Migrate existing code

Integrations/Kea/KeaDhcp4LeaseHandler.cs

@@ -0,0 +1,32 @@
+using DotNetDDI.Services.Dhcp;
+
+using nietras.SeparatedValues;
+
+namespace DotNetDDI.Integrations.Kea;
+
+public class KeaDhcp4LeaseHandler : IKeaDhcpLeaseHandler
+{
+	public DhcpLeaseChange? Handle(in SepReader.Row row)
+	{
+		if (KeaDhcp4Lease.Parse(row) is not { } lease)
+		{
+			goto exitNull;
+		}
+
+		if (lease.State != 0)
+		{
+			goto exitNull;
+		}
+
+		DhcpLeaseIdentifier identifier = lease.ClientId switch
+		{
+			string clientId when !string.IsNullOrWhiteSpace(clientId) => new DhcpLeaseClientIdentifier(clientId),
+			_ => new DhcpLeaseHWAddrIdentifier(lease.HWAddr)
+		};
+
+		return new(lease.Address, lease.Hostname, identifier, lease.ValidLifetime);
+
+	exitNull:
+		return null;
+	}
+}