watch.js

/* eslint-disable no-console */
import sane from 'sane';
import { resolve as resolvePath } from 'path';
import { spawn } from 'child_process';
import flowBinPath from 'flow-bin';

process.env.PATH += ':./node_modules/.bin';

var cmd = resolvePath(__dirname);
var srcDir = resolvePath(cmd, './src');

function exec(command, options) {
  return new Promise((resolve, reject) => {
    var child = spawn(command, options, {
      cmd,
      env: process.env,
      stdio: 'inherit',
    });
    child.on('exit', code => {
      if (code === 0) {
        resolve(true);
      } else {
        reject(new Error('Error code: ' + code));
      }
    });
  });
}

var flowServer = spawn(flowBinPath, ['server'], {
  cmd,
  env: process.env,
});

var watcher = sane(srcDir, { glob: ['**/*.js'] })
  .on('ready', startWatch)
  .on('add', changeFile)
  .on('delete', deleteFile)
  .on('change', changeFile);

process.on('SIGINT', () => {
  watcher.close();
  flowServer.kill();
  console.log(CLEARLINE + yellow(invert('stopped watching')));
  process.exit();
});

var isChecking;
var needsCheck;
var toCheck = {};
var timeout;

function startWatch() {
  process.stdout.write(CLEARSCREEN + green(invert('watching...')));
}

function changeFile(filepath, root, stat) {
  if (!stat.isDirectory()) {
    toCheck[filepath] = true;
    debouncedCheck();
  }
}

function deleteFile(filepath) {
  delete toCheck[filepath];
  debouncedCheck();
}

function debouncedCheck() {
  needsCheck = true;
  clearTimeout(timeout);
  timeout = setTimeout(guardedCheck, 250);
}

function guardedCheck() {
  if (isChecking || !needsCheck) {
    return;
  }
  isChecking = true;
  var filepaths = Object.keys(toCheck);
  toCheck = {};
  needsCheck = false;
  checkFiles(filepaths).then(() => {
    isChecking = false;
    process.nextTick(guardedCheck);
  });
}

function checkFiles(filepaths) {
  console.log('\u001b[2J');

  return parseFiles(filepaths)
    .then(() => runTests(filepaths))
    .then(testSuccess =>
      lintFiles(filepaths).then(lintSuccess =>
        typecheckStatus().then(
          typecheckSuccess => testSuccess && lintSuccess && typecheckSuccess,
        ),
      ),
    )
    .catch(() => false)
    .then(success => {
      process.stdout.write(
        '\n' + (success ? '' : '\x07') + green(invert('watching...')),
      );
    });
}

// Checking steps

function parseFiles(filepaths) {
  console.log('Checking Syntax');

  return Promise.all(
    filepaths.map(filepath => {
      if (isJS(filepath) && !isTest(filepath)) {
        return exec('babel', [
          '--optional',
          'runtime',
          '--out-file',
          '/dev/null',
          srcPath(filepath),
        ]);
      }
    }),
  );
}

function runTests(filepaths) {
  console.log('\nRunning Tests');

  return exec(
    'jest',
    allTests(filepaths) ? filepaths.map(srcPath) : ['src'],
  ).catch(() => false);
}

function lintFiles(filepaths) {
  console.log('Linting Code\n');

  return filepaths.reduce(
    (prev, filepath) =>
      prev.then(prevSuccess => {
        if (isJS(filepath)) {
          process.stdout.write('  ' + filepath + ' ...');
          return exec('eslint', [srcPath(filepath)])
            .catch(() => false)
            .then(success => {
              console.log(
                CLEARLINE + '  ' + (success ? CHECK : X) + ' ' + filepath,
              );
              return prevSuccess && success;
            });
        }
        return prevSuccess;
      }),
    Promise.resolve(true),
  );
}

function typecheckStatus() {
  console.log('\nType Checking\n');
  return exec(flowBinPath, ['status']).catch(() => false);
}

// Filepath

function srcPath(filepath) {
  return resolvePath(srcDir, filepath);
}

// Predicates

function isJS(filepath) {
  return filepath.indexOf('.js') === filepath.length - 3;
}

function allTests(filepaths) {
  return filepaths.length > 0 && filepaths.every(isTest);
}

function isTest(filepath) {
  return isJS(filepath) && filepath.indexOf('__tests__/') !== -1;
}

// Print helpers

var CLEARSCREEN = '\u001b[2J';
var CLEARLINE = '\r\x1B[K';
var CHECK = green('\u2713');
var X = red('\u2718');

function invert(str) {
  return `\u001b[7m ${str} \u001b[27m`;
}

function red(str) {
  return `\x1B[K\u001b[1m\u001b[31m${str}\u001b[39m\u001b[22m`;
}

function green(str) {
  return `\x1B[K\u001b[1m\u001b[32m${str}\u001b[39m\u001b[22m`;
}

function yellow(str) {
  return `\x1B[K\u001b[1m\u001b[33m${str}\u001b[39m\u001b[22m`;
}