env-type-defs/src/utils/generate-types.ts

Automatically generate TypeScript type definitions for environment variables based on the content of your env files.

import { DIRECTORY_PATH, ENV_TYPE_PATH } from "../config";
import { getEnvPath } from "./paths";
import dotenv from "dotenv";
import path from "path";
import fs from "fs";
import { determineType } from "./determine-type";

type envT = {
  [key: string]: string;
};

const envs: envT = {};

export const generateEnvTypes = (pathArg?: string) => {
  const envFiles = getEnvPath();
  envFiles.forEach((env) => {
    const envPath = pathArg || path.join(DIRECTORY_PATH, env);
    const envConfig = dotenv.parse(fs.readFileSync(envPath));
    Object.keys(envConfig).forEach((key: string) => {
      envs[key] = determineType(envConfig[key]);
    });
  });
  const envPathName = path.join(DIRECTORY_PATH, ENV_TYPE_PATH);
  let envObject = "";
  const envObjKeys = Object.keys(envs);
  envObjKeys.forEach((key, index) => {
    envObject += "\t" + key + ":" + envs[key];
    if (index != envObjKeys.length - 1) {
      envObject += ",\n\t";
    }
  });
  fs.writeFileSync(
    envPathName,
    `// generated by env-type-defs https://www.npmjs.com/package/env-type-defs\ndeclare global {\n  namespace NodeJS {\n    interface ProcessEnv {\n  ${envObject}\n    }\n  }\n}\nexport {};\n  `,
    {}
  );
  return envs;
};