Extract data fields for particles

src/main/kotlin/de/snowii/extractor/extractors/Particles.kt

@@ -2,9 +2,13 @@ package de.snowii.extractor.extractors
 
 import com.google.gson.JsonArray
 import com.google.gson.JsonElement
+import com.google.gson.JsonObject
 import de.snowii.extractor.Extractor
+import net.minecraft.core.particles.ParticleTypes
+import net.minecraft.core.particles.SimpleParticleType
 import net.minecraft.core.registries.BuiltInRegistries
 import net.minecraft.server.MinecraftServer
+import java.lang.reflect.ParameterizedType
 
 
 class Particles : Extractor.Extractor {
@@ -13,10 +17,42 @@ class Particles : Extractor.Extractor {
     }
 
     override fun extract(server: MinecraftServer): JsonElement {
-        val particlesJson = JsonArray()
+        val particlesJson = JsonObject()
+
         for (particle in BuiltInRegistries.PARTICLE_TYPE) {
+            val fields = JsonArray()
+
+            // Extract the fields of the particle type, using the class of the particle type
+            // This is done using the constructor of the particle type and reading the parameters
+            // SimpleParticleType does not have any fields, so we skip particles of this type
+            if (particle !is SimpleParticleType) {
+                val id = BuiltInRegistries.PARTICLE_TYPE.getKey(particle)!!.path
+                val particleType = ParticleTypes::class.java.getDeclaredField(id.uppercase()).genericType
+
+                if (particleType is ParameterizedType) {
+                    // The registry items are ParticleType<T>, we need to get the type T using reflection
+                    val parameterizedType = particleType as ParameterizedType?
+                    val typeArguments = parameterizedType!!.actualTypeArguments
+                    val typeArg = typeArguments[0]
+
+                    if (typeArg is Class<*>) {
+                        // Based on the type T, we convert it back to a class and get the parameters using reflection
+                        val typeClass = typeArg as Class<*>?
+
+                        for (field in typeClass?.constructors?.first()?.parameters!!) {
+                            val name = field.name
+
+                            // Parameter 'type' is in every constructor, we do not need it for our purposes
+                            if (name != "type") {
+                                fields.add(name)
+                            }
+                        }
+                    }
+                }
+            }
+
             particlesJson.add(
-                BuiltInRegistries.PARTICLE_TYPE.getKey(particle)!!.path,
+                BuiltInRegistries.PARTICLE_TYPE.getKey(particle)!!.path, fields
             )
         }
 

src/main/resources/extractor.accesswidener

@@ -34,4 +34,9 @@ accessible field net/minecraft/stats/Stat value Ljava/lang/Object;
 accessible field net/minecraft/stats/StatType registry Lnet/minecraft/core/Registry;
 accessible field net/minecraft/stats/StatType displayName Lnet/minecraft/network/chat/Component;
 # accessible field net/minecraft/entity/data/TrackedDataHandlerRegistry DATA_HANDLERS Lnet/minecraft/util/collection/Int2ObjectBiMap;
-# accessible field net/minecraft/entity/data/DataTracker CLASS_TO_LAST_ID Lnet/minecraft/util/collection/Class2IntMap;
+# accessible field net/minecraft/entity/data/DataTracker CLASS_TO_LAST_ID Lnet/minecraft/util/collection/Class2IntMap;
+
+# For some reason, these constructors are private. We need them to be public to read the parameters from them
+accessible method net/minecraft/core/particles/PowerParticleOption <init> (Lnet/minecraft/core/particles/ParticleType;F)V
+accessible method net/minecraft/core/particles/SpellParticleOption <init> (Lnet/minecraft/core/particles/ParticleType;IF)V
+accessible method net/minecraft/core/particles/ColorParticleOption <init> (Lnet/minecraft/core/particles/ParticleType;I)V