add LocaleChanged content event (#766)

5 files changed, 100 insertions, 22 deletions

diff --git a/src/SMAPI/Events/IContentEvents.cs b/src/SMAPI/Events/IContentEvents.cs
index abbaaf33..d537db70 100644
--- a/src/SMAPI/Events/IContentEvents.cs
+++ b/src/SMAPI/Events/IContentEvents.cs
@@ -19,5 +19,9 @@ namespace StardewModdingAPI.Events
         /// <summary>Raised after an asset is loaded by the content pipeline, after all mod edits specified via <see cref="AssetRequested"/> have been applied.</summary>
         /// <remarks>This event is only raised if something requested the asset from the content pipeline. Invalidating an asset from the content cache won't necessarily reload it automatically.</remarks>
         event EventHandler<AssetReadyEventArgs> AssetReady;
+
+        /// <summary>Raised after the game language changes.</summary>
+        /// <remarks>For non-English players, this may be raised during startup when the game switches to the previously selected language.</remarks>
+        event EventHandler<LocaleChangedEventArgs> LocaleChanged;
     }
 }
diff --git a/src/SMAPI/Events/LocaleChangedEventArgs.cs b/src/SMAPI/Events/LocaleChangedEventArgs.cs
new file mode 100644
index 00000000..09d3f6e5
--- /dev/null
+++ b/src/SMAPI/Events/LocaleChangedEventArgs.cs
@@ -0,0 +1,45 @@
+using System;
+using LanguageCode = StardewValley.LocalizedContentManager.LanguageCode;
+
+namespace StardewModdingAPI.Events
+{
+    /// <summary>Event arguments for an <see cref="IContentEvents.LocaleChanged"/> event.</summary>
+    public class LocaleChangedEventArgs : EventArgs
+    {
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>The previous language enum value.</summary>
+        /// <remarks>For a custom language, this is always <see cref="LanguageCode.mod"/>.</remarks>
+        public LanguageCode OldLanguage { get; }
+
+        /// <summary>The previous locale code.</summary>
+        /// <remarks>This is the locale code as it appears in asset names, like <c>fr-FR</c> in <c>Maps/springobjects.fr-FR</c>. The locale code for English is an empty string.</remarks>
+        public string OldLocale { get; }
+
+        /// <summary>The new language enum value.</summary>
+        /// <remarks><inheritdoc cref="OldLanguage" select="remarks" /></remarks>
+        public LanguageCode NewLanguage { get; }
+
+        /// <summary>The new locale code.</summary>
+        /// <remarks><inheritdoc cref="OldLocale" select="remarks" /></remarks>
+        public string NewLocale { get; }
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="oldLanguage">The previous language enum value.</param>
+        /// <param name="oldLocale">The previous locale code.</param>
+        /// <param name="newLanguage">The new language enum value.</param>
+        /// <param name="newLocale">The new locale code.</param>
+        internal LocaleChangedEventArgs(LanguageCode oldLanguage, string oldLocale, LanguageCode newLanguage, string newLocale)
+        {
+            this.OldLanguage = oldLanguage;
+            this.OldLocale = oldLocale;
+            this.NewLanguage = newLanguage;
+            this.NewLocale = newLocale;
+        }
+    }
+}
diff --git a/src/SMAPI/Framework/Events/EventManager.cs b/src/SMAPI/Framework/Events/EventManager.cs
index bcfd7dd7..41540047 100644
--- a/src/SMAPI/Framework/Events/EventManager.cs
+++ b/src/SMAPI/Framework/Events/EventManager.cs
@@ -20,6 +20,9 @@ namespace StardewModdingAPI.Framework.Events
         /// <inheritdoc cref="IContentEvents.AssetReady" />
         public readonly ManagedEvent<AssetReadyEventArgs> AssetReady;
 
+        /// <inheritdoc cref="IContentEvents.LocaleChanged" />
+        public readonly ManagedEvent<LocaleChangedEventArgs> LocaleChanged;
+
 
