import 'dart:async';

import 'package:halkyon_learn_agent/src/agent_sync.dart';
import 'package:test/test.dart';

/// The agent's sync (Halkyon's ADR 0044, D7), the `SyncRequests` its
/// gateways ask: a burst of requests syncs once after a pause, a tool's
/// sync runs at once and says whether it went, and what a sync merged is
/// heard.
void main() {
  late List<String> runs;
  late Exception? fails;
  late AgentSync sync;

  setUp(() {
    runs = [];
    fails = null;
    sync = AgentSync(({required onMerge}) async {
      runs.add('sync');
      if (fails case final error?) {
        throw error;
      }
      onMerge();
    }, debounce: const Duration(milliseconds: 50));
    addTearDown(sync.dispose);
  });

  test('requests in a burst sync once, after the pause', () async {
    sync
      ..requestSync()
      ..requestSync()
      ..requestSync();
    expect(runs, isEmpty);

    await Future<void>.delayed(const Duration(milliseconds: 150));

    expect(runs, ['sync']);
  });

  test('a sync now runs at once, and what it merged is heard', () async {
    final merged = sync.merges.first;
    final synced = sync.synced.first;

    await sync.syncNow();

    expect(runs, ['sync']);
    await merged;
    await synced;
  });

  test('a sync now that fails says so; the next that goes through '
      "doesn't", () async {
    fails = Exception('offline');
    await expectLater(sync.syncNow(), throwsA(isA<Exception>()));

    fails = null;
    await sync.syncNow();
    expect(runs, ['sync', 'sync']);
  });
}