Fix getItemDetail showing raw translation keys.

The dedicated server always uses the default Language instance, as it's
setter method is stripped from the server jar. So if we mixin to this
instance's creation and load it with mods' en_us lang files, we will be
able to "translate" text on the server. Translate in quotes as we're
only loading en_us files, but mojang was the one who left out
translations on the dedicated server we shouldn't feel too bad.

config/checkstyle/suppressions.xml

@@ -7,6 +7,9 @@
     <suppress checks="StaticVariableName" files=".*[\\/]ComputerCraft.java" />
     <suppress checks="StaticVariableName" files=".*[\\/]ComputerCraftAPI.java" />
 
+    <!-- Some shadowed fields in mixins can't be renamed -->
+    <suppress checks="StaticVariableName" files=".*[\\/]mixin[\\/].*" />
+
     <!-- The commands API is documented in Lua. -->
     <suppress checks="SummaryJavadocCheck" files=".*[\\/]CommandAPI.java" />
 </suppressions>

src/main/java/dan200/computercraft/fabric/mixin/MixinLanguage.java

@@ -0,0 +1,75 @@
+/*
+ * This file is part of ComputerCraft - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2021. Do not distribute without permission.
+ * Send enquiries to dratcliffe@gmail.com
+ */
+
+package dan200.computercraft.fabric.mixin;
+
+import com.google.common.collect.ImmutableMap;
+import com.google.gson.JsonParseException;
+import dan200.computercraft.shared.peripheral.generic.data.ItemData;
+import net.fabricmc.loader.api.FabricLoader;
+import net.minecraft.util.Language;
+import org.apache.logging.log4j.Logger;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;
+import org.spongepowered.asm.mixin.injection.callback.LocalCapture;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.HashMap;
+import java.util.function.BiConsumer;
+
+/**
+ * Loads all mods en_us lang file into the default Language instance on the dedicated server.
+ * Needed so that lua code running on the server can access the display name of items.
+ *
+ * @see ItemData#fill
+ */
+@Mixin( Language.class )
+public class MixinLanguage
+{
+    @Shadow
+    private static Logger LOGGER;
+
+    @Shadow
+    public static void load( InputStream inputStream, BiConsumer<String, String> entryConsumer )
+    {
+    }
+
+    private static void loadModLangFile( String modId, BiConsumer<String, String> biConsumer )
+    {
+        String path = "/assets/" + modId + "/lang/en_us.json";
+
+        try ( InputStream inputStream = Language.class.getResourceAsStream( path ) )
+        {
+            if ( inputStream == null ) return;
+            load( inputStream, biConsumer );
+        }
+        catch ( JsonParseException | IOException e )
+        {
+            LOGGER.error( "Couldn't read strings from " + path, e );
+        }
+    }
+
+    @Inject( method = "create", locals = LocalCapture.CAPTURE_FAILSOFT, at = @At( value = "INVOKE", remap = false, target = "Lcom/google/common/collect/ImmutableMap$Builder;build()Lcom/google/common/collect/ImmutableMap;" ) )
+    private static void create( CallbackInfoReturnable<Language> cir, ImmutableMap.Builder<String, String> builder )
+    {
+        /*  We must ensure that the keys are de-duplicated because we can't catch the error that might otherwise
+         *  occur when the injected function calls build() on the ImmutableMap builder. So we use our own hash map and
+         *  exclude "minecraft", as the injected function has already loaded those keys at this point.
+         */
+        HashMap<String, String> translations = new HashMap<>();
+
+        FabricLoader.getInstance().getAllMods().stream().map( modContainer -> modContainer.getMetadata().getId() )
+            .filter( id -> !id.equals( "minecraft" ) ).forEach( id -> {
+                loadModLangFile( id, translations::put );
+            } );
+
+        builder.putAll( translations );
+    }
+}

src/main/resources/computercraft.mixins.json

@@ -25,6 +25,9 @@
         "MixinScreen",
         "MixinWorldRenderer"
     ],
+    "server": [
+        "MixinLanguage"
+    ],
     "injectors": {
         "defaultRequire": 1
     }