         /****
         ** Display
@@ -204,6 +207,7 @@ namespace StardewModdingAPI.Framework.Events
             this.AssetRequested = ManageEventOf<AssetRequestedEventArgs>(nameof(IModEvents.Content), nameof(IContentEvents.AssetRequested));
             this.AssetsInvalidated = ManageEventOf<AssetsInvalidatedEventArgs>(nameof(IModEvents.Content), nameof(IContentEvents.AssetsInvalidated));
             this.AssetReady = ManageEventOf<AssetReadyEventArgs>(nameof(IModEvents.Content), nameof(IContentEvents.AssetReady));
+            this.LocaleChanged = ManageEventOf<LocaleChangedEventArgs>(nameof(IModEvents.Content), nameof(IContentEvents.LocaleChanged));
 
             this.MenuChanged = ManageEventOf<MenuChangedEventArgs>(nameof(IModEvents.Display), nameof(IDisplayEvents.MenuChanged));
             this.Rendering = ManageEventOf<RenderingEventArgs>(nameof(IModEvents.Display), nameof(IDisplayEvents.Rendering), isPerformanceCritical: true);
diff --git a/src/SMAPI/Framework/Events/ModContentEvents.cs b/src/SMAPI/Framework/Events/ModContentEvents.cs
index cb242e99..beb96031 100644
--- a/src/SMAPI/Framework/Events/ModContentEvents.cs
+++ b/src/SMAPI/Framework/Events/ModContentEvents.cs
@@ -30,6 +30,13 @@ namespace StardewModdingAPI.Framework.Events
             remove => this.EventManager.AssetReady.Remove(value);
         }
 
+        /// <inheritdoc />
+        public event EventHandler<LocaleChangedEventArgs> LocaleChanged
+        {
+            add => this.EventManager.LocaleChanged.Add(value, this.Mod);
+            remove => this.EventManager.LocaleChanged.Remove(value);
+        }
+
 
         /*********
         ** Public methods
diff --git a/src/SMAPI/Framework/SCore.cs b/src/SMAPI/Framework/SCore.cs
index eab977ac..5deb177c 100644
--- a/src/SMAPI/Framework/SCore.cs
+++ b/src/SMAPI/Framework/SCore.cs
@@ -46,6 +46,7 @@ using StardewModdingAPI.Utilities;
 using StardewValley;
 using StardewValley.Menus;
 using xTile.Display;
+using LanguageCode = StardewValley.LocalizedContentManager.LanguageCode;
 using MiniMonoModHotfix = MonoMod.Utils.MiniMonoModHotfix;
 using PathUtilities = StardewModdingAPI.Toolkit.Utilities.PathUtilities;
 using SObject = StardewValley.Object;
@@ -62,7 +63,7 @@ namespace StardewModdingAPI.Framework
         ** Low-level components
         ****/
         /// <summary>Tracks whether the game should exit immediately and any pending initialization should be cancelled.</summary>
-        private readonly CancellationTokenSource CancellationToken = new CancellationTokenSource();
+        private readonly CancellationTokenSource CancellationToken = new();
 
         /// <summary>Manages the SMAPI console window and log file.</summary>
         private readonly LogManager LogManager;
@@ -71,16 +72,16 @@ namespace StardewModdingAPI.Framework
         private Monitor Monitor => this.LogManager.Monitor;
 
         /// <summary>Simplifies access to private game code.</summary>
-        private readonly Reflector Reflection = new Reflector();
+        private readonly Reflector Reflection = new();
 
         /// <summary>Encapsulates access to SMAPI core translations.</summary>
-        private readonly Translator Translator = new Translator();
+        private readonly Translator Translator = new();
 
         /// <summary>The SMAPI configuration settings.</summary>
         private readonly SConfig Settings;
 
         /// <summary>The mod toolkit used for generic mod interactions.</summary>
-        private readonly ModToolkit Toolkit = new ModToolkit();
+        private readonly ModToolkit Toolkit = new();
 
         /****
         ** Higher-level components
@@ -99,7 +100,7 @@ namespace StardewModdingAPI.Framework
 
         /// <summary>Tracks the installed mods.</summary>
         /// <remarks>This is initialized after the game starts.</remarks>
-        private readonly ModRegistry ModRegistry = new ModRegistry();
+        private readonly ModRegistry ModRegistry = new();
 
         /// <summary>Manages SMAPI events for mods.</summary>
         private readonly EventManager EventManager;
@@ -129,18 +130,21 @@ namespace StardewModdingAPI.Framework
         /// <summary>Whether the player just returned to the title screen.</summary>
         public bool JustReturnedToTitle { get; set; }
 
+        /// <summary>The last language set by the game.</summary>
+        private (string Locale, LanguageCode Code) LastLanguage { get; set; } = ("", LanguageCode.en);
+
         /// <summary>The maximum number of consecutive attempts SMAPI should make to recover from an update error.</summary>
-        private readonly Countdown UpdateCrashTimer = new Countdown(60); // 60 ticks = roughly one second
+        private readonly Countdown UpdateCrashTimer = new(60); // 60 ticks = roughly one second
 
