"use strict";

const os = require('os');

const Promise = require('bluebird');

const Xvfb = require('@cypress/xvfb');

const {
  stripIndent
} = require('common-tags');

const Debug = require('debug');

const {
  throwFormErrorText,
  errors
} = require('../errors');

const util = require('../util');

const debug = Debug('cypress:cli');
const debugXvfb = Debug('cypress:xvfb');
debug.Debug = debugXvfb.Debug = Debug;
const xvfbOptions = {
  timeout: 30000,
  // milliseconds
  // need to explicitly define screen otherwise electron will crash
  // https://github.com/cypress-io/cypress/issues/6184
  xvfb_args: ['-screen', '0', '1280x1024x24'],

  onStderrData(data) {
    if (debugXvfb.enabled) {
      debugXvfb(data.toString());
    }
  }

};
const xvfb = Promise.promisifyAll(new Xvfb(xvfbOptions));
module.exports = {
  _debugXvfb: debugXvfb,
  // expose for testing
  _xvfb: xvfb,
  // expose for testing
  _xvfbOptions: xvfbOptions,

  // expose for testing
  start() {
    debug('Starting Xvfb');
    return xvfb.startAsync().return(null).catch({
      nonZeroExitCode: true
    }, throwFormErrorText(errors.nonZeroExitCodeXvfb)).catch(err => {
      if (err.known) {
        throw err;
      }

      return throwFormErrorText(errors.missingXvfb)(err);
    });
  },

  stop() {
    debug('Stopping Xvfb');
    return xvfb.stopAsync().return(null).catch(() => {// noop
    });
  },

  isNeeded() {
    if (os.platform() !== 'linux') {
      return false;
    }

    if (process.env.DISPLAY) {
      const issueUrl = util.getGitHubIssueUrl(4034);
      const message = stripIndent`
        DISPLAY environment variable is set to ${process.env.DISPLAY} on Linux
        Assuming this DISPLAY points at working X11 server,
        Cypress will not spawn own Xvfb

        NOTE: if the X11 server is NOT working, Cypress will exit without explanation,
          see ${issueUrl}
        Solution: Unset the DISPLAY variable and try again:
          DISPLAY= npx cypress run ...
      `;
      debug(message);
      return false;
    }

    debug('undefined DISPLAY environment variable');
    debug('Cypress will spawn its own Xvfb');
    return true;
  },

  // async method, resolved with Boolean
  verify() {
    return xvfb.startAsync().return(true).catch(err => {
      debug('Could not verify xvfb: %s', err.message);
      return false;
    }).finally(xvfb.stopAsync);
  }

};