<?php
//====================================================
// LOGGING FUNCTIONS
//====================================================

function logging_errors($error_code, $data) {
    switch ($error_code) {
        case '400': $redirect = 'error/400'; break;
        case '401': $redirect = 'error/401'; break;
        case '403': $redirect = 'error/403'; break;
        case '404': $redirect = 'error/404'; break;
        case '405': $redirect = 'error/405'; break;
        case '408': $redirect = 'error/408'; break;
        case '409': $redirect = 'error/409'; break;
        case '410': $redirect = 'error/410'; break;
        case '415': $redirect = 'error/415'; break;
        case '429': $redirect = 'error/429'; break;
        case '500': $redirect = 'error/500'; break;
        case '501': $redirect = 'error/501'; break;
        case '502': $redirect = 'error/502'; break;
        case '503': $redirect = 'error/503'; break;
        case '504': $redirect = 'error/504'; break;
        default: $redirect = 'error/default'; break;
    }

    $visitor = !empty($_SESSION['VISITOR']) && is_array($_SESSION['VISITOR']) ? $_SESSION['VISITOR'] : [];

    $log_data = [
        'correlation_id' => $_SESSION['ID'] ?? 'unknown',
        'timestamp' => gmdate(DATE_ATOM),
        'error_code' => $error_code,
        'log_data' => $data,
        'ip' => $visitor['ip'] ?? 'unknown',
        'state' => $visitor['state'] ?? 'unknown',
        'country' => $visitor['country'] ?? 'unknown'
    ];

    $log_entry = json_encode($log_data, JSON_UNESCAPED_SLASHES);
    $week = gmdate('o-\WW');
    file_put_contents(__ROOT__ . '/logs/errors_' . $week . '.log', $log_entry . PHP_EOL, FILE_APPEND | LOCK_EX);
    return $redirect;
}

function logging_requests() {
    $requests_per_second = calculateRequestVelocity($_SESSION['ID']);
    $visitor = !empty($_SESSION['VISITOR']) && is_array($_SESSION['VISITOR']) ? $_SESSION['VISITOR'] : [];

    if($requests_per_second < BLOCK_THRESHOLD) {
        $log_data = [
            'correlation_id' => $_SESSION['ID'],
            'timestamp' => gmdate(DATE_ATOM),
        ];

        if(isRealVisitor() == true) {
            $log_data['type'] = 'visitor';
            sendVisitorNotification();
        } else {
            $log_data['type'] = 'bot';
        }

        $log_data = array_merge($log_data, [
            'method' => $_SERVER['REQUEST_METHOD'] ?? 'UNKNOWN',
            'uri' => $_SERVER['REQUEST_URI'] ?? 'UNKNOWN',
            'ip' => $visitor['ip'] ?? 'unknown',
            'state' => $visitor['state'] ?? 'unknown',
            'country' => $visitor['country'] ?? 'unknown',
            'user_agent' => $_SERVER['HTTP_USER_AGENT'] ?? 'UNKNOWN',
            'requests_per_second' => $requests_per_second
        ]);

        $log_entry = json_encode($log_data, JSON_UNESCAPED_SLASHES);
        $week = gmdate('o-\WW');
        file_put_contents(__ROOT__ . '/logs/requests_' . $week . '.log', $log_entry . PHP_EOL, FILE_APPEND | LOCK_EX);
    } else {
        $redirect = logging_errors("429", $_SERVER['REQUEST_URI']);
        header('Location: ' . __URL__ . $redirect);
        exit;
    }
}

//====================================================
// SECURITY FUNCTIONS
//====================================================

function calculateRequestVelocity($session_id) {
    $velocity_file = __ROOT__ . '/logs/velocity.csv';
    $now = time();
    $csv_line = $session_id . ',' . $now . PHP_EOL;
    file_put_contents($velocity_file, $csv_line, FILE_APPEND | LOCK_EX);

