path: root/src/SMAPI/Framework/SMultiplayer.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using Galaxy.Api;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
using StardewModdingAPI.Events;
using StardewModdingAPI.Framework.Events;
using StardewModdingAPI.Framework.Networking;
using StardewModdingAPI.Framework.Reflection;
using StardewModdingAPI.Internal;
using StardewModdingAPI.Toolkit.Serialization;
using StardewModdingAPI.Utilities;
using StardewValley;
using StardewValley.Network;
using StardewValley.SDKs;

namespace StardewModdingAPI.Framework
{
    /// <summary>SMAPI's implementation of the game's core multiplayer logic.</summary>
    /// <remarks>
    /// SMAPI syncs mod context to all players through the host as such:
    ///   1. Farmhand sends ModContext + PlayerIntro.
    ///   2. If host receives ModContext: it stores the context, replies with known contexts, and forwards it to other farmhands.
    ///   3. If host receives PlayerIntro before ModContext: it stores a 'vanilla player' context, and forwards it to other farmhands.
    ///   4. If farmhand receives ModContext: it stores it.
    ///   5. If farmhand receives ServerIntro without a preceding ModContext: it stores a 'vanilla host' context.
    ///   6. If farmhand receives PlayerIntro without a preceding ModContext AND it's not the host peer: it stores a 'vanilla player' context.
    ///
    /// Once a farmhand/server stored a context, messages can be sent to that player through the SMAPI APIs.
    /// </remarks>
    internal class SMultiplayer : Multiplayer
    {
        /*********
        ** Fields
        *********/
        /// <summary>Encapsulates monitoring and logging.</summary>
        private readonly IMonitor Monitor;

        /// <summary>Tracks the installed mods.</summary>
        private readonly ModRegistry ModRegistry;

        /// <summary>Encapsulates SMAPI's JSON file parsing.</summary>
        private readonly JsonHelper JsonHelper;

        /// <summary>Simplifies access to private code.</summary>
        private readonly Reflector Reflection;

        /// <summary>Manages SMAPI events.</summary>
        private readonly EventManager EventManager;

        /// <summary>A callback to invoke when a mod message is received.</summary>
        private readonly Action<ModMessageModel> OnModMessageReceived;

        /// <summary>Whether to log network traffic.</summary>
        private readonly bool LogNetworkTraffic;

        /// <summary>The backing field for <see cref="Peers"/>.</summary>
        private readonly PerScreen<IDictionary<long, MultiplayerPeer>> PeersImpl = new(() => new Dictionary<long, MultiplayerPeer>());

        /// <summary>The backing field for <see cref="HostPeer"/>.</summary>
        private readonly PerScreen<MultiplayerPeer?> HostPeerImpl = new();


        /*********
        ** Accessors
        *********/
        /// <summary>The metadata for each connected peer.</summary>
        public IDictionary<long, MultiplayerPeer> Peers => this.PeersImpl.Value;

        /// <summary>The metadata for the host player, if the current player is a farmhand.</summary>
        public MultiplayerPeer? HostPeer
        {
            get => this.HostPeerImpl.Value;
            private set => this.HostPeerImpl.Value = value;
        }


        /*********
        ** Public methods
        *********/
        /// <summary>Construct an instance.</summary>
        /// <param name="monitor">Encapsulates monitoring and logging.</param>
        /// <param name="eventManager">Manages SMAPI events.</param>
        /// <param name="jsonHelper">Encapsulates SMAPI's JSON file parsing.</param>
        /// <param name="modRegistry">Tracks the installed mods.</param>
        /// <param name="reflection">Simplifies access to private code.</param>
        /// <param name="onModMessageReceived">A callback to invoke when a mod message is received.</param>
        /// <param name="logNetworkTraffic">Whether to log network traffic.</param>
        public SMultiplayer(IMonitor monitor, EventManager eventManager, JsonHelper jsonHelper, ModRegistry modRegistry, Reflector reflection, Action<ModMessageModel> onModMessageReceived, bool logNetworkTraffic)
        {
            this.Monitor = monitor;
            this.EventManager = eventManager;
            this.JsonHelper = jsonHelper;
            this.ModRegistry = modRegistry;
            this.Reflection = reflection;
            this.OnModMessageReceived = onModMessageReceived;
            this.LogNetworkTraffic = logNetworkTraffic;
        }

