: type ?? this.type,
      categoryId: categoryId ?? this.categoryId,
      amount: amount == _sentinel ? this.amount : amount as double?,
      billDate: billDate ?? this.billDate,
      description: description ?? this.description,
      submitting: submitting ?? this.submitting,
      revision: revision ?? this.revision,
    );
  }

  static const _sentinel = Object();
}

class BillEditNotifier extends Notifier<BillEditState> {
  BillEditNotifier(this.billId);

  final int billId;

  @override
  BillEditState build() {
    _load();
    return BillEditState(billDate: formatDate(DateTime.now()), loading: true);
  }

  Future<void> _load() async {
    try {
      final bill = await ref.read(billApiProvider).getBill(billId);
      if (!ref.mounted) return;
      state = BillEditState(
        type: bill.type,
        categoryId: bill.categoryId,
        amount: bill.absAmount,
        billDate: bill.billDate,
        description: bill.description,
        revision: state.revision + 1,
      );
    } on ApiException catch (e) {
      if (!ref.mounted) return;
      state = state.copyWith(loading: false, loadError: e.message);
    } catch (_) {
      if (!ref.mounted) return;
      state = state.copyWith(loading: false, loadError: '账单加载失败');
    }
  }

  /// 重新加载（错误重试用）
  void reload() {
    state = state.copyWith(loading: true, loadError: null);
    _load();
  }

  void setType(int type) {
    if (type == state.type) return;
    // 切换收支后分类需重选（与记账页行为一致）
    state = state.copyWith(type: type, categoryId: null);
  }

  void setCategory(int id) => state = state.copyWith(categoryId: id);

  void setAmount(double? value) => state = state.copyWith(amount: value);

  void setDate(String date) => state = state.copyWith(billDate: date);

  void setDescription(String desc) => state = state.copyWith(description: desc);

  /// 保存：必须回传全部字段，否则后端会把 description 覆盖成 null
  Future<void> save() async {
    final s = state;
    if (s.categoryId == null) throw ApiException(-1, '请选择分类');
    if (s.amount == null || s.amount! <= 0) throw ApiException(-1, '请输入有效金额');

    state = state.copyWith(submitting: true);
    try {
      await ref.read(billApiProvider).updateBill(
            billId,
            BillRequest(
              categoryId: s.categoryId!,
              amount: s.amount!,
              description: s.description,
              billDate: s.billDate,
              type: s.type,
            ),
          );
      if (!ref.mounted) return;
      invalidateBillData(ref);
    } finally {
      if (ref.mounted) state = state.copyWith(submitting: false);
    }
  }

  /// 删除该账单
  Future<void> remove() async {
    state = state.copyWith(submitting: true);
    try {
      await ref.read(billApiProvider).deleteBill(billId);
      if (!ref.mounted) return;
      invalidateBillData(ref);
    } finally {
      if (ref.mounted) state = state.copyWith(submitting: false);
    }
  }
}

final billEditProvider = NotifierProvider.autoDispose
    .family<BillEditNotifier, BillEditState, int>(BillEditNotifier.new);