import { notEmpty } from './array'

type SystemTypes = 'os' | 'browser'

type SystemData = {
  name: string
  codeName: string
  versionPrefix: string
}

type SystemInfo = {
  name: string
  version: string
}

type SystemMapping = Record<SystemTypes, SystemData[]>

const SYSTEMS_MAPPING: SystemMapping = {
  os: [
    {
      name: 'Windows Phone',
      codeName: 'Windows Phone',
      versionPrefix: 'Windows Phone',
    },
    { name: 'Windows', codeName: 'Win', versionPrefix: 'NT' },
    { name: 'iPhone', codeName: 'iPhone', versionPrefix: 'OS' },
    { name: 'iPad', codeName: 'iPad', versionPrefix: 'OS' },
    { name: 'Kindle', codeName: 'Silk', versionPrefix: 'Silk' },
    { name: 'Android', codeName: 'Android', versionPrefix: 'Android' },
    { name: 'PlayBook', codeName: 'PlayBook', versionPrefix: 'OS' },
    { name: 'BlackBerry', codeName: 'BlackBerry', versionPrefix: '/' },
    { name: 'Macintosh', codeName: 'Mac', versionPrefix: 'OS X' },
    { name: 'Linux', codeName: 'Linux', versionPrefix: 'rv' },
    { name: 'Palm', codeName: 'Palm', versionPrefix: 'PalmOS' },
  ],
  browser: [
    // List of detectable browsers. Notes that their order is important!
    { name: 'BlackBerry', codeName: 'CLDC', versionPrefix: 'CLDC' },
    { name: 'Edge', codeName: 'Edg', versionPrefix: 'Edg' },
    { name: 'Opera', codeName: 'OPR', versionPrefix: 'OPR' },
    { name: 'Opera Touch', codeName: 'OPT', versionPrefix: 'OPT' },
    {
      name: 'Samsung Browser',
      codeName: 'SamsungBrowser',
      versionPrefix: 'SamsungBrowser',
    },
    { name: 'UC Browser', codeName: 'UCBrowser', versionPrefix: 'UCBrowser' },
    { name: 'Yandex', codeName: 'YaBrowser', versionPrefix: 'YaBrowser' },
    { name: 'Firefox', codeName: 'Firefox', versionPrefix: 'Firefox' },
    { name: 'Firefox iOS', codeName: 'FxiOS', versionPrefix: 'FxiOS' },
    {
      name: 'Internet Explorer Mobile',
      codeName: 'IEMobile',
      versionPrefix: 'IEMobile',
    },
    { name: 'Internet Explorer', codeName: 'MSIE', versionPrefix: 'MSIE' },
    { name: 'Internet Explorer', codeName: 'rv', versionPrefix: 'rv' },
    { name: 'Chrome', codeName: 'Chrome', versionPrefix: 'Chrome' },
    { name: 'Chrome iOS', codeName: 'CriOS', versionPrefix: 'CriOS' },
    { name: 'Safari', codeName: 'Safari', versionPrefix: 'Version' },
    { name: 'Mozilla', codeName: 'Mozilla', versionPrefix: 'Mozilla' },
  ],
}

const detectSystem = (systemType: SystemTypes): SystemInfo => {
  const userAgent = [
    window.navigator.platform,
    window.navigator.userAgent,
    window.navigator.appVersion,
    window.navigator.vendor,
  ].join(' ')

  const matchedSystems = SYSTEMS_MAPPING[systemType].map(
    ({ codeName, name, versionPrefix }) => {
      const codeNameRegex = new RegExp(codeName, 'gi')

      // No system codeNames found
      if (!codeNameRegex.test(userAgent)) {
        return null
      }

      /**
       * RegExp pattern to find all matched user agents
       * with syntax: <product> / <product-version> <comment>
       * - Starts with a unique name `versionPrefix`
       * - Followed by any possible separators `-`, ` ` (space), `/`, `:` or `;`
       * - Ended by a string with numbers joined by `.` or `_`
       */
      const versionRegex = new RegExp(
        `${versionPrefix}[-\\s\\/:;]([\\d\\._]+)`,
        'i'
      )
      const matches = userAgent.match(versionRegex)
      // Convert version string from `1_0_0` (or any non-digit separtors) into `1.0.0`
      const version =
        matches && matches[1] ? matches[1].split(/[^\d]+/).join('.') : '0'

      return {
        name,
        version,
      }
    }
  )

  // Return first non-nullish result
  return matchedSystems.filter(notEmpty)[0]
}

export default detectSystem