/** Device / platform metadata attached to checkout analytics events. */

export type DeviceType = 'mobile' | 'tablet' | 'desktop';
export type CheckoutPlatform = 'web' | 'ios' | 'android';

/** Detect coarse device class from viewport / user agent (web only). */
export function detectDeviceType(userAgent?: string): DeviceType {
  if (typeof window !== 'undefined') {
    const w = window.innerWidth;
    if (w < 768) return 'mobile';
    if (w < 1024) return 'tablet';
    return 'desktop';
  }
  const ua = (userAgent ?? '').toLowerCase();
  if (/ipad|tablet/.test(ua)) return 'tablet';
  if (/mobile|iphone|android/.test(ua)) return 'mobile';
  return 'desktop';
}

/** Web checkout platform; native widgets pass platform explicitly. */
export function detectPlatform(): CheckoutPlatform {
  return 'web';
}

/** Best-effort user agent string (empty on native when unavailable). */
export function getUserAgent(): string | undefined {
  if (typeof navigator !== 'undefined' && navigator.userAgent) {
    return navigator.userAgent.slice(0, 512);
  }
  return undefined;
}

export interface DeviceContext {
  deviceType: DeviceType;
  platform: CheckoutPlatform;
  userAgent?: string;
}

/** Build device context for web embeds. */
export function getWebDeviceContext(): DeviceContext {
  const userAgent = getUserAgent();
  return {
    deviceType: detectDeviceType(userAgent),
    platform: detectPlatform(),
    userAgent,
  };
}