import path from "node:path";
import { pathToFileURL } from "node:url";
import type { PackageQueryGenerator } from "./assembly.js";

/** The build invoker selects this executable explicitly. Never resolve a
 * generator by a capability name or execute a module discovered in user QX. */
export async function loadQueryGenerator(filename?: string): Promise<PackageQueryGenerator | undefined> {
  if (!filename) return undefined;
  const module = await import(pathToFileURL(path.resolve(filename)).href);
  if (typeof module.generatePackageQueries !== "function")
    throw new Error("Query generator must export generatePackageQueries");
  const generator: PackageQueryGenerator = module.generatePackageQueries;
  if (module.completeWorkspace !== undefined) {
    if (typeof module.completeWorkspace !== "function") throw new Error("completeWorkspace must be a function");
    generator.completeWorkspace = module.completeWorkspace;
  }
  return generator;
}