import "server-only";
import { getViewer } from "@/lib/auth";
import { canWrite, findRepo, repoAccess, type Access } from "@/lib/repos";

export class ActionError extends Error {}

export async function viewerOrThrow() {
  const viewer = await getViewer();
  if (!viewer) throw new ActionError("You must be signed in to do that.");
  return viewer;
}

/** Loads a repository for a server action and checks the viewer's access level. */
export async function repoForAction(owner: string, name: string, need: "read" | "write" | "admin") {
  const viewer = await viewerOrThrow();
  const repo = findRepo(owner, name);
  const access: Access = repo ? repoAccess(repo, viewer.id) : null;
  if (!repo || !access) throw new ActionError("Repository not found.");
  if (need === "write" && !canWrite(access)) throw new ActionError("You don't have push access to this repository.");
  if (need === "admin" && access !== "admin") throw new ActionError("Only the owner can change these settings.");
  return { repo, viewer, access };
}