<?php
require_once __DIR__ . '/db/config.php';

// Prevent multiple instances
$lockFile = __DIR__ . '/monitor.lock';
$fp = fopen($lockFile, 'c');
if (!flock($fp, LOCK_EX | LOCK_NB)) {
    // Silently exit if already running (good for cron)
    exit(0);
}

echo "Monitoring started with Multi-Threading...\n";

function sendTelegramNotification($message) {
    try {
        $db = db();
        $stmt = $db->query("SELECT name, value FROM settings WHERE name IN ('telegram_bot_token', 'telegram_chat_id')");
        $settings = [];
        while ($row = $stmt->fetch()) {
            $settings[$row['name']] = $row['value'];
        }

        if (empty($settings['telegram_bot_token']) || empty($settings['telegram_chat_id'])) {
            return;
        }

        $url = "https://api.telegram.org/bot" . $settings['telegram_bot_token'] . "/sendMessage";
        $data = [
            'chat_id' => $settings['telegram_chat_id'],
            'text' => $message,
            'parse_mode' => 'HTML'
        ];

        $ch = curl_init($url);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($ch, CURLOPT_POST, true);
        curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($data));
        curl_setopt($ch, CURLOPT_TIMEOUT, 10);
        curl_exec($ch);
        curl_close($ch);
    } catch (Exception $e) {
        // Suppress errors to not break the monitor loop
    }
}

// Loop indefinitely
while (true) {
    try {
        $db = db();
        $urls = $db->query("SELECT * FROM urls WHERE is_active = 1")->fetchAll();

        if (count($urls) > 0) {
            $mh = curl_multi_init();
            $curl_arr = [];
            $url_info = [];

            // Add handles
            foreach ($urls as $urlData) {
                $ch = curl_init($urlData['url']);
                curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
                curl_setopt($ch, CURLOPT_HEADER, false); // We don't need body, just headers
                curl_setopt($ch, CURLOPT_NOBODY, true);  // HEAD request is faster
                curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
                curl_setopt($ch, CURLOPT_TIMEOUT, 10); // 10s timeout
                curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
                curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, false);
                
                curl_multi_add_handle($mh, $ch);
                $curl_arr[] = $ch;
                // Store info mapped by intval of handle
                $url_info[(int)$ch] = $urlData;
            }

            // Execute handles
            $active = null;
            do {
                $mrc = curl_multi_exec($mh, $active);
            } while ($mrc == CURLM_CALL_MULTI_PERFORM);

            while ($active && $mrc == CURLM_OK) {
                if (curl_multi_select($mh) != -1) {
                    do {
                        $mrc = curl_multi_exec($mh, $active);
                    } while ($mrc == CURLM_CALL_MULTI_PERFORM);
                }
            }

            // Read results
            foreach ($curl_arr as $ch) {
                $ch_id = (int)$ch;
                $urlData = $url_info[$ch_id];
                
                $http_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
                $total_time = curl_getinfo($ch, CURLINFO_TOTAL_TIME);
                $total_time_ms = round($total_time * 1000);
                
                // Determine new status: UP if 200-399
                $new_status = ($http_code >= 200 && $http_code < 400) ? 'UP' : 'DOWN';
                $old_status = $urlData['status'];

                // Update database
                $stmt = $db->prepare("UPDATE urls SET status = ?, last_checked = NOW() WHERE id = ?");
                $stmt->execute([$new_status, $urlData['id']]);

                $stmt = $db->prepare("INSERT INTO logs (url_id, status, response_time, checked_at) VALUES (?, ?, ?, NOW())");
                $stmt->execute([$urlData['id'], $new_status, $total_time_ms]);

                // Check for status change and notify
                if ($old_status && $old_status !== $new_status) {
                    $icon = $new_status === 'UP' ? '✅' : '🚨';
                    $msg = "{$icon} <b>Monitor Alert</b>\n\n";
                    $msg .= "<b>URL:</b> {$urlData['url']}\n";
                    $msg .= "<b>Status:</b> {$new_status} (HTTP {$http_code})\n";
                    $msg .= "<b>Response:</b> {$total_time_ms}ms";
                    sendTelegramNotification($msg);
                }

                curl_multi_remove_handle($mh, $ch);
                curl_close($ch);
            }
            curl_multi_close($mh);
        }
    } catch (Exception $e) {
        echo "Error: " . $e->getMessage() . "\n";
    }

    // Wait 30 seconds before next check
    sleep(30);
}