import 'dart:convert';

import 'package:flutter_test/flutter_test.dart';
import 'package:uto_manager/domain/services/command_event_store.dart';

void main() {
  // ---------------------------------------------------------------------------
  // CommandEvent
  // ---------------------------------------------------------------------------

  group('CommandEvent', () {
    test('toJson / fromJson round-trip preserves all fields', () {
      final event = CommandEvent(
        eventId: 'evt-001',
        type: CommandEventType.attachNode,
        payload: CommandPayloads.attachNode(
          unitId: 'unit-1',
          newParentId: 'unit-2',
          previousParentId: 'unit-0',
        ),
        occurredAt: DateTime.utc(2026, 8, 9, 10, 0, 0),
        isSynced: false,
      );

      final json = event.toJson();
      final restored = CommandEvent.fromJson(json);

      expect(restored.eventId, event.eventId);
      expect(restored.type, event.type);
      expect(restored.payload['unitId'], 'unit-1');
      expect(restored.payload['newParentId'], 'unit-2');
      expect(restored.payload['previousParentId'], 'unit-0');
      expect(restored.occurredAt, event.occurredAt);
      expect(restored.isSynced, false);
    });

    test('fromJson handles missing isSynced (defaults to false)', () {
      final map = {
        'eventId': 'evt-002',
        'type': 'detachNode',
        'payload': {'unitId': 'u1', 'previousParentId': 'u0'},
        'occurredAt': '2026-08-09T10:00:00.000Z',
        // isSynced intentionally omitted
      };
      final event = CommandEvent.fromJson(map);
      expect(event.isSynced, false);
    });

    test('toString includes eventId, type, and synced flag', () {
      final event = CommandEvent(
        eventId: 'evt-003',
        type: CommandEventType.assignPersonnel,
        payload: {},
        occurredAt: DateTime.now(),
      );
      final str = event.toString();
      expect(str, contains('evt-003'));
      expect(str, contains('assignPersonnel'));
      expect(str, contains('false'));
    });
  });

  // ---------------------------------------------------------------------------
  // CommandPayloads
  // ---------------------------------------------------------------------------

  group('CommandPayloads', () {
    test('attachNode includes optional previousParentId when provided', () {
      final p = CommandPayloads.attachNode(
        unitId: 'u1',
        newParentId: 'u2',
        previousParentId: 'u0',
      );
      expect(p['unitId'], 'u1');
      expect(p['newParentId'], 'u2');
      expect(p['previousParentId'], 'u0');
    });

    test('attachNode omits previousParentId when null', () {
      final p = CommandPayloads.attachNode(unitId: 'u1', newParentId: 'u2');
      expect(p.containsKey('previousParentId'), false);
    });

    test('detachNode payload is correct', () {
      final p = CommandPayloads.detachNode(unitId: 'u1', previousParentId: 'u0');
      expect(p['unitId'], 'u1');
      expect(p['previousParentId'], 'u0');
    });

    test('assignPersonnel payload is correct', () {
      final p = CommandPayloads.assignPersonnel(
        soldierId: 's1',
        slotId: 'sl1',
        unitId: 'u1',
      );
      expect(p['soldierId'], 's1');
      expect(p['slotId'], 'sl1');
      expect(p['unitId'], 'u1');
    });

    test('unassignPersonnel payload is correct', () {
      final p = CommandPayloads.unassignPersonnel(
        soldierId: 's1',
        slotId: 'sl1',
        unitId: 'u1',
      );
      expect(p['soldierId'], 's1');
      expect(p['slotId'], 'sl1');
    });

    test('modifySlot payload includes changes map', () {
      final p = CommandPayloads.modifySlot(
        slotId: 'sl1',
        unitId: 'u1',
        changes: {'positionTitle': 'Squad Leader'},
      );
      expect(p['slotId'], 'sl1');
      expect((p['changes'] as Map)['positionTitle'], 'Squad Leader');
    });
  });

