PHP script for a Telegram bot that forwards incoming messages

EchoTelegramBot.php

<?php

// URL for Telegram API functions
const TELEGRAM_API_URL = "https://api.telegram.org/botYOUR-TOKEN/";

// Get the JSON data from the incoming POST request
$data = json_decode(file_get_contents("php://input"), true);

// Check if the message is set and is not "/start"
if (isset($data["message"]) && (!isset($data["message"]["text"]) || $data["message"]["text"] !== "/start")) {
    $chat_id = $data["message"]["chat"]["id"];
    
    $caption = isset($data["message"]["caption"]) ? $data["message"]["caption"] : null;
    
    if (isset($data["message"]["text"])) { // Text message
        $text = $data["message"]["text"];
        $sendMessageData = [
            "chat_id" => $chat_id,
            "text" => $text
        ];
        file_get_contents(TELEGRAM_API_URL . "sendMessage?" . http_build_query($sendMessageData));

    } elseif (isset($data["message"]["photo"])) { // Photo message
        $photo_id = $data["message"]["photo"][0]["file_id"];
        $sendMessageData = [
            "chat_id" => $chat_id,
            "photo" => $photo_id,
            "caption" => $caption
        ];
        file_get_contents(TELEGRAM_API_URL . "sendPhoto?" . http_build_query($sendMessageData));

    } elseif (isset($data["message"]["audio"])) { // Audio message
        $audio_id = $data["message"]["audio"]["file_id"];
        $sendMessageData = [
            "chat_id" => $chat_id,
            "audio" => $audio_id,
            "caption" => $caption
        ];
        file_get_contents(TELEGRAM_API_URL . "sendAudio?" . http_build_query($sendMessageData));

    } elseif (isset($data["message"]["document"])) { // Document message
        $document_id = $data["message"]["document"]["file_id"];
        $sendMessageData = [
            "chat_id" => $chat_id,
            "document" => $document_id,
            "caption" => $caption
        ];
        file_get_contents(TELEGRAM_API_URL . "sendDocument?" . http_build_query($sendMessageData));

    } elseif (isset($data["message"]["video"])) { // Video message
        $video_id = $data["message"]["video"]["file_id"];
        $sendMessageData = [
            "chat_id" => $chat_id,
            "video" => $video_id,
            "caption" => $caption
        ];
        file_get_contents(TELEGRAM_API_URL . "sendVideo?" . http_build_query($sendMessageData));

    } else { // Other unsupported message types
        $sendMessageData = [
            "chat_id" => $chat_id,
            "text" => "This type of message is not supported by the bot."
        ];
        file_get_contents(TELEGRAM_API_URL . "sendMessage?" . http_build_query($sendMessageData));
    }

}

?>