Add logic to clear air items of NBT from Patchouli book registry

build.gradle

@@ -64,6 +64,7 @@ repositories {
     maven { // CTM
         url "https://maven.tterrag.com/"
     }
+    maven { url 'https://maven.blamejared.com' }
 }
 
 dependencies {
@@ -103,6 +104,7 @@ dependencies {
     modCompileOnly("curse.maven:valhesiastructures-347488:3476252")
     modCompileOnly files("deps/starlight-1.2.jar")
     modCompileOnly("appeng:appliedenergistics2:8.4.7")
+    modCompileOnly("vazkii.patchouli:Patchouli:1.16.4-53.3")
 }
 
 tasks.withType(JavaCompile) {

src/main/java/org/embeddedt/modernfix/core/config/ModernFixEarlyConfig.java

@@ -83,6 +83,7 @@ public class ModernFixEarlyConfig {
         this.addMixinRule("perf.deduplicate_location", false);
         this.addMixinRule("perf.cache_blockstate_cache_arrays", true);
         this.addMixinRule("perf.cache_model_materials", true);
+        this.addMixinRule("perf.patchouli_deduplicate_books", modPresent("patchouli"));
         this.addMixinRule("perf.datapack_reload_exceptions", true);
         this.addMixinRule("perf.async_locator", true);
         this.addMixinRule("perf.faster_texture_stitching", true);

src/main/java/org/embeddedt/modernfix/mixin/perf/patchouli_deduplicate_books/ClientBookRegistryMixin.java

@@ -0,0 +1,68 @@
+package org.embeddedt.modernfix.mixin.perf.patchouli_deduplicate_books;
+
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.item.Items;
+import net.minecraftforge.fml.common.ObfuscationReflectionHelper;
+import org.embeddedt.modernfix.ModernFix;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+import vazkii.patchouli.client.book.BookEntry;
+import vazkii.patchouli.client.book.BookPage;
+import vazkii.patchouli.client.book.ClientBookRegistry;
+import vazkii.patchouli.client.book.page.PageTemplate;
+import vazkii.patchouli.client.book.template.BookTemplate;
+import vazkii.patchouli.client.book.template.TemplateComponent;
+import vazkii.patchouli.client.book.template.component.ComponentItemStack;
+import vazkii.patchouli.common.book.Book;
+import vazkii.patchouli.common.book.BookRegistry;
+
+import java.lang.reflect.Field;
+import java.util.ArrayList;
+import java.util.List;
+
+@Mixin(ClientBookRegistry.class)
+public class ClientBookRegistryMixin {
+    @Inject(method = "reload", at = @At("RETURN"), remap = false)
+    private void performDeduplication(CallbackInfo ci) {
+        Field templateField = ObfuscationReflectionHelper.findField(PageTemplate.class, "template");
+        Field componentsField = ObfuscationReflectionHelper.findField(BookTemplate.class, "components");
+        Field itemsField = ObfuscationReflectionHelper.findField(ComponentItemStack.class, "items");
+        int numItemsCleared = 0;
+        for(Book book : BookRegistry.INSTANCE.books.values()) {
+            for(BookEntry entry : book.contents.entries.values()) {
+                for(BookPage page : entry.getPages()) {
+                    if(page instanceof PageTemplate) {
+                        List<TemplateComponent> components;
+                        try {
+                            BookTemplate template = (BookTemplate)templateField.get(page);
+                            components = (List<TemplateComponent>)componentsField.get(template);
+                            for(TemplateComponent component : components) {
+                                if(component instanceof ComponentItemStack) {
+                                    ItemStack[] items = (ItemStack[])itemsField.get(component);
+                                    for(ItemStack item : items) {
+                                        if(item.getItem() == Items.AIR) {
+                                            // remove any NBT
+                                            CompoundTag tag = item.getTag();
+                                            if(tag != null) {
+                                                numItemsCleared++;
+                                                List<String> keys = new ArrayList<>(tag.getAllKeys());
+                                                for(String key : keys)
+                                                    item.removeTagKey(key);
+                                            }
+                                        }
+                                    }
+                                }
+                            }
+                        } catch(ReflectiveOperationException e) {
+                            continue;
+                        }
+                    }
+                }
+            }
+        }
+        ModernFix.LOGGER.info("Cleared {} unneeded book NBT tags", numItemsCleared);
+    }
+}

src/main/resources/modernfix.mixins.json

@@ -95,6 +95,7 @@
     "perf.model_optimizations.TransformationMatrixMixin",
     "perf.model_optimizations.BooleanPropertyMixin",
     "perf.model_optimizations.PropertyMixin",
+    "perf.patchouli_deduplicate_books.ClientBookRegistryMixin",
     "perf.async_jei.InputConstantsMixin",
     "perf.async_jei.IngredientListElementFactoryMixin",
     "perf.async_jei.ClientLifecycleHandlerMixin",