         /// <summary>Asset interceptors added or removed since the last tick.</summary>
-        private readonly List<AssetInterceptorChange> ReloadAssetInterceptorsQueue = new List<AssetInterceptorChange>();
+        private readonly List<AssetInterceptorChange> ReloadAssetInterceptorsQueue = new();
 
         /// <summary>A list of queued commands to parse and execute.</summary>
         /// <remarks>This property must be thread-safe, since it's accessed from a separate console input thread.</remarks>
-        private readonly ConcurrentQueue<string> RawCommandQueue = new ConcurrentQueue<string>();
+        private readonly ConcurrentQueue<string> RawCommandQueue = new();
 
         /// <summary>A list of commands to execute on each screen.</summary>
-        private readonly PerScreen<List<Tuple<Command, string, string[]>>> ScreenCommandQueue = new PerScreen<List<Tuple<Command, string, string[]>>>(() => new List<Tuple<Command, string, string[]>>());
+        private readonly PerScreen<List<Tuple<Command, string, string[]>>> ScreenCommandQueue = new(() => new List<Tuple<Command, string, string[]>>());
 
 
         /*********
@@ -369,13 +373,13 @@ namespace StardewModdingAPI.Framework
             xTile.Format.FormatManager.Instance.RegisterMapFormat(new TMXTile.TMXFormat(Game1.tileSize / Game1.pixelZoom, Game1.tileSize / Game1.pixelZoom, Game1.pixelZoom, Game1.pixelZoom));
 
             // load mod data
-            ModToolkit toolkit = new ModToolkit();
+            ModToolkit toolkit = new();
             ModDatabase modDatabase = toolkit.GetModDatabase(Constants.ApiMetadataPath);
 
             // load mods
             {
                 this.Monitor.Log("Loading mod metadata...", LogLevel.Debug);
-                ModResolver resolver = new ModResolver();
+                ModResolver resolver = new();
 
                 // log loose files
                 {
@@ -1048,7 +1052,7 @@ namespace StardewModdingAPI.Framework
 
             // get locale
             string locale = this.ContentCore.GetLocale();
-            LocalizedContentManager.LanguageCode languageCode = this.ContentCore.Language;
+            LanguageCode languageCode = this.ContentCore.Language;
 
             // update core translations
             this.Translator.SetLocale(locale, languageCode);
@@ -1061,6 +1065,20 @@ namespace StardewModdingAPI.Framework
                 foreach (ContentPack contentPack in mod.GetFakeContentPacks())
                     contentPack.TranslationImpl.SetLocale(locale, languageCode);
             }
+
+            // raise event
+            if (this.EventManager.LocaleChanged.HasListeners())
+            {
+                this.EventManager.LocaleChanged.Raise(
+                    new LocaleChangedEventArgs(
+                        oldLanguage: this.LastLanguage.Code,
+                        oldLocale: this.LastLanguage.Locale,
+                        newLanguage: languageCode,
+                        newLocale: locale
+                    )
+                );
+            }
+            this.LastLanguage = (locale, languageCode);
         }
 
         /// <summary>Raised when the low-level stage while loading a save changes.</summary>
@@ -1385,7 +1403,7 @@ namespace StardewModdingAPI.Framework
             {
                 // create client
                 string url = this.Settings.WebApiBaseUrl;
-                WebApiClient client = new WebApiClient(url, Constants.ApiVersion);
+                WebApiClient client = new(url, Constants.ApiVersion);
                 this.Monitor.Log("Checking for updates...");
 
                 // check SMAPI version
@@ -1569,7 +1587,7 @@ namespace StardewModdingAPI.Framework
 
