refactor content API to fix load errors with decentralised cache (#524)

11 files changed, 966 insertions, 709 deletions

diff --git a/src/SMAPI/Framework/ContentCoordinator.cs b/src/SMAPI/Framework/ContentCoordinator.cs
index 397a9d90..c2614001 100644
--- a/src/SMAPI/Framework/ContentCoordinator.cs
+++ b/src/SMAPI/Framework/ContentCoordinator.cs
@@ -5,10 +5,14 @@ using System.IO;
 using System.Linq;
 using System.Reflection;
 using Microsoft.Xna.Framework.Content;
+using Microsoft.Xna.Framework.Graphics;
 using StardewModdingAPI.Framework.Content;
+using StardewModdingAPI.Framework.ContentManagers;
 using StardewModdingAPI.Framework.Reflection;
+using StardewModdingAPI.Framework.Utilities;
 using StardewModdingAPI.Metadata;
 using StardewValley;
+using xTile;
 
 namespace StardewModdingAPI.Framework
 {
@@ -18,6 +22,9 @@ namespace StardewModdingAPI.Framework
         /*********
         ** Properties
         *********/
+        /// <summary>An asset key prefix for assets from SMAPI mod folders.</summary>
+        private readonly string ManagedPrefix = "SMAPI";
+
         /// <summary>Encapsulates monitoring and logging.</summary>
         private readonly IMonitor Monitor;
 
@@ -28,7 +35,7 @@ namespace StardewModdingAPI.Framework
         private readonly Reflector Reflection;
 
         /// <summary>The loaded content managers (including the <see cref="MainContentManager"/>).</summary>
-        private readonly IList<SContentManager> ContentManagers = new List<SContentManager>();
+        private readonly IList<IContentManager> ContentManagers = new List<IContentManager>();
 
         /// <summary>Whether the content coordinator has been disposed.</summary>
         private bool IsDisposed;
@@ -38,7 +45,7 @@ namespace StardewModdingAPI.Framework
         ** Accessors
         *********/
         /// <summary>The primary content manager used for most assets.</summary>
-        public SContentManager MainContentManager { get; private set; }
+        public GameContentManager MainContentManager { get; private set; }
 
         /// <summary>The current language as a constant.</summary>
         public LocalizedContentManager.LanguageCode Language => this.MainContentManager.Language;
@@ -68,28 +75,110 @@ namespace StardewModdingAPI.Framework
             this.Reflection = reflection;
             this.FullRootDirectory = Path.Combine(Constants.ExecutionPath, rootDirectory);
             this.ContentManagers.Add(
-                this.MainContentManager = new SContentManager("Game1.content", serviceProvider, rootDirectory, currentCulture, this, monitor, reflection, this.OnDisposing, isModFolder: false)
+                this.MainContentManager = new GameContentManager("Game1.content", serviceProvider, rootDirectory, currentCulture, this, monitor, reflection, this.OnDisposing)
             );
-            this.CoreAssets = new CoreAssetPropagator(this.MainContentManager.NormaliseAssetName, reflection);
+            this.CoreAssets = new CoreAssetPropagator(this.MainContentManager.AssertAndNormaliseAssetName, reflection);
+        }
+
+        /// <summary>Get a new content manager which handles reading files from the game content folder with support for interception.</summary>
+        /// <param name="name">A name for the mod manager. Not guaranteed to be unique.</param>
+        public GameContentManager CreateGameContentManager(string name)
+        {
+            GameContentManager manager = new GameContentManager(name, this.MainContentManager.ServiceProvider, this.MainContentManager.RootDirectory, this.MainContentManager.CurrentCulture, this, this.Monitor, this.Reflection, this.OnDisposing);
+            this.ContentManagers.Add(manager);
+            return manager;
         }
 
-        /// <summary>Get a new content manager which defers loading to the content core.</summary>
+        /// <summary>Get a new content manager which handles reading files from a SMAPI mod folder with support for unpacked files.</summary>
         /// <param name="name">A name for the mod manager. Not guaranteed to be unique.</param>
-        /// <param name="isModFolder">Whether this content manager is wrapped around a mod folder.</param>
-        /// <param name="rootDirectory">The root directory to search for content (or <c>null</c>. for the default)</param>
-        public SContentManager CreateContentManager(string name, bool isModFolder, string rootDirectory = null)
+        /// <param name="rootDirectory">The root directory to search for content (or <c>null</c> for the default).</param>
