// Fills process.env from the gitignored `.config/<category>/<vendor>.env`
// files, the local home of every credential the app reads. Deployed code
// never sees this directory: Vercel holds the same variables as project
// environment variables.
//
// Called from next.config.ts and drizzle.config.ts. Nothing under src/
// imports it: app code only reads process.env, so no bundle pulls in node:fs.
import { existsSync, readdirSync, readFileSync } from "node:fs";
import { join } from "node:path";
import { parseEnv } from "node:util";

export const LOCAL_ENV_DIR = ".config";

/**
 * Every `<root>/.config/<category>/<vendor>.env`, in a stable order.
 * @param {string} [root]
 * @returns {string[]}
 */
export function localEnvFiles(root = process.cwd()) {
  const dir = join(root, LOCAL_ENV_DIR);
  if (!existsSync(dir)) return [];
  /** @type {string[]} */
  const files = [];
  for (const category of readdirSync(dir, { withFileTypes: true })) {
    if (!category.isDirectory()) continue;
    for (const entry of readdirSync(join(dir, category.name), {
      withFileTypes: true,
    })) {
      if (entry.isFile() && entry.name.endsWith(".env")) {
        files.push(join(dir, category.name, entry.name));
      }
    }
  }
  return files.sort();
}

/**
 * Loads each file into process.env. A variable already in the environment
 * wins over the file, so a value exported in the shell or set by Vercel is
 * never overwritten. An absent `.config/` is a no-op, which is the deployed
 * case.
 * @param {string} [root]
 * @returns {string[]}
 */
export function loadLocalEnv(root = process.cwd()) {
  const files = localEnvFiles(root);
  for (const file of files) {
    for (const [name, value] of Object.entries(
      parseEnv(readFileSync(file, "utf8")),
    )) {
      if (process.env[name] === undefined) process.env[name] = value;
    }
  }
  return files;
}