import 'dart:convert';

import 'package:flutter_test/flutter_test.dart';
import 'package:http/http.dart' as http;
import 'package:nearle_pos/core/config/sync_config.dart';
import 'package:nearle_pos/data/remote/pos_auth_api.dart';
import 'package:nearle_pos/domain/entities/pos_session.dart';

/// Sign-in used to be two constants compiled into the app, compared after a
/// fake 600ms delay. The store id came from a field in Settings, so a till
/// named its own outlet and was believed — one number changed on one screen
/// moved a terminal into another tenant's books.
///
/// These cover the replacement: the outlet arrives *from* the back office, and
/// everything the till does with that answer.

void main() {
  group('a session read off the wire', () {
    test('takes its outlet from the back office, not from the till', () {
      final session = PosSession.fromJson({
        'token': 'abc.def',
        'expires_at': '2026-09-05T10:00:00Z',
        'user_id': 1229,
        'full_name': 'Selvapuram',
        'tenant_id': 1087,
        'tenant_name': 'Ragul Stores',
        'store_id': '1135',
        'location_id': 1135,
        'location_name': 'Ragul stores Selvapuram',
      });

      expect(session.storeId, '1135');
      expect(session.locationId, 1135);
      expect(session.tenantId, 1087);
    });

    test('reads an id whether it arrives quoted or bare', () {
      // The backend sends `location_id` as a number and `store_id` as a string
      // for the same value. A till that accepted only one shape would read zero
      // for the other — which looks like "no outlet" rather than like a bug.
      final quoted = PosSession.fromJson({
        'location_id': '1135',
        'token': 't',
        'expires_at': '2026-09-05T10:00:00Z',
      });
      final bare = PosSession.fromJson({
        'location_id': 1135,
        'token': 't',
        'expires_at': '2026-09-05T10:00:00Z',
      });

      expect(quoted.locationId, 1135);
      expect(bare.locationId, 1135);
    });

    test('falls back to the location id when no store id is sent', () {
      final session = PosSession.fromJson({
        'token': 't',
        'expires_at': '2026-09-05T10:00:00Z',
        'location_id': 1135,
      });

      expect(session.storeId, '1135');
    });

    test('an unreadable expiry counts as already finished', () {
      // Guessing "valid" here would keep a till sending a token the server
      // stopped honouring hours ago, and reading the resulting refusals as a
      // server fault.
      final session = PosSession.fromJson({
        'token': 't',
        'location_id': 1135,
        'expires_at': 'not a date',
      });

      expect(session.isValidAt(DateTime.now()), isFalse);
    });

    test('survives a round trip through storage', () {
      final original = PosSession.fromJson({
        'token': 'abc.def',
        'expires_at': '2026-09-05T10:00:00Z',
        'user_id': 1305,
        'full_name': 'Gokul R',
        'email': 'raguladmin@example.test',
        'tenant_id': 1087,
        'tenant_name': 'Ragul Stores',
        'store_id': '1097',
        'location_id': 1097,
        'location_name': 'Ragul stores',
        'gstin': '33AABCU9603R1ZM',
        'locations': [
          {'location_id': 1097, 'location_name': 'Ragul stores'},
          {'location_id': 1135, 'location_name': 'Ragul stores Selvapuram'},
        ],
      });

      final restored = PosSession.fromJson(
        jsonDecode(jsonEncode(original.toJson())) as Map<String, Object?>,
      );

      expect(restored.token, original.token);
      expect(restored.locationId, original.locationId);
      expect(restored.gstin, original.gstin);
      expect(restored.outlets.length, 2);
      expect(restored.expiresAt.toUtc(), original.expiresAt.toUtc());
    });

    test('offers a choice only when there is one', () {
      final single = PosSession.fromJson({
        'token': 't',
        'expires_at': '2026-09-05T10:00:00Z',
        'location_id': 1135,
        'locations': [
          {'location_id': 1135, 'location_name': 'Selvapuram'},
        ],
      });
      final several = PosSession.fromJson({
        'token': 't',
        'expires_at': '2026-09-05T10:00:00Z',
        'location_id': 1097,
        'locations': [
          {'location_id': 1097, 'location_name': 'Ragul stores'},
          {'location_id': 1135, 'location_name': 'Selvapuram'},
        ],
      });

      expect(single.hasChoiceOfOutlet, isFalse);
      expect(several.hasChoiceOfOutlet, isTrue);
    });
  });