+        public ModContentManager CreateModContentManager(string name, string rootDirectory)
         {
-            SContentManager manager = new SContentManager(name, this.MainContentManager.ServiceProvider, rootDirectory ?? this.MainContentManager.RootDirectory, this.MainContentManager.CurrentCulture, this, this.Monitor, this.Reflection, this.OnDisposing, isModFolder);
+            ModContentManager manager = new ModContentManager(name, this.MainContentManager.ServiceProvider, rootDirectory, this.MainContentManager.CurrentCulture, this, this.Monitor, this.Reflection, this.OnDisposing);
             this.ContentManagers.Add(manager);
             return manager;
         }
 
         /// <summary>Get the current content locale.</summary>
-        public string GetLocale() => this.MainContentManager.GetLocale(LocalizedContentManager.CurrentLanguageCode);
+        public string GetLocale()
+        {
+            return this.MainContentManager.GetLocale(LocalizedContentManager.CurrentLanguageCode);
+        }
+
+        /// <summary>Get whether this asset is mapped to a mod folder.</summary>
+        /// <param name="key">The asset key.</param>
+        public bool IsManagedAssetKey(string key)
+        {
+            return key.StartsWith(this.ManagedPrefix);
+        }
+
+        /// <summary>Parse a managed SMAPI asset key which maps to a mod folder.</summary>
+        /// <param name="key">The asset key.</param>
+        /// <param name="contentManagerID">The unique name for the content manager which should load this asset.</param>
+        /// <param name="relativePath">The relative path within the mod folder.</param>
+        /// <returns>Returns whether the asset was parsed successfully.</returns>
+        public bool TryParseManagedAssetKey(string key, out string contentManagerID, out string relativePath)
+        {
+            contentManagerID = null;
+            relativePath = null;
+
+            // not a managed asset
+            if (!key.StartsWith(this.ManagedPrefix))
+                return false;
 
-        /// <summary>Convert an absolute file path into a appropriate asset name.</summary>
-        /// <param name="absolutePath">The absolute path to the file.</param>
-        public string GetAssetNameFromFilePath(string absolutePath) => this.MainContentManager.GetAssetNameFromFilePath(absolutePath, ContentSource.GameContent);
+            // parse
+            string[] parts = PathUtilities.GetSegments(key, 3);
+            if (parts.Length != 3) // managed key prefix, mod id, relative path
+                return false;
+            contentManagerID = Path.Combine(parts[0], parts[1]);
+            relativePath = parts[2];
+            return true;
+        }
+
+        /// <summary>Get the managed asset key prefix for a mod.</summary>
+        /// <param name="modID">The mod's unique ID.</param>
+        public string GetManagedAssetPrefix(string modID)
+        {
+            return Path.Combine(this.ManagedPrefix, modID.ToLower());
+        }
+
+        /// <summary>Get a copy of an asset from a mod folder.</summary>
+        /// <typeparam name="T">The asset type.</typeparam>
+        /// <param name="internalKey">The internal asset key.</param>
+        /// <param name="contentManagerID">The unique name for the content manager which should load this asset.</param>
+        /// <param name="relativePath">The internal SMAPI asset key.</param>
+        /// <param name="language">The language code for which to load content.</param>
+        public T LoadAndCloneManagedAsset<T>(string internalKey, string contentManagerID, string relativePath, LocalizedContentManager.LanguageCode language)
+        {
+            // get content manager
+            IContentManager contentManager = this.ContentManagers.FirstOrDefault(p => p.Name == contentManagerID);
+            if (contentManager == null)
+                throw new InvalidOperationException($"The '{contentManagerID}' prefix isn't handled by any mod.");
+
+            // get cloned asset
+            T data = contentManager.Load<T>(internalKey, language);
+            switch (data as object)
+            {
+                case Texture2D source:
+                    {
+                        int[] pixels = new int[source.Width * source.Height];
+                        source.GetData(pixels);
+
+                        Texture2D clone = new Texture2D(source.GraphicsDevice, source.Width, source.Height);
+                        clone.SetData(pixels);
+                        return (T)(object)clone;
