import type { AnalyticsEventProperties, AnalyticsService } from './analytics-service';

/**
 * Type definition for the Umami global object.
 *
 * This represents the `window.umami` object that the Umami script exposes.
 * The `track` function can accept either an event name or a URL.
 */
type UmamiGlobal = {
  track?: (eventOrUrl: string, props?: AnalyticsEventProperties) => void;
};

/**
 * Configuration options for UmamiAnalyticsService.
 *
 * @property enabled - Whether analytics are enabled
 */
export type UmamiAnalyticsServiceOptions = {
  enabled: boolean;
};

/**
 * Umami Analytics Service Implementation.
 *
 * This service implements the AnalyticsService interface for Umami analytics.
 * It provides type-safe event tracking and pageview tracking.
 *
 * @example
 * ```typescript
 * // Service creation (usually done by create-services.ts)
 * const service = new UmamiAnalyticsService({ enabled: true });
 *
 * // Track events
 * service.track('button_click', { button_id: 'cta' });
 * service.trackPageview('/products/123');
 * ```
 *
 * @example
 * ```typescript
 * // Using through the service layer (recommended)
 * import { getAppServices } from '@/lib/services/create-services';
 *
 * const services = getAppServices();
 * services.analytics.track('product_add_to_cart', {
 *   product_id: '123',
 *   price: 99.99,
 * });
 * ```
 */
export class UmamiAnalyticsService implements AnalyticsService {
  constructor(private readonly options: UmamiAnalyticsServiceOptions) {}

  /**
   * Track a custom event with optional properties.
   *
   * This method checks if analytics are enabled and if we're in a browser environment
   * before attempting to track the event.
   *
   * @param eventName - The name of the event to track
   * @param props - Optional event properties
   *
   * @example
   * ```typescript
   * service.track('product_add_to_cart', {
   *   product_id: '123',
   *   product_name: 'Cable',
   *   price: 99.99,
   *   quantity: 1,
   * });
   * ```
   */
  track(eventName: string, props?: AnalyticsEventProperties) {
    if (!this.options.enabled) return;
    
    // Server-side tracking via proxy
    if (typeof window === 'undefined') {
      const { getServerAppServices } = require('../create-services.server');
      const { config } = require('../../config');
      const websiteId = config.analytics.umami.websiteId;
      const umamiUrl = config.analytics.umami.scriptUrl.replace('/script.js', '');
      
      if (!websiteId) return;

      const logger = getServerAppServices().logger.child({ component: 'analytics' });
      logger.info('Sending analytics event', { eventName, props });

      fetch(`${umamiUrl}/api/send`, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json', 'User-Agent': 'KLZ-Server' },
        body: JSON.stringify({ type: 'event', payload: { website: websiteId, name: eventName, data: props } }),
      }).catch((error) => {
        logger.error('Failed to send analytics event', { eventName, props, error });
      });
      return;
    }

    const umami = (window as unknown as { umami?: UmamiGlobal }).umami;
    umami?.track?.(eventName, props);
  }

  /**
   * Track a pageview.
   *
   * This method checks if analytics are enabled and if we're in a browser environment
   * before attempting to track the pageview.
   *
   * Umami treats `track(url)` as a pageview override, so we can use the same
   * `track` function for both events and pageviews.
   *
   * @param url - The URL to track (defaults to current location)
   *
   * @example
   * ```typescript
   * // Track current page
   * service.trackPageview();
   *
   * // Track custom URL
   * service.trackPageview('/products/123?category=cables');
   * ```
   */
  trackPageview(url?: string) {
    if (!this.options.enabled) return;

    // Server-side tracking via proxy
    if (typeof window === 'undefined') {
      const { getServerAppServices } = require('../create-services.server');
      const { config } = require('../../config');
      const websiteId = config.analytics.umami.websiteId;
      const umamiUrl = config.analytics.umami.scriptUrl.replace('/script.js', '');
      
      if (!websiteId || !url) return;

      const logger = getServerAppServices().logger.child({ component: 'analytics' });
      logger.info('Sending analytics pageview', { url });

      fetch(`${umamiUrl}/api/send`, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json', 'User-Agent': 'KLZ-Server' },
        body: JSON.stringify({ type: 'event', payload: { website: websiteId, url } }),
      }).catch((error) => {
        logger.error('Failed to send analytics pageview', { url, error });
      });
      return;
    }

    const umami = (window as unknown as { umami?: UmamiGlobal }).umami;

    // Umami treats `track(url)` as a pageview override.
    if (url) umami?.track?.(url);
    else umami?.track?.(window.location.pathname + window.location.search);
  }
}