Pong/Assets/Scripts/NetworkCommandLine.cs

using System;
using System.Collections.Generic;
using Unity.Netcode;
using UnityEngine;

public class NetworkCommandLine : MonoBehaviour {
	private NetworkManager _netManager;

	private void Start() {
		_netManager = GetComponentInParent<NetworkManager>();

		if (Application.isEditor)
			return;

		var args = GetCommandlineArgs();

		if (args.TryGetValue("-mode", out var mode))
			switch (mode) {
				case "server":
					_netManager.StartServer();
					break;
				case "host":
					_netManager.StartHost();
					break;
				case "client":
					_netManager.StartClient();
					break;
			}
	}

	private static Dictionary<string, string> GetCommandlineArgs() {
		var argDictionary = new Dictionary<string, string>();

		var args = Environment.GetCommandLineArgs();

		for (var i = 0; i < args.Length; ++i) {
			var arg = args[i].ToLower();
			if (arg.StartsWith("-")) {
				var value = i < args.Length - 1 ? args[i + 1].ToLower() : null;
				value = value?.StartsWith("-") ?? false ? null : value;

				argDictionary.Add(arg, value);
			}
		}

		return argDictionary;
	}
}