Move mapping mediator builder into core package

Author: osoykan

projects/kediatr-core/src/main/kotlin/com/trendyol/kediatr/DependencyProvider.kt

@@ -1,7 +1,16 @@
 package com.trendyol.kediatr
 
+/**
+ * Dependency provider interface.
+ */
 interface DependencyProvider {
+  /**
+   * Gets a single instance of the specified class.
+   */
   fun <T> getSingleInstanceOf(clazz: Class<T>): T
 
+  /**
+   * Gets all subtypes of the specified class.
+   */
   fun <T> getSubTypesOf(clazz: Class<T>): Collection<Class<T>>
 }

projects/kediatr-core/src/main/kotlin/com/trendyol/kediatr/MappingDependencyProvider.kt

@@ -0,0 +1,56 @@
+@file:Suppress("UNCHECKED_CAST")
+
+package com.trendyol.kediatr
+
+import java.lang.reflect.ParameterizedType
+
+/**
+ * Dependency provider that uses a map to resolve dependencies.
+ * @param handlerMap A map that contains the handlers.
+ * The key is the handler class and the value is the handler instance.
+ * @see DependencyProvider
+ */
+class MappingDependencyProvider(
+  private val handlerMap: HashMap<Class<*>, Any>
+) : DependencyProvider {
+  override fun <T> getSingleInstanceOf(clazz: Class<T>): T = handlerMap[clazz] as T
+
+  override fun <T> getSubTypesOf(clazz: Class<T>): Collection<Class<T>> = handlerMap.keys
+    .filter { isCompatibleType(it, clazz) }
+    .map { it as Class<T> }
+
+  private fun <T> isCompatibleType(
+    handler: Class<*>,
+    interfaceOrBaseClass: Class<T>
+  ): Boolean = when {
+    interfaceOrBaseClass.isAssignableFrom(handler) -> true
+    handler.genericInterfaces
+      .filterIsInstance<ParameterizedType>()
+      .any { it.rawType == interfaceOrBaseClass } -> true
+
+    else -> when (val superclass = handler.genericSuperclass) {
+      is ParameterizedType -> {
+        val inheritedHandler = superclass.rawType as Class<*>
+        inheritedHandler.genericInterfaces
+          .filterIsInstance<ParameterizedType>()
+          .any { it.rawType == interfaceOrBaseClass }
+      }
+
+      is Class<*> -> interfaceOrBaseClass.isAssignableFrom(superclass)
+      else -> false
+    }
+  }
+
+  companion object {
+    /**
+     * Creates a mediator with the given handlers.
+     * @param handlers The handlers to be used by the mediator. Can also be [PipelineBehavior] instances.
+     * @return A mediator instance.
+     */
+    fun createMediator(handlers: List<Any> = emptyList()): Mediator {
+      val provider = MappingDependencyProvider(handlers.associateBy { it.javaClass } as HashMap<Class<*>, Any>)
+      val mediator = MediatorBuilder(provider).build()
+      return mediator
+    }
+  }
+}

projects/kediatr-core/src/test/kotlin/com/trendyol/kediatr/MediatorTests.kt

@@ -1,12 +1,13 @@
 package com.trendyol.kediatr
 
+import com.trendyol.kediatr.MappingDependencyProvider.Companion.createMediator
 import com.trendyol.kediatr.testing.*
 import io.kotest.matchers.shouldBe
 import org.junit.jupiter.api.Test
 
 class MediatorTests : MediatorUseCases() {
   override fun provideMediator(): Mediator = createMediator(
-    types = listOf(
+    handlers = listOf(
       TestCommandHandler(mediator = { testMediator }),
       TestPipelineCommandHandler(mediator = { testMediator }),
       TestCommandWithResultCommandHandler(mediator = { testMediator }),

projects/kediatr-core/src/testFixtures/kotlin/com/trendyol/kediatr/testing/MappingDependencyProvider.kt

@@ -1,16 +1,9 @@
 package com.trendyol.kediatr.testing
 
-import com.trendyol.kediatr.*
+import com.trendyol.kediatr.Mediator
 
-@Suppress("UNCHECKED_CAST")
 abstract class MediatorTestConvention {
   abstract fun provideMediator(): Mediator
 
   val testMediator by lazy { provideMediator() }
-
-  protected fun createMediator(types: List<Any> = emptyList()): Mediator {
-    val provider = MappingDependencyProvider(types.associateBy { it.javaClass } as HashMap<Class<*>, Any>)
-    val mediator = MediatorBuilder(provider).build()
-    return mediator
-  }
 }