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

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

/**
 * Umami Analytics Service Implementation (Script-less/Proxy edition).
 *
 * This version implements the Umami tracking protocol directly via fetch,
 * eliminating the need to load an external script.js file.
 *
 * In the browser, it gathers standard metadata (screen, language, referrer)
 * and sends it to the proxied '/stats/api/send' endpoint.
 */
export class UmamiAnalyticsService implements AnalyticsService {
  private websiteId?: string;
  private endpoint: string;

  constructor(private readonly options: UmamiAnalyticsServiceOptions) {
    this.websiteId = config.analytics.umami.websiteId;

    // On server, use the full internal URL; on client, use the proxied path
    this.endpoint = typeof window === 'undefined' ? config.analytics.umami.apiEndpoint : '/stats';
  }

  /**
   * Internal method to send the payload to Umami API.
   */
  private async sendPayload(type: 'event', data: Record<string, any>) {
    if (!this.options.enabled || !this.websiteId) return;

    try {
      const payload = {
        website: this.websiteId,
        hostname: typeof window !== 'undefined' ? window.location.hostname : 'server',
        screen:
          typeof window !== 'undefined'
            ? `${window.screen.width}x${window.screen.height}`
            : undefined,
        language: typeof window !== 'undefined' ? navigator.language : undefined,
        referrer: typeof window !== 'undefined' ? document.referrer : undefined,
        ...data,
      };

      const response = await fetch(`${this.endpoint}/api/send`, {
        method: 'POST',
        headers: {
          'Content-Type': 'application/json',
          'User-Agent': typeof window === 'undefined' ? 'KLZ-Server' : navigator.userAgent,
        },
        body: JSON.stringify({ type, payload }),
        // Use keepalive for page navigation events to ensure they complete
        keepalive: true,
      } as any);

      if (!response.ok && process.env.NODE_ENV === 'development') {
        const errorText = await response.text();
        console.warn(`[Umami] API responded with ${response.status}: ${errorText}`);
      }
    } catch (error) {
      if (process.env.NODE_ENV === 'development') {
        console.error('[Umami] Failed to send analytics:', error);
      }
    }
  }

  /**
   * Track a custom event.
   */
  track(eventName: string, props?: AnalyticsEventProperties) {
    this.sendPayload('event', {
      name: eventName,
      data: props,
      url:
        typeof window !== 'undefined'
          ? window.location.pathname + window.location.search
          : undefined,
    });
  }

  /**
   * Track a pageview.
   */
  trackPageview(url?: string) {
    this.sendPayload('event', {
      url:
        url ||
        (typeof window !== 'undefined'
          ? window.location.pathname + window.location.search
          : undefined),
    });
  }
}