import type { BunextPageModuleServerReturn, BunxRouteParams } from "../types";

type Params = {
    serverRes: BunextPageModuleServerReturn;
    routeParams?: BunxRouteParams;
};

/**
 * Builds the redirect Response for a server function that returned
 * `redirect`. An explicit `status_code` wins; otherwise `permanent` picks
 * 301, and the default is 302. Headers from `response_options` (e.g. a
 * Set-Cookie on login) and `res_transform` apply to the redirect too.
 */
export default async function grabRedirectResponse({
    serverRes,
    routeParams,
}: Params): Promise<Response> {
    const redirect = serverRes.redirect!;
    const status = redirect.status_code || (redirect.permanent ? 301 : 302);

    const headers = new Headers(serverRes.response_options?.headers);
    headers.set("Location", redirect.destination);

    const res = new Response(null, { status, headers });

    // Same precedence as HTML responses
    if (routeParams?.res_transform) {
        return await routeParams.res_transform(res);
    }

    if (serverRes.res_transform) {
        return await serverRes.res_transform(res);
    }

    return res;
}