             // load mods
             IList<IModMetadata> skippedMods = new List<IModMetadata>();
-            using (AssemblyLoader modAssemblyLoader = new AssemblyLoader(Constants.Platform, this.Monitor, this.Settings.ParanoidWarnings, this.Settings.RewriteMods))
+            using (AssemblyLoader modAssemblyLoader = new(Constants.Platform, this.Monitor, this.Settings.ParanoidWarnings, this.Settings.RewriteMods))
             {
                 // init
                 HashSet<string> suppressUpdateChecks = new HashSet<string>(this.Settings.SuppressUpdateChecks, StringComparer.OrdinalIgnoreCase);
@@ -1758,7 +1776,7 @@ namespace StardewModdingAPI.Framework
                 IManifest manifest = mod.Manifest;
                 IMonitor monitor = this.LogManager.GetMonitor(mod.DisplayName);
                 IContentHelper contentHelper = new ContentHelper(this.ContentCore, mod.DirectoryPath, manifest.UniqueID, mod.DisplayName, monitor);
-                TranslationHelper translationHelper = new TranslationHelper(manifest.UniqueID, contentCore.GetLocale(), contentCore.Language);
+                TranslationHelper translationHelper = new(manifest.UniqueID, contentCore.GetLocale(), contentCore.Language);
                 IContentPack contentPack = new ContentPack(mod.DirectoryPath, manifest, contentHelper, translationHelper, jsonHelper);
                 mod.SetMod(contentPack, monitor, translationHelper);
                 this.ModRegistry.Add(mod);
@@ -1831,16 +1849,16 @@ namespace StardewModdingAPI.Framework
 
                     // init mod helpers
                     IMonitor monitor = this.LogManager.GetMonitor(mod.DisplayName);
-                    TranslationHelper translationHelper = new TranslationHelper(manifest.UniqueID, contentCore.GetLocale(), contentCore.Language);
+                    TranslationHelper translationHelper = new(manifest.UniqueID, contentCore.GetLocale(), contentCore.Language);
                     IModHelper modHelper;
                     {
                         IContentPack CreateFakeContentPack(string packDirPath, IManifest packManifest)
                         {
                             IMonitor packMonitor = this.LogManager.GetMonitor(packManifest.Name);
                             IContentHelper packContentHelper = new ContentHelper(contentCore, packDirPath, packManifest.UniqueID, packManifest.Name, packMonitor);
-                            TranslationHelper packTranslationHelper = new TranslationHelper(packManifest.UniqueID, contentCore.GetLocale(), contentCore.Language);
+                            TranslationHelper packTranslationHelper = new(packManifest.UniqueID, contentCore.GetLocale(), contentCore.Language);
 
-                            ContentPack contentPack = new ContentPack(packDirPath, packManifest, packContentHelper, packTranslationHelper, this.Toolkit.JsonHelper);
+                            ContentPack contentPack = new(packDirPath, packManifest, packContentHelper, packTranslationHelper, this.Toolkit.JsonHelper);
                             this.ReloadTranslationsForTemporaryContentPack(mod, contentPack);
                             mod.FakeContentPacks.Add(new WeakReference<ContentPack>(contentPack));
                             return contentPack;
@@ -1982,7 +2000,7 @@ namespace StardewModdingAPI.Framework
             // read translation files
             var translations = new Dictionary<string, IDictionary<string, string>>();
             errors = new List<string>();
-            DirectoryInfo translationsDir = new DirectoryInfo(folderPath);
+            DirectoryInfo translationsDir = new(folderPath);
             if (translationsDir.Exists)
             {
                 foreach (FileInfo file in translationsDir.EnumerateFiles("*.json"))
@@ -2038,7 +2056,7 @@ namespace StardewModdingAPI.Framework
         {
             // default path
             {
-                FileInfo defaultFile = new FileInfo(Path.Combine(Constants.LogDir, $"{Constants.LogFilename}.{Constants.LogExtension}"));
+                FileInfo defaultFile = new(Path.Combine(Constants.LogDir, $"{Constants.LogFilename}.{Constants.LogExtension}"));
                 if (!defaultFile.Exists)
                     return defaultFile.FullName;
             }
@@ -2046,7 +2064,7 @@ namespace StardewModdingAPI.Framework
             // get first disambiguated path
             for (int i = 2; i < int.MaxValue; i++)
             {
-                FileInfo file = new FileInfo(Path.Combine(Constants.LogDir, $"{Constants.LogFilename}.player-{i}.{Constants.LogExtension}"));
+                FileInfo file = new(Path.Combine(Constants.LogDir, $"{Constants.LogFilename}.player-{i}.{Constants.LogExtension}"));
                 if (!file.Exists)
                     return file.FullName;
             }
@@ -2058,7 +2076,7 @@ namespace StardewModdingAPI.Framework
         /// <summary>Delete normal (non-crash) log files created by SMAPI.</summary>
         private void PurgeNormalLogs()
         {
-            DirectoryInfo logsDir = new DirectoryInfo(Constants.LogDir);
+            DirectoryInfo logsDir = new(Constants.LogDir);
             if (!logsDir.Exists)
                 return;