import 'dart:convert';

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

/// Never actually waits: the poll loop's pacing is injected so a test that
/// exercises `slow_down` does not take 15 real seconds.
Future<void> noDelay(Duration _) async {}

GitHubDeviceAuth authWith(
  MockClient client, {
  String scope = 'repo',
}) => GitHubDeviceAuth(
  clientId: 'cid',
  scope: scope,
  httpClient: client,
  delay: noDelay,
);

void main() {
  group('pollForToken', () {
    const device = DeviceCodeResponse(
      deviceCode: 'dc',
      userCode: 'UC',
      verificationUri: 'u',
      interval: 1,
      expiresIn: 60,
    );

    test('returns the token once the user authorizes', () async {
      var calls = 0;
      final auth = authWith(
        MockClient((_) async {
          calls += 1;
          // First poll pending, second succeeds -- the normal path.
          return http.Response(
            calls == 1
                ? jsonEncode({'error': 'authorization_pending'})
                : jsonEncode({'access_token': 'tok'}),
            200,
          );
        }),
      );
      expect(await auth.pollForToken(device), 'tok');
      expect(calls, 2);
    });

    test('obeys slow_down by taking GitHub s new interval', () async {
      var calls = 0;
      final auth = authWith(
        MockClient((_) async {
          calls += 1;
          return http.Response(
            calls == 1
                ? jsonEncode({'error': 'slow_down', 'interval': 30})
                : jsonEncode({'access_token': 'tok'}),
            200,
          );
        }),
      );
      expect(await auth.pollForToken(device), 'tok');
    });

    test('slow_down without an interval still backs off', () async {
      var calls = 0;
      final auth = authWith(
        MockClient((_) async {
          calls += 1;
          return http.Response(
            calls == 1
                ? jsonEncode({'error': 'slow_down'})
                : jsonEncode({'access_token': 'tok'}),
            200,
          );
        }),
      );
      expect(await auth.pollForToken(device), 'tok');
    });

    test('throws on a terminal error', () async {
      final auth = authWith(
        MockClient(
          (_) async => http.Response(
            jsonEncode({
              'error': 'access_denied',
              'error_description': 'user said no',
            }),
            200,
          ),
        ),
      );
      await expectLater(
        auth.pollForToken(device),
        throwsA(
          isA<DeviceAuthException>()
              .having((e) => e.code, 'code', 'access_denied')
              .having((e) => e.message, 'message', 'user said no'),
        ),
      );
    });

    test('falls back to the code when no description is given', () async {
      final auth = authWith(
        MockClient(
          (_) async => http.Response(jsonEncode({'error': 'expired'}), 200),
        ),
      );
      await expectLater(
        auth.pollForToken(device),
        throwsA(
          isA<DeviceAuthException>().having((e) => e.message, 'msg', 'expired'),
        ),
      );
    });

    test('throws on a response with neither a token nor an error', () async {
      final auth = authWith(
        MockClient((_) async => http.Response(jsonEncode({'x': 1}), 200)),
      );
      await expectLater(
        auth.pollForToken(device),
        throwsA(
          isA<DeviceAuthException>().having((e) => e.code, 'code', 'unknown'),
        ),
      );
    });

    test('retries a transient network failure instead of giving up', () async {
      // GitHub can close the connection at the moment the user authorizes,
      // and a phone can drop its network mid-poll. Losing an approved grant
      // to a socket blip is the bug this retry exists to prevent.
      var calls = 0;
      final auth = authWith(
        MockClient((_) async {
          calls += 1;
          if (calls == 1) {
            throw http.ClientException('Connection closed before full header');
          }
          return http.Response(jsonEncode({'access_token': 'tok'}), 200);
        }),
      );
      expect(await auth.pollForToken(device), 'tok');
      expect(calls, 2);
    });

    test('gives up once the device code has expired', () async {
      const expired = DeviceCodeResponse(
        deviceCode: 'dc',
        userCode: 'UC',
        verificationUri: 'u',
        interval: 1,
        // Already in the past, so the loop body never runs.
        expiresIn: -1,
      );
      final auth = authWith(MockClient((_) async => http.Response('{}', 200)));
      await expectLater(
        auth.pollForToken(expired),
        throwsA(
          isA<DeviceAuthException>().having(
            (e) => e.code,
            'code',
            'expired_token',
          ),
        ),
      );
    });
  });

  test('close() is safe to call', () {
    authWith(MockClient((_) async => http.Response('{}', 200))).close();
  });

  test('constructs with a real http client and default scope', () {
    final auth = GitHubDeviceAuth(clientId: 'cid')..close();
    expect(auth.scope, 'repo');
  });

  test('polls the overridden token endpoint', () async {
    late Uri seen;
    final auth = GitHubDeviceAuth(
      clientId: 'cid',
      tokenUrl: 'http://127.0.0.1:9/gh/auth/device/poll',
      httpClient: MockClient((req) async {
        seen = req.url;
        return http.Response(jsonEncode({'access_token': 'tok'}), 200);
      }),
      delay: noDelay,
    );

    await auth.pollForToken(
      const DeviceCodeResponse(
        deviceCode: 'dc',
        userCode: 'UC',
        verificationUri: 'u',
        interval: 1,
        expiresIn: 60,
      ),
    );

    expect(seen.toString(), 'http://127.0.0.1:9/gh/auth/device/poll');
  });
}