/*
===========================================================================
referrals.mjs - referral/UTM hand-off on the homepage and play navigation.
No credentials or raw fingerprints are stored. This key/shape is shared with
traffic.mjs and client referral-attribution.ts; cross-origin navigation carries query values.
===========================================================================
*/
import { captureTraffic, appendTraffic } from "./traffic.mjs";
export const ATTRIBUTION_KEY = "varkand_traffic";
export const DEVICE_KEY = "varkand.referral-device.v1";

/*
================
mergeAttribution
================
*/
export function mergeAttribution( search, previous = {} ) {
	const result = { ...previous };
	const query = new URLSearchParams( search );
	const ref = query.get( "ref" )?.toUpperCase();
	if ( ref && /^[A-Z2-7]{8}$/.test( ref ) ) result.ref = ref;
	for ( const key of [ "utm_source", "utm_medium", "utm_campaign" ] ) {
		const value = query.get( key );
		if ( value && value.length <= 128 ) result[key] = value;
	}
	return result;
}

/*
================
captureReferralTraffic
Keep first-touch UTM, but an explicit referral link must not be swallowed by
an earlier marketing cookie. Inviter immutability begins at account creation.
================
*/
export function captureReferralTraffic() {
	const here = typeof location === "undefined" ? { search: "" } : location;
	const doc = typeof document === "undefined" ? { cookie: "" } : document;
	const values = captureTraffic( here, doc );
	const ref = new URLSearchParams( here.search ).get( "ref" )?.toUpperCase();
	if ( ref && /^[A-Z2-7]{8}$/.test( ref ) && values.ref !== ref ) {
		values.ref = ref;
		try {
			const raw = doc.cookie.split( ";" ).map( v => v.trim() ).find( v => v.startsWith( ATTRIBUTION_KEY + "=" ) );
			const saved = raw ? JSON.parse( decodeURIComponent( raw.slice( ATTRIBUTION_KEY.length + 1 ) ) ) : null;
			const now = Date.now(), expires = saved?.expires ?? now + 30 * 86400000;
			doc.cookie = ATTRIBUTION_KEY + "=" + encodeURIComponent( JSON.stringify( { expires, values } ) ) +
				"; Max-Age=" + Math.max( 0, Math.floor( (expires - now) / 1000 ) ) + "; Path=/; SameSite=Lax; Secure";
		} catch {}
	}
	return values;
}

/*
================
referralSignupMetadata
================
*/
export function referralSignupMetadata() {
	const attribution = captureReferralTraffic();
	let device = "";
	try {
		device = localStorage.getItem( DEVICE_KEY ) ?? "";
		if ( !/^[a-zA-Z0-9-]{16,128}$/.test( device ) ) {
			device = crypto.randomUUID();
			localStorage.setItem( DEVICE_KEY, device );
		}
	} catch {
		device = "";
	}
	return { ref: typeof attribution.ref === "string" ? attribution.ref : "", device };
}

/*
================
carryReferralLinks
Only authored same-site play links receive hand-off metadata.
================
*/
export function carryReferralLinks( root = document ) {
	if ( typeof location === "undefined" || typeof root.querySelectorAll !== "function" ) return;
	referralSignupMetadata();
	const attribution = captureReferralTraffic();
	for ( const anchor of root.querySelectorAll( "a[href]" ) ) {
		anchor.href = appendTraffic( anchor.href, location.href, attribution );
	}
}

if ( typeof document !== "undefined" ) carryReferralLinks( document );