Introduce game rule for long reach increment

This feature allows players to configure the increment of the long reach effect on a per-world basis. The default value is now '2' as opposed to the previously hardcoded '5', because I felt it was too powerful.

src/main/java/dev/sapphic/beacons/BeaconMobEffects.java

@@ -3,25 +3,57 @@
 import com.google.common.collect.ObjectArrays;
 import com.jamieswhiteshirt.reachentityattributes.ReachEntityAttributes;
 import dev.sapphic.beacons.mixin.BeaconBlockEntityAccessor;
-import dev.sapphic.beacons.mixin.MobEffectAccessor;
+import dev.sapphic.beacons.mixin.GameRulesAccessor;
+import dev.sapphic.beacons.mixin.IntegerValueAccessor;
 import net.fabricmc.api.ModInitializer;
 import net.minecraft.core.Registry;
 import net.minecraft.resources.ResourceLocation;
 import net.minecraft.world.effect.MobEffect;
 import net.minecraft.world.effect.MobEffectCategory;
 import net.minecraft.world.effect.MobEffects;
 import net.minecraft.world.entity.LivingEntity;
+import net.minecraft.world.entity.ai.attributes.AttributeInstance;
+import net.minecraft.world.entity.ai.attributes.AttributeMap;
+import net.minecraft.world.entity.ai.attributes.AttributeModifier;
 import net.minecraft.world.entity.ai.attributes.AttributeModifier.Operation;
 import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.level.GameRules;
 import net.minecraft.world.level.block.entity.BeaconBlockEntity;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 import java.util.Arrays;
 import java.util.stream.Collectors;
 
 public final class BeaconMobEffects implements ModInitializer {
-  public static final MobEffect LONG_REACH = MobEffectAccessor.newMobEffect(MobEffectCategory.BENEFICIAL, 0xDEF58F)
-    .addAttributeModifier(ReachEntityAttributes.REACH, "C20A0A8F-83DF-4C37-BC34-3678C24C3F01", 5.0, Operation.ADDITION)
-    .addAttributeModifier(ReachEntityAttributes.ATTACK_RANGE, "C764C44F-FC32-498B-98EB-B3262BA58B3B", 5.0, Operation.ADDITION);
+  public static final GameRules.Key<GameRules.IntegerValue> LONG_REACH_INCREMENT = GameRulesAccessor.callRegister(
+    "longReachIncrement", GameRules.Category.PLAYER, IntegerValueAccessor.callCreate(2));
+
+  public static final MobEffect LONG_REACH = new MobEffect(MobEffectCategory.BENEFICIAL, 0xDEF58F) {
+    private static double getLongReachAmount(final LivingEntity entity, final int mul) {
+      return Math.max(0, entity.level.getGameRules().getInt(LONG_REACH_INCREMENT)) * (mul + 1);
+    }
+
+    @Override
+    public void addAttributeModifiers(final LivingEntity entity, final AttributeMap attributes, final int mul) {
+      for (final var entry : this.getAttributeModifiers().entrySet()) {
+        final @Nullable AttributeInstance instance = attributes.getInstance(entry.getKey());
+
+        if (instance != null) {
+          final var modifier = entry.getValue();
+
+          instance.removeModifier(modifier);
+          instance.addPermanentModifier(new AttributeModifier(
+            modifier.getId(), this.getDescriptionId() + ' ' + mul,
+            getLongReachAmount(entity, mul), modifier.getOperation()
+          ));
+        }
+      }
+    }
+  }.addAttributeModifier(ReachEntityAttributes.ATTACK_RANGE,
+    "C764C44F-FC32-498B-98EB-B3262BA58B3B", Double.NaN, Operation.ADDITION
+  ).addAttributeModifier(ReachEntityAttributes.REACH,
+    "C20A0A8F-83DF-4C37-BC34-3678C24C3F01", Double.NaN, Operation.ADDITION
+  );
 
   public static final MobEffect NUTRITION = new MobEffect(MobEffectCategory.BENEFICIAL, 0xC75F79) {
     @Override
@@ -39,11 +71,7 @@ public boolean isDurationEffectTick(final int duration, final int amplifier) {
 
   static final String NAMESPACE = "beaconoverhaul";
 
-  public BeaconMobEffects() {
-    appendAdditionalEffects();
-  }
-
-  private static void appendAdditionalEffects() {
+  static {
     final var effects = BeaconBlockEntity.BEACON_EFFECTS;
 
     effects[0] = ObjectArrays.concat(effects[0], MobEffects.NIGHT_VISION);

src/main/java/dev/sapphic/beacons/mixin/GameRulesAccessor.java

@@ -0,0 +1,15 @@
+package dev.sapphic.beacons.mixin;
+
+import net.minecraft.world.level.GameRules;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.gen.Invoker;
+
+@Mixin(GameRules.class)
+public interface GameRulesAccessor {
+  @Invoker
+  static <T extends GameRules.Value<T>> GameRules.Key<T> callRegister(
+    final String name, final GameRules.Category category, final GameRules.Type<T> type
+  ) {
+    throw new AssertionError();
+  }
+}

src/main/java/dev/sapphic/beacons/mixin/IntegerValueAccessor.java

@@ -0,0 +1,13 @@
+package dev.sapphic.beacons.mixin;
+
+import net.minecraft.world.level.GameRules;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.gen.Invoker;
+
+@Mixin(GameRules.IntegerValue.class)
+public interface IntegerValueAccessor {
+  @Invoker
+  static GameRules.Type<GameRules.IntegerValue> callCreate(final int defaultValue) {
+    throw new AssertionError();
+  }
+}

src/main/resources/mixins/beaconoverhaul/mixins.server.json

@@ -8,8 +8,9 @@
     "BeaconBlockEntityMixin",
     "BeaconBlockEntityMixin$DataAccessMixin",
     "BeaconMenuMixin",
+    "GameRulesAccessor",
+    "IntegerValueAccessor",
     "LivingEntityMixin",
-    "MobEffectAccessor",
     "PlayerMixin"
   ],
   "refmap": "mixins/beaconoverhaul/refmap.json"