import type {NextRequest} from 'next/server';
import {reportsApi} from '@/services/api/reportsApi';
import {toConversion} from '@/services/api/reportMapper';
import {toReportWindow, toSiteParam} from '@/services/api/range';
import {previousWindow} from '@/services/api/previousWindow';
import {serveUpstream} from '@/shared/services/bff';
import type {ApiConversionReport, BucketSize} from '@/services/api/types';

export const dynamic = 'force-dynamic';

const BUCKETS: BucketSize[] = ['hour', 'day', 'week', 'month'];

/** GET /api/reports/conversion — purchases, revenue and basket size. */
export async function GET(req: NextRequest) {
  const url = new URL(req.url);
  const bucketParam = url.searchParams.get('bucket');
  const bucket = BUCKETS.includes(bucketParam as BucketSize)
    ? (bucketParam as BucketSize)
    : undefined;
  const wantsPrevious = url.searchParams.get('compare') === 'previous';

  return serveUpstream(req, async (token, query) => {
    const window = toReportWindow(query.range, new Date(query.nowMs), bucket);
    const site = toSiteParam(query.storeId);

    const [current, previous] = await Promise.all([
      reportsApi.conversion(token, window, site),
      wantsPrevious
        ? reportsApi.conversion(token, previousWindow(window), site)
        : Promise.resolve(null as ApiConversionReport | null),
    ]);

    return toConversion(current, previous);
  });
}