Build a Reliable Local Telegram Bot Loop in PHP with getUpdates

<?php
// bot.php

declare(strict_types=1);

$token = getenv('TELEGRAM_BOT_TOKEN');
if (!$token) {
    fwrite(STDERR, "Error: TELEGRAM_BOT_TOKEN environment variable is not set.\n");
    exit(1);
}

$offset = 0;
$limit = 100;
$timeout = 30; // Long polling timeout in seconds

echo "Starting Telegram Bot long polling loop...\n";

// Handle graceful shutdown on Unix systems
$running = true;
if (extension_loaded('pcntl')) {
    pcntl_async_signals(true);
    pcntl_signal(SIGINT, function () use (&$running) {
        echo "\nGracefully shutting down...\n";
        $running = false;
    });
}

while ($running) {
    $url = sprintf('https://api.telegram.org/bot%s/getUpdates', $token);
    $payload = [
        'offset' => $offset,
        'limit' => $limit,
        'timeout' => $timeout,
    ];

    $ch = curl_init($url);
    curl_setopt_array($ch, [
        CURLOPT_RETURNTRANSFER => true,
        CURLOPT_POST => true,
        CURLOPT_POSTFIELDS => json_encode($payload),
        CURLOPT_HTTPHEADER => ['Content-Type: application/json'],
        CURLOPT_TIMEOUT => $timeout + 5, // Must be higher than Telegram's timeout
        CURLOPT_CONNECTTIMEOUT => 10,
    ]);

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

    if ($response === false) {
        fwrite(STDERR, "cURL Error: {$curlError}. Retrying in 5 seconds...\n");
        sleep(5);
        continue;
    }

    if ($httpCode !== 200) {
        fwrite(STDERR, "HTTP Error: Received status code {$httpCode}. Retrying in 5 seconds...\n");
        sleep(5);
        continue;
    }

    $data = json_decode($response, true);
    if (json_last_error() !== JSON_ERROR_NONE) {
        fwrite(STDERR, "JSON Decode Error: " . json_last_error_msg() . ". Retrying in 5 seconds...\n");
        sleep(5);
        continue;
    }

    if (!isset($data['ok']) || !$data['ok']) {
        $description = $data['description'] ?? 'Unknown error';
        fwrite(STDERR, "Telegram API Error: {$description}. Retrying in 5 seconds...\n");
        sleep(5);
        continue;
    }

    $updates = $data['result'] ?? [];
    foreach ($updates as $update) {
        $updateId = $update['update_id'];

        try {
            processUpdate($update);
        } catch (Throwable $e) {
            fwrite(STDERR, "Error processing update {$updateId}: " . $e->getMessage() . "\n");
        }

        // Increment offset to acknowledge this update and all prior updates
        $offset = $updateId + 1;
    }

    // Yield CPU cycles if no updates were returned
    if (empty($updates)) {
        usleep(100000); // 100ms
    }
}

function processUpdate(array $update): void

{
    if (isset($update['message'])) {
        $message = $update['message'];
        $chatId = $message['chat']['id'] ?? null;
        $text = $message['text'] ?? '';

        if ($chatId && $text !== '') {
            echo "Received message from Chat ID {$chatId}: {$text}\n";
            // Implement your routing and business logic here
        }
    }
}

export TELEGRAM_BOT_TOKEN="123456:ABC-DEF1234ghIkl-zyx57W2v1u123ew11"
php bot.php

// Example idempotency check using a PDO database connection
$stmt = $pdo->prepare("INSERT INTO processed_updates (update_id) VALUES (:id)");
try {
    $stmt->execute([':id' => $updateId]);
} catch (PDOException $e) {
    if ($e->getCode() === '23000') { // Unique constraint violation
        echo "Update {$updateId} already processed. Skipping.\n";
        return;
    }
    throw $e;
}