import type { TrackingManager } from '$lib/tracking.svelte';
import type {
	ConversionErrorResponseBody,
	ConversionEventParams,
	ConversionRequestBody,
	ConversionResponseBody,
	ConversionUserData
} from '$lib/types/conversion.js';
import type { StandardEventName } from '$lib/types/fbq.js';

/**
 * Client for sending conversion events to a server endpoint.
 */
export class ConversionClient {
	private _href: string;
	private _trackingManager: TrackingManager;

	/**
	 * Creates a new ConversionClient.
	 *
	 * @param serverHref - The server endpoint URL.
	 * @param trackingManager - The tracking manager instance.
	 */
	constructor(serverHref: string, trackingManager: TrackingManager) {
		this._href = serverHref;
		this._trackingManager = trackingManager;
	}

	/**
	 * Sends a conversion event to the server.
	 *
	 * @param eventName - The name of the standard event to send.
	 * @param options - Additional options for the event.
	 * @returns A promise that resolves to the event response or error.
	 */
	async trackEvent(
		eventName: StandardEventName,
		options: {
			eventID: string;
			user?: Omit<ConversionUserData, 'ip' | 'fbp' | 'fbc' | 'ua'>;
			customData?: ConversionEventParams;
		}
	): Promise<ConversionResponseBody | ConversionErrorResponseBody> {
		// Extract user data
		const fbp = await cookieStore.get('_fbp');
		const fbc = await cookieStore.get('_fbc');

		const user: ConversionUserData = {
			...options.user,
			fbp: fbp?.value,
			fbc: fbc?.value
		};

		// Get event source URL & extract UTM params if present
		const eventSourceURL = window.location.href;
		const url = new URL(eventSourceURL);
		const utms: Record<string, string> = {};
		url.searchParams.forEach((value, key) => {
			if (key.startsWith('utm_')) {
				utms[key] = value;
			}
		});

		// Build request body
		const requestBody: ConversionRequestBody = {
			consent: this._trackingManager.consent === true,
			eventName,
			eventID: options.eventID,
			user,
			eventSourceURL,
			utms,
			customData: options.customData
		};

		// Send request to server
		const response = await fetch(this._href, {
			method: 'POST',
			headers: {
				'Content-Type': 'application/json'
			},
			body: JSON.stringify(requestBody)
		});

		if (response.ok) {
			const data = (await response.json()) as ConversionResponseBody;
			return data;
		} else {
			const errorData = (await response.json()) as ConversionErrorResponseBody;
			return errorData;
		}
	}
}