  // ---------------------------------------------------------------------------
  // CommandEventStore
  // ---------------------------------------------------------------------------

  group('CommandEventStore', () {
    late CommandEventStore store;

    setUp(() => store = CommandEventStore());

    test('starts empty', () {
      expect(store.eventCount, 0);
      expect(store.pendingCount, 0);
      expect(store.allEvents, isEmpty);
      expect(store.pendingEvents, isEmpty);
    });

    test('append adds event to store', () {
      final event = _makeEvent('e1', CommandEventType.attachNode);
      store.append(event);
      expect(store.eventCount, 1);
      expect(store.pendingCount, 1);
    });

    test('allEvents is unmodifiable', () {
      store.append(_makeEvent('e1', CommandEventType.attachNode));
      expect(() => store.allEvents.add(_makeEvent('e2', CommandEventType.detachNode)),
          throwsUnsupportedError);
    });

    test('pendingEvents excludes synced events', () {
      final e1 = _makeEvent('e1', CommandEventType.attachNode);
      final e2 = _makeEvent('e2', CommandEventType.detachNode);
      store.append(e1);
      store.append(e2);
      store.markSynced('e1');

      expect(store.pendingCount, 1);
      expect(store.pendingEvents.first.eventId, 'e2');
    });

    test('markSynced returns true for existing event', () {
      store.append(_makeEvent('e1', CommandEventType.attachNode));
      expect(store.markSynced('e1'), true);
      expect(store.pendingCount, 0);
    });

    test('markSynced returns false for unknown eventId', () {
      expect(store.markSynced('nonexistent'), false);
    });

    test('markAllSynced marks every event', () {
      store.append(_makeEvent('e1', CommandEventType.attachNode));
      store.append(_makeEvent('e2', CommandEventType.assignPersonnel));
      store.append(_makeEvent('e3', CommandEventType.modifySlot));
      store.markAllSynced();
      expect(store.pendingCount, 0);
    });

    test('exportPendingToJson produces valid JSON array', () {
      store.append(_makeEvent('e1', CommandEventType.attachNode));
      store.append(_makeEvent('e2', CommandEventType.detachNode));
      store.markSynced('e1'); // e1 is synced, only e2 should appear

      final json = store.exportPendingToJson();
      final decoded = jsonDecode(json) as List<dynamic>;
      expect(decoded.length, 1);
      expect((decoded.first as Map)['eventId'], 'e2');
    });

    test('clear removes all events', () {
      store.append(_makeEvent('e1', CommandEventType.attachNode));
      store.append(_makeEvent('e2', CommandEventType.detachNode));
      store.clear();
      expect(store.eventCount, 0);
    });

    test('multiple event types can be stored together', () {
      for (final type in CommandEventType.values) {
        store.append(_makeEvent(type.name, type));
      }
      expect(store.eventCount, CommandEventType.values.length);
    });
  });

  // ---------------------------------------------------------------------------
  // DeltaSynchronizer
  // ---------------------------------------------------------------------------

  group('DeltaSynchronizer', () {
    late CommandEventStore store;
    late DeltaSynchronizer sync;

    setUp(() {
      store = CommandEventStore();
      sync = DeltaSynchronizer(store: store);
    });

    test('syncIfOnline returns 0 when no pending events', () async {
      final count = await sync.syncIfOnline();
      expect(count, 0);
    });

    test('syncIfOnline returns 0 when offline', () async {
      store.append(_makeEvent('e1', CommandEventType.attachNode));
      sync.isOnline = false;
      final count = await sync.syncIfOnline();
      expect(count, 0);
      expect(store.pendingCount, 1); // still pending
    });

    test('syncIfOnline transmits pending events when online', () async {
      store.append(_makeEvent('e1', CommandEventType.attachNode));
      store.append(_makeEvent('e2', CommandEventType.assignPersonnel));
      sync.isOnline = true;

      final count = await sync.syncIfOnline();
      expect(count, 2);
      expect(store.pendingCount, 0); // all marked synced
    });

    test('isOnline getter reflects set value', () {
      sync.isOnline = false;
      expect(sync.isOnline, false);
      sync.isOnline = true;
      expect(sync.isOnline, true);
    });

    test('already-synced events are not re-transmitted', () async {
      final e1 = _makeEvent('e1', CommandEventType.attachNode);
      final e2 = _makeEvent('e2', CommandEventType.detachNode);
      store.append(e1);
      store.append(e2);
      store.markSynced('e1');

      final count = await sync.syncIfOnline();
      expect(count, 1); // only e2 was pending
    });
  });
}

// ---------------------------------------------------------------------------
// Helpers
// ---------------------------------------------------------------------------

CommandEvent _makeEvent(String id, CommandEventType type) {
  return CommandEvent(
    eventId: id,
    type: type,
    payload: {'test': id},
    occurredAt: DateTime.utc(2026, 8, 9),
  );
}