Merge branch 'feature/mod-provided-apis' into develop

7 files changed, 251 insertions, 51 deletions

diff --git a/src/SMAPI/Framework/DeprecationManager.cs b/src/SMAPI/Framework/DeprecationManager.cs
index 20bb0d2d..7a824a05 100644
--- a/src/SMAPI/Framework/DeprecationManager.cs
+++ b/src/SMAPI/Framework/DeprecationManager.cs
@@ -37,7 +37,7 @@ namespace StardewModdingAPI.Framework
         /// <param name="severity">How deprecated the code is.</param>
         public void Warn(string nounPhrase, string version, DeprecationLevel severity)
         {
-            this.Warn(this.ModRegistry.GetModFromStack(), nounPhrase, version, severity);
+            this.Warn(this.ModRegistry.GetFromStack()?.DisplayName, nounPhrase, version, severity);
         }
 
         /// <summary>Log a deprecation warning.</summary>
@@ -82,7 +82,7 @@ namespace StardewModdingAPI.Framework
         /// <returns>Returns whether the deprecation was successfully marked as warned. Returns <c>false</c> if it was already marked.</returns>
         public bool MarkWarned(string nounPhrase, string version)
         {
-            return this.MarkWarned(this.ModRegistry.GetModFromStack(), nounPhrase, version);
+            return this.MarkWarned(this.ModRegistry.GetFromStack()?.DisplayName, nounPhrase, version);
         }
 
         /// <summary>Mark a deprecation warning as already logged.</summary>
diff --git a/src/SMAPI/Framework/IModMetadata.cs b/src/SMAPI/Framework/IModMetadata.cs
index c21734a7..a36994fd 100644
--- a/src/SMAPI/Framework/IModMetadata.cs
+++ b/src/SMAPI/Framework/IModMetadata.cs
@@ -30,6 +30,9 @@ namespace StardewModdingAPI.Framework
         /// <summary>The mod instance (if it was loaded).</summary>
         IMod Mod { get; }
 
+        /// <summary>The mod-provided API (if any).</summary>
+        object Api { get; }
+
 
         /*********
         ** Public methods
@@ -43,5 +46,9 @@ namespace StardewModdingAPI.Framework
         /// <summary>Set the mod instance.</summary>
         /// <param name="mod">The mod instance to set.</param>
         IModMetadata SetMod(IMod mod);
+
+        /// <summary>Set the mod-provided API instance.</summary>
+        /// <param name="api">The mod-provided API.</param>
+        IModMetadata SetApi(object api);
     }
 }
diff --git a/src/SMAPI/Framework/ModHelpers/ModRegistryHelper.cs b/src/SMAPI/Framework/ModHelpers/ModRegistryHelper.cs
index 9e824694..ea0dbb38 100644
--- a/src/SMAPI/Framework/ModHelpers/ModRegistryHelper.cs
+++ b/src/SMAPI/Framework/ModHelpers/ModRegistryHelper.cs
@@ -1,4 +1,6 @@
-using System.Collections.Generic;
+using System.Collections.Generic;
+using System.Linq;
+using StardewModdingAPI.Framework.Reflection;
 
 namespace StardewModdingAPI.Framework.ModHelpers
 {
@@ -11,6 +13,15 @@ namespace StardewModdingAPI.Framework.ModHelpers
         /// <summary>The underlying mod registry.</summary>
         private readonly ModRegistry Registry;
 
+        /// <summary>Encapsulates monitoring and logging for the mod.</summary>
+        private readonly IMonitor Monitor;
+
+        /// <summary>The mod IDs for APIs accessed by this instanced.</summary>
+        private readonly HashSet<string> AccessedModApis = new HashSet<string>();
+
+        /// <summary>Generates proxy classes to access mod APIs through an arbitrary interface.</summary>
+        private readonly InterfaceProxyBuilder ProxyBuilder;
+
 
