/*
 * fork from https://github.com/domenic/opener
 */
import childProcess from 'child_process'
import os from 'os'

module.exports = function opener(
  args: string | string[],
  tool: string | undefined
) {
  let platform = process.platform
  args = [].concat(args)

  // Attempt to detect Windows Subystem for Linux (WSL).
  // WSL  itself as Linux (which works in most cases), but in
  // this specific case we need to treat it as actually being Windows.
  // The "Windows-way" of opening things through cmd.exe works just fine here,
  // whereas using xdg-open does not, since there is no X Windows in WSL.
  if (platform === 'linux' && os.release().toLowerCase().indexOf('microsoft') !== -1) {
    platform = 'win32'
  }

  // http://stackoverflow.com/q/1480971/3191, but see below for Windows.
  let command
  switch (platform) {
    case 'win32': {
      command = 'cmd.exe'
      if (tool) {
        args.unshift(tool)
      }
      break
    }
    case 'darwin': {
      command = 'open'
      if (tool) {
        args.unshift(tool)
        args.unshift('-a')
      }
      break
    }
    default: {
      command = tool || 'xdg-open'
      break
    }
  }

  if (platform === 'win32') {
    // On Windows, we really want to use the "start" command.
    // But, the rules regarding arguments with spaces, and escaping them with quotes,
    // can get really arcane. So the easiest way to deal with this is to pass off the
    // responsibility to "cmd /c", which has that logic built in.
    //
    // Furthermore, if "cmd /c" double-quoted the first parameter,
    // then "start" will interpret it as a window title,
    // so we need to add a dummy empty-string window title: http://stackoverflow.com/a/154090/3191
    //
    // Additionally, on Windows ampersand needs to be escaped when passed to "start"
    args = args.map(value => {
      return value.replace(/&/g, '^&')
    })
    args = ['/c', 'start', '""'].concat(args)
  }

  return childProcess.spawn(command, args, {
    shell: false,
    detached: true
  })
}