import { write, close } from 'node:fs';
import { spawn } from 'node:child_process';

import { file } from 'tmp-promise';

import { renderFile } from './src/template_engine.mjs';


if (process.argv.length <= 2) {
  console.error(
    `Usage: n0m [options] template_file.n0m\n` +
    `Options:\n` +
    `  -c compile (by default the script will be executed)`
  )
  process.exit(1);
}

let compileOnly = false;

const args = process.argv
  .slice(2)
  .filter(arg => {
    if (arg.toLocaleLowerCase() === '-c') {
      compileOnly = true;
      return false;
    }
    return true;
  });

const fileName = args[0];
const scriptArgs = args.slice(1);

let rendered;
try {
  rendered = await renderFile(fileName);
} catch (e) {
  console.log("Error Rendering Template:")
  console.log(e?.message || "Unknown Error");
  process.exit(0);
}

if (compileOnly) {
  process.stdout.write(rendered);
  process.exit(0);
}

// Create temporary file
const { fd, path, cleanup } = await file({
  mode: 0o744,
  detachDescriptor: true
});

// Write script to temporary file and close file if successful
await new Promise((resolve, reject) => {
  write(fd, rendered, async writeErr => {
    if (writeErr) {
      reject(writeErr);
      return;
    }

    close(fd, (closeErr) => {
      if (closeErr) {
        reject(closeErr);
        return;
      }
      resolve();
    });
  });
});

// Spawn child process to execute script
let child = spawn(
  '/usr/bin/env', [
    '-u', 'PKG_EXECPATH',
    path,
    ...scriptArgs
  ], {
    stdio: 'inherit',
    argv0: fileName
  }
);

// Clean up temporary files once the child exits
child.on('close', async () => {
  await cleanup();
});