export interface NavigatorInfo {
  userAgent: string;

  userAgentData?: {
    brands?: { brand: string; version: string }[];
    platform?: string;
  };
}

/**
 * Get a minimal representation of browser, version and operating system.
 *
 * The goal is to get enough environemnt info to reproduce issues, but no
 * more.
 */
export function getUserAgentInfo(nav?: NavigatorInfo): string[] {
  nav ??= navigator;

  const browser = getBrowserInfo(nav);
  const os = getOsInfo(nav);
  // The cast below is to cater for TypeScript < 5.5.0
  return [browser, os].filter((v) => v != null) as string[];
}

function getBrowserInfo(nav: NavigatorInfo): string | null {
  const brands = nav.userAgentData?.brands;
  if (brands != null) {
    const tests = [
      { name: 'Google Chrome', value: 'Chrome' },
      { name: 'Opera', value: 'Opera' },
      { name: 'Edge', value: 'Edge' },
      { name: 'Chromium', value: 'Chromium' }
    ];
    for (let { name, value } of tests) {
      const brand = brands.find((b) => b.brand == name);
      if (brand != null) {
        return `${value}/${brand.version}`;
      }
    }
  }

  const ua = nav.userAgent;
  const regexps = [
    { re: /(?:firefox|fxios)\/(\d+)/i, value: 'Firefox' },
    { re: /(?:edg|edge|edga|edgios)\/(\d+)/i, value: 'Edge' },
    { re: /opr\/(\d+)/i, value: 'Opera' },
    { re: /(?:chrome|chromium|crios)\/(\d+)/i, value: 'Chrome' },
    { re: /version\/(\d+).*safari/i, value: 'Safari' }
  ];
  for (let { re, value } of regexps) {
    const match = re.exec(ua);
    if (match != null) {
      return `${value}/${match[1]}`;
    }
  }
  return null;
}

function getOsInfo(nav: NavigatorInfo): string | null {
  if (nav.userAgentData?.platform != null) {
    return nav.userAgentData.platform.toLowerCase();
  }

  const ua = nav.userAgent;
  const regexps = [
    { re: /windows/i, value: 'windows' },
    { re: /android/i, value: 'android' },
    { re: /linux/i, value: 'linux' },
    { re: /iphone|ipad|ipod/i, value: 'ios' },
    { re: /macintosh|mac os x/i, value: 'macos' }
  ];
  for (let { re, value } of regexps) {
    if (re.test(ua)) {
      return value;
    }
  }
  return null;
}