import { currentTimestamp } from '@posthog/core'
import { version } from './version'

export function getContext(window: Window | undefined): any {
  let context = {}
  if (window?.navigator) {
    const userAgent = window.navigator.userAgent
    const osValue = os(window)
    context = {
      ...context,
      ...(osValue !== undefined && { $os: osValue }),
      $browser: browser(userAgent, window.navigator.vendor, !!(window as any).opera),
      $referrer: window.document.referrer,
      $referring_domain: referringDomain(window.document.referrer),
      $device: device(userAgent),
      $current_url: window.location.href,
      $host: window.location.host,
      $pathname: window.location.pathname,
      $browser_version: browserVersion(userAgent, window.navigator.vendor, !!(window as any).opera),
      $screen_height: window.screen.height,
      $screen_width: window.screen.width,
      $screen_dpr: window.devicePixelRatio,
    }
  }

  context = {
    ...context,
    $lib: 'js',
    $lib_version: version,
    $insert_id: Math.random().toString(36).substring(2, 10) + Math.random().toString(36).substring(2, 10),
    $time: currentTimestamp() / 1000, // epoch time in seconds
  }
  return context // TODO: strip empty props?
}

function includes(haystack: string, needle: string): boolean {
  return haystack.indexOf(needle) >= 0
}

function browser(userAgent: string, vendor: string, opera: boolean): string {
  vendor = vendor || '' // vendor is undefined for at least IE9
  if (opera || includes(userAgent, ' OPR/')) {
    if (includes(userAgent, 'Mini')) {
      return 'Opera Mini'
    }
    return 'Opera'
  } else if (/(BlackBerry|PlayBook|BB10)/i.test(userAgent)) {
    return 'BlackBerry'
  } else if (includes(userAgent, 'IEMobile') || includes(userAgent, 'WPDesktop')) {
    return 'Internet Explorer Mobile'
  } else if (includes(userAgent, 'SamsungBrowser/')) {
    // https://developer.samsung.com/internet/user-agent-string-format
    return 'Samsung Internet'
  } else if (includes(userAgent, 'Edge') || includes(userAgent, 'Edg/')) {
    return 'Microsoft Edge'
  } else if (includes(userAgent, 'FBIOS')) {
    return 'Facebook Mobile'
  } else if (includes(userAgent, 'Chrome')) {
    return 'Chrome'
  } else if (includes(userAgent, 'CriOS')) {
    return 'Chrome iOS'
  } else if (includes(userAgent, 'UCWEB') || includes(userAgent, 'UCBrowser')) {
    return 'UC Browser'
  } else if (includes(userAgent, 'FxiOS')) {
    return 'Firefox iOS'
  } else if (includes(vendor, 'Apple')) {
    if (includes(userAgent, 'Mobile')) {
      return 'Mobile Safari'
    }
    return 'Safari'
  } else if (includes(userAgent, 'Android')) {
    return 'Android Mobile'
  } else if (includes(userAgent, 'Konqueror')) {
    return 'Konqueror'
  } else if (includes(userAgent, 'Firefox')) {
    return 'Firefox'
  } else if (includes(userAgent, 'MSIE') || includes(userAgent, 'Trident/')) {
    return 'Internet Explorer'
  } else if (includes(userAgent, 'Gecko')) {
    return 'Mozilla'
  } else {
    return ''
  }
}

function browserVersion(userAgent: string, vendor: string, opera: boolean): number | null {
  const regexList = {
    'Internet Explorer Mobile': /rv:(\d+(\.\d+)?)/,
    'Microsoft Edge': /Edge?\/(\d+(\.\d+)?)/,
    Chrome: /Chrome\/(\d+(\.\d+)?)/,
    'Chrome iOS': /CriOS\/(\d+(\.\d+)?)/,
    'UC Browser': /(UCBrowser|UCWEB)\/(\d+(\.\d+)?)/,
    Safari: /Version\/(\d+(\.\d+)?)/,
    'Mobile Safari': /Version\/(\d+(\.\d+)?)/,
    Opera: /(Opera|OPR)\/(\d+(\.\d+)?)/,
    Firefox: /Firefox\/(\d+(\.\d+)?)/,
    'Firefox iOS': /FxiOS\/(\d+(\.\d+)?)/,
    Konqueror: /Konqueror:(\d+(\.\d+)?)/,
    BlackBerry: /BlackBerry (\d+(\.\d+)?)/,
    'Android Mobile': /android\s(\d+(\.\d+)?)/,
    'Samsung Internet': /SamsungBrowser\/(\d+(\.\d+)?)/,
    'Internet Explorer': /(rv:|MSIE )(\d+(\.\d+)?)/,
    Mozilla: /rv:(\d+(\.\d+)?)/,
  }

  const browserString = browser(userAgent, vendor, opera) as keyof typeof regexList
  const regex: RegExp = regexList[browserString] || undefined

  if (regex === undefined) {
    return null
  }
  const matches = userAgent.match(regex)
  if (!matches) {
    return null
  }
  return parseFloat(matches[matches.length - 2])
}

function os(window: Window | undefined): string | undefined {
  if (!window?.navigator) {
    return undefined
  }
  const a = window.navigator.userAgent
  if (/Windows/i.test(a)) {
    if (/Phone/.test(a) || /WPDesktop/.test(a)) {
      return 'Windows Phone'
    }
    return 'Windows'
  } else if (/(iPhone|iPad|iPod)/.test(a)) {
    return 'iOS'
  } else if (/Android/.test(a)) {
    return 'Android'
  } else if (/(BlackBerry|PlayBook|BB10)/i.test(a)) {
    return 'BlackBerry'
  } else if (/Mac/i.test(a)) {
    return 'Mac OS X'
  } else if (/Linux/.test(a)) {
    return 'Linux'
  } else if (/CrOS/.test(a)) {
    return 'Chrome OS'
  } else {
    return undefined
  }
}

function device(userAgent: string): string {
  if (/Windows Phone/i.test(userAgent) || /WPDesktop/.test(userAgent)) {
    return 'Windows Phone'
  } else if (/iPad/.test(userAgent)) {
    return 'iPad'
  } else if (/iPod/.test(userAgent)) {
    return 'iPod Touch'
  } else if (/iPhone/.test(userAgent)) {
    return 'iPhone'
  } else if (/(BlackBerry|PlayBook|BB10)/i.test(userAgent)) {
    return 'BlackBerry'
  } else if (/Android/.test(userAgent)) {
    return 'Android'
  } else {
    return ''
  }
}

function referringDomain(referrer: string): string {
  const split = referrer.split('/')
  if (split.length >= 3) {
    return split[2]
  }
  return ''
}