Improve the xor codec error messages

Author: ErrorCraft

src/main/java/net/errorcraft/codecium/mixin/mojang/serialization/codecs/EitherCodecExtender.java

@@ -10,7 +10,6 @@
 import org.spongepowered.asm.mixin.injection.At;
 import org.spongepowered.asm.mixin.injection.ModifyArg;
 
-import java.util.Objects;
 import java.util.function.Supplier;
 
 @Mixin(value = EitherCodec.class, remap = false)
@@ -23,16 +22,6 @@ public class EitherCodecExtender<F, S> {
         )
     )
     private <T> Supplier<String> useBetterErrorMessage(Supplier<String> message, @Local(name = "firstRead") final DataResult<Pair<Either<F, S>, T>> firstRead, @Local(name = "secondRead") final DataResult<Pair<Either<F, S>, T>> secondRead) {
-        return () -> {
-            String first = firstRead.error().orElseThrow().message();
-            String second = secondRead.error().orElseThrow().message();
-            if (Objects.equals(first, second)) {
-                return first;
-            }
-            return "Failed to decode either:\n" + StringUtil.indent(
-                "1: " + first + "\n" +
-                "2: " + second
-            );
-        };
+        return StringUtil.supplyEitherErrorMessage(firstRead, secondRead);
     }
 }

src/main/java/net/errorcraft/codecium/mixin/mojang/serialization/codecs/XorCodecExtender.java

@@ -0,0 +1,41 @@
+package net.errorcraft.codecium.mixin.mojang.serialization.codecs;
+
+import com.llamalad7.mixinextras.injector.ModifyReturnValue;
+import com.llamalad7.mixinextras.sugar.Local;
+import com.mojang.datafixers.util.Either;
+import com.mojang.datafixers.util.Pair;
+import com.mojang.serialization.DataResult;
+import com.mojang.serialization.codecs.XorCodec;
+import net.errorcraft.codecium.util.StringUtil;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.ModifyArg;
+
+import java.util.Optional;
+import java.util.function.Supplier;
+
+@Mixin(value = XorCodec.class, remap = false)
+public class XorCodecExtender<F, S> {
+    @ModifyArg(
+        method = "decode",
+        at = @At(
+            value = "INVOKE",
+            target = "Lcom/mojang/serialization/DataResult;error(Ljava/util/function/Supplier;Ljava/lang/Object;)Lcom/mojang/serialization/DataResult;"
+        )
+    )
+    @SuppressWarnings({ "OptionalUsedAsFieldOrParameterType", "OptionalGetWithoutIsPresent" })
+    private <T> Supplier<String> useBetterErrorMessage(Supplier<String> message, @Local(name = "firstResult") final Optional<Pair<Either<F, S>, T>> firstResult, @Local(name = "secondResult") final Optional<Pair<Either<F, S>, T>> secondResult) {
+        return () -> "Decoded both alternatives successfully, cannot pick the correct one:\n" + StringUtil.indent(
+            "1: " + firstResult.get() + "\n" +
+            "2: " + secondResult.get()
+        );
+    }
+
+    @ModifyReturnValue(
+        method = "decode",
+        at = @At("TAIL")
+    )
+    private <T> DataResult<Pair<Either<F, S>, T>> useBetterErrorMessage(DataResult<Pair<Either<F, S>, T>> original, @Local(name = "firstRead") final DataResult<Pair<Either<F, S>, T>> firstRead, @Local(name = "secondRead") final DataResult<Pair<Either<F, S>, T>> secondRead) {
+        return DataResult.error(StringUtil.supplyEitherErrorMessage(firstRead, secondRead));
+    }
+}

src/main/java/net/errorcraft/codecium/util/StringUtil.java

@@ -1,6 +1,9 @@
 package net.errorcraft.codecium.util;
 
+import com.mojang.serialization.DataResult;
+
 import java.util.Objects;
+import java.util.function.Supplier;
 import java.util.stream.Stream;
 
 public class StringUtil {
@@ -31,4 +34,18 @@ private static String indent(Stream<String> lines, String indentation) {
         builder.setLength(builder.length() - 1);
         return builder.toString();
     }
+
+    public static <T> Supplier<String> supplyEitherErrorMessage(final DataResult<T> first, final DataResult<T> second) {
+        return () -> {
+            String firstMessage = first.error().orElseThrow().message();
+            String secondMessage = second.error().orElseThrow().message();
+            if (Objects.equals(firstMessage, secondMessage)) {
+                return firstMessage;
+            }
+            return "Failed to decode either:\n" + indent(
+                "1: " + firstMessage + "\n" +
+                "2: " + secondMessage
+            );
+        };
+    }
 }

src/main/resources/codecium.mixins.json

@@ -19,7 +19,8 @@
     "mojang.serialization.codecs.KeyDispatchCodecExtender",
     "mojang.serialization.codecs.ListCodecExtender",
     "mojang.serialization.codecs.OptionalFieldCodecExtender",
-    "mojang.serialization.codecs.RecordCodecBuilderExtender$RecordMapCodecExtender"
+    "mojang.serialization.codecs.RecordCodecBuilderExtender$RecordMapCodecExtender",
+    "mojang.serialization.codecs.XorCodecExtender"
   ],
   "injectors": {
     "defaultRequire": 1