import 'dart:async';
import 'dart:convert';

import 'package:flutter_test/flutter_test.dart';
import 'package:http/http.dart' as http;
import 'package:http/testing.dart';
import 'package:shared_preferences/shared_preferences.dart';

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

/// ─────────────────────────────────────────────────────────────────────────
/// ONE DAY'S WORK, FETCHED ONCE
///
/// Home, Deliveries and Activity asked the same question independently: three
/// timers, three copies, three ideas of what had been accepted. Switching tabs
/// re-fetched; a rebuild re-fetched; accepting a stop on one screen left the
/// other two showing the old answer until their own poll came round.
///
/// These pin the three properties that make one copy safe to share.
/// ─────────────────────────────────────────────────────────────────────────
void main() {
  TestWidgetsFlutterBinding.ensureInitialized();

  final repo = WorkRepository.instance;
  late int requests;

  Map<String, dynamic> booking(String id) => {
    'bookingid': id,
    'orderid': id,
    'pickupcustomer': 'Stop $id',
    'pickupaddress': '12 Main Rd, Coimbatore',
    'status': 'Miler_Assigned',
  };

  void stub({
    List<Map<String, dynamic>>? rows,
    Object? rawData,
    int code = 200,
    Object? error,
    Duration delay = Duration.zero,
  }) {
    requests = 0;
    MilerApi.client = MockClient((req) async {
      // ── Only the day's own request is counted ──
      //
      // The repository also asks `/miler/assignments` for the hub's stop
      // sequence (see `WorkRepository._stampSequence`). That is a different
      // endpoint answering a different question, and counting it here would
      // make the dedupe assertions below read 2 for one load — so the stub
      // answers it with an empty list and the counter stays on the property
      // these tests are actually about: **one `/miler/bookings` per load**.
      if (req.url.path.endsWith('/miler/assignments')) {
        return http.Response(
          json.encode({'success': true, 'data': const []}),
          200,
          headers: const {'content-type': 'application/json'},
        );
      }
      requests++;
      if (delay > Duration.zero) await Future.delayed(delay);
      if (error != null) throw error;
      return http.Response(
        json.encode({
          'success': code < 400,
          'data': rawData ?? rows ?? const [],
        }),
        code,
        headers: const {'content-type': 'application/json'},
      );
    });
  }

  setUp(() async {
    MockBackend.enabled = false;
    ServiceProfile.setActive(ServiceProfile.parcel);
    SharedPreferences.setMockInitialValues({'authtoken': 't'});
    await ApiConfig.setToken('t');
    repo.resetForTest();
    stub();
  });

  tearDown(() {
    MilerApi.client = http.Client();
    MockBackend.enabled = kMockBackend;
    ServiceProfile.setActive(ServiceProfile.parcel);
    repo.resetForTest();
  });

  group('one request, however many askers', () {
    test('three screens mounting together produce one request', () async {
      stub(rows: [booking('A')], delay: const Duration(milliseconds: 20));

      final results = await Future.wait([
        repo.load(),
        repo.load(),
        repo.load(),
      ]);

      expect(requests, 1, reason: 'the 2nd and 3rd await the same future');
      for (final r in results) {
        expect(r, isA<LoadData<List<Map<String, dynamic>>>>());
      }
    });

    test(
      'a tab switch inside the freshness window does not re-fetch',
      () async {
        stub(rows: [booking('A')]);
        await repo.load();
        await repo.load();
        await repo.load();
        expect(requests, 1);
      },
    );

    test('but a pull-to-refresh always asks', () async {
      stub(rows: [booking('A')]);
      await repo.load();
      await repo.load(force: true);
      expect(requests, 2);
    });

    test('a mutation invalidates, so the next read is authoritative', () async {
      stub(rows: [booking('A')]);
      await repo.load();
      await repo.invalidate();
      expect(requests, 2);
    });
  });

  // ── The classic pull-to-refresh regression ──
  //
  // A slow earlier request finishing after a fast later one used to overwrite
  // it, and the list visibly went backwards.
  test('a late response cannot overwrite a newer one', () async {
    var call = 0;
    final gate = Completer<void>();
    MilerApi.client = MockClient((req) async {
      if (req.url.path.endsWith('/miler/assignments')) {
        return http.Response(
          json.encode({'success': true, 'data': const []}),
          200,
          headers: const {'content-type': 'application/json'},
        );
      }
      call++;
      final isFirst = call == 1;
      if (isFirst) await gate.future; // the slow one
      return http.Response(
        json.encode({
          'success': true,
          'data': [booking(isFirst ? 'STALE' : 'FRESH')],
        }),
        200,
        headers: const {'content-type': 'application/json'},
      );
    });