         /*********
         ** Public methods
@@ -18,16 +29,20 @@ namespace StardewModdingAPI.Framework.ModHelpers
         /// <summary>Construct an instance.</summary>
         /// <param name="modID">The unique ID of the relevant mod.</param>
         /// <param name="registry">The underlying mod registry.</param>
-        public ModRegistryHelper(string modID, ModRegistry registry)
+        /// <param name="proxyBuilder">Generates proxy classes to access mod APIs through an arbitrary interface.</param>
+        /// <param name="monitor">Encapsulates monitoring and logging for the mod.</param>
+        public ModRegistryHelper(string modID, ModRegistry registry, InterfaceProxyBuilder proxyBuilder, IMonitor monitor)
             : base(modID)
         {
             this.Registry = registry;
+            this.ProxyBuilder = proxyBuilder;
+            this.Monitor = monitor;
         }
 
         /// <summary>Get metadata for all loaded mods.</summary>
         public IEnumerable<IManifest> GetAll()
         {
-            return this.Registry.GetAll();
+            return this.Registry.GetAll().Select(p => p.Manifest);
         }
 
         /// <summary>Get metadata for a loaded mod.</summary>
@@ -35,14 +50,56 @@ namespace StardewModdingAPI.Framework.ModHelpers
         /// <returns>Returns the matching mod's metadata, or <c>null</c> if not found.</returns>
         public IManifest Get(string uniqueID)
         {
-            return this.Registry.Get(uniqueID);
+            return this.Registry.Get(uniqueID)?.Manifest;
         }
 
         /// <summary>Get whether a mod has been loaded.</summary>
         /// <param name="uniqueID">The mod's unique ID.</param>
         public bool IsLoaded(string uniqueID)
         {
-            return this.Registry.IsLoaded(uniqueID);
+            return this.Registry.Get(uniqueID) != null;
+        }
+
+        /// <summary>Get the API provided by a mod, or <c>null</c> if it has none. This signature requires using the <see cref="IModHelper.Reflection"/> API to access the API's properties and methods.</summary>
+        public object GetApi(string uniqueID)
+        {
+            IModMetadata mod = this.Registry.Get(uniqueID);
+            if (mod?.Api != null && this.AccessedModApis.Add(mod.Manifest.UniqueID))
+                this.Monitor.Log($"Accessed mod-provided API for {mod.DisplayName}.", LogLevel.Trace);
+            return mod?.Api;
+        }
+
+        /// <summary>Get the API provided by a mod, mapped to a given interface which specifies the expected properties and methods. If the mod has no API or it's not compatible with the given interface, get <c>null</c>.</summary>
+        /// <typeparam name="TInterface">The interface which matches the properties and methods you intend to access.</typeparam>
+        /// <param name="uniqueID">The mod's unique ID.</param>
+        public TInterface GetApi<TInterface>(string uniqueID) where TInterface : class
+        {
+            // validate
+            if (!this.Registry.AreAllModsInitialised)
+            {
+                this.Monitor.Log("Tried to access a mod-provided API before all mods were initialised.", LogLevel.Error);
+                return null;
+            }
+            if (!typeof(TInterface).IsInterface)
+            {
+                this.Monitor.Log("Tried to map a mod-provided API to a class; must be a public interface.", LogLevel.Error);
+                return null;
+            }
+            if (!typeof(TInterface).IsPublic)
+            {
+                this.Monitor.Log("Tried to map a mod-provided API to a non-public interface; must be a public interface.", LogLevel.Error);
+                return null;
+            }
+
+            // get raw API
+            object api = this.GetApi(uniqueID);
+            if (api == null)
+                return null;
+
+            // get API of type
+            if (api is TInterface castApi)
+                return castApi;
+            return this.ProxyBuilder.CreateProxy<TInterface>(api, this.ModID, uniqueID);
         }
     }
 }
diff --git a/src/SMAPI/Framework/ModLoading/ModMetadata.cs b/src/SMAPI/Framework/ModLoading/ModMetadata.cs
index 5055da75..30fe211b 100644
--- a/src/SMAPI/Framework/ModLoading/ModMetadata.cs
+++ b/src/SMAPI/Framework/ModLoading/ModMetadata.cs
@@ -29,6 +29,9 @@ namespace StardewModdingAPI.Framework.ModLoading
         /// <summary>The mod instance (if it was loaded).</summary>
         public IMod Mod { get; private set; }
 