  group('the session is what authenticates a request', () {
    test('takes precedence over a static api key', () {
      // The key says "this came from our fleet". The session says which outlet
      // it came from — and only the second can stop a till reaching another
      // tenant's books.
      const config = SyncConfig(
        apiKey: 'fleet-wide-key',
        sessionToken: 'per-user-session',
      );

      expect(config.bearerToken, 'per-user-session');
    });

    test('falls back to the api key before a terminal has signed in', () {
      const config = SyncConfig(apiKey: 'fleet-wide-key');

      expect(config.bearerToken, 'fleet-wide-key');
    });

    test('an emptied session does not authenticate as itself', () {
      // Sign-out clears the token by writing an empty string rather than by
      // rebuilding the config. If that read as a credential, a signed-out till
      // would keep uploading as the shop that signed in this morning.
      const config = SyncConfig(sessionToken: '', apiKey: '');

      expect(config.bearerToken, isNull);
    });
  });

  group('signing in against the back office', () {
    PosAuthApi apiReturning(int status, Object body) => PosAuthApi(
          baseUrl: 'https://example.invalid/pos',
          client: MockClient(
            (_) async => http.Response(jsonEncode(body), status,
                headers: {'content-type': 'application/json'},),
          ),
        );

    test('returns the outlet the back office named', () async {
      final api = apiReturning(200, {
        'code': 200,
        'status': true,
        'details': {
          'token': 'abc.def',
          'expires_at': '2026-09-05T10:00:00Z',
          'location_id': 1135,
          'store_id': '1135',
          'location_name': 'Ragul stores Selvapuram',
        },
      });

      final session = await api.login(authname: 'a@b.test', password: 'pw');

      expect(session.storeId, '1135');
      expect(session.token, 'abc.def');
    });

    test('a wrong password is reported as one worth re-typing', () async {
      final api = apiReturning(401, {
        'code': 401,
        'status': false,
        'message': 'those sign-in details were not recognised',
      });

      await expectLater(
        api.login(authname: 'a@b.test', password: 'wrong'),
        throwsA(
          isA<PosAuthException>()
              .having((e) => e.isCredentialFailure, 'credential failure', true),
        ),
      );
    });

    test('a refused outlet is not reported as a wrong password', () async {
      // 403 is a real account that may not open this till. Telling someone to
      // re-type a password that was correct sends them round a loop.
      final api = apiReturning(403, {
        'code': 403,
        'status': false,
        'message': 'this account cannot open a till at outlet 1185',
      });

      await expectLater(
        api.login(authname: 'a@b.test', password: 'pw'),
        throwsA(
          isA<PosAuthException>()
              .having((e) => e.isCredentialFailure, 'credential failure', false),
        ),
      );
    });

    test('a session with no token is refused rather than saved', () async {
      // Saving it would fail against every later request instead of here, which
      // is much harder to diagnose from a shop floor.
      final api = apiReturning(200, {
        'code': 200,
        'status': true,
        'details': {'location_id': 1135, 'expires_at': '2026-09-05T10:00:00Z'},
      });

      await expectLater(
        api.login(authname: 'a@b.test', password: 'pw'),
        throwsA(isA<PosAuthException>()),
      );
    });

    test('a session naming no outlet is refused', () async {
      final api = apiReturning(200, {
        'code': 200,
        'status': true,
        'details': {'token': 'abc.def', 'expires_at': '2026-09-05T10:00:00Z'},
      });

      await expectLater(
        api.login(authname: 'a@b.test', password: 'pw'),
        throwsA(isA<PosAuthException>()),
      );
    });

    test('an unconfigured terminal says so instead of failing obscurely',
        () async {
      final api = PosAuthApi(baseUrl: '');

      await expectLater(
        api.login(authname: 'a@b.test', password: 'pw'),
        throwsA(
          isA<PosAuthException>().having(
            (e) => e.message,
            'message',
            contains('no back office configured'),
          ),
        ),
      );
    });
  });
}

/// A client answering with one canned response.
///
/// Hand-rolled rather than pulled from `http/testing.dart` so the test suite
/// does not gain a dependency for four lines.
class MockClient extends http.BaseClient {
  MockClient(this._handler);

  final Future<http.Response> Function(http.BaseRequest) _handler;

  @override
  Future<http.StreamedResponse> send(http.BaseRequest request) async {
    final response = await _handler(request);
    return http.StreamedResponse(
      Stream.value(response.bodyBytes),
      response.statusCode,
      headers: response.headers,
    );
  }
}