<?php
/**
 * Bot Filter — Unified bot/spider detection for all pixel endpoints.
 *
 * Consolidates the various bot keyword lists from:
 * - pixel-article.cfm: EZAutoInsert, bot, spider
 * - sitepixel.cfm: bot, spider, crawler, slurp, mediapartners, baidu, yandex
 * - pixel-people.cfm: bot, spider, slurp, MSIE 6, addthis, crawler, EZAutoInsert
 */
class BotFilter
{
    private const BOT_KEYWORDS = [
        'bot',
        'spider',
        'crawler',
        'slurp',
        'mediapartners',
        'baidu',
        'yandex',
        'ezautoinsert',
        'addthis',
    ];

    /**
     * Returns true if this request should be tracked (i.e. NOT a bot).
     */
    public static function shouldTrack(?string $userAgent = null): bool
    {
        $ua = $userAgent ?? ($_SERVER['HTTP_USER_AGENT'] ?? '');
        if ($ua === '') {
            return false;
        }

        $uaLower = strtolower($ua);
        foreach (self::BOT_KEYWORDS as $keyword) {
            if (str_contains($uaLower, $keyword)) {
                return false;
            }
        }

        return true;
    }
}