1 files changed, 51 insertions, 0 deletions
diff --git a/src/main/kotlin/moe/nea/ledger/utils/di/DIProvider.kt b/src/main/kotlin/moe/nea/ledger/utils/di/DIProvider.kt
new file mode 100644
index 0000000..b5ce550
--- /dev/null
+++ b/src/main/kotlin/moe/nea/ledger/utils/di/DIProvider.kt
@@ -0,0 +1,51 @@
+package moe.nea.ledger.utils.di
+
+import java.lang.reflect.AnnotatedElement
+import java.lang.reflect.Constructor
+
+fun interface DIProvider<T : Any> : BaseDIProvider<T, Unit> {
+	override fun provideWithContext(di: DI, context: Unit): T {
+		return provide(di)
+	}
+
+	override fun createContext(element: AnnotatedElement) {
+	}
+
+	override fun createEmptyContext() {
+	}
+
+	fun provide(di: DI): T
+
+	companion object {
+
+		fun <T : Any> fromInjectableClass(clazz: Class<T>): DIProvider<T> {
+			@Suppress("UNCHECKED_CAST")
+			val cons = (clazz.constructors.find { it.getAnnotation(Inject::class.java) != null }
+				?: clazz.constructors.find { it.parameterCount == 0 }
+				?: error("Could not find DI injection entrypoint for class $clazz"))
+					as Constructor<out T>
+			return DIProvider { di ->
+				val typArgs = cons.parameters.map {
+					di.provide(it.type, it)
+				}.toTypedArray()
+				val instance = cons.newInstance(*typArgs)
+				for (it in clazz.fields) {
+					if (it.getAnnotation(Inject::class.java) == null) continue
+					it.set(instance, di.provide(it.type, it))
+				}
+				instance
+			}
+		}
+
+		fun <T : Any> singeleton(value: T): DIProvider<T> {
+			return DIProvider { _ -> value }
+		}
+	}
+
+}
+
+interface BaseDIProvider<T : Any, C> {
+	fun createContext(element: AnnotatedElement): C
+	fun provideWithContext(di: DI, context: C): T
+	fun createEmptyContext(): C
+}