feat(event-handler): add base router class

packages/event-handler/src/rest/BaseRouter.ts

@@ -0,0 +1,70 @@
+import { isRecord } from '@aws-lambda-powertools/commons/typeutils';
+import {
+  getStringFromEnv,
+  isDevMode,
+} from '@aws-lambda-powertools/commons/utils/env';
+import type { GenericLogger } from '../types/appsync-events.js';
+import type {
+  RouteHandler,
+  RouteOptions,
+  RouterOptions,
+} from '../types/rest.js';
+
+abstract class BaseRouter {
+  protected context: Record<string, unknown>; // TODO: should this be a map instead?
+  /**
+   * A logger instance to be used for logging debug, warning, and error messages.
+   *
+   * When no logger is provided, we'll only log warnings and errors using the global `console` object.
+   */
+  protected readonly logger: Pick<GenericLogger, 'debug' | 'warn' | 'error'>;
+  /**
+   * Whether the router is running in development mode.
+   */
+  protected readonly isDev: boolean = false;
+
+  public constructor(options?: RouterOptions) {
+    this.context = {};
+    const alcLogLevel = getStringFromEnv({
+      key: 'AWS_LAMBDA_LOG_LEVEL',
+      defaultValue: '',
+    });
+    this.logger = options?.logger ?? {
+      debug: alcLogLevel === 'DEBUG' ? console.debug : () => undefined,
+      error: console.error,
+      warn: console.warn,
+    };
+    this.isDev = isDevMode();
+  }
+
+  public abstract route(handler: RouteHandler, options: RouteOptions): void;
+
+  public get(path: string, handler: RouteHandler, options?: RouteOptions): void;
+  public get(path: string, options?: RouteOptions): MethodDecorator;
+  public get(
+    path: string,
+    handler?: RouteHandler | RouteOptions,
+    options?: RouteOptions
+  ): MethodDecorator | undefined {
+    if (handler && typeof handler === 'function') {
+      this.route(handler, {
+        ...(options || {}),
+        method: 'GET',
+        path,
+      });
+      return;
+    }
+
+    return (_target, _propertyKey, descriptor: PropertyDescriptor) => {
+      const routeOptions = isRecord(handler) ? handler : options;
+      this.route(descriptor.value, {
+        ...(routeOptions || {}),
+        method: 'GET',
+        path,
+      });
+      return descriptor;
+    };
+  }
+}
+
+export { BaseRouter };

packages/event-handler/src/types/rest.ts

@@ -0,0 +1,24 @@
+import type { BaseRouter } from '../rest/BaseRouter.js';
+import type { GenericLogger } from './appsync-events.js';
+
+/**
+ * Options for the {@link BaseRouter} class
+ */
+type RouterOptions = {
+  /**
+   * A logger instance to be used for logging debug, warning, and error messages.
+   *
+   * When no logger is provided, we'll only log warnings and errors using the global `console` object.
+   */
+  logger?: GenericLogger;
+};
+
+// biome-ignore lint/suspicious/noExplicitAny: we want to keep arguments and return types as any to accept any type of function
+type RouteHandler<T = any, R = any> = (...args: T[]) => R;
+
+type RouteOptions = {
+  method?: string;
+  path?: string;
+};
+
+export type { RouterOptions, RouteHandler, RouteOptions };