Add preliminary checks.

webhook.php

@@ -0,0 +1,76 @@
+<?php
+$bot_name = "nukist_bot";
+$bot_api = require('api_key.php');
+
+
+// Send text back to the sender.
+function send_text($post_message, $reply=false) {
+  global $decoded;
+  global $bot_api;
+  global $chat_id;
+  $url = 'https://api.telegram.org/bot' . $bot_api . '/sendMessage';
+  $post_msg = array('chat_id' => $chat_id, 'text' =>$post_message );
+  if ($reply != false) {
+    if ($reply === true){
+      $post_msg['reply_to_message_id'] = $decoded->{'message'}->{'message_id'};
+    }
+    else {
+      $post_msg['reply_to_message_id'] = $reply;
+    }
+  }
+  $options = array(
+    'http' => array(
+      'header' => "Content-type: application/x-www-form-urlencoded\r\n",
+      'method' => 'POST',
+      'content' => http_build_query($post_msg)
+    )
+  );
+  $context = stream_context_create($options);
+  $result = file_get_contents($url, false, $context);
+}
+
+function check_admin($user_id) {
+  global $decoded;
+  global $bot_api;
+  global $chat_id;
+  $url = 'https://api.telegram.org/bot' . $bot_api . '/getChatMember';
+  $post_msg = array('chat_id' => $chat_id, 'user_id' =>$user_id );
+  $options = array(
+    'http' => array(
+      'header' => "Content-type: application/x-www-form-urlencoded\r\n",
+      'method' => 'POST',
+      'content' => http_build_query($post_msg)
+    )
+  );
+  $context = stream_context_create($options);
+  $result = file_get_contents($url, false, $context);
+  $user_json = json_decode($result);
+  if ($user_json->{"status"} == "creator" || $user_json->{"status"} == "administrator"){
+    return True;
+  }
+  else {
+    return False;
+  }
+}
+
+// Get JSON from post, store it and decode it.
+$var = file_get_contents('php://input');
+$decoded = json_decode($var);
+
+// Store the chat ID
+$chat_id = $decoded->{"message"}->{"chat"}->{"id"};
+$command_list = explode(" ", $decoded->{"message"}->{"text"});
+
+if ($command_list[0] != "/nuke" && $command_list[0] != "/nuke@$bot_name") {
+  exit();
+}
+if ($decoded->{"chat"}->{"type"} != "supergroup" ){
+  send_text("The bot only works in supergroups.", True);
+  exit();
+}
+
+if (!check_admin($decoded->{"chat"}->{"user"}->{"id"})){
+  send_text("Only admins can run this");
+}
+
+?>