/**
 * POST /api/gbp/compare — compare metrics across selected locations.
 */
import { NextResponse } from "next/server";
import { getCurrentUser } from "@/lib/auth";
import { prisma } from "@/lib/prisma";
import { compareLocations } from "@/lib/services/gbp-multi-location";

export const dynamic = "force-dynamic";

export async function POST(req: Request) {
  const user = await getCurrentUser();
  if (!user) return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
  const body = await req.json().catch(() => null) as { brandId?: string; locationIds?: string[]; days?: number } | null;
  if (!body?.brandId || !Array.isArray(body.locationIds)) return NextResponse.json({ error: "brandId and locationIds[] required" }, { status: 400 });

  const brand = await prisma.brand.findUnique({ where: { id: body.brandId }, include: { organization: { include: { memberships: true } } } });
  if (!brand) return NextResponse.json({ error: "Brand not found" }, { status: 404 });
  if (!brand.organization.memberships.some((m) => m.userId === user.id)) return NextResponse.json({ error: "Access denied" }, { status: 403 });

  const comparison = await compareLocations(body.locationIds, body.days || 30);
  return NextResponse.json({ comparison });
}
