bot.php

<?php

define('BOT_TOKEN', '12345678:replace-me-with-real-token');
define('API_URL', 'https://api.telegram.org/bot'.BOT_TOKEN.'/');

define('WEBHOOK_URL', 'https://my-site.example.com/secret-path-for-webhooks/');

//define('CHAT_ID', -1);
// This example will save logs to file 'telegram_logs/channel-name_<year>.<week>.txt'
//define('LOG_PREFIX', 'telegram_logs/channel-name_');
//define('LOG_FORMAT', 'Y.W\.\t\x\t');
//define('DATE_FORMAT', 'Y-m-d H:i:s');
//define('DATETIME_ZONE', 'Europe/Moscow');


function apiRequestWebhook($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;
	}

	$parameters["method"] = $method;

	header("Content-Type: application/json");
	echo json_encode($parameters);
	return true;
}

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);
		}
	}
	$url = API_URL.$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 apiRequestJson($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;
	}

	$parameters["method"] = $method;

	$handle = curl_init(API_URL);
	curl_setopt($handle, CURLOPT_RETURNTRANSFER, true);
	curl_setopt($handle, CURLOPT_CONNECTTIMEOUT, 5);
	curl_setopt($handle, CURLOPT_TIMEOUT, 60);
	curl_setopt($handle, CURLOPT_POSTFIELDS, json_encode($parameters));
	curl_setopt($handle, CURLOPT_HTTPHEADER, array("Content-Type: application/json"));

	return exec_curl_request($handle);
}

function saveMessage($message) {
	$date = new DateTime(date("r", $message["date"]));
	if (defined("DATETIME_ZONE"))
		$date->setTimeZone(new DateTimeZone(DATETIME_ZONE));
	$s_date = $date->format(DATE_FORMAT);

	$log_file = LOG_PREFIX . $date->format(LOG_FORMAT);
	if (!file_exists($log_file)) {
		file_put_contents($log_file, b"\xEF\xBB\xBF");
	}

	$text = $message['text'];
	$from = $message['from']['first_name'];

	file_put_contents($log_file, $s_date . ": " . $from . "> " . $text . "\n", FILE_APPEND);
}

function processMessage($message) {
	// process incoming message
	$message_id = $message['message_id'];
	$chat_id = $message['chat']['id'];

	// Process only specified channel
	if ($chat_id !== CHAT_ID)
		return false;

	if (isset($message['text'])) {
		saveMessage($message);

		// Do not send responses
		return;

		// incoming text message
		$text = $message['text'];

		if (strpos($text, "/start") === 0) {
			apiRequestJson("sendMessage", array('chat_id' => $chat_id, "text" => 'Hello', 'reply_markup' => array(
							'keyboard' => array(array('Hello', 'Hi')),
							'one_time_keyboard' => true,
							'resize_keyboard' => true)));
		} else if ($text === "Hello" || $text === "Hi") {
			apiRequest("sendMessage", array('chat_id' => $chat_id, "text" => 'Nice to meet you'));
		} else if (strpos($text, "/stop") === 0) {
			// stop now
		} else {
			apiRequestWebhook("sendMessage", array('chat_id' => $chat_id, "reply_to_message_id" => $message_id, "text" => 'Cool'));
		}
	} else {
		apiRequest("sendMessage", array('chat_id' => $chat_id, "text" => 'I understand only text messages'));
	}
}


function checkParam($param_name) {
	if (defined($param_name))
		return true;

	if (php_sapi_name() == 'cli')
		echo $param_name . " is not defined.\n";
	exit;	
}

checkParam('CHAT_ID');
checkParam("LOG_PREFIX");
checkParam("LOG_FORMAT");
checkParam("DATE_FORMAT");


if (php_sapi_name() == 'cli') {
	// if run from console, set or delete webhook
	apiRequest('setWebhook', array('url' => isset($argv[1]) && $argv[1] == 'delete' ? '' : WEBHOOK_URL));
	exit;
}


$content = file_get_contents("php://input");
$update = json_decode($content, true);

if (!$update) {
	// receive wrong update, must not happen
	exit;
}

if (isset($update["message"])) {
	processMessage($update["message"]);
}