resolve-app-function.ts

import resolveModule from "resolve";

const defaultOptions: ResolveOptions = {};

export const resolveAppFunction = async (
  appFnId: string,
  opts?: ResolveOptions,
) => {
  opts = opts || defaultOptions;
  // These are mostly to ease testing
  const basedir = opts.basedir || process.cwd();
  const resolver: Resolver = opts.resolver || resolveModule.sync;
  const appFnPath = resolver(appFnId, { basedir });
  // On windows, an absolute path may start with a drive letter, e.g. C:/path/to/file.js
  // This can be interpreted as a protocol, so ensure it's prefixed with file://
  const appFnPathWithFileProtocol = appFnPath.replace(
    /^([a-zA-Z]:)/,
    "file://$1",
  );
  const { default: mod } = await import(appFnPathWithFileProtocol);
  // mod.default gets exported by transpiled TypeScript code
  return mod.__esModule && mod.default ? mod.default : mod;
};

export type Resolver = (appFnId: string, opts: { basedir: string }) => string;

export interface ResolveOptions {
  basedir?: string;
  resolver?: Resolver;
}