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

const util = require('../util')
const state = require('../tasks/state')
const xvfb = require('./xvfb')
const { throwFormErrorText, errors } = require('../errors')

const isXlibOrLibudevRe = /^(?:Xlib|libudev)/
const isHighSierraWarningRe = /\*\*\* WARNING/

function isPlatform (platform) {
  return os.platform() === platform
}

function needsStderrPiped (needsXvfb) {
  return isPlatform('darwin') || (needsXvfb && isPlatform('linux'))
}

function needsEverythingPipedDirectly () {
  return isPlatform('win32')
}

function getStdio (needsXvfb) {
  if (needsEverythingPipedDirectly()) {
    return 'pipe'
  }

  // https://github.com/cypress-io/cypress/issues/921
  // https://github.com/cypress-io/cypress/issues/1143
  // https://github.com/cypress-io/cypress/issues/1745
  if (needsStderrPiped(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 (args, options = {}) {
    const needsXvfb = xvfb.isNeeded()
    let executable = state.getPathToExecutable(state.getBinaryDir())

    if (util.getEnv('CYPRESS_RUN_BINARY')) {
      executable = util.getEnv('CYPRESS_RUN_BINARY')
    }

    debug('needs XVFB?', needsXvfb)

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

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

    const spawn = () => {
      return new Promise((resolve, reject) => {
        if (options.dev) {
          // if we're in dev then reset
          // the launch cmd to be 'npm run dev'
          executable = 'node'
          args.unshift(path.resolve(__dirname, '..', '..', '..', 'scripts', 'start.js'))
        }

        const overrides = util.getEnvOverrides()

        debug('spawning Cypress with executable: %s', executable)
        debug('spawn forcing env overrides %o', overrides)
        debug('spawn args %o %o', args, _.omit(options, 'env'))

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

        // figure out if we're going to be force enabling or disabling colors.
        // also figure out whether we should force stdout and stderr into thinking
        // it is a tty as opposed to a pipe.
        options.env = _.extend({}, options.env, overrides)

        const child = cp.spawn(executable, args, options)
        child.on('close', resolve)
        child.on('error', reject)

        child.stdin && child.stdin.pipe(process.stdin)
        child.stdout && child.stdout.pipe(process.stdout)

        // if this is defined then we are manually piping for linux
        // to filter out the garbage
        child.stderr && child.stderr.on('data', (data) => {
          const str = data.toString()

          // bail if this is warning line garbage
          if (isXlibOrLibudevRe.test(str) || isHighSierraWarningRe.test(str)) {
            return
          }

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

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

    const userFriendlySpawn = () => {
      return spawn()
      .catch(throwFormErrorText(errors.unexpected))
    }

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