import { NextResponse } from "next/server";
import { getPayload } from "payload";
import config from "@payload-config";
import { combineDateAndTime } from "@/lib/meeting/status";
import { withBookingTransaction } from "@/lib/booking/transaction";

export const dynamic = "force-dynamic";

type Args = { params: Promise<{ id: string }> };

export async function POST(request: Request, { params }: Args) {
  const { id } = await params;

  try {
    const payload = await getPayload({ config });
    const { user } = await payload.auth({ headers: request.headers });
    if (!user || user.collection !== "customers") {
      return NextResponse.json({ error: "Bitte melde dich an." }, { status: 401 });
    }
    if (!user.emailVerified) {
      return NextResponse.json({ error: "Bitte bestätige zuerst deine E-Mail-Adresse.", code: "EMAIL_NOT_VERIFIED" }, { status: 403 });
    }

    return await withBookingTransaction(payload, `booking:${id}`, async (req) => {
      const { docs } = await payload.find({ collection: "booking-requests", where: { id: { equals: id } }, depth: 0, limit: 1, req });
      const booking = docs[0];
      if (!booking || Number(booking.user) !== Number(user.id)) {
        return NextResponse.json({ error: "Buchung nicht gefunden." }, { status: 404 });
      }
      const alternative = booking.proposedAlternative;
      if (booking.status !== "pending" || !alternative?.date || !alternative.startTime || !alternative.endTime) {
        return NextResponse.json({ error: "Für diese Buchung liegt kein alternativer Termin vor." }, { status: 409 });
      }

      const alternativeStart = combineDateAndTime(alternative.date, alternative.startTime);
      if (!Number.isFinite(alternativeStart.getTime()) || alternativeStart <= new Date()) {
        return NextResponse.json({ error: "Dieser Terminvorschlag liegt bereits in der Vergangenheit." }, { status: 409 });
      }

      // The beforeChange hook on booking-requests re-checks for conflicts
      // (with an advisory lock) before allowing this to become "confirmed" -
      // the alternative slot may have been taken by someone else since it was
      // proposed.
      await payload.update({
        collection: "booking-requests",
        id,
        req,
        data: {
          status: "confirmed",
          date: alternative.date,
          startTime: alternative.startTime,
          endTime: alternative.endTime,
        },
      });

      return NextResponse.json({ ok: true });
    });
  } catch (error) {
    if (error instanceof Error && "status" in error && (error as { status: number }).status === 409) {
      return NextResponse.json({ error: error.message }, { status: 409 });
    }
    console.error("accept-alternative failed", error);
    return NextResponse.json({ error: "Der Termin konnte nicht angenommen werden." }, { status: 500 });
  }
}