switch to simpler approach for mod-provided APIs (#409)

9 files changed, 40 insertions, 88 deletions

diff --git a/src/SMAPI/Framework/IModMetadata.cs b/src/SMAPI/Framework/IModMetadata.cs
index c4be7daf..a36994fd 100644
--- a/src/SMAPI/Framework/IModMetadata.cs
+++ b/src/SMAPI/Framework/IModMetadata.cs
@@ -31,7 +31,7 @@ namespace StardewModdingAPI.Framework
         IMod Mod { get; }
 
         /// <summary>The mod-provided API (if any).</summary>
-        IModProvidedApi Api { get; }
+        object Api { get; }
 
 
         /*********
@@ -45,7 +45,10 @@ namespace StardewModdingAPI.Framework
 
         /// <summary>Set the mod instance.</summary>
         /// <param name="mod">The mod instance to set.</param>
-        /// <param name="api">The mod-provided API (if any).</param>
-        IModMetadata SetMod(IMod mod, IModProvidedApi api);
+        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 340205f3..949d986a 100644
--- a/src/SMAPI/Framework/ModHelpers/ModRegistryHelper.cs
+++ b/src/SMAPI/Framework/ModHelpers/ModRegistryHelper.cs
@@ -47,7 +47,7 @@ namespace StardewModdingAPI.Framework.ModHelpers
         }
 
         /// <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 IModProvidedApi GetApi(string uniqueID)
+        public object GetApi(string uniqueID)
         {
             return this.Registry.Get(uniqueID)?.Api;
         }
diff --git a/src/SMAPI/Framework/ModLoading/ModMetadata.cs b/src/SMAPI/Framework/ModLoading/ModMetadata.cs
index 2e5c27be..30fe211b 100644
--- a/src/SMAPI/Framework/ModLoading/ModMetadata.cs
+++ b/src/SMAPI/Framework/ModLoading/ModMetadata.cs
@@ -30,7 +30,7 @@ namespace StardewModdingAPI.Framework.ModLoading
         public IMod Mod { get; private set; }
 
         /// <summary>The mod-provided API (if any).</summary>
-        public IModProvidedApi Api { get; private set; }
+        public object Api { get; private set; }
 
 
         /*********
@@ -62,10 +62,16 @@ namespace StardewModdingAPI.Framework.ModLoading
 
         /// <summary>Set the mod instance.</summary>
         /// <param name="mod">The mod instance to set.</param>
-        /// <param name="api">The mod-provided API (if any).</param>
-        public IModMetadata SetMod(IMod mod, IModProvidedApi api)
+        public IModMetadata SetMod(IMod mod)
         {
             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/IMod.cs b/src/SMAPI/IMod.cs
index 35ac7c0f..44ef32c9 100644
--- a/src/SMAPI/IMod.cs
+++ b/src/SMAPI/IMod.cs
@@ -1,4 +1,4 @@
-namespace StardewModdingAPI
+namespace StardewModdingAPI
 {
     /// <summary>The implementation for a Stardew Valley mod.</summary>
     public interface IMod
@@ -22,5 +22,8 @@
         /// <summary>The mod entry point, called after the mod is first loaded.</summary>
         /// <param name="helper">Provides simplified APIs for writing mods.</param>
         void Entry(IModHelper helper);
+
+        /// <summary>Get an API that other mods can access. This is always called after <see cref="Entry"/>.</summary>
+        object GetApi();
     }
-}
\ No newline at end of file
+}
diff --git a/src/SMAPI/IModProvidedApi.cs b/src/SMAPI/IModProvidedApi.cs
deleted file mode 100644
index 9884ca78..00000000
--- a/src/SMAPI/IModProvidedApi.cs
+++ /dev/null
@@ -1,6 +0,0 @@
-namespace StardewModdingAPI
-{
-    /// <summary>An API provided by a mod for other mods to use.</summary>
-    /// <remarks>This is a marker interface. Each mod can only have one implementation of <see cref="IModProvidedApi"/>.</remarks>
-    public interface IModProvidedApi { }
-}
diff --git a/src/SMAPI/IModRegistry.cs b/src/SMAPI/IModRegistry.cs
index fd71d72a..f84cfcfb 100644
--- a/src/SMAPI/IModRegistry.cs
+++ b/src/SMAPI/IModRegistry.cs
@@ -19,6 +19,6 @@ namespace StardewModdingAPI
 
         /// <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>
         /// <param name="uniqueID">The mod's unique ID.</param>
-        IModProvidedApi GetApi(string uniqueID);
+        object GetApi(string uniqueID);
     }
 }
diff --git a/src/SMAPI/Mod.cs b/src/SMAPI/Mod.cs
index ee75ba54..3a753afc 100644
--- a/src/SMAPI/Mod.cs
+++ b/src/SMAPI/Mod.cs
@@ -25,6 +25,9 @@ namespace StardewModdingAPI
         /// <param name="helper">Provides simplified APIs for writing mods.</param>
         public abstract void Entry(IModHelper helper);
 
+        /// <summary>Get an API that other mods can access. This is always called after <see cref="Entry"/>.</summary>
+        public virtual object GetApi() => null;
+
         /// <summary>Release or reset unmanaged resources.</summary>
         public void Dispose()
         {
diff --git a/src/SMAPI/Program.cs b/src/SMAPI/Program.cs
index 6330cc1a..e7552630 100644
--- a/src/SMAPI/Program.cs
+++ b/src/SMAPI/Program.cs
@@ -711,11 +711,9 @@ namespace StardewModdingAPI
                             modHelper = new ModHelper(manifest.UniqueID, metadata.DirectoryPath, jsonHelper, contentHelper, commandHelper, modRegistryHelper, reflectionHelper, translationHelper);
                         }
 
