rely/lib/features/sync/sync_auto_trigger_controller.dart

import 'dart:math' as math;

import 'package:flutter/foundation.dart';
import 'package:relationship_saver/features/sync/sync_coordinator.dart';

typedef SyncNowRunner = Future<SyncRunResult> Function();

/// Coordinates auto-triggered sync calls with cooldown and concurrency guards.
class SyncAutoTriggerController {
  SyncAutoTriggerController({
    required SyncNowRunner syncNow,
    required DateTime Function() now,
    this.minimumInterval = const Duration(minutes: 3),
  }) : _syncNow = syncNow,
       _now = now;

  final SyncNowRunner _syncNow;
  final DateTime Function() _now;
  final Duration minimumInterval;

  bool _running = false;
  DateTime? _lastTriggeredAt;
  int _consecutiveFailures = 0;

  @visibleForTesting
  bool get isRunning => _running;

  @visibleForTesting
  DateTime? get lastTriggeredAt => _lastTriggeredAt;

  @visibleForTesting
  int get consecutiveFailures => _consecutiveFailures;

  /// Triggers `syncNow` when not already running and outside cooldown window.
  Future<bool> trigger({bool ignoreCooldown = false}) async {
    if (_running) {
      return false;
    }

    final DateTime now = _now();
    final DateTime? last = _lastTriggeredAt;
    if (!ignoreCooldown &&
        last != null &&
        now.difference(last) < _cooldownForCurrentState()) {
      return false;
    }

    _running = true;
    _lastTriggeredAt = now;
    try {
      final SyncRunResult result = await _syncNow();
      if (result.success) {
        _consecutiveFailures = 0;
      } else {
        _consecutiveFailures += 1;
      }
      return true;
    } catch (_) {
      _consecutiveFailures += 1;
      return true;
    } finally {
      _running = false;
    }
  }

  Duration _cooldownForCurrentState() {
    if (_consecutiveFailures <= 0) {
      return minimumInterval;
    }
    final int cappedFailures = math.min(_consecutiveFailures, 4);
    final int multiplier = 1 << cappedFailures;
    return minimumInterval * multiplier;
  }
}