+        /// <summary>The mod-provided API (if any).</summary>
+        public object Api { get; private set; }
+
 
         /*********
         ** Public methods
@@ -64,5 +67,13 @@ namespace StardewModdingAPI.Framework.ModLoading
             this.Mod = mod;
             return this;
         }
+
+        /// <summary>Set the mod-provided API instance.</summary>
+        /// <param name="api">The mod-provided API.</param>
+        public IModMetadata SetApi(object api)
+        {
+            this.Api = api;
+            return this;
+        }
     }
 }
diff --git a/src/SMAPI/Framework/ModRegistry.cs b/src/SMAPI/Framework/ModRegistry.cs
index 9dde7a20..453d2868 100644
--- a/src/SMAPI/Framework/ModRegistry.cs
+++ b/src/SMAPI/Framework/ModRegistry.cs
@@ -15,26 +15,34 @@ namespace StardewModdingAPI.Framework
         /// <summary>The registered mod data.</summary>
         private readonly List<IModMetadata> Mods = new List<IModMetadata>();
 
-        /// <summary>The friendly mod names treated as deprecation warning sources (assembly full name => mod name).</summary>
-        private readonly IDictionary<string, string> ModNamesByAssembly = new Dictionary<string, string>();
+        /// <summary>An assembly full name => mod lookup.</summary>
+        private readonly IDictionary<string, IModMetadata> ModNamesByAssembly = new Dictionary<string, IModMetadata>();
+
+        /// <summary>Whether all mods have been initialised and their <see cref="IMod.Entry"/> method called.</summary>
+        public bool AreAllModsInitialised { get; set; }
 
 
         /*********
         ** Public methods
         *********/
-        /****
-        ** Basic metadata
-        ****/
+        /// <summary>Register a mod as a possible source of deprecation warnings.</summary>
+        /// <param name="metadata">The mod metadata.</param>
+        public void Add(IModMetadata metadata)
+        {
+            this.Mods.Add(metadata);
+            this.ModNamesByAssembly[metadata.Mod.GetType().Assembly.FullName] = metadata;
+        }
+
         /// <summary>Get metadata for all loaded mods.</summary>
-        public IEnumerable<IManifest> GetAll()
+        public IEnumerable<IModMetadata> GetAll()
         {
-            return this.Mods.Select(p => p.Manifest);
+            return this.Mods.Select(p => p);
         }
 
         /// <summary>Get metadata for a loaded mod.</summary>
         /// <param name="uniqueID">The mod's unique ID.</param>
         /// <returns>Returns the matching mod's metadata, or <c>null</c> if not found.</returns>
-        public IManifest Get(string uniqueID)
+        public IModMetadata Get(string uniqueID)
         {
             // normalise search ID
             if (string.IsNullOrWhiteSpace(uniqueID))
@@ -42,37 +50,13 @@ namespace StardewModdingAPI.Framework
             uniqueID = uniqueID.Trim();
 
             // find match
-            return this.GetAll().FirstOrDefault(p => p.UniqueID.Trim().Equals(uniqueID, StringComparison.InvariantCultureIgnoreCase));
-        }
-
-        /// <summary>Get whether a mod has been loaded.</summary>
-        /// <param name="uniqueID">The mod's unique ID.</param>
-        public bool IsLoaded(string uniqueID)
-        {
-            return this.Get(uniqueID) != null;
-        }
-
-        /****
-        ** Mod data
-        ****/
-        /// <summary>Register a mod as a possible source of deprecation warnings.</summary>
-        /// <param name="metadata">The mod metadata.</param>
-        public void Add(IModMetadata metadata)
-        {
-            this.Mods.Add(metadata);
-            this.ModNamesByAssembly[metadata.Mod.GetType().Assembly.FullName] = metadata.DisplayName;
-        }
-
-        /// <summary>Get all enabled mods.</summary>
-        public IEnumerable<IModMetadata> GetMods()
-        {
-            return (from mod in this.Mods select mod);
+            return this.GetAll().FirstOrDefault(p => p.Manifest.UniqueID.Trim().Equals(uniqueID, StringComparison.InvariantCultureIgnoreCase));
         }
 
