import 'package:miler/data/api_config.dart';
import 'package:miler/data/work_repository.dart';
import 'package:miler/data/load_state.dart';
import 'package:miler/data/miler_api.dart';

/// Reads the rider's bookings.
///
/// ── What this used to be ──
///
/// Three near-identical methods — `getPickupQueues`, `getCurrentPickups`,
/// `getPickupQueuesPicked` — each with its own legacy URL, its own
/// `fromdate`/`todate`/`userid` query and its own hand-rolled envelope
/// unwrapping, and each opening with `if (ApiConfig.useNewApi) return
/// _getBookingsNew(...)`. All three legacy paths hit different endpoints on a
/// backend that is no longer deployed, and all three new paths were the same
/// call. What is left is that one call.
///
/// The three names survive because three call sites read differently — Home
/// wants the queue, Bookings wants the accepted work — even though the request
/// is identical and the filtering happens client-side. Collapsing them into one
/// method is a separate change to the screens, not to this file.
class PickupProvider {
  /// `GET /miler/bookings` → the list, mapped into the legacy stop shape the
  /// cards read.
  ///
  /// The mapping lives in [ApiConfig.pickupFromBooking] rather than here: it is
  /// the one place that knows how a v1 booking becomes a stop, and the same
  /// translation is needed by anything else that receives a booking.
  /// ── One request, however many screens ask ──
  ///
  /// Home, Bookings, Activity and the post-delivery screen all call this, and
  /// each of them used to produce its own `GET /miler/bookings` — on mount, on
  /// tab switch, and on every poll. Four timers, four copies of the day, and
  /// four ideas of what had been accepted, reconciled only by whichever
  /// happened to refresh last.
  ///
  /// They all go through [WorkRepository] now, which collapses concurrent
  /// callers into one request, keeps one copy, and drops a response that lands
  /// out of order. Nothing at the call sites changed: this still returns a list
  /// or throws, which is the contract the screens were written against.
  ///
  /// The richer answer — loading, empty, offline, unavailable — is on the
  /// repository for screens that want to render it properly rather than
  /// flattening it into an exception. See [LoadState].
  Future<List<dynamic>> _bookings({String? status}) async {
    // A filtered read is a different question and is not the one the shared
    // copy answers. Nothing calls this with a status today; if something does,
    // it gets its own request rather than silently receiving the whole day.
    if (status != null && status.isNotEmpty) {
      final res = await MilerApi.bookings(status: status);
      if (!res.ok) {
        throw Exception(
          'Failed (${res.status})'
          '${res.message.isEmpty ? '' : ': ${res.message}'}',
        );
      }
      return ApiConfig.pickupsFromBookings(res.list);
    }

    final state = await WorkRepository.instance.load();
    return switch (state) {
      LoadData<List<Map<String, dynamic>>>(:final value) => value,
      // A real empty day. The screens render their own empty state from this.
      LoadEmpty<List<Map<String, dynamic>>>() => const <dynamic>[],
      // No endpoint for this line of work — neither waiting nor retrying helps,
      // so it must not arrive as an empty day. See [LineNotServedException].
      LoadUnavailable<List<Map<String, dynamic>>>() =>
        throw const LineNotServedException(),
      LoadFailure<List<Map<String, dynamic>>>(:final kind, :final message) =>
        throw Exception(
          message.isEmpty ? 'Could not load your work ($kind)' : message,
        ),
      // Only reachable if the repository handed back its pre-load state, which
      // it does not. Treated as a failure rather than as an empty day.
      LoadLoading<List<Map<String, dynamic>>>() => throw Exception(
        'Still loading',
      ),
    };
  }

  /// Everything the hub has put in front of this rider today.
  Future<List<dynamic>> getPickupQueues({String? orderstatus}) =>
      _bookings(status: orderstatus);

  /// The stops he is working now.
  Future<List<dynamic>> getCurrentPickups() => _bookings();

  /// The stops he has accepted.
  Future<List<dynamic>> getPickupQueuesPicked() => _bookings();
}

/// The rider's line of work has no backend to ask.
///
/// Distinct from an empty day and from a failed request, because the rider's
/// answer is different in each case: wait, retry, or "your hub has not switched
/// this on yet". Screens catch this to render the unavailable state rather than
/// the empty one.
class LineNotServedException implements Exception {
  const LineNotServedException();

  @override
  String toString() =>
      'This line of work is not served by the backend yet — there is no '
      'bookings endpoint for it. See ServiceProfile.hasBookingsEndpoint.';
}