using System;

namespace UtopiaCanteenSystem.Helpers;

/// <summary>
/// Helper for scan session rules: limit one scan per minute (1-minute session).
/// </summary>
public static class ScanSessionHelper
{
    /// <summary>
    /// Checks if a new scan is allowed: no other scan in the same minute (UTC).
    /// </summary>
    /// <param name="lastScanTimeUtc">Last scan time in UTC; null if none.</param>
    /// <param name="nowUtc">Current time in UTC.</param>
    /// <returns>True if a new scan is allowed.</returns>
    public static bool IsNewScanAllowed(DateTime? lastScanTimeUtc, DateTime nowUtc)
    {
        if (lastScanTimeUtc == null)
            return true;

        // Same minute (year, month, day, hour, minute) = not allowed
        var last = lastScanTimeUtc.Value;
        if (last.Year == nowUtc.Year &&
            last.Month == nowUtc.Month &&
            last.Day == nowUtc.Day &&
            last.Hour == nowUtc.Hour &&
            last.Minute == nowUtc.Minute)
            return false;

        return true;
    }

    /// <summary>
    /// Truncates the given UTC time to the start of its minute (session window).
    /// </summary>
    public static DateTime TruncateToMinute(DateTime utc)
    {
        return new DateTime(utc.Year, utc.Month, utc.Day, utc.Hour, utc.Minute, 0, DateTimeKind.Utc);
    }
}