Implement Mediator.send

packages/extensions.dependency-injection.abstractions/src/extensions/ServiceCollectionDescriptorExtensions.ts

@@ -20,7 +20,21 @@ export function tryAddServiceDescriptor(
 export function tryAddServiceDescriptorIterable(
 	collection: IServiceCollection,
 	descriptor: ServiceDescriptor,
+): void;
+export function tryAddServiceDescriptorIterable(
+	collection: IServiceCollection,
+	descriptors: ServiceDescriptor[],
+): void;
+export function tryAddServiceDescriptorIterable(
+	collection: IServiceCollection,
+	descriptorOrDescriptors: ServiceDescriptor | ServiceDescriptor[],
 ): void {
-	// TODO
-	tryAddServiceDescriptor(collection, descriptor);
+	if (descriptorOrDescriptors instanceof Array) {
+		for (const descriptor of descriptorOrDescriptors) {
+			tryAddServiceDescriptor(collection, descriptor);
+		}
+	} else {
+		// TODO
+		tryAddServiceDescriptor(collection, descriptorOrDescriptors);
+	}
 }

packages/third-party.mediatr/src/mediatr/IPipelineBehavior.ts

@@ -0,0 +1,9 @@
+export type RequestHandlerDelegate<TResponse> = () => Promise<TResponse>;
+
+// https://github.com/jbogard/MediatR/blob/e611b1bcc00b10244810abeea2f7c62f155beb5e/src/MediatR/IPipelineBehavior.cs#L20
+export interface IPipelineBehavior<TRequest, TResponse> {
+	handle(
+		request: TRequest,
+		next: RequestHandlerDelegate<TResponse>,
+	): Promise<TResponse>;
+}

packages/third-party.mediatr/src/mediatr/Mediatr.ts

@@ -10,9 +10,17 @@ import {
 	NotificationHandlerWrapper,
 	NotificationHandlerWrapperImpl,
 } from './wrappers/NotificationHandlerWrapper';
+import {
+	RequestHandlerBase,
+	RequestHandlerWrapperImpl,
+} from './wrappers/RequestHandlerWrapper';
 
 // https://github.com/jbogard/MediatR/blob/f4de8196adafd37faff274ce819ada93a3d7531b/src/MediatR/Mediator.cs#L16
 export class Mediator implements IMediator {
+	private readonly requestHandlers = new Map<
+		Ctor<IRequest<unknown>>,
+		RequestHandlerBase
+	>();
 	private readonly notificationHandlers = new Map<
 		Ctor<INotification>,
 		NotificationHandlerWrapper
@@ -26,7 +34,16 @@ export class Mediator implements IMediator {
 	) {}
 
 	send<TResponse>(request: IRequest<TResponse>): Promise<TResponse> {
-		throw new Error('Method not implemented.');
+		const handler = getOrAdd(
+			this.requestHandlers,
+			request.constructor as Ctor<IRequest<TResponse>>,
+			(requestCtor) => {
+				const wrapper = new RequestHandlerWrapperImpl(requestCtor);
+				return wrapper as RequestHandlerBase;
+			},
+		);
+
+		return handler.handle(request, this.serviceProvider);
 	}
 
 	/**

packages/third-party.mediatr/src/mediatr/extensions-di/MediatRServiceConfig.ts

@@ -1,11 +1,14 @@
 import { Ctor } from '@yohira/base';
-import { ServiceLifetime } from '@yohira/extensions.dependency-injection.abstractions';
+import {
+	ServiceDescriptor,
+	ServiceLifetime,
+} from '@yohira/extensions.dependency-injection.abstractions';
 
 import { INotificationPublisher } from '../INotificationPublisher';
 import { Mediator } from '../Mediatr';
 import { ForOfAwaitPublisher } from '../notification-publishers/ForOfAwaitPublisher';
 