+                    }
+
+                case Dictionary<string, string> source:
+                    return (T)(object)new Dictionary<string, string>(source);
+
+                case Dictionary<int, string> source:
+                    return (T)(object)new Dictionary<int, string>(source);
+
+                default:
+                    return data;
+            }
+        }
 
         /// <summary>Purge assets from the cache that match one of the interceptors.</summary>
         /// <param name="editors">The asset editors for which to purge matching assets.</param>
@@ -129,7 +218,7 @@ namespace StardewModdingAPI.Framework
             string locale = this.GetLocale();
             return this.InvalidateCache((assetName, type) =>
             {
-                IAssetInfo info = new AssetInfo(locale, assetName, type, this.MainContentManager.NormaliseAssetName);
+                IAssetInfo info = new AssetInfo(locale, assetName, type, this.MainContentManager.AssertAndNormaliseAssetName);
                 return predicate(info);
             });
         }
@@ -142,7 +231,7 @@ namespace StardewModdingAPI.Framework
         {
             // invalidate cache
             HashSet<string> removedAssetNames = new HashSet<string>();
-            foreach (SContentManager contentManager in this.ContentManagers)
+            foreach (IContentManager contentManager in this.ContentManagers)
             {
                 foreach (string name in contentManager.InvalidateCache(predicate, dispose))
                     removedAssetNames.Add(name);
@@ -172,7 +261,7 @@ namespace StardewModdingAPI.Framework
             this.IsDisposed = true;
 
             this.Monitor.Log("Disposing the content coordinator. Content managers will no longer be usable after this point.", LogLevel.Trace);
-            foreach (SContentManager contentManager in this.ContentManagers)
+            foreach (IContentManager contentManager in this.ContentManagers)
                 contentManager.Dispose();
             this.ContentManagers.Clear();
             this.MainContentManager = null;
@@ -184,7 +273,7 @@ namespace StardewModdingAPI.Framework
         *********/
         /// <summary>A callback invoked when a content manager is disposed.</summary>
         /// <param name="contentManager">The content manager being disposed.</param>
-        private void OnDisposing(SContentManager contentManager)
+        private void OnDisposing(IContentManager contentManager)
         {
             if (this.IsDisposed)
                 return;
diff --git a/src/SMAPI/Framework/ContentManagers/BaseContentManager.cs b/src/SMAPI/Framework/ContentManagers/BaseContentManager.cs
new file mode 100644
index 00000000..ff0e2de4
--- /dev/null
+++ b/src/SMAPI/Framework/ContentManagers/BaseContentManager.cs
@@ -0,0 +1,268 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using System.Diagnostics.Contracts;
+using System.Globalization;
+using System.IO;
+using System.Linq;
+using Microsoft.Xna.Framework.Content;
+using StardewModdingAPI.Framework.Content;
+using StardewModdingAPI.Framework.Exceptions;
+using StardewModdingAPI.Framework.Reflection;
+using StardewValley;
+
+namespace StardewModdingAPI.Framework.ContentManagers
+{
+    /// <summary>A content manager which handles reading files from a SMAPI mod folder with support for unpacked files.</summary>
+    internal abstract class BaseContentManager : LocalizedContentManager, IContentManager
+    {
+        /*********
+        ** Properties
+        *********/
+        /// <summary>The central coordinator which manages content managers.</summary>
+        protected readonly ContentCoordinator Coordinator;
+
+        /// <summary>The underlying asset cache.</summary>
+        protected readonly ContentCache Cache;
+
+        /// <summary>Encapsulates monitoring and logging.</summary>
+        protected readonly IMonitor Monitor;
+
+        /// <summary>Whether the content coordinator has been disposed.</summary>
+        private bool IsDisposed;
+
+        /// <summary>The language enum values indexed by locale code.</summary>
+        private readonly IDictionary<string, LanguageCode> LanguageCodes;
+
+        /// <summary>A callback to invoke when the content manager is being disposed.</summary>
+        private readonly Action<BaseContentManager> OnDisposing;
+
+
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>A name for the mod manager. Not guaranteed to be unique.</summary>
+        public string Name { get; }
+
+        /// <summary>The current language as a constant.</summary>
