1 files changed, 47 insertions, 0 deletions
diff --git a/src/main/kotlin/util/compatloader/CompatLoader.kt b/src/main/kotlin/util/compatloader/CompatLoader.kt
new file mode 100644
index 0000000..c5d45bc
--- /dev/null
+++ b/src/main/kotlin/util/compatloader/CompatLoader.kt
@@ -0,0 +1,47 @@
+package moe.nea.firmament.util.compatloader
+
+import java.util.ServiceLoader
+import net.fabricmc.loader.api.FabricLoader
+import kotlin.streams.asSequence
+import moe.nea.firmament.Firmament
+
+abstract class CompatLoader<T : Any>(val kClass: Class<T>) {
+	val loader: ServiceLoader<T> = ServiceLoader.load(kClass)
+	val allValidInstances by lazy {
+		loader.reload()
+		loader.stream()
+			.asSequence()
+			.filter { provider ->
+				runCatching {
+					shouldLoad(provider.type())
+				}.getOrElse {
+					Firmament.logger.error("Could not determine whether to load a ${kClass.name} subclass", it)
+					false
+				}
+			}
+			.mapNotNull { provider ->
+				runCatching {
+					provider.get()
+				}.getOrElse {
+					Firmament.logger.error(
+						"Could not load desired instance ${provider.type().name} for ${kClass.name}",
+						it)
+					null
+				}
+			}
+			.toList()
+	}
+	val singleInstance by lazy { allValidInstances.singleOrNull() }
+
+	open fun shouldLoad(type: Class<out T>): Boolean {
+		return checkRequiredModsPresent(type)
+	}
+
+	fun checkRequiredModsPresent(type: Class<*>): Boolean {
+		val requiredMods = type.getAnnotationsByType(RequireMod::class.java)
+		return requiredMods.all { FabricLoader.getInstance().isModLoaded(it.modId) }
+	}
+
+	@Repeatable
+	annotation class RequireMod(val modId: String)
+}