implement post /donations endpoint with validation and auth

apps/backend/lambdas/donors/README.md

@@ -10,7 +10,7 @@ Lambda for managing donors.
 |--------|------|-------------|
 | GET | /health | Health check |
 | GET | /donors |  |
-| GET | /donations |  |
+| POST | /donations |  |
 | POST | /donors |  |
 
 ## Setup

apps/backend/lambdas/donors/handler.ts

@@ -135,6 +135,44 @@ export const handler = async (event: any): Promise<APIGatewayProxyResult> => {
       return json(200, { data: donations });
     }
 
+    // POST /donations
+    if (normalizedPath === '/donations' && method === 'POST') {
+      const body = event.body ? JSON.parse(event.body) as Record<string, unknown> : {};
+      const { donor_id, project_id, amount } = body;
+
+      if (donor_id === undefined || project_id === undefined || amount === undefined) {
+        return json(400, { message: 'donor_id, project_id, and amount are required' });
+      }
+      if (!Number.isInteger(donor_id) || (donor_id as number) < 1) {
+        return json(400, { message: 'donor_id must be a positive integer' });
+      }
+      if (!Number.isInteger(project_id) || (project_id as number) < 1) {
+        return json(400, { message: 'project_id must be a positive integer' });
+      }
+      if (typeof amount !== 'number' || amount <= 0 || !isFinite(amount)) {
+        return json(400, { message: 'amount must be a positive number' });
+      }
+
+      try {
+      const donation = await db
+        .insertInto('branch.project_donations')
+        .values({
+          donor_id: donor_id as number,
+          project_id: project_id as number,
+          amount: amount as number,
+        })
+        .returningAll()
+        .executeTakeFirstOrThrow();
+
+      return json(201, { data: donation });
+    } catch (err: any) {
+      if (err?.code === '23505') {
+        return json(409, { message: 'A donation from this donor to this project already exists' });
+      }
+      throw err;
+    }
+    }
+
     // POST /donors
     if ((normalizedPath === '/' || normalizedPath === '/donors') && method === 'POST') {
       const body = event.body ? JSON.parse(event.body) as Record<string, unknown> : {};

apps/backend/lambdas/donors/test/donors.test.ts

@@ -247,6 +247,41 @@ describe("Donor API with data", () => {
     const res = await handler(createEvent('GET', '/donations'));
     expect(res.statusCode).toBe(401);
   });
+  test("POST /donations returns 201 and created donation", async () => {
+    mockAuthenticateRequest.mockResolvedValueOnce(authenticatedUser);
+    const res = await handler(createEvent('POST', '/donations', {
+      donor_id: 1, project_id: 4, amount: 500,
+    }));
+    const body = JSON.parse(res.body);
+    expect(res.statusCode).toBe(201);
+    expect(body.data.donor_id).toBe(1);
+    expect(body.data.project_id).toBe(4);
+    expect(Number(body.data.amount)).toBe(500);
+  });
+
+  test("POST /donations returns 400 when donor_id is missing", async () => {
+    mockAuthenticateRequest.mockResolvedValueOnce(authenticatedUser);
+    const res = await handler(createEvent('POST', '/donations', { project_id: 1, amount: 100 }));
+    expect(res.statusCode).toBe(400);
+  });
+
+  test("POST /donations returns 400 when amount is zero", async () => {
+    mockAuthenticateRequest.mockResolvedValueOnce(authenticatedUser);
+    const res = await handler(createEvent('POST', '/donations', { donor_id: 1, project_id: 1, amount: 0 }));
+    expect(res.statusCode).toBe(400);
+  });
+
+  test("POST /donations returns 400 when amount is negative", async () => {
+    mockAuthenticateRequest.mockResolvedValueOnce(authenticatedUser);
+    const res = await handler(createEvent('POST', '/donations', { donor_id: 1, project_id: 1, amount: -50 }));
+    expect(res.statusCode).toBe(400);
+  });
+
+  test("POST /donations returns 401 when unauthenticated", async () => {
+    mockAuthenticateRequest.mockResolvedValueOnce({ isAuthenticated: false });
+    const res = await handler(createEvent('POST', '/donations', { donor_id: 1, project_id: 1, amount: 100 }));
+    expect(res.statusCode).toBe(401);
+  });
 });
 
 describe("Donor API when DB is empty", () => {