+        public LanguageCode Language => this.GetCurrentLanguage();
+
+        /// <summary>The absolute path to the <see cref="ContentManager.RootDirectory"/>.</summary>
+        public string FullRootDirectory => Path.Combine(Constants.ExecutionPath, this.RootDirectory);
+
+        /// <summary>Whether this content manager is for a mod folder.</summary>
+        public bool IsModContentManager { get; }
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="name">A name for the mod manager. Not guaranteed to be unique.</param>
+        /// <param name="serviceProvider">The service provider to use to locate services.</param>
+        /// <param name="rootDirectory">The root directory to search for content.</param>
+        /// <param name="currentCulture">The current culture for which to localise content.</param>
+        /// <param name="coordinator">The central coordinator which manages content managers.</param>
+        /// <param name="monitor">Encapsulates monitoring and logging.</param>
+        /// <param name="reflection">Simplifies access to private code.</param>
+        /// <param name="onDisposing">A callback to invoke when the content manager is being disposed.</param>
+        /// <param name="isModFolder">Whether this content manager is for a mod folder.</param>
+        protected BaseContentManager(string name, IServiceProvider serviceProvider, string rootDirectory, CultureInfo currentCulture, ContentCoordinator coordinator, IMonitor monitor, Reflector reflection, Action<BaseContentManager> onDisposing, bool isModFolder)
+                : base(serviceProvider, rootDirectory, currentCulture)
+        {
+            // init
+            this.Name = name;
+            this.Coordinator = coordinator ?? throw new ArgumentNullException(nameof(coordinator));
+            this.Cache = new ContentCache(this, reflection);
+            this.Monitor = monitor ?? throw new ArgumentNullException(nameof(monitor));
+            this.OnDisposing = onDisposing;
+            this.IsModContentManager = isModFolder;
+
+            // get asset data
+            this.LanguageCodes = this.GetKeyLocales().ToDictionary(p => p.Value, p => p.Key, StringComparer.InvariantCultureIgnoreCase);
+        }
+
+        /// <summary>Load an asset that has been processed by the content pipeline.</summary>
+        /// <typeparam name="T">The type of asset to load.</typeparam>
+        /// <param name="assetName">The asset path relative to the loader root directory, not including the <c>.xnb</c> extension.</param>
+        public override T Load<T>(string assetName)
+        {
+            return this.Load<T>(assetName, LocalizedContentManager.CurrentLanguageCode);
+        }
+
+        /// <summary>Load the base asset without localisation.</summary>
+        /// <typeparam name="T">The type of asset to load.</typeparam>
+        /// <param name="assetName">The asset path relative to the loader root directory, not including the <c>.xnb</c> extension.</param>
+        public override T LoadBase<T>(string assetName)
+        {
+            return this.Load<T>(assetName, LanguageCode.en);
+        }
+
+        /// <summary>Inject an asset into the cache.</summary>
+        /// <typeparam name="T">The type of asset to inject.</typeparam>
+        /// <param name="assetName">The asset path relative to the loader root directory, not including the <c>.xnb</c> extension.</param>
+        /// <param name="value">The asset value.</param>
+        public void Inject<T>(string assetName, T value)
+        {
+            assetName = this.AssertAndNormaliseAssetName(assetName);
+            this.Cache[assetName] = value;
+
+        }
+
+        /// <summary>Normalise path separators in a file path. For asset keys, see <see cref="AssertAndNormaliseAssetName"/> instead.</summary>
+        /// <param name="path">The file path to normalise.</param>
+        [Pure]
+        public string NormalisePathSeparators(string path)
+        {
+            return this.Cache.NormalisePathSeparators(path);
+        }
+
+        /// <summary>Assert that the given key has a valid format and return a normalised form consistent with the underlying cache.</summary>
+        /// <param name="assetName">The asset key to check.</param>
+        /// <exception cref="SContentLoadException">The asset key is empty or contains invalid characters.</exception>
+        [SuppressMessage("ReSharper", "ParameterOnlyUsedForPreconditionCheck.Local", Justification = "Parameter is only used for assertion checks by design.")]
