mod/notification-telegram: introduce $GetTelegramChatId

doc/mod/notification-telegram.md

@@ -38,14 +38,21 @@ create your own bot:
 
 ![create new bot](notification-telegram.d/newbot.avif)
 
-Now open a chat with your bot and start it by clicking the `START` button.
+Set that token from *BotFather* (use your own!) to `TelegramTokenId`, for
+now just temporarily:
 
-Open just another chat with [GetIDs Bot](https://t.me/getidsbot), again start
-with the `START` button. It will send you some information, including the
-`id`, just below `You`.
+    :set TelegramTokenId "5214364459:AAHLwf1o7ybbKDo6pY24Kd2bZ5rjCakDXTc";
+
+Now open a chat with your bot and start it by clicking the `START` button,
+then send your first message. Any text will do. On your device run
+`$GetTelegramChatId` to retrieve the chat id:
+
+    $GetTelegramChatId;
+
+![get chat id](notification-telegram.d/getchatid.avif)
 
 Finally edit `global-config-overlay`, add `TelegramTokenId` with the token
-from *BotFather* and `TelegramChatId` with your id from *GetIDs Bot*. Then
+from *BotFather* and `TelegramChatId` with your retrieved chat id. Then
 reload the configuration.
 
 > ℹ️ **Info**: Copy relevant configuration from
@@ -54,9 +61,10 @@ reload the configuration.
 
 ### Notifications to a group
 
-Sending notifications to a group is possible as well. Add your bot and the
-*GetIDs Bot* to a group, then use the group's id (which starts with a dash)
-for `TelegramChatId`. Then remove *GetIDs Bot* from group.
+Sending notifications to a group is possible as well. Add your bot to a group
+and make it an admin (required for read access!) and send a message and run
+`$GetTelegramChatId` again. Then use that chat id (which starts with a dash)
+for `TelegramChatId`.
 
 Groups can enable the `Topics` feature. Use `TelegramThreadId` to send to a
 specific topic in a group.

global-functions.rsc

@@ -15,7 +15,7 @@
 # Git commit id & info, expected configuration version
 :global CommitId "unknown";
 :global CommitInfo "unknown";
-:global ExpectedConfigVersion 134;
+:global ExpectedConfigVersion 135;
 
 # global variables not to be changed by user
 :global GlobalFunctionsReady false;

mod/notification-telegram.rsc

@@ -10,6 +10,7 @@
 # https://rsc.eworm.de/doc/mod/notification-telegram.md
 
 :global FlushTelegramQueue;
+:global GetTelegramChatId;
 :global NotificationFunctions;
 :global PurgeTelegramQueue;
 :global SendTelegram;
@@ -58,6 +59,39 @@
   :global ExitError; $ExitError false $0;
 } }
 
+# get the chat id
+:set GetTelegramChatId do={ :do {
+  :global TelegramTokenId;
+
+  :global CertificateAvailable;
+  :global LogPrint;
+
+  :if ([ $CertificateAvailable "Go Daddy Root Certificate Authority - G2" ] = false) do={
+    $LogPrint warning $0 ("Downloading required certificate failed.");
+    :return false;
+  }
+
+  :local Data;
+  :do {
+    :set Data ([ /tool/fetch check-certificate=yes-without-crl output=user \
+       ("https://api.telegram.org/bot" . $TelegramTokenId . "/getUpdates?offset=0" . \
+       "&allowed_updates=%5B%22message%22%5D") as-value ]->"data");
+  } on-error={
+    $LogPrint warning $0 ("Fetching data failed!");
+    :return false;
+  }
+
+  :local JSON [ :deserialize from=json value=$Data ];
+  :foreach Update in=($JSON->"result") do={
+    $LogPrint info $0 ("The chat id is: " . ($Update->"message"->"chat"->"id"));
+    :return true;
+  }
+
+  $LogPrint info $0 ("No message received.");
+} on-error={ 
+  :global ExitError; $ExitError false $0;
+} } 
+
 # send notification via telegram - expects one array argument
 :set ($NotificationFunctions->"telegram") do={
   :local Notification $1;

news-and-changes.rsc

@@ -59,6 +59,7 @@
   132="Split off plugins from 'check-health', so the script works on all devices to monitor CPU and RAM. The supported plugins for sensors in hardware are installed automatically.";
   133="Updated the default configuration for 'fw-addr-lists', deprecated lists were removed, a collective list was added.";
   134="Enhanced 'mod/notification-telegram' and 'telegram-chat' to support topics in groups.";
+  135="Introduced helper function '\$GetTelegramChatId' for 'mod/notification-telegram' which helps retrieve information.";
 };
 
 # Migration steps to be applied on script updates