Object EventBusSubscriber registration (#34)

* Object EventBusSubscriber registration

* Register from construction and handle companion objects

* Rename construction event listener

* Syntax changes

* Add test mod

src/main/kotlin/net/shadowfacts/forgelin/Forgelin.kt

@@ -1,6 +1,10 @@
 package net.shadowfacts.forgelin
 
+import net.minecraftforge.fml.common.FMLCommonHandler
+import net.minecraftforge.fml.common.Loader
 import net.minecraftforge.fml.common.Mod
+import net.minecraftforge.fml.common.Mod.EventHandler
+import net.minecraftforge.fml.common.event.FMLConstructionEvent
 
 /**
  * @author shadowfacts
@@ -12,4 +16,10 @@ object Forgelin {
 	const val NAME = "Forgelin"
 	const val VERSION = "@VERSION@"
 
-}
+	@EventHandler
+	fun onConstruction(event: FMLConstructionEvent) {
+		Loader.instance().modList.forEach {
+			ForgelinAutomaticEventSubscriber.subscribeAutomatic(it, event.asmHarvestedData, FMLCommonHandler.instance().side)
+		}
+	}
+}

src/main/kotlin/net/shadowfacts/forgelin/ForgelinAutomaticEventSubscriber.kt

@@ -0,0 +1,78 @@
+package net.shadowfacts.forgelin
+
+import net.minecraftforge.common.MinecraftForge
+import net.minecraftforge.fml.common.Loader
+import net.minecraftforge.fml.common.LoaderException
+import net.minecraftforge.fml.common.Mod
+import net.minecraftforge.fml.common.ModContainer
+import net.minecraftforge.fml.common.discovery.ASMDataTable
+import net.minecraftforge.fml.common.discovery.ASMDataTable.ASMData
+import net.minecraftforge.fml.common.discovery.asm.ModAnnotation.EnumHolder
+import net.minecraftforge.fml.relauncher.Side
+import org.apache.logging.log4j.LogManager
+import java.util.EnumSet
+import kotlin.reflect.full.companionObjectInstance
+
+object ForgelinAutomaticEventSubscriber {
+    private val DEFAULT_SUBSCRIPTION_SIDES = EnumSet.allOf(Side::class.java)
+    private val LOGGER = LogManager.getLogger(ForgelinAutomaticEventSubscriber::class.java)
+
+    fun subscribeAutomatic(mod: ModContainer, asm: ASMDataTable, currentSide: Side) {
+        LOGGER.debug("Attempting to register Kotlin @EventBusSubscriber objects for {}", mod.modId)
+
+        val modAnnotations = asm.getAnnotationsFor(mod) ?: return
+
+        val containedMods = modAnnotations.get(Mod::class.java.name)
+        val subscribers = modAnnotations.get(Mod.EventBusSubscriber::class.java.name)
+                .filter { parseTargetSides(it).contains(currentSide) }
+
+        val loader = Loader.instance().modClassLoader
+
+        for (subscriber in subscribers) {
+            try {
+                val ownerModId = parseModId(containedMods, subscriber)
+                if (ownerModId.isNullOrEmpty()) {
+                    LOGGER.warn("Could not determine owning mod for @EventBusSubscriber on {} for mod {}", subscriber.className, mod.modId)
+                    continue
+                }
+
+                if (mod.modId != ownerModId) {
+                    LOGGER.debug("Skipping @EventBusSubscriber injection for {} since it is not for mod {}", subscriber.className, mod.modId)
+                    continue
+                }
+
+                LOGGER.debug("Registering @EventBusSubscriber object for {} for mod {}", subscriber.className, mod.modId)
+
+                val subscriberClass = Class.forName(subscriber.className, false, loader)?.kotlin ?: continue
+                val subscriberInstance = subscriberClass.objectInstance ?: subscriberClass.companionObjectInstance ?: continue
+
+                MinecraftForge.EVENT_BUS.register(subscriberInstance)
+                LOGGER.debug("Registered @EventBusSubscriber object {}", subscriber.className)
+            } catch (e: Throwable) {
+                LOGGER.error("An error occurred trying to load an @EventBusSubscriber object {} for modid {}", mod.modId, e)
+                throw LoaderException(e)
+            }
+        }
+    }
+
+    private fun parseModId(containedMods: MutableSet<ASMData>, subscriber: ASMData): String? {
+        val parsedModId: String? = subscriber.annotationInfo["modid"] as? String
+        if (parsedModId.isNullOrEmpty()) {
+            return parsedModId
+        }
+
+        return ASMDataTable.getOwnerModID(containedMods, subscriber)
+    }
+
+    private fun parseTargetSides(subscriber: ASMData): EnumSet<Side> {
+        val parsedSides: List<EnumHolder>? = subscriber.annotationInfo["value"] as? List<EnumHolder>
+        if (parsedSides != null) {
+            val targetSides = EnumSet.noneOf(Side::class.java)
+            for (parsed in parsedSides) {
+                targetSides.add(Side.valueOf(parsed.value))
+            }
+            return targetSides
+        }
+        return DEFAULT_SUBSCRIPTION_SIDES
+    }
+}

src/test/kotlin/net/shadowfacts/forgelin/AutomaticKtSubscriberTest.kt

@@ -0,0 +1,19 @@
+package net.shadowfacts.forgelin
+
+import net.minecraftforge.event.entity.player.PlayerInteractEvent.RightClickBlock
+import net.minecraftforge.fml.common.Mod
+import net.minecraftforge.fml.common.Mod.EventBusSubscriber
+import net.minecraftforge.fml.common.eventhandler.SubscribeEvent
+
+@Mod(modid = AutomaticKtSubscriberTest.MODID, modLanguageAdapter = "net.shadowfacts.forgelin.KotlinAdapter")
+object AutomaticKtSubscriberTest {
+    const val MODID = "ktsubtest"
+
+    @EventBusSubscriber(modid = AutomaticKtSubscriberTest.MODID)
+    object EventSubscriber {
+        @SubscribeEvent
+        fun onRightClickBlock(event: RightClickBlock) {
+            println("Automatic KT subscriber: Right click ${event.pos}")
+        }
+    }
+}