namespace StudySystemClient.Request {
	public class Request {
		private Der.Datum datum;

		public Request(uint16 transaction_id, Body body) {
			datum = new Der.Sequence(
				{ new Der.Integer(transaction_id), body.datum });
		}

		public uint8[] encode() {
			return datum.encode();
		}
	}

	public abstract class Body {
		protected enum Tag {
			PING = 0,
			LIST_ACTIVITIES = 1,
			LOG_SESSION = 2,
		}

		internal Der.Datum datum;

		protected Body(Tag tag, Der.Datum datum) {
			this.datum = new Der.Choice(tag, datum);
		}
	}

	public class Ping : Body {
		public Ping() {
			base(Tag.PING, new Der.Null());
		}
	}

	public class ListActivities : Body {
		public ListActivities() {
			base(Tag.LIST_ACTIVITIES, new Der.Null());
		}
	}

	public class LogSession : Body {
		public LogSession(string subject, ActivityType type,
						  int64 timestamp, int minutes)
		{
			var fields = new Der.Datum[] {
				new Der.Utf8String(subject),
				new Der.Enumerated((int)type),
				new Der.Integer(timestamp),
				new Der.Integer(minutes),
			};
			base(Tag.LOG_SESSION, new Der.Sequence(fields));
		}
	}
}