+        public string AssertAndNormaliseAssetName(string assetName)
+        {
+            // NOTE: the game checks for ContentLoadException to handle invalid keys, so avoid
+            // throwing other types like ArgumentException here.
+            if (string.IsNullOrWhiteSpace(assetName))
+                throw new SContentLoadException("The asset key or local path is empty.");
+            if (assetName.Intersect(Path.GetInvalidPathChars()).Any())
+                throw new SContentLoadException("The asset key or local path contains invalid characters.");
+
+            return this.Cache.NormaliseKey(assetName);
+        }
+
+        /****
+        ** Content loading
+        ****/
+        /// <summary>Get the current content locale.</summary>
+        public string GetLocale()
+        {
+            return this.GetLocale(this.GetCurrentLanguage());
+        }
+
+        /// <summary>The locale for a language.</summary>
+        /// <param name="language">The language.</param>
+        public string GetLocale(LanguageCode language)
+        {
+            return this.LanguageCodeString(language);
+        }
+
+        /// <summary>Get whether the content manager has already loaded and cached the given asset.</summary>
+        /// <param name="assetName">The asset path relative to the loader root directory, not including the <c>.xnb</c> extension.</param>
+        public bool IsLoaded(string assetName)
+        {
+            assetName = this.Cache.NormaliseKey(assetName);
+            return this.IsNormalisedKeyLoaded(assetName);
+        }
+
+        /// <summary>Get the cached asset keys.</summary>
+        public IEnumerable<string> GetAssetKeys()
+        {
+            return this.Cache.Keys
+                .Select(this.GetAssetName)
+                .Distinct();
+        }
+
+        /****
+        ** Cache invalidation
+        ****/
+        /// <summary>Purge matched assets from the cache.</summary>
+        /// <param name="predicate">Matches the asset keys to invalidate.</param>
+        /// <param name="dispose">Whether to dispose invalidated assets. This should only be <c>true</c> when they're being invalidated as part of a dispose, to avoid crashing the game.</param>
+        /// <returns>Returns the number of invalidated assets.</returns>
+        public IEnumerable<string> InvalidateCache(Func<string, Type, bool> predicate, bool dispose = false)
+        {
+            HashSet<string> removeAssetNames = new HashSet<string>(StringComparer.InvariantCultureIgnoreCase);
+            this.Cache.Remove((key, type) =>
+            {
+                this.ParseCacheKey(key, out string assetName, out _);
+
+                if (removeAssetNames.Contains(assetName) || predicate(assetName, type))
+                {
+                    removeAssetNames.Add(assetName);
+                    return true;
+                }
+                return false;
+            });
+
+            return removeAssetNames;
+        }
+
+        /// <summary>Dispose held resources.</summary>
+        /// <param name="isDisposing">Whether the content manager is being disposed (rather than finalized).</param>
+        protected override void Dispose(bool isDisposing)
+        {
+            if (this.IsDisposed)
+                return;
+            this.IsDisposed = true;
+
+            this.OnDisposing(this);
+            base.Dispose(isDisposing);
+        }
+
+        /// <inheritdoc />
+        public override void Unload()
+        {
+            if (this.IsDisposed)
+                return; // base logic doesn't allow unloading twice, which happens due to SMAPI and the game both unloading
+
+            base.Unload();
+        }
+
+
+        /*********
+        ** Private methods
+        *********/
+        /// <summary>Get the locale codes (like <c>ja-JP</c>) used in asset keys.</summary>
+        private IDictionary<LanguageCode, string> GetKeyLocales()
+        {
+            // create locale => code map
+            IDictionary<LanguageCode, string> map = new Dictionary<LanguageCode, string>();
+            foreach (LanguageCode code in Enum.GetValues(typeof(LanguageCode)))
+                map[code] = this.GetLocale(code);
+
+            return map;
+        }
+
+        /// <summary>Get the asset name from a cache key.</summary>
+        /// <param name="cacheKey">The input cache key.</param>
+        private string GetAssetName(string cacheKey)
