<?php
/**
 * Pixel Article Tracking Endpoint
 * Replaces: pixel-article.cfm
 *
 * Tracks article views, enriches user interest cookies,
 * and queues interaction data for batch processing.
 */

require_once __DIR__ . '/config.php';
require_once __DIR__ . '/PixelResponse.php';
require_once __DIR__ . '/BotFilter.php';
require_once __DIR__ . '/EventBuffer.php';
require_once __DIR__ . '/CookieManager.php';
require_once __DIR__ . '/TopicCache.php';

// --- Validate inputs ---
$id        = filter_input(INPUT_GET, 'id', FILTER_VALIDATE_INT);
$headline  = filter_input(INPUT_GET, 'headline', FILTER_VALIDATE_INT) ?: 1;
$hot       = filter_input(INPUT_GET, 'hot', FILTER_VALIDATE_INT);
$prodid    = filter_input(INPUT_GET, 'prodid', FILTER_VALIDATE_INT);
$sourcevar = isset($_GET['sourcevar']) ? trim($_GET['sourcevar']) : '';
$uuid      = isset($_GET['uuid']) ? trim($_GET['uuid']) : '';
$prod      = isset($_GET['prod']) ? trim($_GET['prod']) : '';

if ($sourcevar !== '' && strlen($sourcevar) > SOURCEVAR_MAX_LENGTH) {
    // Prevent oversized referrers from rolling back entire articlesource batches.
    $sourcevar = substr($sourcevar, 0, SOURCEVAR_MAX_LENGTH);
}

// --- Check if we should skip processing (but still return pixel) ---
$userAgent = $_SERVER['HTTP_USER_AGENT'] ?? '';
$skipProcessing = (stripos($userAgent, 'EZAutoInsert') !== false);

// --- Cookie operations (MUST happen before GIF flush) ---
if (!$skipProcessing) {
    CookieManager::resetInterestsIfOversized();
    CookieManager::clearLegacyCookies();

    // Rolling article cookie
    if ($id) {
        CookieManager::updateArticleCookie($id);
    }

    // Topic interest enrichment via ?hot= param
    if ($hot && !in_array($hot, EXCLUDED_TOPIC_IDS, true)) {
        $topicName = TopicCache::getTopicName($hot);
        if ($topicName !== null) {
            CookieManager::updateInterestsCookie($topicName);
        }
    }

    // Direct production name enrichment via ?prod= param
    if ($prod !== '') {
        CookieManager::updateInterestsCookie($prod);
    }
}

// --- Send 1x1 GIF and close client connection ---
PixelResponse::sendPixelAndFlush();

// --- Everything below is invisible to the client ---

if ($skipProcessing || !BotFilter::shouldTrack($userAgent)) {
    exit;
}

$today    = date('Y-m-d');
$datetime = date('Y-m-d H:i:s');

// Article stats
if ($id) {
    EventBuffer::append('articlestats', [
        'id'       => $id,
        'date'     => $today,
        'type'     => 'story2',
        'headline' => $headline,
    ]);

    // Source tracking
    if ($sourcevar !== '') {
        EventBuffer::append('articlesource', [
            'id'        => $id,
            'date'      => $today,
            'sourcevar' => $sourcevar,
        ]);
    }
}

// Production stats
if ($prodid) {
    EventBuffer::append('prodstats', [
        'id' => $prodid,
    ]);
}

// Interaction logging — UUID path vs IP path
$interactionProdId = ($hot && $hot > 0) ? $hot : 0;

if ($uuid !== '' && $id) {
    EventBuffer::append('uuidinteractions', [
        'user_id'    => $uuid,
        'article_id' => $id,
        'timestamp'  => $datetime,
        'showid'     => $interactionProdId,
    ]);
} elseif ($id) {
    $ip = getClientIp();
    if ($ip !== '' && $ip !== '0.0.0.0') {
        EventBuffer::append('noidinteractions', [
            'user_id'    => $ip,
            'article_id' => $id,
            'timestamp'  => $datetime,
            'showid'     => $interactionProdId,
        ]);
    }
}