-// https://github.com/jbogard/MediatR/blob/f4de8196adafd37faff274ce819ada93a3d7531b/src/MediatR/MicrosoftExtensionsDI/MediatrServiceConfiguration.cs#L9
+// https://github.com/jbogard/MediatR/blob/8b1ee39fe29fd12c8042d22f9fd1a969b5fcbc16/src/MediatR/MicrosoftExtensionsDI/MediatrServiceConfiguration.cs#L12
 export class MediatRServiceConfig {
 	/**
 	 * Mediator implementation type to register. Default is {@link Mediator}
@@ -23,4 +26,12 @@ export class MediatRServiceConfig {
 	 * Service lifetime to register services under. Default value is {@link ServiceLifetime.Transient}
 	 */
 	lifetime: ServiceLifetime = ServiceLifetime.Transient;
+	/**
+	 * List of request pre processors to register in specific order
+	 */
+	requestPreProcessorsToRegister: ServiceDescriptor[] = [];
+	/**
+	 * List of request post processors to register in specific order
+	 */
+	requestPostProcessorsToRegister: ServiceDescriptor[] = [];
 }

packages/third-party.mediatr/src/mediatr/pipeline/RequestPostProcessorBehavior.ts

@@ -0,0 +1,19 @@
+import {
+	IPipelineBehavior,
+	RequestHandlerDelegate,
+} from '../IPipelineBehavior';
+
+// https://github.com/jbogard/MediatR/blob/e611b1bcc00b10244810abeea2f7c62f155beb5e/src/MediatR/Pipeline/RequestPostProcessorBehavior.cs#L12
+/**
+ * Behavior for executing all <see cref="IRequestPostProcessor{TRequest,TResponse}"/> instances after handling the request
+ */
+export class RequestPostProcessorBehavior<TRequest, TResponse>
+	implements IPipelineBehavior<TRequest, TResponse>
+{
+	handle(
+		request: TRequest,
+		next: RequestHandlerDelegate<TResponse>,
+	): Promise<TResponse> {
+		throw new Error('Method not implemented.');
+	}
+}

packages/third-party.mediatr/src/mediatr/pipeline/RequestPreProcessorBehavior.ts

@@ -0,0 +1,19 @@
+import {
+	IPipelineBehavior,
+	RequestHandlerDelegate,
+} from '../IPipelineBehavior';
+
+// https://github.com/jbogard/MediatR/blob/e611b1bcc00b10244810abeea2f7c62f155beb5e/src/MediatR/Pipeline/RequestPreProcessorBehavior.cs#L12
+/**
+ * Behavior for executing all <see cref="IRequestPreProcessor{TRequest}"/> instances before handling a request
+ */
+export class RequestPreProcessorBehavior<TRequest, TResponse>
+	implements IPipelineBehavior<TRequest, TResponse>
+{
+	handle(
+		request: TRequest,
+		next: RequestHandlerDelegate<TResponse>,
+	): Promise<TResponse> {
+		throw new Error('Method not implemented.');
+	}
+}

packages/third-party.mediatr/src/mediatr/registrar/ServiceRegistrar.ts

@@ -3,11 +3,14 @@ import {
 	ServiceDescriptor,
 	ServiceLifetime,
 	tryAddServiceDescriptor,
+	tryAddServiceDescriptorIterable,
 } from '@yohira/extensions.dependency-injection.abstractions';
 
 import { IMediator } from '../IMediator';
 import { INotificationPublisher } from '../INotificationPublisher';
 import { MediatRServiceConfig } from '../extensions-di/MediatRServiceConfig';
+import { RequestPostProcessorBehavior } from '../pipeline/RequestPostProcessorBehavior';
+import { RequestPreProcessorBehavior } from '../pipeline/RequestPreProcessorBehavior';
 
