// Guest-only fingerprinting module
// Only guests are fingerprinted - registered users are NOT fingerprinted for privacy
import { browser } from '$app/environment';

let cachedFingerprint = null;
let fingerprintPromise = null;

export async function getGuestFingerprint() {
    if (!browser) return null;

    // Return cached fingerprint if available
    if (cachedFingerprint) return cachedFingerprint;

    // Return existing promise if fingerprint is being generated
    if (fingerprintPromise) return fingerprintPromise;

    fingerprintPromise = generateFingerprint();
    cachedFingerprint = await fingerprintPromise;
    fingerprintPromise = null;

    return cachedFingerprint;
}

async function generateFingerprint() {
    try {
        const FingerprintJS = await import('@fingerprintjs/fingerprintjs');
        const fp = await FingerprintJS.load();
        const result = await fp.get();
        return result.visitorId;
    } catch (error) {
        console.error('Failed to generate fingerprint:', error);
        // Fallback: generate a simple fingerprint from available data
        return generateFallbackFingerprint();
    }
}

function generateFallbackFingerprint() {
    // Fallback fingerprint using basic browser data
    const data = [
        navigator.userAgent,
        navigator.language,
        screen.width + 'x' + screen.height,
        screen.colorDepth,
        new Date().getTimezoneOffset(),
        navigator.hardwareConcurrency || 0,
        navigator.deviceMemory || 0
    ].join('|');

    // Simple hash function
    let hash = 0;
    for (let i = 0; i < data.length; i++) {
        const char = data.charCodeAt(i);
        hash = ((hash << 5) - hash) + char;
        hash = hash & hash;
    }
    return 'fallback_' + Math.abs(hash).toString(36);
}

// Clear cached fingerprint (useful for testing)
export function clearCachedFingerprint() {
    cachedFingerprint = null;
    fingerprintPromise = null;
}