        /// <summary>Perform cleanup needed when a multiplayer session ends.</summary>
        public void CleanupOnMultiplayerExit()
        {
            this.Peers.Clear();
            this.HostPeer = null;
        }

        /// <summary>Initialize a client before the game connects to a remote server.</summary>
        /// <param name="client">The client to initialize.</param>
        public override Client InitClient(Client client)
        {
            switch (client)
            {
                case LidgrenClient:
                    {
                        string address = this.Reflection.GetField<string?>(client, "address").GetValue() ?? throw new InvalidOperationException("Can't initialize base networking client: no valid address found.");
                        return new SLidgrenClient(address, this.OnClientProcessingMessage, this.OnClientSendingMessage);
                    }

                case GalaxyNetClient:
                    {
                        GalaxyID address = this.Reflection.GetField<GalaxyID?>(client, "lobbyId").GetValue() ?? throw new InvalidOperationException("Can't initialize GOG networking client: no valid address found.");
                        return new SGalaxyNetClient(address, this.OnClientProcessingMessage, this.OnClientSendingMessage);
                    }

                default:
                    this.Monitor.Log($"Unknown multiplayer client type: {client.GetType().AssemblyQualifiedName}");
                    return client;
            }
        }

        /// <summary>Initialize a server before the game connects to an incoming player.</summary>
        /// <param name="server">The server to initialize.</param>
        public override Server InitServer(Server server)
        {
            switch (server)
            {
                case LidgrenServer:
                    {
                        IGameServer gameServer = this.Reflection.GetField<IGameServer?>(server, "gameServer").GetValue() ?? throw new InvalidOperationException("Can't initialize base networking client: the required 'gameServer' field wasn't found.");
                        return new SLidgrenServer(gameServer, this, this.OnServerProcessingMessage);
                    }

                case GalaxyNetServer:
                    {
                        IGameServer gameServer = this.Reflection.GetField<IGameServer?>(server, "gameServer").GetValue() ?? throw new InvalidOperationException("Can't initialize GOG networking client: the required 'gameServer' field wasn't found.");
                        return new SGalaxyNetServer(gameServer, this, this.OnServerProcessingMessage);
                    }

                default:
                    this.Monitor.Log($"Unknown multiplayer server type: {server.GetType().AssemblyQualifiedName}");
                    return server;
            }
        }

        /// <summary>A callback raised when sending a message as a farmhand.</summary>
        /// <param name="message">The message being sent.</param>
        /// <param name="sendMessage">Send an arbitrary message through the client.</param>
        /// <param name="resume">Resume sending the underlying message.</param>
        protected void OnClientSendingMessage(OutgoingMessage message, Action<OutgoingMessage> sendMessage, Action resume)
        {
            if (this.LogNetworkTraffic)
                this.Monitor.Log($"CLIENT SEND {(MessageType)message.MessageType} {message.FarmerID}");

            switch (message.MessageType)
            {
                // sync mod context (step 1)
                case (byte)MessageType.PlayerIntroduction:
                    sendMessage(new OutgoingMessage((byte)MessageType.ModContext, Game1.player.UniqueMultiplayerID, this.GetContextSyncMessageFields()));
                    resume();
                    break;

                // run default logic
                default:
                    resume();
                    break;
            }
        }

        /// <summary>Process an incoming network message as the host player.</summary>
        /// <param name="message">The message to process.</param>
        /// <param name="sendMessage">A method which sends the given message to the client.</param>
        /// <param name="resume">Process the message using the game's default logic.</param>
        public void OnServerProcessingMessage(IncomingMessage message, Action<OutgoingMessage> sendMessage, Action resume)
        {
            if (this.LogNetworkTraffic)
                this.Monitor.Log($"SERVER RECV {(MessageType)message.MessageType} {message.FarmerID}");

            switch (message.MessageType)
            {
                // sync mod context (step 2)
                case (byte)MessageType.ModContext:
                    {
                        // parse message
                        RemoteContextModel? model = this.ReadContext(message.Reader);
                        this.Monitor.Log($"Received context for farmhand {message.FarmerID} running {(model != null ? $"SMAPI {model.ApiVersion} with {model.Mods.Length} mods" : "vanilla")}.");

                        // store peer
                        MultiplayerPeer newPeer = new(
                            playerID: message.FarmerID,
                            screenID: this.GetScreenId(message.FarmerID),
                            model: model,
                            sendMessage: sendMessage,
                            <