// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'package:meta/meta.dart';
import 'package:platform/platform.dart';

import 'io.dart';
import 'net.dart';

class BotDetector {
  BotDetector({
    @required HttpClientFactory httpClientFactory,
    @required Platform platform,
  }) :
    _platform = platform,
    _azureDetector = AzureDetector(
      httpClientFactory: httpClientFactory,
    );

  final Platform _platform;
  final AzureDetector _azureDetector;

  bool _isRunningOnBot;

  Future<bool> get isRunningOnBot async {
    if (_isRunningOnBot != null) {
      return _isRunningOnBot;
    }
    if (
      // Explicitly stated to not be a bot.
      _platform.environment['BOT'] == 'false'

      // Set by the IDEs to the IDE name, so a strong signal that this is not a bot.
      || _platform.environment.containsKey('FLUTTER_HOST')
      // When set, GA logs to a local file (normally for tests) so we don't need to filter.
      || _platform.environment.containsKey('FLUTTER_ANALYTICS_LOG_FILE')
    ) {
      return _isRunningOnBot = false;
    }

    return _isRunningOnBot = _platform.environment['BOT'] == 'true'

      // https://docs.travis-ci.com/user/environment-variables/#Default-Environment-Variables
      || _platform.environment['TRAVIS'] == 'true'
      || _platform.environment['CONTINUOUS_INTEGRATION'] == 'true'
      || _platform.environment.containsKey('CI') // Travis and AppVeyor

      // https://www.appveyor.com/docs/environment-variables/
      || _platform.environment.containsKey('APPVEYOR')

      // https://cirrus-ci.org/guide/writing-tasks/#environment-variables
      || _platform.environment.containsKey('CIRRUS_CI')

      // https://docs.aws.amazon.com/codebuild/latest/userguide/build-env-ref-env-vars.html
      || (_platform.environment.containsKey('AWS_REGION') &&
          _platform.environment.containsKey('CODEBUILD_INITIATOR'))

      // https://wiki.jenkins.io/display/JENKINS/Building+a+software+project#Buildingasoftwareproject-belowJenkinsSetEnvironmentVariables
      || _platform.environment.containsKey('JENKINS_URL')

      // Properties on Flutter's Chrome Infra bots.
      || _platform.environment['CHROME_HEADLESS'] == '1'
      || _platform.environment.containsKey('BUILDBOT_BUILDERNAME')
      || _platform.environment.containsKey('SWARMING_TASK_ID')
      || await _azureDetector.isRunningOnAzure;
  }
}

// Are we running on Azure?
// https://docs.microsoft.com/en-us/azure/virtual-machines/linux/instance-metadata-service
@visibleForTesting
class AzureDetector {
  AzureDetector({
    @required HttpClientFactory httpClientFactory,
  }) : _httpClientFactory = httpClientFactory;

  static const String _serviceUrl = 'http://169.254.169.254/metadata/instance';

  final HttpClientFactory _httpClientFactory;

  bool _isRunningOnAzure;

  Future<bool> get isRunningOnAzure async {
    if (_isRunningOnAzure != null) {
      return _isRunningOnAzure;
    }
    final HttpClient client = _httpClientFactory()
      ..connectionTimeout = const Duration(seconds: 1);
    try {
      final HttpClientRequest request = await client.getUrl(
        Uri.parse(_serviceUrl),
      );
      request.headers.add('Metadata', true);
      await request.close();
    } on SocketException catch (e) {
      if (e.toString().contains('HTTP connection timed out')) {
        // If the connection attempt times out, assume that the service is not
        // available, and that we are not running on Azure.
        return _isRunningOnAzure = false;
      }
      // If it's some other socket exception, then there is a bug in the
      // detection code that should go to crash logging.
      rethrow;
    } on HttpException {
      // If the connection gets set up, but encounters an error condition, it
      // still means we're on Azure.
      return _isRunningOnAzure = true;
    }
    // We got a response, we're running on Azure.
    return _isRunningOnAzure = true;
  }
}