    $time_window = 1;
    $requests_per_second = calculateRecentRequests($session_id, $time_window);
    return $requests_per_second;
}

function calculateRecentRequests($session_id, $time_window = 1) {
    $velocity_file = __ROOT__ . '/logs/velocity.csv';
    $now = time();
    $count = 0;

    if (!file_exists($velocity_file)) {
        return 0;
    }

    $file = fopen($velocity_file, 'r');
    while (($line = fgetcsv($file)) !== FALSE) {
        if (count($line) >= 2) {
            $stored_session = $line[0];
            $timestamp = (int)$line[1];
            if ($stored_session === $session_id && ($now - $timestamp) <= $time_window) {
                $count++;
            }
        }
    }
    fclose($file);
    return $count;
}

function calculateTotalSessionRequests($session_id) {
    $velocity_file = __ROOT__ . '/logs/velocity.csv';
    $count = 0;

    if (!file_exists($velocity_file)) {
        return 0;
    }

    $file = fopen($velocity_file, 'r');
    while (($line = fgetcsv($file)) !== FALSE) {
        if (count($line) >= 2 && $line[0] === $session_id) {
            $count++;
        }
    }
    fclose($file);
    return $count;
}

function sendVisitorNotification() {
    if (!defined('TELEGRAM_BOT_TOKEN') || empty(TELEGRAM_BOT_TOKEN)) return;
    if (isset($_SESSION['visitor_notification_sent'])) return;

    $total_requests = calculateTotalSessionRequests($_SESSION['ID']);
    $visitor = !empty($_SESSION['VISITOR']) && is_array($_SESSION['VISITOR']) ? $_SESSION['VISITOR'] : [];

    if ($total_requests >= 2) {
        $_SESSION['visitor_notification_sent'] = true;

        $ua = $_SERVER['HTTP_USER_AGENT'] ?? 'UNKNOWN';
        $ua_short = strlen($ua) > 80 ? substr($ua, 0, 77) . '...' : $ua;
        $referrer = $_SERVER['HTTP_REFERER'] ?? 'direct';
        $timestamp = gmdate('Y-m-d H:i:s') . ' UTC';

        $message = "👤 *Visitor — " . ($visitor['country'] ?? 'Unknown') . "*\n"
                 . "• *Time:* $timestamp\n"
                 . "• *Page:* " . ($_SERVER['REQUEST_URI'] ?? '/') . "\n"
                 . "• *Referrer:* $referrer\n"
                 . "• *IP:* " . ($visitor['ip'] ?? 'unknown') . "\n"
                 . "• *Location:* " . ($visitor['city'] ?? '') . ", " . ($visitor['country'] ?? '') . "\n"
                 . "• *Pages:* " . $total_requests . "\n"
                 . "• *Browser:* $ua_short\n"
                 . "• *Session:* `" . $_SESSION['ID'] . "`";

        send2telegram($message);
    }
}

function isRealVisitor() {
    $user_agent = $_SERVER['HTTP_USER_AGENT'] ?? '';
    $uri = $_SERVER['REQUEST_URI'] ?? '';
    $method = $_SERVER['REQUEST_METHOD'] ?? '';
    $accept = $_SERVER['HTTP_ACCEPT'] ?? '';
    $accept_lang = $_SERVER['HTTP_ACCEPT_LANGUAGE'] ?? '';

    $browser_patterns = [
        '/Mozilla\/5\.0.*(Chrome|Firefox|Safari|Edg)\//i',
        '/Mozilla\/5\.0.*Mobile.*Safari/i',
        '/Mozilla\/5\.0.*(iPhone|Android).*(Chrome|Safari)/i',
    ];
    foreach ($browser_patterns as $pattern) {
        if (preg_match($pattern, $user_agent)) return true;
    }

    foreach (BOT_USER_AGENT_PATTERNS as $pattern) {
        if (preg_match($pattern, $user_agent)) return false;
    }

    if (empty($accept) || empty($accept_lang)) return false;
    if (empty($user_agent) || $user_agent === 'UNKNOWN' || strlen($user_agent) < 20) return false;

    foreach (BLOCKED_PATHS as $path) {
        if (strpos($uri, $path) !== false) return false;
    }

    $allowed_methods = ['GET', 'POST', 'HEAD'];
    if (!in_array($method, $allowed_methods)) return false;

    return true;
}

//====================================================
// UTILITY FUNCTIONS
//====================================================

function getVisitor() {
    if (!defined('GEO_KEY') || empty(GEO_KEY)) return false;

    if (!empty($_SERVER['HTTP_X_REAL_IP'])) {
        $ip = $_SERVER['HTTP_X_REAL_IP'];
    } elseif (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) {
        $ipList = explode(',', $_SERVER['HTTP_X_FORWARDED_FOR']);
        $ip = trim($ipList[0]);
    } elseif (!empty($_SERVER['HTTP_CLIENT_IP'])) {
        $ip = $_SERVER['HTTP_CLIENT_IP'];
    } else {
        $ip = $_SERVER['REMOTE_ADDR'];
    }

