discover.ts

import { execSync } from 'child_process';
import * as path from 'path';
import { Readable } from 'stream';
import * as zlib from 'zlib';
import * as fs from 'fs-extra';
import * as tar from 'tar-fs';
import * as yargs from 'yargs';

import { JsiiType } from '../../inventory';

class Command implements yargs.CommandModule {
  public readonly command = 'discover NPM-MODULE';
  public readonly describe = 'Discovers project types from remote npm packages';

  public builder(args: yargs.Argv) {
    return args;
  }

  async handler(opts: any) {
    const module = opts.npmModule;
    const packageDir = await downloadExtractRemoteModule(module);

    const jsii: { [name: string]: JsiiType } = fs.readJsonSync(path.join(packageDir, '.jsii')).types;
    // TODO: implement the rest...
  }
}

async function downloadExtractRemoteModule(module: string): Promise<string> {
  const output = execSync(`npm pack ${module}`, { stdio: ['inherit', 'pipe', 'ignore'] });

  const baseDir = process.cwd();
  const packageZip = path.join(baseDir, output.toString('utf-8').trim());

  const target = './tmp';
  const fileData = fs.readFileSync(packageZip);
  const tarData = zlib.gunzipSync(fileData);

  // Readable.from() doesn't work in TS?
  // const stream = Readable.from(tarData);
  // stream.pipe(tar.extract(target),); // consume the stream

  const readable = new Readable();
  readable._read = () => { }; // _read is required but you can noop it
  readable.push(tarData);
  readable.push(null);

  await new Promise((resolve, reject) => {
    // consume the stream
    readable.pipe(
      tar.extract(target)
        .on('finish', resolve)
        .on('error', reject)
    );
  });

  return path.join(baseDir, target, 'package');
}

module.exports = new Command();