life-helper/app/lib/domain/rules/active_habit_quota.dart

import '../models/habit.dart';

/// R1/R2: max active habits per type.
/// - build: ≤ 3
/// - break: ≤ 1
const int kMaxActiveBuild = 3;
const int kMaxActiveBreak = 1;

class QuotaResult {
  final HabitType type;
  final int currentCount;
  final int limit;
  final bool allowed;

  const QuotaResult({
    required this.type,
    required this.currentCount,
    required this.limit,
    required this.allowed,
  });

  String get reason {
    if (allowed) return 'ok';
    return type == HabitType.build
        ? 'build habit quota reached (≤ $kMaxActiveBuild active)'
        : 'break habit quota reached (≤ $kMaxActiveBreak active)';
  }
}

/// Pure judgment: caller passes in the current active count.
QuotaResult judgeActiveHabitQuota({
  required HabitType type,
  required int currentActiveCount,
}) {
  final limit = type == HabitType.build ? kMaxActiveBuild : kMaxActiveBreak;
  return QuotaResult(
    type: type,
    currentCount: currentActiveCount,
    limit: limit,
    allowed: currentActiveCount < limit,
  );
}