add APIs to send/receive messages in multiplayer (#480)

2 files changed, 81 insertions, 5 deletions

diff --git a/src/SMAPI/Framework/Networking/ModMessageModel.cs b/src/SMAPI/Framework/Networking/ModMessageModel.cs
new file mode 100644
index 00000000..7ee39863
--- /dev/null
+++ b/src/SMAPI/Framework/Networking/ModMessageModel.cs
@@ -0,0 +1,72 @@
+using System.Linq;
+using Newtonsoft.Json.Linq;
+
+namespace StardewModdingAPI.Framework.Networking
+{
+    /// <summary>The metadata for a mod message.</summary>
+    internal class ModMessageModel
+    {
+        /*********
+        ** Accessors
+        *********/
+        /****
+        ** Origin
+        ****/
+        /// <summary>The unique ID of the player who broadcast the message.</summary>
+        public long FromPlayerID { get; set; }
+
+        /// <summary>The unique ID of the mod which broadcast the message.</summary>
+        public string FromModID { get; set; }
+
+        /****
+        ** Destination
+        ****/
+        /// <summary>The players who should receive the message, or <c>null</c> for all players.</summary>
+        public long[] ToPlayerIDs { get; set; }
+
+        /// <summary>The mods which should receive the message, or <c>null</c> for all mods.</summary>
+        public string[] ToModIDs { get; set; }
+
+        /// <summary>A message type which receiving mods can use to decide whether it's the one they want to handle, like <c>SetPlayerLocation</c>. This doesn't need to be globally unique, since mods should check the originating mod ID.</summary>
+        public string Type { get; set; }
+
+        /// <summary>The custom mod data being broadcast.</summary>
+        public JToken Data { get; set; }
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        public ModMessageModel() { }
+
+        /// <summary>Construct an instance.</summary>
+        /// <param name="fromPlayerID">The unique ID of the player who broadcast the message.</param>
+        /// <param name="fromModID">The unique ID of the mod which broadcast the message.</param>
+        /// <param name="toPlayerIDs">The players who should receive the message, or <c>null</c> for all players.</param>
+        /// <param name="toModIDs">The mods which should receive the message, or <c>null</c> for all mods.</param>
+        /// <param name="type">A message type which receiving mods can use to decide whether it's the one they want to handle, like <c>SetPlayerLocation</c>. This doesn't need to be globally unique, since mods should check the originating mod ID.</param>
+        /// <param name="data">The custom mod data being broadcast.</param>
+        public ModMessageModel(long fromPlayerID, string fromModID, long[] toPlayerIDs, string[] toModIDs, string type, JToken data)
+        {
+            this.FromPlayerID = fromPlayerID;
+            this.FromModID = fromModID;
+            this.ToPlayerIDs = toPlayerIDs;
+            this.ToModIDs = toModIDs;
+            this.Type = type;
+            this.Data = data;
+        }
+
+        /// <summary>Construct an instance.</summary>
+        /// <param name="message">The message to clone.</param>
+        public ModMessageModel(ModMessageModel message)
+        {
+            this.FromPlayerID = message.FromPlayerID;
+            this.FromModID = message.FromModID;
+            this.ToPlayerIDs = message.ToPlayerIDs?.ToArray();
+            this.ToModIDs = message.ToModIDs?.ToArray();
+            this.Type = message.Type;
+            this.Data = message.Data;
+        }
+    }
+}
diff --git a/src/SMAPI/Framework/Networking/MultiplayerPeer.cs b/src/SMAPI/Framework/Networking/MultiplayerPeer.cs
index e97e36bc..c7f8ffad 100644
--- a/src/SMAPI/Framework/Networking/MultiplayerPeer.cs
+++ b/src/SMAPI/Framework/Networking/MultiplayerPeer.cs
@@ -30,7 +30,7 @@ namespace StardewModdingAPI.Framework.Networking
         public long PlayerID { get; }
 
         /// <summary>Whether this is a connection to the host player.</summary>
-        public bool IsHostPlayer => this.PlayerID == Game1.MasterPlayer.UniqueMultiplayerID;
+        public bool IsHost { get; }
 
         /// <summary>Whether the player has SMAPI installed.</summary>
         public bool HasSmapi => this.ApiVersion != null;
@@ -57,9 +57,11 @@ namespace StardewModdingAPI.Framework.Networking
         /// <param name="server">The server through which to send messages.</param>
         /// <param name="serverConnection">The server connection through which to send messages.</param>
         /// <param name="client">The client through which to send messages.</param>
-        public MultiplayerPeer(long playerID, RemoteContextModel model, SLidgrenServer server, NetConnection serverConnection, SLidgrenClient client)
+        /// <param name="isHost">Whether this is a connection to the host player.</param>
+        public MultiplayerPeer(long playerID, RemoteContextModel model, SLidgrenServer server, NetConnection serverConnection, SLidgrenClient client, bool isHost)
         {
             this.PlayerID = playerID;
+            this.IsHost = isHost;
             if (model != null)
             {
                 this.Platform = model.Platform;
@@ -84,7 +86,8 @@ namespace StardewModdingAPI.Framework.Networking
                 model: model,
                 server: server,
                 serverConnection: serverConnection,
-                client: null
+                client: null,
+                isHost: false
             );
         }
 
@@ -99,7 +102,8 @@ namespace StardewModdingAPI.Framework.Networking
                 model: model,
                 server: null,
                 serverConnection: null,
-                client: client
+                client: client,
+                isHost: true
             );
         }
 
@@ -119,7 +123,7 @@ namespace StardewModdingAPI.Framework.Networking
         /// <param name="message">The message to send.</param>
         public void SendMessage(OutgoingMessage message)
         {
-            if (this.IsHostPlayer)
+            if (this.IsHost)
                 this.Client.sendMessage(message);
             else
                 this.Server.SendMessage(this.ServerConnection, message);