    // Two forced loads: a pull-to-refresh does not join a request that started
    // before the gesture, so this really is two sequences racing.
    final slow = repo.load(force: true);
    final fast = repo.load(force: true);

    gate.complete();
    await Future.wait([slow, fast]);

    final value = repo.state.valueOrNull;
    expect(value, isNotNull);
    expect(
      value!.single['orderid'],
      'FRESH',
      reason: 'the slow response landed last and must have been dropped',
    );
  });

  group('the three empties are three answers', () {
    test('nothing today is empty, not a failure', () async {
      stub(rows: const []);
      final s = await repo.load();
      expect(s, isA<LoadEmpty<List<Map<String, dynamic>>>>());
    });

    test('a milk-man rider is asked for, not written off', () async {
      // The regression this replaces: the milk-man line was believed to have no
      // endpoint, so this returned [LoadUnavailable] after **zero** requests —
      // and a rider on tenant 13 whom the hub had assigned a booking saw an
      // empty Home, an empty Bookings tab and an empty Activity, with no error
      // anywhere to explain it. The hub dispatches that line through the same
      // bookings the console assigns, so the request has to be made.
      stub(rows: [booking('MILK-1')]);
      ServiceProfile.setActive(ServiceProfile.milkMan);
      repo.resetForTest();

      final s = await repo.load();
      expect(s, isA<LoadData<List<Map<String, dynamic>>>>());
      expect(s.valueOrNull?.single['orderid'], 'MILK-1');
      expect(requests, 1, reason: 'his work has to be asked for to arrive');
    });

    test('a dead connection is offline, and retryable', () async {
      stub(error: const _Dead());
      final s = await repo.load() as LoadFailure<List<Map<String, dynamic>>>;
      expect(s.kind, LoadFailureKind.offline);
      expect(s.kind.isRetryable, isTrue);
    });

    test(
      'a 401 is unauthorized, and offering a retry would be a lie',
      () async {
        stub(code: 401);
        final s = await repo.load() as LoadFailure<List<Map<String, dynamic>>>;
        expect(s.kind, LoadFailureKind.unauthorized);
        expect(s.kind.isRetryable, isFalse);
      },
    );

    test('a 429 is rate limited, not a server fault', () async {
      stub(code: 429);
      final s = await repo.load() as LoadFailure<List<Map<String, dynamic>>>;
      expect(s.kind, LoadFailureKind.rateLimited);
    });

    test(
      'rows that arrive and do not map are a fault, not an empty day',
      () async {
        // A payload whose rows are not objects at all. The adapter maps every
        // Map it is given, so this is what a genuine shape mismatch looks like —
        // and it renders as "no work today" if you only count the mapped list,
        // which is the difference between waiting and reporting a broken feed.
        stub(rawData: const ['not', 'objects']);
        final s = await repo.load();
        expect(s, isA<LoadFailure<List<Map<String, dynamic>>>>());
      },
    );
  });

  test('a refresh keeps the current data on screen', () async {
    stub(rows: [booking('A')]);
    await repo.load();

    stub(rows: [booking('A')], delay: const Duration(milliseconds: 30));
    final seen = <LoadState<List<Map<String, dynamic>>>>[];
    final sub = repo.changes.listen(seen.add);

    await repo.load(force: true);
    await sub.cancel();

    final duringRefresh = seen.first;
    expect(duringRefresh, isA<LoadData<List<Map<String, dynamic>>>>());
    expect(
      (duringRefresh as LoadData).refreshing,
      isTrue,
      reason: 'a pull to refresh must not blank the list it is refreshing',
    );
  });

  test('every listener sees the same answer', () async {
    stub(rows: [booking('A')]);
    final a = <LoadState<List<Map<String, dynamic>>>>[];
    final b = <LoadState<List<Map<String, dynamic>>>>[];
    final subA = repo.changes.listen(a.add);
    final subB = repo.changes.listen(b.add);

    await repo.load();
    // Let the broadcast drain before cancelling — a stream event is delivered
    // on a microtask, so cancelling in the same turn drops the last one.
    await Future<void>.delayed(Duration.zero);
    await subA.cancel();
    await subB.cancel();

    // Both listeners saw the same sequence of the same objects: there is one
    // copy of the day in memory, not one per screen.
    expect(a, hasLength(b.length));
    for (var i = 0; i < a.length; i++) {
      expect(identical(a[i], b[i]), isTrue, reason: 'event $i differed');
    }
    expect(a.last.valueOrNull, isNotNull);
    expect(identical(a.last, repo.state), isTrue);
  });
}

class _Dead implements Exception {
  const _Dead();
}