add attendance

API/ROLAC.API/Services/IMealAttendanceService.cs

@@ -0,0 +1,27 @@
+using ROLAC.API.DTOs.MealAttendance;
+
+namespace ROLAC.API.Services;
+
+public interface IMealAttendanceService
+{
+    /// <summary>Today's date in the server's local time zone (the church's "current Sunday").</summary>
+    DateOnly Today { get; }
+
+    /// <summary>Returns the counts for <paramref name="date"/>, creating a zeroed row if none exists.</summary>
+    Task<AttendanceCountsDto> GetOrCreateAsync(DateOnly date);
+
+    /// <summary>
+    /// Atomically adds <paramref name="delta"/> (may be negative) to one age-group column,
+    /// clamped at zero, and returns the resulting authoritative counts.
+    /// </summary>
+    Task<AttendanceCountsDto> IncrementAsync(DateOnly date, string category, int delta);
+
+    /// <summary>
+    /// Sets one age-group column to an absolute <paramref name="value"/> (clamped at zero),
+    /// overwriting the current count, and returns the resulting authoritative counts.
+    /// </summary>
+    Task<AttendanceCountsDto> SetAsync(DateOnly date, string category, int value);
+
+    /// <summary>Returns the daily counts within the inclusive date range, ordered by date (for the dashboard).</summary>
+    Task<IReadOnlyList<AttendanceCountsDto>> GetRangeAsync(DateOnly from, DateOnly to);
+}