-        /// <summary>Get the friendly mod name which defines a type.</summary>
+        /// <summary>Get the mod metadata from one of its assemblies.</summary>
         /// <param name="type">The type to check.</param>
         /// <returns>Returns the mod name, or <c>null</c> if the type isn't part of a known mod.</returns>
-        public string GetModFrom(Type type)
+        public IModMetadata GetFrom(Type type)
         {
             // null
             if (type == null)
@@ -89,7 +73,7 @@ namespace StardewModdingAPI.Framework
 
         /// <summary>Get the friendly name for the closest assembly registered as a source of deprecation warnings.</summary>
         /// <returns>Returns the source name, or <c>null</c> if no registered assemblies were found.</returns>
-        public string GetModFromStack()
+        public IModMetadata GetFromStack()
         {
             // get stack frames
             StackTrace stack = new StackTrace();
@@ -101,9 +85,9 @@ namespace StardewModdingAPI.Framework
             foreach (StackFrame frame in frames)
             {
                 MethodBase method = frame.GetMethod();
-                string name = this.GetModFrom(method.ReflectedType);
-                if (name != null)
-                    return name;
+                IModMetadata mod = this.GetFrom(method.ReflectedType);
+                if (mod != null)
+                    return mod;
             }
 
             // no known assembly found
diff --git a/src/SMAPI/Framework/Reflection/InterfaceProxyBuilder.cs b/src/SMAPI/Framework/Reflection/InterfaceProxyBuilder.cs
new file mode 100644
index 00000000..5abebc18
--- /dev/null
+++ b/src/SMAPI/Framework/Reflection/InterfaceProxyBuilder.cs
@@ -0,0 +1,138 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+using System.Reflection.Emit;
+
+namespace StardewModdingAPI.Framework.Reflection
+{
+    /// <summary>Generates proxy classes to access mod APIs through an arbitrary interface.</summary>
+    internal class InterfaceProxyBuilder
+    {
+        /*********
+        ** Properties
+        *********/
+        /// <summary>The CLR module in which to create proxy classes.</summary>
+        private readonly ModuleBuilder ModuleBuilder;
+
+        /// <summary>The generated proxy types.</summary>
+        private readonly IDictionary<string, Type> GeneratedTypes = new Dictionary<string, Type>();
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        public InterfaceProxyBuilder()
+        {
+            AssemblyBuilder assemblyBuilder = AppDomain.CurrentDomain.DefineDynamicAssembly(new AssemblyName($"StardewModdingAPI.Proxies, Version={this.GetType().Assembly.GetName().Version}, Culture=neutral"), AssemblyBuilderAccess.Run);
+            this.ModuleBuilder = assemblyBuilder.DefineDynamicModule("StardewModdingAPI.Proxies");
+        }
+
+        /// <summary>Create an API proxy.</summary>
+        /// <typeparam name="TInterface">The interface through which to access the API.</typeparam>
+        /// <param name="instance">The API instance to access.</param>
+        /// <param name="sourceModID">The unique ID of the mod consuming the API.</param>
+        /// <param name="targetModID">The unique ID of the mod providing the API.</param>
+        public TInterface CreateProxy<TInterface>(object instance, string sourceModID, string targetModID)
+            where TInterface : class
+        {
+            // validate
+            if (instance == null)
+                throw new InvalidOperationException("Can't proxy access to a null API.");
+            if (!typeof(TInterface).IsInterface)
+                throw new InvalidOperationException("The proxy type must be an interface, not a class.");
+
+            // get proxy type
+            Type targetType = instance.GetType();
+            string proxyTypeName = $"StardewModdingAPI.Proxies.From<{sourceModID}_{typeof(TInterface).FullName}>_To<{targetModID}_{targetType.FullName}>";
+            if (!this.GeneratedTypes.TryGetValue(proxyTypeName, out Type type))