+        {
+            this.ParseCacheKey(cacheKey, out string assetName, out string _);
+            return assetName;
+        }
+
+        /// <summary>Parse a cache key into its component parts.</summary>
+        /// <param name="cacheKey">The input cache key.</param>
+        /// <param name="assetName">The original asset name.</param>
+        /// <param name="localeCode">The asset locale code (or <c>null</c> if not localised).</param>
+        protected void ParseCacheKey(string cacheKey, out string assetName, out string localeCode)
+        {
+            // handle localised key
+            if (!string.IsNullOrWhiteSpace(cacheKey))
+            {
+                int lastSepIndex = cacheKey.LastIndexOf(".", StringComparison.InvariantCulture);
+                if (lastSepIndex >= 0)
+                {
+                    string suffix = cacheKey.Substring(lastSepIndex + 1, cacheKey.Length - lastSepIndex - 1);
+                    if (this.LanguageCodes.ContainsKey(suffix))
+                    {
+                        assetName = cacheKey.Substring(0, lastSepIndex);
+                        localeCode = cacheKey.Substring(lastSepIndex + 1, cacheKey.Length - lastSepIndex - 1);
+                        return;
+                    }
+                }
+            }
+
+            // handle simple key
+            assetName = cacheKey;
+            localeCode = null;
+        }
+
+        /// <summary>Get whether an asset has already been loaded.</summary>
+        /// <param name="normalisedAssetName">The normalised asset name.</param>
+        protected abstract bool IsNormalisedKeyLoaded(string normalisedAssetName);
+    }
+}
diff --git a/src/SMAPI/Framework/ContentManagers/GameContentManager.cs b/src/SMAPI/Framework/ContentManagers/GameContentManager.cs
new file mode 100644
index 00000000..cfedb5af
--- /dev/null
+++ b/src/SMAPI/Framework/ContentManagers/GameContentManager.cs
@@ -0,0 +1,252 @@
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.Linq;
+using StardewModdingAPI.Framework.Content;
+using StardewModdingAPI.Framework.Reflection;
+using StardewModdingAPI.Framework.Utilities;
+using StardewValley;
+
+namespace StardewModdingAPI.Framework.ContentManagers
+{
+    /// <summary>A content manager which handles reading files from the game content folder with support for interception.</summary>
+    internal class GameContentManager : BaseContentManager
+    {
+        /*********
+        ** Properties
+        *********/
+        /// <summary>The assets currently being intercepted by <see cref="IAssetLoader"/> instances. This is used to prevent infinite loops when a loader loads a new asset.</summary>
+        private readonly ContextHash<string> AssetsBeingLoaded = new ContextHash<string>();
+
+        /// <summary>Interceptors which provide the initial versions of matching assets.</summary>
+        private IDictionary<IModMetadata, IList<IAssetLoader>> Loaders => this.Coordinator.Loaders;
+
+        /// <summary>Interceptors which edit matching assets after they're loaded.</summary>
+        private IDictionary<IModMetadata, IList<IAssetEditor>> Editors => this.Coordinator.Editors;
+
+        /// <summary>A lookup which indicates whether the asset is localisable (i.e. the filename contains the locale), if previously loaded.</summary>
+        private readonly IDictionary<string, bool> IsLocalisableLookup;
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="name">A name for the mod manager. Not guaranteed to be unique.</param>
+        /// <param name="serviceProvider">The service provider to use to locate services.</param>
+        /// <param name="rootDirectory">The root directory to search for content.</param>
+        /// <param name="currentCulture">The current culture for which to localise content.</param>
+        /// <param name="coordinator">The central coordinator which manages content managers.</param>
+        /// <param name="monitor">Encapsulates monitoring and logging.</param>
+        /// <param name="reflection">Simplifies access to private code.</param>
+        /// <param name="onDisposing">A callback to invoke when the content manager is being disposed.</param>
+        public GameContentManager(string name, IServiceProvider serviceProvider, string rootDirectory, CultureInfo currentCulture, ContentCoordinator coordinator, IMonitor monitor, Reflector reflection, Action<BaseContentManager> onDisposing)
