<?php

$botToken = “123456:ABC-DEF1234ghIkl-zyx57W2v1u123ew11”;

$botAPI = “https://api.telegram.org/bot” . $botToken; $update = file_get_contents(‘php://input’);

$update = json_decode($update, TRUE);

if (!$update) { exit; }

$message = isset($update[‘message’]) ? $update[‘message’] : “”;

where
$botToken is the bot token, generated by BotFather for your bot and used to register the bot on the Webhook service
$botAPI is the URL used to send commands to the Telegram API
file_get_contents(‘php://input’) handle the call incoming from Telegram server
json_decode($update, TRUE) decode communication message in a JSON structure
if (!$update) { exit; } if it’s not a valid JSON command, it exits the script
$message if it’s a valid command, it extracts the sent message

The script can already be published; it still does nothing but works already.
Now let’s add some lines to extract useful data from the message incoming


$messageId = isset($message['message_id']) ? $message['message_id'] : "";

$messageText = isset($message['text']) ? $message['text'] : "";
$messageText = trim($messageText);
$messageText = strtolower($messageText);
                        
$date = isset($message['date']) ? $message['date'] : "";
                        
$chatId = isset($message['chat']['id']) ? $message['chat']['id'] : "";
$username = isset($message['chat']['username']) ? $message['chat']['username'] : "";
$firstname = isset($message['chat']['first_name']) ? $message['chat']['first_name'] : "";
$lastname = isset($message['chat']['last_name']) ? $message['chat']['last_name'] : "";

where
$messageId is the unique identification number of the chat message
$messageText if it is a text message, the text contained in the message sent
$date is the date the message was sent
$chatId is the unique id of the user who sent the message
$username is the username of the user who sent the message
$firstname is the firs tname of the user who sent the message
$lastname is the last name of the user who sent the message

Message is not necessarily a text, it is possible to managed the type of incoming message with the following lines


if (isset($message['text'])) {
    $response = "Received a text message: " . $message['text'];
} elseif (isset($message['audio'])) {
    $response = "Received an audio message";
} elseif (isset($message['document'])) {
    $response = "Received a document message";
} elseif (isset($message['photo'])) {
    $response = "Received a photo message";
} elseif (isset($message['sticker'])) {
    $response = "Received a sticker message";
} elseif (isset($message['video'])) {
    $response = "Received a video message";
} elseif (isset($message['voice'])) {
    $response = "Received a voice message";
} elseif (isset($message['contact'])) {
    $response = "Received a contact message";
} elseif (isset($message['location'])) {
    $response = "Received a location message";
} elseif (isset($message['venue'])) {
    $response = "Received a venue message";
} else {
    $response = "I received a message?";
}

When a photo is sent to the bot, you can retrieve the file and its info from Telegram API.


if (isset($message['photo'])) {
    $fileAPI = "https://api.telegram.org/file/bot" . $botToken;
    $url = $GLOBALS[botAPI] . '/getFile?file_id=' . $message['photo'][0]['file_id'];
    $fileinfo = file_get_contents($url);
    $fileinfo = json_decode($fileinfo, TRUE);                          
    $filePath = $fileinfo['result']['file_path'];
    $url = $GLOBALS[fileAPI] . '/' . $filePath;
                          
    $imgData = "File size: " . $message['photo'][0]['file_size'] . "byte" . chr(10)
        . "Width: " . $message['photo'][0]['width'] . "px" . chr(10)
        . "Height: " . $message['photo'][0]['height'] . "px" . chr(10)
        . "URL: " . $url);
}

where
$fileAPI is the URL used to retrieve file info from Telegram API
$fileinfo the script performs an HTTP GET call to get file info in JSON format
$filePath the script get the URL path of file
$message[‘photo’][0][‘file_size’] is the size of the first file in byte
$message[‘photo’][0][‘width’] and $message[‘photo’][0][‘height’] are the dimension of the first file in pixels

Bot can send several type of message to the chat

Text messages


$url = $GLOBALS[botAPI] . '/sendMessage?chat_id=' . $chatId . '&text=' . urlencode($message);
file_get_contents($url);

Photo messages


$url = $GLOBALS[botAPI] . '/sendPhoto?chat_id=' . $chatId . '&photo=' . urlencode("https://webnoos.altervista.org/noos.jpeg");
file_get_contents($url);

Location messages


$url = $GLOBALS[botAPI] . '/sendLocation?chat_id=' . $chatId . '&latitude=' . urlencode("45.1") . '&longitude=' . urlencode("11.3");
file_get_contents($url);

Telegram also features the ability to display keyboards in chat like this


header("Content-Type: application/json");
$parameters = array('chat_id' => $chatId, "text" => $messageText);
$parameters["method"] = "sendMessage";
$parameters["reply_markup"] = '{ "keyboard": [["uno", "due"], ["tre"], ["quattro", "5", "6"]], "one_time_keyboard": false}';
echo json_encode($parameters);

The current keyboard can be removed from the chat in this way


header("Content-Type: application/json");
$parameters = array('chat_id' => $chatId, "text" => $messageText);
$parameters["method"] = "sendMessage";
$parameters["reply_markup"] = '{ "remove_keyboard" : true}';
echo json_encode($parameters);

You can also display an inline keyboard


header("Content-Type: application/json");
$parameters = array('chat_id' => $chatId, "text" => $messageText);
$parameters["method"] = "sendMessage";
$keyboard = ['inline_keyboard' => [[
    ['text' =>  'Vai su Google', 'url' => 'https://www.google.com'],
    ['text' => 'Vai su Microsoft', 'url' => 'https://www.microsoft.com']
]]];
$parameters["reply_markup"] = json_encode($keyboard, true);
echo json_encode($parameters);

Finally, you have the ability to manage messages sent to the bot as a series of commands, to do different things, as in this example


switch ($messageText) {
    case "/hi":
        // TODO
        break;
                          
    default:
        // TODO
}

from Bruno Tessaro