 // https://github.com/jbogard/MediatR/blob/43fb46f39020ab4880fefe75fa2315351f347742/src/MediatR/Registration/ServiceRegistrar.cs#L300
 export function addRequiredServices(
@@ -38,4 +41,38 @@ export function addRequiredServices(
 				);
 
 	tryAddServiceDescriptor(services, notificationPublisherServiceDescriptor);
+
+	// TODO
+
+	if (serviceConfig.requestPreProcessorsToRegister.length > 0) {
+		tryAddServiceDescriptorIterable(
+			services,
+			ServiceDescriptor.fromCtor(
+				ServiceLifetime.Transient,
+				Symbol.for('IPipelineBehavior<>'),
+				RequestPreProcessorBehavior,
+			),
+		);
+		tryAddServiceDescriptorIterable(
+			services,
+			serviceConfig.requestPreProcessorsToRegister,
+		);
+	}
+
+	if (serviceConfig.requestPostProcessorsToRegister.length > 0) {
+		tryAddServiceDescriptorIterable(
+			services,
+			ServiceDescriptor.fromCtor(
+				ServiceLifetime.Transient,
+				Symbol.for('IPipelineBehavior<>'),
+				RequestPostProcessorBehavior,
+			),
+		);
+		tryAddServiceDescriptorIterable(
+			services,
+			serviceConfig.requestPostProcessorsToRegister,
+		);
+	}
+
+	// TODO
 }

packages/third-party.mediatr/src/mediatr/wrappers/RequestHandlerWrapper.ts

@@ -0,0 +1,62 @@
+import { Ctor, IServiceProvider } from '@yohira/base';
+import {
+	getRequiredService,
+	getServices,
+} from '@yohira/extensions.dependency-injection.abstractions';
+
+import { IRequest } from '../../mediatr.contracts/IRequest';
+import {
+	IPipelineBehavior,
+	RequestHandlerDelegate,
+} from '../IPipelineBehavior';
+import { IRequestHandler } from '../IRequestHandler';
+
+// https://github.com/jbogard/MediatR/blob/761fb0b1b420f5a8c2cb4a751617dce7ab9c3fe3/src/MediatR/Wrappers/RequestHandlerWrapper.cs#L9
+export abstract class RequestHandlerBase {
+	abstract handle(
+		request: object,
+		serviceProvider: IServiceProvider,
+	): Promise<any /* TODO */>;
+}
+
+// https://github.com/jbogard/MediatR/blob/761fb0b1b420f5a8c2cb4a751617dce7ab9c3fe3/src/MediatR/Wrappers/RequestHandlerWrapper.cs#L15
+export abstract class RequestHandlerWrapper<
+	TResponse,
+> extends RequestHandlerBase {
+	abstract handle(
+		request: IRequest<TResponse>,
+		serviceProvider: IServiceProvider,
+	): Promise<TResponse>;
+}
+
+// https://github.com/jbogard/MediatR/blob/761fb0b1b420f5a8c2cb4a751617dce7ab9c3fe3/src/MediatR/Wrappers/RequestHandlerWrapper.cs#L27
+export class RequestHandlerWrapperImpl<
+	TRequest extends IRequest<TResponse>,
+	TResponse,
+> extends RequestHandlerWrapper<TResponse> {
+	constructor(private readonly requestCtor: Ctor<TRequest>) {
+		super();
+	}
+
+	handle(
+		request: IRequest<TResponse>,
+		serviceProvider: IServiceProvider,
+	): Promise<TResponse> {
+		const handler = (): Promise<TResponse> =>
+			getRequiredService<IRequestHandler<TRequest, TResponse>>(
+				serviceProvider,
+				Symbol.for(`IRequestHandler<${this.requestCtor.name}>`),
+			).handle(request as TRequest);
+
+		return getServices<IPipelineBehavior<TRequest, TResponse>>(
+			serviceProvider,
+			Symbol.for(`IPipelineBehavior<${this.requestCtor.name}>`),
+		)
+			.reverse()
+			.reduce(
+				(next, pipeline) => () =>
+					pipeline.handle(request as TRequest, next),
+				handler as RequestHandlerDelegate<TResponse>,
+			)();
+	}
+}