fin-tracker/app/lib/features/tax/data/tax_api.dart

/// Hand-written client for `/api/v1/tax`.
///
/// **Temporary.** The tax routes are not in `openapi/openapi.json` yet, so
/// `app/packages/api_client` has no generated models or methods for them. Everything here
/// follows `docs/ai/phase4-contract.md` §5 literally and is meant to be **replaced by the
/// generated client** once the routes land in the spec and `just gen-client` runs.
///
/// Raw Dio comes from `ref.read(apiProvider).dio`: base URL, bearer header and the one-shot
/// refresh on 401 are already wired there.
library;

import 'package:dio/dio.dart';

import '../../../core/cache/cached.dart';
import '../../../core/utils/json.dart';

/// Per-account (or total) tax figures for a year. Every number is an **estimate**: the tax
/// agent is the broker, and these exist so that the broker's statement can be checked.
class TaxRow {
  const TaxRow({
    this.accountId,
    this.accountName,
    this.dividendsGrossRub,
    this.couponsGrossRub,
    this.taxWithheldRub,
    this.realizedGainRub,
    this.realizedLossRub,
    this.ldvExemptRub,
    this.taxableBaseRub,
    this.estimatedTaxRub,
  });

  final int? accountId;
  final String? accountName;
  final String? dividendsGrossRub;
  final String? couponsGrossRub;
  final String? taxWithheldRub;
  final String? realizedGainRub;
  final String? realizedLossRub;
  final String? ldvExemptRub;
  final String? taxableBaseRub;
  final String? estimatedTaxRub;

  String get title => accountName ?? (accountId == null ? 'Итого' : 'Счёт #$accountId');

  static TaxRow fromJson(Map<String, dynamic> json) => TaxRow(
        accountId: asInt(json['account_id']),
        accountName: asString(json['account_name']),
        dividendsGrossRub: asString(json['dividends_gross_rub']),
        couponsGrossRub: asString(json['coupons_gross_rub']),
        taxWithheldRub: asString(json['tax_withheld_rub']),
        realizedGainRub: asString(json['realized_gain_rub']),
        realizedLossRub: asString(json['realized_loss_rub']),
        ldvExemptRub: asString(json['ldv_exempt_rub']),
        taxableBaseRub: asString(json['taxable_base_rub']),
        estimatedTaxRub: asString(json['estimated_tax_rub']),
      );
}

class TaxSummary {
  const TaxSummary({
    required this.year,
    required this.estimated,
    this.taxRate,
    this.accounts = const [],
    this.totals,
    this.disclaimer,
  });

  final int year;

  /// Always true per the contract — and shown on screen, not hidden in a tooltip.
  final bool estimated;
  final String? taxRate;
  final List<TaxRow> accounts;
  final TaxRow? totals;
  final String? disclaimer;

  static const defaultDisclaimer =
      'Оценка. Налоговый агент — брокер; сверяйтесь с его справкой.';

  static TaxSummary fromJson(Map<String, dynamic> json) {
    final totals = asObject(json['totals']);
    return TaxSummary(
      year: asInt(json['year']) ?? DateTime.now().year,
      estimated: json.containsKey('estimated') ? asBool(json['estimated']) : true,
      taxRate: asString(json['tax_rate']),
      accounts: asObjects(json['accounts']).map(TaxRow.fromJson).toList(),
      totals: totals == null ? null : TaxRow.fromJson(totals),
      disclaimer: asString(json['disclaimer']),
    );
  }
}

/// An open lot with the date after which a sale falls under ЛДВ (the three-year exemption).
class TaxLot {
  const TaxLot({
    required this.lotId,
    required this.ldvEligible,
    this.instrumentId,
    this.ticker,
    this.accountId,
    this.openDate,
    this.qtyRemaining,
    this.costRub,
    this.marketValueRub,
    this.unrealizedGainRub,
    this.ldvDate,
    this.daysToLdv,
    this.taxIfSoldNowRub,
  });

  final int lotId;
  final int? instrumentId;
  final String? ticker;
  final int? accountId;
  final DateTime? openDate;
  final String? qtyRemaining;
  final String? costRub;
  final String? marketValueRub;
  final String? unrealizedGainRub;
  final bool ldvEligible;
  final DateTime? ldvDate;
  final int? daysToLdv;
  final String? taxIfSoldNowRub;

  /// Close enough to ЛДВ that selling now is an expensive mistake. Six months is the
  /// horizon at which a person can still decide to wait.
  bool get nearLdv => !ldvEligible && daysToLdv != null && daysToLdv! <= 183;

  String get title => ticker ?? (instrumentId == null ? '#$lotId' : '#$instrumentId');

  static TaxLot fromJson(Map<String, dynamic> json) => TaxLot(
        lotId: asInt(json['lot_id']) ?? 0,
        instrumentId: asInt(json['instrument_id']),
        ticker: asString(json['ticker']),
        accountId: asInt(json['account_id']),
        openDate: asDate(json['open_date']),
        qtyRemaining: asString(json['qty_remaining']),
        costRub: asString(json['cost_rub']),
        marketValueRub: asString(json['market_value_rub']),
        unrealizedGainRub: asString(json['unrealized_gain_rub']),
        ldvEligible: asBool(json['ldv_eligible']),
        ldvDate: asDate(json['ldv_date']),
        daysToLdv: asInt(json['days_to_ldv']),
        taxIfSoldNowRub: asString(json['tax_if_sold_now_rub']),
      );
}

class TaxApi {
  const TaxApi(this._dio);

  final Dio _dio;

  static const _base = '/api/v1/tax';

  /// See `docs/ai/offline-cache.md`: this hand-written client returns `Cached<T>` directly
  /// (there is no generated `Response<T>` for the screen to unwrap `r.cached` from).
  Future<Cached<TaxSummary>> summary({required int year, int? accountId}) async {
    final r = await _dio.get<Map<String, dynamic>>(
      _base,
      queryParameters: {'year': year, 'account_id': ?accountId},
    );
    return Cached(TaxSummary.fromJson(r.data ?? const {}), fetchedAt: r.extra['fetchedAt'] as DateTime?);
  }

  Future<Cached<List<TaxLot>>> lots({required int year, int? accountId}) async {
    final r = await _dio.get<Map<String, dynamic>>(
      '$_base/lots',
      queryParameters: {'year': year, 'account_id': ?accountId},
    );
    final lots = asObjects((r.data ?? const {})['lots']).map(TaxLot.fromJson).toList();
    return Cached(lots, fetchedAt: r.extra['fetchedAt'] as DateTime?);
  }
}