feat: implement complex selection flow

apps/backend/src/modules/complex/handlers/select-complex.handler.ts

@@ -0,0 +1,38 @@
+import { selectComplex } from '@/modules/complex/services/complex.service';
+import type { AppContext } from '@/types/hono';
+import { setCookie } from 'hono/cookie';
+import { z } from 'zod';
+
+const SELECTED_COMPLEX_COOKIE = 'selected-complex-id';
+const COOKIE_MAX_AGE = 60 * 60 * 24 * 30;
+
+const selectComplexSchema = z.object({
+  complexId: z.string().uuid(),
+});
+
+export async function selectComplexHandler(c: AppContext) {
+  const user = c.get('user');
+  const body = await c.req.json();
+  const result = selectComplexSchema.safeParse(body);
+
+  if (!result.success) {
+    return c.json({ message: 'Invalid payload', issues: result.error.issues }, { status: 400 });
+  }
+
+  const { complexId } = result.data;
+  const complex = await selectComplex(user.id, complexId);
+
+  if (!complex) {
+    return c.json({ message: 'Complex not found or not associated with user' }, { status: 404 });
+  }
+
+  setCookie(c, SELECTED_COMPLEX_COOKIE, complexId, {
+    httpOnly: true,
+    secure: process.env.NODE_ENV === 'production',
+    sameSite: 'strict',
+    path: '/',
+    maxAge: COOKIE_MAX_AGE,
+  });
+
+  return c.json(complex);
+}