+            : base(name, serviceProvider, rootDirectory, currentCulture, coordinator, monitor, reflection, onDisposing, isModFolder: false)
+        {
+            this.IsLocalisableLookup = reflection.GetField<IDictionary<string, bool>>(this, "_localizedAsset").GetValue();
+        }
+
+        /// <summary>Load an asset that has been processed by the content pipeline.</summary>
+        /// <typeparam name="T">The type of asset to load.</typeparam>
+        /// <param name="assetName">The asset path relative to the loader root directory, not including the <c>.xnb</c> extension.</param>
+        /// <param name="language">The language code for which to load content.</param>
+        public override T Load<T>(string assetName, LanguageCode language)
+        {
+            assetName = this.AssertAndNormaliseAssetName(assetName);
+
+            // get from cache
+            if (this.IsLoaded(assetName))
+                return base.Load<T>(assetName, language);
+
+            // get managed asset
+            if (this.Coordinator.TryParseManagedAssetKey(assetName, out string contentManagerID, out string relativePath))
+            {
+                T managedAsset = this.Coordinator.LoadAndCloneManagedAsset<T>(assetName, contentManagerID, relativePath, language);
+                this.Inject(assetName, managedAsset);
+                return managedAsset;
+            }
+
+            // load asset
+            T data;
+            if (this.AssetsBeingLoaded.Contains(assetName))
+            {
+                this.Monitor.Log($"Broke loop while loading asset '{assetName}'.", LogLevel.Warn);
+                this.Monitor.Log($"Bypassing mod loaders for this asset. Stack trace:\n{Environment.StackTrace}", LogLevel.Trace);
+                data = base.Load<T>(assetName, language);
+            }
+            else
+            {
+                data = this.AssetsBeingLoaded.Track(assetName, () =>
+                {
+                    string locale = this.GetLocale(language);
+                    IAssetInfo info = new AssetInfo(locale, assetName, typeof(T), this.AssertAndNormaliseAssetName);
+                    IAssetData asset =
+                        this.ApplyLoader<T>(info)
+                        ?? new AssetDataForObject(info, base.Load<T>(assetName, language), this.AssertAndNormaliseAssetName);
+                    asset = this.ApplyEditors<T>(info, asset);
+                    return (T)asset.Data;
+                });
+            }
+
+            // update cache & return data
+            this.Inject(assetName, data);
+            return data;
+        }
+
+        /// <summary>Create a new content manager for temporary use.</summary>
+        public override LocalizedContentManager CreateTemporary()
+        {
+            return this.Coordinator.CreateGameContentManager("(temporary)");
+        }
+
+
+        /*********
+        ** Private methods
+        *********/
+        /// <summary>Get whether an asset has already been loaded.</summary>
+        /// <param name="normalisedAssetName">The normalised asset name.</param>
+        protected override bool IsNormalisedKeyLoaded(string normalisedAssetName)
+        {
+            // default English
+            if (this.Language == LocalizedContentManager.LanguageCode.en || this.Coordinator.IsManagedAssetKey(normalisedAssetName))
+                return this.Cache.ContainsKey(normalisedAssetName);
+
+            // translated
+            string localeKey = $"{normalisedAssetName}.{this.GetLocale(this.GetCurrentLanguage())}";
+            if (this.IsLocalisableLookup.TryGetValue(localeKey, out bool localisable))
+            {
+                return localisable
+                    ? this.Cache.ContainsKey(localeKey)
+                    : this.Cache.ContainsKey(normalisedAssetName);
+            }
+
+            // not loaded yet
+            return false;
+        }
+
+        /// <summary>Load the initial asset from the registered <see cref="Loaders"/>.</summary>
+        /// <param name="info">The basic asset metadata.</param>
+        /// <returns>Returns the loaded asset metadata, or <c>null</c> if no loader matched.</returns>
+        private IAssetData ApplyLoader<T>(IAssetInfo info)
+        {
+            // find matching loaders
+            var loaders = this.GetInterceptors(this.Loaders)
+                .Where(entry =>
+                {
+                    try
