using System.Security.Cryptography;
using System.Text;

namespace ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian;

/// <summary>Stable delivery GUIDs for persisted alarm queue rows.</summary>
public static class AlarmDeliveryIds
{
    /// <summary>
    /// Converts an existing durable row key into a nonzero version-8 GUID. Version 1 of this encoding hashes
    /// UTF-8 "OtOpcUa.AlarmDelivery/v1\0" followed by the exact persisted key with SHA-256, takes the first
    /// 16 bytes, sets the UUID version/variant bits, and interprets the bytes in network order.
    /// This encoding must remain stable across retries, upgrades and replicated failover.
    /// </summary>
    /// <param name="queueId">The persisted row key, never a hash recomputed from the current payload.</param>
    /// <returns>The row's stable delivery identity.</returns>
    public static Guid FromQueueId(string queueId)
    {
        ArgumentException.ThrowIfNullOrWhiteSpace(queueId);
        var digest = SHA256.HashData(Encoding.UTF8.GetBytes("OtOpcUa.AlarmDelivery/v1\0" + queueId));
        digest[6] = (byte)((digest[6] & 0x0F) | 0x80);
        digest[8] = (byte)((digest[8] & 0x3F) | 0x80);
        return new Guid(digest.AsSpan(0, 16), bigEndian: true);
    }
}