refactor(iam): move logic from controller down to use-case

src/application.module.ts

@@ -2,13 +2,15 @@ import { Logger, Module, OnApplicationShutdown } from "@nestjs/common";
 import { ConfigModule } from "@nestjs/config";
 import { HealthCheckHttpController } from "./shared-kernel/use-cases/health-check/http.controller.js";
 import { SignInWithOAuthProviderHttpController } from "@identity-and-access/use-cases/sign-in-with-oauth-provider/http.controller.js";
+import { SignInWithOAuthProviderUseCase } from "@identity-and-access/use-cases/sign-in-with-oauth-provider/use-case.js";
 
 @Module({
   imports: [ConfigModule.forRoot()],
   controllers: [
     HealthCheckHttpController,
     SignInWithOAuthProviderHttpController,
   ],
+  providers: [SignInWithOAuthProviderUseCase],
 })
 export class ApplicationModule implements OnApplicationShutdown {
   private readonly logger = new Logger(ApplicationModule.name);

src/identity-and-access/use-cases/sign-in-with-oauth-provider/http.controller.e2e.spec.ts

@@ -1,16 +1,20 @@
 import { describe, expect, it } from "vitest";
 
 describe("SignInWithOAuthProviderUseCase", () => {
-  it("should initiate the OAuth flow by redirecting to the IDP's authorization endpoint", async () => {
-    // Act
-    const response = await fetch(
-      "http://localhost:8080/identity-and-access/oauth/google"
-    );
+  it.each`
+    provider    | expectedRedirectUrl
+    ${"google"} | ${"https://accounts.google.com/v3/signin/identifier"}
+  `(
+    "should initiate the $provider OAuth flow by redirecting to the IDP's authorization endpoint",
+    async ({ provider, expectedRedirectUrl }) => {
+      // Act
+      const response = await fetch(
+        `http://localhost:8080/identity-and-access/oauth/${provider}`
+      );
 
-    // Assert
-    expect(response.redirected).toBe(true);
-    expect(response.url).toMatch(
-      "https://accounts.google.com/v3/signin/identifier"
-    );
-  });
+      // Assert
+      expect(response.redirected).toBe(true);
+      expect(response.url).toMatch(expectedRedirectUrl);
+    }
+  );
 });

src/identity-and-access/use-cases/sign-in-with-oauth-provider/http.controller.ts

@@ -3,29 +3,19 @@ import {
   Get,
   HttpCode,
   HttpStatus,
+  Param,
   Redirect,
 } from "@nestjs/common";
-import { ConfigService } from "@nestjs/config";
+import { SignInWithOAuthProviderUseCase } from "./use-case.js";
 
 @Controller()
 export class SignInWithOAuthProviderHttpController {
-  constructor(private readonly config: ConfigService) {}
+  constructor(private readonly useCase: SignInWithOAuthProviderUseCase) {}
 
-  @Get("/identity-and-access/oauth/google")
+  @Get("/identity-and-access/oauth/:provider")
   @HttpCode(HttpStatus.PERMANENT_REDIRECT)
   @Redirect()
-  async signInWithGoogle() {
-    const baseAuthorizationUrl = `https://accounts.google.com/o/oauth2/v2/auth`;
-    const authorizationUrlParameters = new URLSearchParams({
-      client_id: await this.config.getOrThrow("OAUTH_GOOGLE_CLIENT_ID"),
-      redirect_uri:
-        "http://localhost:8080/identity-and-access/oauth/google/callback",
-      response_type: "code",
-      scope: "email",
-    });
-
-    return {
-      url: `${baseAuthorizationUrl}?${authorizationUrlParameters}`,
-    };
+  async signInWithGoogle(@Param("provider") provider: string) {
+    return await this.useCase.execute({ provider });
   }
 }

src/identity-and-access/use-cases/sign-in-with-oauth-provider/use-case.ts

@@ -0,0 +1,34 @@
+import { Injectable, NotImplementedException } from "@nestjs/common";
+import { ConfigService } from "@nestjs/config";
+
+@Injectable()
+export class SignInWithOAuthProviderUseCase {
+  constructor(private readonly config: ConfigService) {}
+
+  async execute(command: SignInWithOAuthProviderCommand) {
+    if (command.provider !== "google") {
+      throw new NotImplementedException();
+    }
+
+    return this.handleSignInWithGoogle();
+  }
+
+  async handleSignInWithGoogle() {
+    const baseAuthorizationUrl = `https://accounts.google.com/o/oauth2/v2/auth`;
+    const authorizationUrlParameters = new URLSearchParams({
+      client_id: await this.config.getOrThrow("OAUTH_GOOGLE_CLIENT_ID"),
+      redirect_uri:
+        "http://localhost:8080/identity-and-access/oauth/google/callback",
+      response_type: "code",
+      scope: "email",
+    });
+
+    return {
+      url: `${baseAuthorizationUrl}?${authorizationUrlParameters}`,
+    };
+  }
+}
+
+type SignInWithOAuthProviderCommand = {
+  provider: string;
+};