/**
 * Browser Compatibility Check Module
 * Detects browser support for Web Bluetooth API and provides compatibility information
 */

export interface BrowserInfo {
  name: string;
  version: string;
  isSupported: boolean;
  hasWebBluetooth: boolean;
  platform: string;
}

export interface RecommendedBrowser {
  name: string;
  minVersion: string;
  downloadUrl: string;
  platforms: string[];
}

/**
 * Detects the current browser name and version from user agent
 */
function detectBrowser(): { name: string; version: string } {
  if (typeof window === 'undefined' || typeof navigator === 'undefined') {
    return { name: 'Unknown', version: '0' };
  }

  const userAgent = navigator.userAgent;
  let name = 'Unknown';
  let version = '0';

  // Chrome (must check before Safari as it contains both, exclude Edge and Opera)
  if (/Chrome\/(\d+)/.test(userAgent) && !/Edg/.test(userAgent) && !/OPR/.test(userAgent)) {
    name = 'Chrome';
    const match = userAgent.match(/Chrome\/(\d+)/);
    version = match ? match[1] : '0';
  }
  // Edge (Chromium-based)
  else if (/Edg\/(\d+)/.test(userAgent)) {
    name = 'Edge';
    const match = userAgent.match(/Edg\/(\d+)/);
    version = match ? match[1] : '0';
  }
  // Opera
  else if (/OPR\/(\d+)/.test(userAgent)) {
    name = 'Opera';
    const match = userAgent.match(/OPR\/(\d+)/);
    version = match ? match[1] : '0';
  }
  // Safari (check after Chrome)
  else if (/Safari\/(\d+)/.test(userAgent) && !/Chrome/.test(userAgent)) {
    name = 'Safari';
    const match = userAgent.match(/Version\/(\d+)/);
    version = match ? match[1] : '0';
  }
  // Firefox
  else if (/Firefox\/(\d+)/.test(userAgent)) {
    name = 'Firefox';
    const match = userAgent.match(/Firefox\/(\d+)/);
    version = match ? match[1] : '0';
  }

  return { name, version };
}

/**
 * Detects the platform/OS
 */
function detectPlatform(): string {
  if (typeof window === 'undefined' || typeof navigator === 'undefined') {
    return 'Unknown';
  }

  const userAgent = navigator.userAgent;
  const platform = navigator.platform;

  if (/Win/.test(platform)) return 'Windows';
  if (/Mac/.test(platform)) return 'macOS';
  if (/Linux/.test(platform)) return 'Linux';
  if (/iPhone|iPad|iPod/.test(userAgent)) return 'iOS';
  if (/Android/.test(userAgent)) return 'Android';

  return 'Unknown';
}

/**
 * Checks if Web Bluetooth API is available
 */
function hasWebBluetoothAPI(): boolean {
  if (typeof navigator === 'undefined') {
    return false;
  }

  return 'bluetooth' in navigator;
}

/**
 * Checks if the current browser is supported for WellNuo Web
 * Supported browsers: Chrome 70+, Edge 79+, Opera 57+ (Windows 10+, macOS)
 */
export function isBrowserSupported(): boolean {
  const { name, version } = detectBrowser();
  const versionNum = parseInt(version, 10);
  const platform = detectPlatform();

  // iOS is not supported (system limitations)
  if (platform === 'iOS') {
    return false;
  }

  // Safari and Firefox don't support Web Bluetooth
  if (name === 'Safari' || name === 'Firefox') {
    return false;
  }

  // Check version requirements
  switch (name) {
    case 'Chrome':
      return versionNum >= 70;
    case 'Edge':
      return versionNum >= 79;
    case 'Opera':
      return versionNum >= 57;
    default:
      return false;
  }
}

/**
 * Gets detailed information about the current browser
 */
export function getBrowserInfo(): BrowserInfo {
  const { name, version } = detectBrowser();
  const platform = detectPlatform();
  const hasWebBluetooth = hasWebBluetoothAPI();
  const isSupported = isBrowserSupported();

  return {
    name,
    version,
    isSupported,
    hasWebBluetooth,
    platform,
  };
}

/**
 * Returns list of recommended browsers with download links
 */
export function getRecommendedBrowsers(): RecommendedBrowser[] {
  return [
    {
      name: 'Google Chrome',
      minVersion: '70',
      downloadUrl: 'https://www.google.com/chrome/',
      platforms: ['Windows 10+', 'macOS', 'Linux'],
    },
    {
      name: 'Microsoft Edge',
      minVersion: '79',
      downloadUrl: 'https://www.microsoft.com/edge',
      platforms: ['Windows 10+', 'macOS'],
    },
    {
      name: 'Opera',
      minVersion: '57',
      downloadUrl: 'https://www.opera.com/',
      platforms: ['Windows', 'macOS', 'Linux'],
    },
  ];
}

/**
 * Gets a user-friendly message explaining why the browser is not supported
 */
export function getUnsupportedMessage(browserInfo: BrowserInfo): string {
  const { name, platform } = browserInfo;

  if (platform === 'iOS') {
    return 'Web Bluetooth is not supported on iOS due to system limitations. Please use a desktop browser or download our mobile app.';
  }

  if (name === 'Safari') {
    return 'Safari does not support Web Bluetooth API. Please use Chrome, Edge, or Opera instead.';
  }

  if (name === 'Firefox') {
    return 'Firefox does not support Web Bluetooth API due to privacy concerns. Please use Chrome, Edge, or Opera instead.';
  }

  if (!browserInfo.hasWebBluetooth) {
    return 'Your browser does not support Web Bluetooth API. Please update to a newer version or try Chrome, Edge, or Opera.';
  }

  return 'Your browser is not supported. Please use Chrome 70+, Edge 79+, or Opera 57+.';
}