function exec_curl_request($handle) {
	$response = curl_exec($handle);

	if ($response === false) {
		$errno = curl_errno($handle);
		$error = curl_error($handle);
		error_log("Curl returned error $errno: $error\n");
		curl_close($handle);
		return false;
	}
	$http_code = intval(curl_getinfo($handle, CURLINFO_HTTP_CODE));
	curl_close($handle);
	if ($http_code >= 500) {
		// do not wat to DDOS server if something goes wrong
		sleep(10);
		return false;
	} else if ($http_code != 200) {
		$response = json_decode($response, true);
		error_log("Request has failed with error {$response['error_code']}: {$response['description']}\n");
		if ($http_code == 401) {
			throw new Exception('Invalid access token provided');
		}
		return false;
	} else {
		$response = json_decode($response, true);
		if (isset($response['description'])) {
			error_log("Request was successfull: {$response['description']}\n");
		}
		$response = $response['result'];
	}
	return $response;
}
function apiRequest($method, $parameters) {
	if (!is_string($method)) {
		error_log("Method name must be a string\n");
		return false;
	}
	if (!$parameters) {
		$parameters = array();
	} else if (!is_array($parameters)) {
		error_log("Parameters must be an array\n");
		return false;
	}
	foreach ($parameters as $key => &$val) {
		// encoding to JSON array parameters, for example reply_markup
		if (!is_numeric($val) && !is_string($val)) {
			$val = json_encode($val);
		}
	}

	$url    = 'https://api.telegram.org/bot'.BOT_TOKEN.'/' . $method . '?' . http_build_query($parameters);
	$handle = curl_init($url);
	curl_setopt($handle, CURLOPT_RETURNTRANSFER, true);
	curl_setopt($handle, CURLOPT_CONNECTTIMEOUT, 5);
	curl_setopt($handle, CURLOPT_TIMEOUT, 60);
	return exec_curl_request($handle);
}
function sendMessage($chat_id, $text_message) {
	$return_send = apiRequest("sendMessage", array(
		'chat_id' => $chat_id,
		'parse_mode' => "html",
		'disable_web_page_preview' => true,
		"text" => $text_message
	));
	return $return_send;
}
function sendPhotoMessage($chat_id, $text_message, $photo) {
	$result_send = apiRequest("sendPhoto", array(
		'chat_id' => $chat_id,
		'parse_mode' => "html",
		'caption' => $text_message,
		'photo' => $photo
	));
	return $return_send;
}