-                        // get mod instances
+                        // get mod instance
                         if (!this.TryLoadModEntry(modAssembly, error => TrackSkip(metadata, error), out Mod mod))
                             continue;
-                        if (this.TryLoadModProvidedApi(modAssembly, modHelper, monitor, error => this.Monitor.Log($"Failed loading {metadata.DisplayName}'s mod-provided API. Integrations may not work correctly. Error: {error}", LogLevel.Warn), out IModProvidedApi api))
-                            this.Monitor.Log($"   Found mod-provided API ({api.GetType().FullName}).", LogLevel.Trace);
 
                         // init mod
                         mod.ModManifest = manifest;
@@ -723,7 +721,7 @@ namespace StardewModdingAPI
                         mod.Monitor = monitor;
 
                         // track mod
-                        metadata.SetMod(mod, api);
+                        metadata.SetMod(mod);
                         this.ModRegistry.Add(metadata);
                     }
                     catch (Exception ex)
@@ -796,6 +794,19 @@ namespace StardewModdingAPI
                 {
                     this.Monitor.Log($"{metadata.DisplayName} failed on entry and might not work correctly. Technical details:\n{ex.GetLogSummary()}", LogLevel.Error);
                 }
+
+                // get mod API
+                try
+                {
+                    object api = metadata.Mod.GetApi();
+                    if (api != null)
+                        this.Monitor.Log($"   Found mod-provided API ({api.GetType().FullName}).", LogLevel.Trace);
+                    metadata.SetApi(api);
+                }
+                catch (Exception ex)
+                {
+                    this.Monitor.Log($"Failed loading mod-provided API for {metadata.DisplayName}. Integrations with other mods may not work. Error: {ex.GetLogSummary()}", LogLevel.Error);
+                }
             }
 
             // invalidate cache entries when needed
@@ -865,73 +876,6 @@ namespace StardewModdingAPI
             return true;
         }
 
-        /// <summary>Load a mod's <see cref="IModProvidedApi"/> implementation.</summary>
-        /// <param name="modAssembly">The mod assembly.</param>
-        /// <param name="modHelper">The mod's helper instance.</param>
-        /// <param name="monitor">The mod's monitor instance.</param>
-        /// <param name="onError">A callback invoked when loading fails.</param>
-        /// <param name="api">The loaded instance.</param>
-        private bool TryLoadModProvidedApi(Assembly modAssembly, IModHelper modHelper, IMonitor monitor, Action<string> onError, out IModProvidedApi api)
-        {
-            api = null;
-
-            // find type
-            TypeInfo[] apis = modAssembly.DefinedTypes.Where(type => typeof(IModProvidedApi).IsAssignableFrom(type) && !type.IsAbstract).Take(2).ToArray();
-            if (apis.Length == 0)
-                return false;
-            if (apis.Length > 1)
-            {
-                onError($"its DLL contains multiple '{nameof(IModProvidedApi)}' implementations.");
-                return false;
-            }
-
-            // get constructor
-            ConstructorInfo constructor = (
-                from constr in apis[0].GetConstructors()
-                let args = constr.GetParameters()
-                where
-                    !args.Any()
-                    || args.All(arg => typeof(IModHelper).IsAssignableFrom(arg.ParameterType) || typeof(IMonitor).IsAssignableFrom(arg.ParameterType))
-                orderby args.Length descending
-                select constr
-            ).FirstOrDefault();
-            if (constructor == null)
-            {
-                onError($"its {nameof(IModProvidedApi)} must have a constructor with zero arguments, or only arguments of type {nameof(IModHelper)} or {nameof(IMonitor)}.");
-                return false;
-            }
-
-            // construct instance
-            try
-            {
-                // prepare constructor args
-                ParameterInfo[] args = constructor.GetParameters();
-                object[] values = new object[args.Length];
-                for (int i = 0; i < args.Length; i++)
-                {
-                    if (typeof(IModHelper).IsAssignableFrom(args[i].ParameterType))
-                        values[i] = modHelper;
-                    else if (typeof(IMonitor).IsAssignableFrom(args[i].ParameterType))
-                        values[i] = monitor;
-                    else
-                    {
-                        // shouldn't happen
-                        onError($"its {nameof(IModProvidedApi)} instance's constructor has unexpected argument type {args[i].ParameterType.FullName}.");
-                        return false;
-                    }
-                }
-
-                // instantiate
-                api = (IModProvidedApi)constructor.Invoke(values);
-                return true;
-            }
-            catch (Exception ex)
-            {
-                onError($"its {nameof(IModProvidedApi)} couldn't be constructed: {ex.GetLogSummary()}");
-                return false;
-            }
-        }
-
         /// <summary>Reload translations for all mods.</summary>
         private void ReloadTranslations()
         {
diff --git a/src/SMAPI/StardewModdingAPI.csproj b/src/SMAPI/StardewModdingAPI.csproj
index 579ed487..0db94843 100644
--- a/src/SMAPI/StardewModdingAPI.csproj
+++ b/src/SMAPI/StardewModdingAPI.csproj
@@ -114,7 +114,6 @@
     <Compile Include="IReflectedField.cs" />
     <Compile Include="IReflectedMethod.cs" />
     <Compile Include="IReflectedProperty.cs" />
-    <Compile Include="IModProvidedApi.cs" />
     <Compile Include="Metadata\CoreAssets.cs" />
     <Compile Include="ContentSource.cs" />
     <Compile Include="Events\ContentEvents.cs" />