Create login route (#45)

* Add login route logic

* Add tests for login route

Author: Advayp

backend/app/api/user/login/route.test.ts

@@ -0,0 +1,43 @@
+import { prismaMock } from '@/__test__/singleton';
+import { User } from '@prisma/client';
+import { POST } from './route';
+import { generateMockRequest } from '@/__test__/utils';
+import { NextRequest } from 'next/server';
+
+jest.mock('@/lib/session', () => ({
+  createSession: jest.fn(async (x: number) => x),
+}));
+
+test('Login succeeds for existing user', async () => {
+  const temporaryUser: User = {
+    id: 1,
+    username: 'test',
+    createdAt: new Date(),
+    updatedAt: new Date(),
+  };
+
+  prismaMock.user.findFirst.mockResolvedValue(temporaryUser);
+
+  const req = generateMockRequest(temporaryUser);
+  const res = await POST(req as NextRequest);
+  const data = await res.json();
+
+  const expected = {
+    ...temporaryUser,
+    updatedAt: temporaryUser.updatedAt.toISOString(),
+    createdAt: temporaryUser.createdAt.toISOString(),
+  };
+
+  expect(data.user).toEqual(expected);
+  expect(data.success).toBeTruthy();
+});
+
+test('Login fails if user does not exist', async () => {
+  prismaMock.user.findFirst.mockResolvedValue(null);
+
+  const req = generateMockRequest({ username: 'test' });
+  const res = await POST(req as NextRequest);
+  const data = await res.json();
+
+  expect(data.error).toEqual("User doesn't exist");
+});

backend/app/api/user/login/route.ts

@@ -0,0 +1,35 @@
+import prisma from '@/lib/prisma';
+import { createSession } from '@/lib/session';
+import { User } from '@prisma/client';
+import { NextRequest, NextResponse } from 'next/server';
+
+type PostRequest = {
+  username: string;
+};
+
+type PostResponse = {
+  success: boolean;
+  user: User;
+};
+
+// Make sure to call Firebase auth in frontend after to ensure correct password
+// This route only ensures that the user exists within our system, nothing else
+export const POST = async (
+  req: NextRequest
+): Promise<NextResponse<PostResponse | { error: string }>> => {
+  const { username }: PostRequest = await req.json();
+
+  const existingUser = await prisma.user.findFirst({
+    where: {
+      username,
+    },
+  });
+
+  if (!existingUser) {
+    return NextResponse.json({ error: "User doesn't exist" }, { status: 404 });
+  }
+
+  await createSession(existingUser.id);
+
+  return NextResponse.json({ success: true, user: existingUser });
+};