AddTimeCommand.cs

using Terraria;
using Terraria.ID;
using Terraria.ModLoader;

namespace ExampleMod.Commands
{
	public class AddTimeCommand : ModCommand
	{
		public override CommandType Type
			=> CommandType.World;

		public override string Command
			=> "addTime";

		public override string Usage
			=> "/addTime numTicks";

		public override string Description
			=> "Add or rewind world time";

		public override void Action(CommandCaller caller, string input, string[] args) {
			double fullTime = Main.time;
			if (!Main.dayTime) {
				fullTime += 54000.0;
			}

			fullTime += int.Parse(args[0]);
			fullTime %= 86400.0;
			if (fullTime < 0) {
				fullTime += 86400;
			}

			Main.dayTime = fullTime < 54000;
			Main.time = fullTime;
			if (!Main.dayTime) {
				Main.time -= 54000;
			}

			if (Main.netMode == 2) {
				NetMessage.SendData(MessageID.WorldData);
			}
		}
	}
}