'use strict';

var _ = require('lodash');
var os = require('os');
var cp = require('child_process');
var tty = require('tty');
var path = require('path');
var Promise = require('bluebird');
var debug = require('debug')('cypress:cli');

var util = require('../util');
var info = require('../tasks/info');
var xvfb = require('./xvfb');

var _require = require('../errors'),
    throwFormErrorText = _require.throwFormErrorText,
    errors = _require.errors;

var isXlibOrLibudevRe = /^(Xlib|libudev)/;

function needsStderrPipe(needsXvfb) {
  return needsXvfb && os.platform() === 'linux';
}

function getStdio(needsXvfb) {
  // https://github.com/cypress-io/cypress/issues/921
  if (needsStderrPipe(needsXvfb)) {
    // returning pipe here so we can massage stderr
    // and remove garbage from Xlib and libuv
    // due to starting the XVFB process on linux
    return ['inherit', 'inherit', 'pipe'];
  }

  return 'inherit';
}

module.exports = {
  start: function start(args) {
    var options = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : {};

    var needsXvfb = xvfb.isNeeded();

    debug('needs XVFB?', needsXvfb);

    // always push cwd into the args
    args = [].concat(args, '--cwd', process.cwd());

    _.defaults(options, {
      detached: false,
      stdio: getStdio(needsXvfb)
    });

    var spawn = function spawn() {
      return new Promise(function (resolve, reject) {
        var cypressPath = info.getPathToExecutable();

        if (options.dev) {
          // if we're in dev then reset
          // the launch cmd to be 'npm run dev'
          cypressPath = 'node';
          args.unshift(path.resolve(__dirname, '..', '..', '..', 'scripts', 'start.js'));
        }

        debug('spawning Cypress %s', cypressPath);
        debug('spawn args %j', args, options);

        // strip dev out of child process options
        options = _.omit(options, 'dev');

        // when running in electron in windows
        // it never supports color but we're
        // going to force it anyway as long
        // as our parent cli process can support
        // colors!
        //
        // also when we are in linux and using the 'pipe'
        // option our process.stderr.isTTY will not be true
        // which ends up disabling the colors =(
        if (util.supportsColor()) {
          process.env.FORCE_COLOR = 1;
          process.env.DEBUG_COLORS = 1;
          process.env.MOCHA_COLORS = 1;
        }

        // if we needed to pipe stderr and we're currently
        // a tty on stderr
        if (needsStderrPipe(needsXvfb) && tty.isatty(2)) {
          // then force stderr tty
          //
          // this is necessary because we want our child
          // electron browser to behave _THE SAME WAY_ as
          // if we aren't using pipe. pipe is necessary only
          // to filter out garbage on stderr -____________-
          process.env.FORCE_STDERR_TTY = 1;
        }

        var child = cp.spawn(cypressPath, args, options);
        child.on('close', resolve);
        child.on('error', reject);

        // if this is defined then we are manually piping for linux
        // to filter out the garbage
        child.stderr && child.stderr.on('data', function (data) {
          // bail if this is a line from xlib or libudev
          if (isXlibOrLibudevRe.test(data.toString())) {
            return;
          }

          // else pass it along!
          process.stderr.write(data);
        });

        if (options.detached) {
          child.unref();
        }
      });
    };

    var userFriendlySpawn = function userFriendlySpawn() {
      return spawn().catch(throwFormErrorText(errors.unexpected));
    };

    if (needsXvfb) {
      return xvfb.start().then(userFriendlySpawn).finally(xvfb.stop);
    } else {
      return userFriendlySpawn();
    }
  }
};