PenguinsTwoChase/Assets/Scripts/Network/Network.cs

using PashaBibko.Pacore.Attributes;
using Unity.Netcode.Transports.UTP;
using UnityEngine.SceneManagement;
using System.Collections;
using Unity.Netcode;
using UnityEngine;
using System;

namespace PashaBibko.PenguinChase.Network
{
    public enum TransportType
    {
        UnityRelay,
        Localhost,
        
        None
    }

    public interface INetworkTransport
    {
        public IEnumerator Join(string code, Action callback);
        public IEnumerator Host(Action callback);
    }

    public class Network : MonoBehaviour
    {
        private static Network sInstance;

        [Header("Transports")]
        [SerializeField] private GameObject LocalHostTransport;
        [SerializeField] private GameObject UnityRelayTransport;

        [Header("View only")] [SerializeField, InspectorReadOnly]
        private TransportType InternalCurrentTransport = TransportType.None;

        public static TransportType CurrentTransport
        {
            get => sInstance?.InternalCurrentTransport ?? TransportType.None;
            set => sInstance?.StartCoroutine(sInstance.ChangeTransport(value));
        }

#if UNITY_EDITOR
        [Header("Editor Only")]
        [SerializeField] private string GameJoinCode;
#endif // UNITY_EDITOR

        private static INetworkTransport sConnectionManager;

        private GameObject mCurrentChildTransport;
        private bool mSafeToConnect = true;

        public static UnityTransport CurrentTransportComponent
        {
            get
            {
                UnityTransport component = null;
                sInstance?.mCurrentChildTransport?.TryGetComponent(out component);
                return component;
            }
        }

        private void Awake()
        {
            // Stops overlapping instances
            if (sInstance is not null)
            {
                Debug.LogError($"Multiple of [{nameof(Network)}] cannot exist.");
                Destroy(gameObject);
                return;
            }

            sInstance = this;
        }

        private IEnumerator HostInternal()
        {
            // Waits for it to be safe to connect, quits after 5 seconds
            float timeout = 0f;
            while (!mSafeToConnect)
            {
                if (timeout > 5f)
                {
                    Debug.LogError("Host timed out");
                    yield break;
                }

                timeout += Time.deltaTime;
                yield return null;
            }
            
            // Then actually hosts the lobby
            yield return sConnectionManager.Host(() =>
            {
                NetworkManager.Singleton.SceneManager.LoadScene("LobbyScene", LoadSceneMode.Single);
                Debug.Log("Hosted");
            });
        }

        public static void Host()
        {
            if (sConnectionManager is null)
            {
                throw new InvalidOperationException("No connection manager has been set.");
            }

            if (sInstance is null)
            {
                throw new InvalidOperationException("No network manager has been set.");
            }

            sInstance.StartCoroutine(sInstance.HostInternal());
        }

        private IEnumerator JoinInternal(string code)
        {
            // Waits for it to be safe to connect, quits after 5 seconds
            float timeout = 0f;
            while (!mSafeToConnect)
            {
                if (timeout > 5f)
                {
                    Debug.LogError("Host timed out");
                    yield break;
                }

                timeout += Time.deltaTime;
                yield return null;
            }
            
            // Then connects to the lobby
            yield return sConnectionManager.Join(code, () =>
            {
                Debug.Log($"Joined {code}");
            });
        }
        
        public static void Join(string code)
        {
            if (sConnectionManager is null)
            {
                throw new InvalidOperationException("No connection manager has been set.");
            }
            
            if (sInstance is null)
            {
                throw new InvalidOperationException("No network manager has been set.");
            }

            sInstance.StartCoroutine(sInstance.JoinInternal(code));
        }

        private IEnumerator ChangeTransport(TransportType transport)
        {
            // Stops network from being restarted when unneeded
            if (transport == InternalCurrentTransport)
            {
                yield break;
            }

            mSafeToConnect = false;
            InternalCurrentTransport = transport;

            // Shutdown existing network manager (if there is one) to stop multiple at once
            if (NetworkManager.Singleton is not null)
            {
                NetworkManager.Singleton.Shutdown();
                while (NetworkManager.Singleton.ShutdownInProgress)
                {
                    yield return null; // Waits for next frame
                }

                Destroy(mCurrentChildTransport);
            }

            // Loads the new transport controller and lets it setup
            switch (InternalCurrentTransport)
            {
                case TransportType.UnityRelay:
                    mCurrentChildTransport = Instantiate(UnityRelayTransport);
                    sConnectionManager = new UnityRelayTransport();
                    break;

                case TransportType.Localhost:
                    mCurrentChildTransport = Instantiate(LocalHostTransport);
                    sConnectionManager = new LocalhostTransport();
                    break;

                case TransportType.None:
                    // Nothing needs to be done here as there is no network controller
                    mCurrentChildTransport = null;
                    yield break;

                default:
                    mSafeToConnect = true;
                    throw new ArgumentOutOfRangeException();
            }
            
            DontDestroyOnLoad(mCurrentChildTransport);
            mSafeToConnect = true;
        }
    }
}