+                    {
+                        return entry.Value.CanLoad<T>(info);
+                    }
+                    catch (Exception ex)
+                    {
+                        entry.Key.LogAsMod($"Mod failed when checking whether it could load asset '{info.AssetName}', and will be ignored. Error details:\n{ex.GetLogSummary()}", LogLevel.Error);
+                        return false;
+                    }
+                })
+                .ToArray();
+
+            // validate loaders
+            if (!loaders.Any())
+                return null;
+            if (loaders.Length > 1)
+            {
+                string[] loaderNames = loaders.Select(p => p.Key.DisplayName).ToArray();
+                this.Monitor.Log($"Multiple mods want to provide the '{info.AssetName}' asset ({string.Join(", ", loaderNames)}), but an asset can't be loaded multiple times. SMAPI will use the default asset instead; uninstall one of the mods to fix this. (Message for modders: you should usually use {typeof(IAssetEditor)} instead to avoid conflicts.)", LogLevel.Warn);
+                return null;
+            }
+
+            // fetch asset from loader
+            IModMetadata mod = loaders[0].Key;
+            IAssetLoader loader = loaders[0].Value;
+            T data;
+            try
+            {
+                data = loader.Load<T>(info);
+                this.Monitor.Log($"{mod.DisplayName} loaded asset '{info.AssetName}'.", LogLevel.Trace);
+            }
+            catch (Exception ex)
+            {
+                mod.LogAsMod($"Mod crashed when loading asset '{info.AssetName}'. SMAPI will use the default asset instead. Error details:\n{ex.GetLogSummary()}", LogLevel.Error);
+                return null;
+            }
+
+            // validate asset
+            if (data == null)
+            {
+                mod.LogAsMod($"Mod incorrectly set asset '{info.AssetName}' to a null value; ignoring override.", LogLevel.Error);
+                return null;
+            }
+
+            // return matched asset
+            return new AssetDataForObject(info, data, this.AssertAndNormaliseAssetName);
+        }
+
+        /// <summary>Apply any <see cref="Editors"/> to a loaded asset.</summary>
+        /// <typeparam name="T">The asset type.</typeparam>
+        /// <param name="info">The basic asset metadata.</param>
+        /// <param name="asset">The loaded asset.</param>
+        private IAssetData ApplyEditors<T>(IAssetInfo info, IAssetData asset)
+        {
+            IAssetData GetNewData(object data) => new AssetDataForObject(info, data, this.AssertAndNormaliseAssetName);
+
+            // edit asset
+            foreach (var entry in this.GetInterceptors(this.Editors))
+            {
+                // check for match
+                IModMetadata mod = entry.Key;
+                IAssetEditor editor = entry.Value;
+                try
+                {
+                    if (!editor.CanEdit<T>(info))
+                        continue;
+                }
+                catch (Exception ex)
+                {
+                    mod.LogAsMod($"Mod crashed when checking whether it could edit asset '{info.AssetName}', and will be ignored. Error details:\n{ex.GetLogSummary()}", LogLevel.Error);
+                    continue;
+                }
+
+                // try edit
+                object prevAsset = asset.Data;
+                try
+                {
+                    editor.Edit<T>(asset);
+                    this.Monitor.Log($"{mod.DisplayName} intercepted {info.AssetName}.", LogLevel.Trace);
+                }
+                catch (Exception ex)
+                {
+                    mod.LogAsMod($"Mod crashed when editing asset '{info.AssetName}', which may cause errors in-game. Error details:\n{ex.GetLogSummary()}", LogLevel.Error);
+                }
+
+                // validate edit
+                if (asset.Data == null)
+                {
+                    mod.LogAsMod($"Mod incorrectly set asset '{info.AssetName}' to a null value; ignoring override.", LogLevel.Warn);
+                    asset = GetNewData(prevAsset);
+                }
+                else if (!(asset.Data is T))
+                {
+                    mod.LogAsMod($"Mod incorrectly set asset '{asset.AssetName}' to incompatible type '{asset.Data.GetType()}', expected '{typeof(T)}'; ignoring override.", LogLevel.Warn);
+