    $curl = curl_init();
    curl_setopt_array($curl, [
        CURLOPT_URL => 'https://api.ipgeolocation.io/v2/ipgeo?apiKey='.GEO_KEY.'&ip='.$ip,
        CURLOPT_RETURNTRANSFER => true,
        CURLOPT_TIMEOUT => 5,
        CURLOPT_CONNECTTIMEOUT => 3,
        CURLOPT_FOLLOWLOCATION => true,
        CURLOPT_MAXREDIRS => 2,
        CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
    ]);

    $response = curl_exec($curl);
    $httpCode = curl_getinfo($curl, CURLINFO_HTTP_CODE);
    $curlError = curl_error($curl);
    curl_close($curl);

    if ($response === false || $httpCode !== 200) {
        $err = $curlError ?: "HTTP $httpCode";
        error_log("Geo API failed ($err) for IP $ip");
        return false;
    }

    $data = json_decode($response, true);
    if (isset($data)) {
        return [
            'ip' => $data['ip'],
            'city' => $data['location']['city'],
            'state' => $data['location']['state_prov'],
            'country' => $data['location']['country_name']
        ];
    }

    return false;
}

function loadLanguage() {
    $language = !empty($_SESSION['SITE']['language']) ? $_SESSION['SITE']['language'] : 'en';
    $languageFile = __ROOT__ . "/lng/{$language}/menu.php";

    if (file_exists($languageFile)) {
        require_once($languageFile);
    } else {
        require_once(__ROOT__ . "/lng/en/menu.php");
    }
}

function generateCorrelationId(): string {
    $data = random_bytes(16);
    $data[6] = chr(ord($data[6]) & 0x0f | 0x40);
    $data[8] = chr(ord($data[8]) & 0x3f | 0x80);
    return vsprintf('%s%s-%s-%s-%s-%s%s%s', str_split(bin2hex($data), 4));
}

function cleanupVelocityLog() {
    $velocity_file = __ROOT__ . '/logs/velocity.csv';
    $temp_file = __ROOT__ . '/logs/velocity_temp.csv';
    $now = time();
    $max_age = 86400;

    if (!file_exists($velocity_file)) return;

    $input = fopen($velocity_file, 'r');
    $output = fopen($temp_file, 'w');

    while (($line = fgetcsv($input)) !== FALSE) {
        if (count($line) >= 2) {
            $timestamp = (int)$line[1];
            if (($now - $timestamp) <= $max_age) {
                fputcsv($output, $line);
            }
        }
    }

    fclose($input);
    fclose($output);
    rename($temp_file, $velocity_file);
}

//====================================================
// TELEGRAM FUNCTIONS — optional, requires TELEGRAM_BOT_TOKEN + TELEGRAM_CHAT_ID
//====================================================

function send2telegram($message) {
    if (!defined('TELEGRAM_BOT_TOKEN') || !defined('TELEGRAM_CHAT_ID') ||
        empty(TELEGRAM_BOT_TOKEN) || empty(TELEGRAM_CHAT_ID)) {
        return false;
    }

    $url = "https://api.telegram.org/bot" . TELEGRAM_BOT_TOKEN . "/sendMessage";
    $data = [
        'chat_id' => TELEGRAM_CHAT_ID,
        'text' => $message,
        'parse_mode' => 'Markdown'
    ];

    $ch = curl_init();
    curl_setopt_array($ch, [
        CURLOPT_URL => $url,
        CURLOPT_POST => true,
        CURLOPT_POSTFIELDS => $data,
        CURLOPT_RETURNTRANSFER => true,
        CURLOPT_TIMEOUT => 3,
        CURLOPT_CONNECTTIMEOUT => 2
    ]);

    $result = curl_exec($ch);
    $httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
    $error = curl_error($ch);
    curl_close($ch);

    if ($error || $httpCode !== 200) {
        error_log("Telegram API failed: " . ($error ?: "HTTP $httpCode"));
        return false;
    }
    return true;
}