feat: add AuthenticatedLdpHandler

src/ldp/AuthenticatedLdpHandler.ts

@@ -0,0 +1,128 @@
+import { Authorizer } from '../authorization/Authorizer';
+import { Credentials } from '../authentication/Credentials';
+import { CredentialsExtractor } from '../authentication/CredentialsExtractor';
+import { HttpHandler } from '../server/HttpHandler';
+import { HttpRequest } from '../server/HttpRequest';
+import { HttpResponse } from '../server/HttpResponse';
+import { Operation } from './operations/Operation';
+import { OperationHandler } from './operations/OperationHandler';
+import { PermissionSet } from './permissions/PermissionSet';
+import { PermissionsExtractor } from './permissions/PermissionsExtractor';
+import { RequestParser } from './http/RequestParser';
+import { ResponseWriter } from './http/ResponseWriter';
+
+/**
+ * Collection of handlers needed for {@link AuthenticatedLdpHandler} to function.
+ */
+export interface AuthenticatedLdpHandlerArgs {
+  /**
+   * Parses the incoming requests.
+   */
+  requestParser: RequestParser;
+  /**
+   * Extracts the credentials from the incoming request.
+   */
+  credentialsExtractor: CredentialsExtractor;
+  /**
+   * Extracts the required permissions from the generated Operation.
+   */
+  permissionsExtractor: PermissionsExtractor;
+  /**
+   * Verifies if the requested operation is allowed.
+   */
+  authorizer: Authorizer;
+  /**
+   * Executed the operation.
+   */
+  operationHandler: OperationHandler;
+  /**
+   * Writes out the response of the operation.
+   */
+  responseWriter: ResponseWriter;
+}
+
+/**
+ * The central manager that connects all the necessary handlers to go from an incoming request to an executed operation.
+ */
+export class AuthenticatedLdpHandler extends HttpHandler {
+  private readonly requestParser: RequestParser;
+
+  private readonly credentialsExtractor: CredentialsExtractor;
+
+  private readonly permissionsExtractor: PermissionsExtractor;
+
+  private readonly authorizer: Authorizer;
+
+  private readonly operationHandler: OperationHandler;
+
+  private readonly responseWriter: ResponseWriter;
+
+  /**
+   * Creates the handler.
+   * @param args - The handlers required. None of them are optional.
+   */
+  public constructor (args: AuthenticatedLdpHandlerArgs) {
+    super();
+    Object.assign(this, args);
+  }
+
+  /**
+   * Checks if the incoming request can be handled. The check is very non-restrictive and will usually be true.
+   * It is based on whether the incoming request can be parsed to an operation.
+   * @param input - Incoming request and response. Only the request will be used.
+   *
+   * @returns A promise resolving if this request can be handled, otherwise rejecting with an Error.
+   */
+  public async canHandle (input: { request: HttpRequest; response: HttpResponse }): Promise<void> {
+    return this.requestParser.canHandle(input.request);
+  }
+
+  /**
+   * Handles the incoming request and writes out the response.
+   * This includes the following steps:
+   *  - Parsing the request to an Operation.
+   *  - Extracting credentials from the request.
+   *  - Extracting the required permissions.
+   *  - Validating if this operation is allowed.
+   *  - Executing the operation.
+   *  - Writing out the response.
+   * @param input - The incoming request and response object to write to.
+   *
+   * @returns A promise resolving when the handling is finished.
+   */
+  public async handle (input: { request: HttpRequest; response: HttpResponse }): Promise<void> {
+    let err: Error;
+    let operation: Operation;
+
+    try {
+      operation = await this.runHandlers(input.request);
+    } catch (error) {
+      err = error;
+    }
+
+    const writeData = { response: input.response, operation, error: err };
+
+    return this.responseWriter.handleSafe(writeData);
+  }
+
+  /**
+   * Runs all handlers except writing the output to the response.
+   * This because any errors thrown here have an impact on the response.
+   * @param request - Incoming request.
+   *
+   * @returns A promise resolving to the generated Operation.
+   */
+  private async runHandlers (request: HttpRequest): Promise<Operation> {
+    const op: Operation = await this.requestParser.handleSafe(request);
+
+    const credentials: Credentials = await this.credentialsExtractor.handleSafe(request);
+
+    const permissions: PermissionSet = await this.permissionsExtractor.handleSafe(op);
+
+    await this.authorizer.handleSafe({ credentials, identifier: op.target, permissions });
+
+    await this.operationHandler.handleSafe(op);
+
+    return op;
+  }
+}

src/ldp/http/ResponseWriter.ts

@@ -0,0 +1,9 @@
+import { AsyncHandler } from '../../util/AsyncHandler';
+import { HttpResponse } from '../../server/HttpResponse';
+import { Operation } from '../operations/Operation';
+
+/**
+ * Writes to the HttpResponse.
+ * Response depends on the operation result and potentially which errors was thrown.
+ */
+export type ResponseWriter = AsyncHandler<{ response: HttpResponse; operation: Operation; error?: Error }>;