add friendly warning when an i18n file has duplicate keys due to case-insensitivity (#448)

2 files changed, 20 insertions, 1 deletions

diff --git a/docs/release-notes.md b/docs/release-notes.md
index f6498f06..b5d6e32a 100644
--- a/docs/release-notes.md
+++ b/docs/release-notes.md
@@ -14,6 +14,7 @@
   * Added `SpecialisedEvents.UnvalidatedUpdateTick` event for specialised use cases.
   * Fixed deadlock in rare cases when injecting a file with an asset loader.
   * Fixed unhelpful error when a mod exposes a non-public API.
+  * Fixed unhelpful error when a translation file has duplicate keys due to case-insensitivity.
   * Fixed input events being raised for keyboard buttons when a textbox is receiving input.
   * Fixed some JSON field names being case-sensitive.
   * Fixed `helper.ReadJsonFile` and `helper.WriteJsonFile` not normalising path separators.
diff --git a/src/SMAPI/Program.cs b/src/SMAPI/Program.cs
index aecf5b30..e9084b2d 100644
--- a/src/SMAPI/Program.cs
+++ b/src/SMAPI/Program.cs
@@ -765,7 +765,7 @@ namespace StardewModdingAPI
                                 IContentHelper packContentHelper = new ContentHelper(contentManager, packDirPath, packManifest.UniqueID, packManifest.Name, packMonitor);
                                 return new ContentPack(packDirPath, packManifest, packContentHelper, this.JsonHelper);
                             }
-                            
+
                             modHelper = new ModHelper(manifest.UniqueID, metadata.DirectoryPath, jsonHelper, contentHelper, commandHelper, modRegistryHelper, reflectionHelper, translationHelper, contentPacks, CreateTransitionalContentPack, this.DeprecationManager);
                         }
 
@@ -993,6 +993,24 @@ namespace StardewModdingAPI
                     }
                 }
 
+                // validate translations
+                foreach (string locale in translations.Keys)
+                {
+                    HashSet<string> keys = new HashSet<string>(StringComparer.InvariantCultureIgnoreCase);
+                    HashSet<string> duplicateKeys = new HashSet<string>(StringComparer.InvariantCultureIgnoreCase);
+                    foreach (string key in translations[locale].Keys.ToArray())
+                    {
+                        if (!keys.Add(key))
+                        {
+                            duplicateKeys.Add(key);
+                            translations[locale].Remove(key);
+                        }
+                    }
+
+                    if (duplicateKeys.Any())
+                        metadata.LogAsMod($"Mod's i18n/{locale}.json has duplicate translation keys: [{string.Join(", ", duplicateKeys)}]. Keys are case-insensitive.", LogLevel.Warn);
+                }
+
                 // update translation
                 TranslationHelper translationHelper = (TranslationHelper)metadata.Mod.Helper.Translation;
                 translationHelper.SetTranslations(translations);