// Copyright 2017 The Fuchsia 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 'dart:async';
import 'dart:convert';

import 'package:lib.app.dart/app.dart';
import 'package:fuchsia.fidl.modular/modular.dart';
import 'package:lib.decomposition.dart/decomposition.dart';
import 'package:fidl/fidl.dart';
import 'package:lib.logging/logging.dart';
import 'package:lib.proposal.dart/proposal.dart';

/// The Concert Agents subscribes to the hotel topic and makes proposals for
/// upcoming concerts (concert list module).

const String _kHotelTopic = 'link/hotel';

/// Global scoping to prevent garbage collection
final ContextReaderProxy _contextReader = new ContextReaderProxy();
ContextListenerImpl _contextListenerImpl;
final ProposalPublisherProxy _proposalPublisher = new ProposalPublisherProxy();
final ApplicationContext _context = new ApplicationContext.fromStartupInfo();

/// Concert ContextListener listens to hotel reservations and makes a concert
/// list proposal
class ContextListenerImpl extends ContextListener {
  final ContextListenerBinding _binding = new ContextListenerBinding();

  /// Gets the [InterfaceHandle]
  ///
  /// The returned handle should only be used once.
  InterfaceHandle<ContextListener> getHandle() => _binding.wrap(this);

  @override
  Future<Null> onContextUpdate(ContextUpdate result) async {
    for (final ContextUpdateEntry entry in result.values) {
      if (entry.key != _kHotelTopic || entry.value.isEmpty) {
        continue;
      }

      // TODO(thatguy): There can be more than one value. At some point, use the
      // entity type in the ContextQuery instead of using topics as if they are
      // types, and handle multiple instances.
      dynamic data = json.decode(entry.value[0].content);
      if (data != null && data['name'] is String) {
        await _createProposal(data['name']);
      }
    }
  }

  /// Creates a concert list proposal
  Future<Null> _createProposal(String hotelName) async {
    String headline = 'Upcoming concerts near $hotelName this week';

    final Uri arg = new Uri(
      host: 'www.songkick.com',
      pathSegments: <String>['metro_areas', '26330-us-sf-bay-area'],
    );

    Proposal proposal = await createProposal(
      id: 'Concerts Near Hotel',
      headline: headline,
      subheadline: 'powered by Songkick',
      color: 0xFF467187,
      imageUrl:
          'https://images.unsplash.com/photo-1486591978090-58e619d37fe7?dpr=1&auto=format&fit=crop&w=300&h=300&q=80&cs=tinysrgb&crop=&bg=',
      actions: <Action>[
        new Action.withCreateStory(new CreateStory(
            moduleId: 'concert_event_list',
            initialData:
                json.encode(<String, dynamic>{'view': decomposeUri(arg)})))
      ],
    );

    log.fine('proposing concert suggestion');
    _proposalPublisher.propose(proposal);
  }
}

Future<Null> main(List<dynamic> args) async {
  setupLogger();

  connectToService(_context.environmentServices, _contextReader.ctrl);
  connectToService(_context.environmentServices, _proposalPublisher.ctrl);
  ContextQuery query =
      const ContextQuery(selector: const <ContextQueryEntry>[const
        ContextQueryEntry(
    key: _kHotelTopic, value: const ContextSelector(
        type: ContextValueType.entity,
        meta: const ContextMetadata(
            entity: const EntityMetadata(topic: _kHotelTopic)))
  )]);
  _contextListenerImpl = new ContextListenerImpl();
  _contextReader.subscribe(query, _contextListenerImpl.getHandle());
}