+            {
+                type = this.CreateProxyType(proxyTypeName, typeof(TInterface), targetType);
+                this.GeneratedTypes[proxyTypeName] = type;
+            }
+
+            // create instance
+            ConstructorInfo constructor = type.GetConstructor(new[] { targetType });
+            if (constructor == null)
+                throw new InvalidOperationException($"Couldn't find the constructor for generated proxy type '{proxyTypeName}'."); // should never happen
+            return (TInterface)constructor.Invoke(new[] { instance });
+        }
+
+
+        /*********
+        ** Private methods
+        *********/
+        /// <summary>Define a class which proxies access to a target type through an interface.</summary>
+        /// <param name="proxyTypeName">The name of the proxy type to generate.</param>
+        /// <param name="interfaceType">The interface type through which to access the target.</param>
+        /// <param name="targetType">The target type to access.</param>
+        private Type CreateProxyType(string proxyTypeName, Type interfaceType, Type targetType)
+        {
+            // define proxy type
+            TypeBuilder proxyBuilder = this.ModuleBuilder.DefineType(proxyTypeName, TypeAttributes.Public | TypeAttributes.Class);
+            proxyBuilder.AddInterfaceImplementation(interfaceType);
+
+            // create field to store target instance
+            FieldBuilder field = proxyBuilder.DefineField("__Target", targetType, FieldAttributes.Private);
+
+            // create constructor which accepts target instance
+            {
+                ConstructorBuilder constructor = proxyBuilder.DefineConstructor(MethodAttributes.Public, CallingConventions.Standard | CallingConventions.HasThis, new[] { targetType });
+                ILGenerator il = constructor.GetILGenerator();
+
+                il.Emit(OpCodes.Ldarg_0); // this
+                // ReSharper disable once AssignNullToNotNullAttribute -- never null
+                il.Emit(OpCodes.Call, typeof(object).GetConstructor(new Type[0])); // call base constructor
+                il.Emit(OpCodes.Ldarg_0);      // this
+                il.Emit(OpCodes.Ldarg_1);      // load argument
+                il.Emit(OpCodes.Stfld, field); // set field to loaded argument
+                il.Emit(OpCodes.Ret);
+            }
+
+            // proxy methods
+            foreach (MethodInfo proxyMethod in interfaceType.GetMethods())
+            {
+                var targetMethod = targetType.GetMethod(proxyMethod.Name, proxyMethod.GetParameters().Select(a => a.ParameterType).ToArray());
+                if (targetMethod == null)
+                    throw new InvalidOperationException($"The {interfaceType.FullName} interface defines method {proxyMethod.Name} which doesn't exist in the API.");
+
+                this.ProxyMethod(proxyBuilder, targetMethod, field);
+            }
+
+            // create type
+            return proxyBuilder.CreateType();
+        }
+
+        /// <summary>Define a method which proxies access to a method on the target.</summary>
+        /// <param name="proxyBuilder">The proxy type being generated.</param>
+        /// <param name="target">The target method.</param>
+        /// <param name="instanceField">The proxy field containing the API instance.</param>
+        private void ProxyMethod(TypeBuilder proxyBuilder, MethodInfo target, FieldBuilder instanceField)
+        {
+            Type[] argTypes = target.GetParameters().Select(a => a.ParameterType).ToArray();
+
+            // create method
+            MethodBuilder methodBuilder = proxyBuilder.DefineMethod(target.Name, MethodAttributes.Public | MethodAttributes.Final | MethodAttributes.Virtual);
+            methodBuilder.SetParameters(argTypes);
+            methodBuilder.SetReturnType(target.ReturnType);
+
+            // create method body
+            {
+                ILGenerator il = methodBuilder.GetILGenerator();
+
+                // load target instance
+                il.Emit(OpCodes.Ldarg_0);
+                il.Emit(OpCodes.Ldfld, instanceField);
+
+                // invoke target method on instance
+                for (int i = 0; i < argTypes.Length; i++)
+                    il.Emit(OpCodes.Ldarg, i + 1);
+                il.Emit(OpCodes.Call, target);
+
+                // return result
+                il.Emit(OpCodes.Ret);
+            }
+        }
+    }
+}
diff --git a/src/SMAPI/Framework/SGame.cs b/src/SMAPI/Framework/SGame.cs
index e9777e0b..0a614f17 100644
--- a/src/SMAPI/Framework/SGame.cs
+++ b/src/SMAPI/Framework/SGame.cs
@@ -557,9 +557,12 @@ namespace StardewModdingAPI.Framework
                 /*********
                 ** Update events
                 *********/
-                GameEvents.InvokeUpdateTick(this.Monitor);
                 if (this.FirstUpdate)
+                {
                     this.FirstUpdate = false;
+                    GameEvents.InvokeFirstUpdateTick(this.Monitor);
+                }
+                GameEvents.InvokeUpdateTick(this.Monitor);
                 if (this.CurrentUpdateTick % 2 == 0)
                     GameEvents.InvokeSecondUpdateTick(this.Monitor);
                 if (this.CurrentUpdateTick % 4 == 0)
@@ -725,7 +728,7 @@ namespace StardewModdingAPI.Framework
                         }
                         if (Game1.overlayMenu != null)
                         {
-                            Game1.spriteBatch.Begin(SpriteSortMode.Deferred, BlendState.AlphaBlend, SamplerState.PointClamp, (DepthStencilState) null, (RasterizerState) null);
+                            Game1.spriteBatch.Begin(SpriteSortMode.Deferred, BlendState.AlphaBlend, SamplerState.PointClamp, (DepthStencilState)null, (RasterizerState)null);
                             Game1.overlayMenu.draw(Game1.spriteBatch);
                             Game1.spriteBatch.End();
                         }
@@ -759,7 +762,7 @@ namespace StardewModdingAPI.Framework
                         }
                         if (Game1.overlayMenu != null)
                         {
-                            Game1.spriteBatch.Begin(SpriteSortMode.Deferred, BlendState.AlphaBlend, SamplerState.PointClamp, (DepthStencilState) null, (RasterizerState) null);
+                            Game1.spriteBatch.Begin(SpriteSortMode.Deferred, BlendState.AlphaBlend, SamplerState.PointClamp, (DepthStencilState)null, (RasterizerState)null);
                             Game1.overlayMenu.draw(Game1.spriteBatch);
                             Game1.spriteBatch.End();
                         }
@@ -793,7 +796,7 @@ namespace StardewModdingAPI.Framework
                         }
                         if (Game1.overlayMenu != null)
                         {
-                            Game1.spriteBatch.Begin(SpriteSortMode.Deferred, BlendState.AlphaBlend, SamplerState.PointClamp, (DepthStencilState) null, (RasterizerState) null);
+                            Game1.spriteBatch.Begin(SpriteSortMode.Deferred, BlendState.AlphaBlend, SamplerState.PointClamp, (DepthStencilState)null, (RasterizerState)null);
                             Game1.overlayMenu.draw(Game1.spriteBatch);
                             Game1.spriteBatch.End();
                         }
@@ -826,7 +829,7 @@ namespace StardewModdingAPI.Framework
                         }
                         if (Game1.overlayMenu != null)
                         {
-                            Game1.spriteBatch.Begin(SpriteSortMode.Deferred, BlendState.AlphaBlend, SamplerState.PointClamp, (DepthStencilState) null, (RasterizerState) null);
+                            Game1.spriteBatch.Begin(SpriteSortMode.Deferred, BlendState.AlphaBlend, SamplerState.PointClamp, (DepthStencilState)null, (RasterizerState)null);
                             Game1.overlayMenu.draw(Game1.spriteBatch);
                             Game1.spriteBatch.End();
                         }