⚡ Add apiEndpoint to Telegram credentials

Create an advanced option for setting custom Telegram's apiEndpoint.

Inspired by https://github.com/go-telegram-bot-api/telegram-bot-api/blob/3834565c356e9b2d94bd8080555aeaf795bbb0ea/bot.go#L100

packages/nodes-base/credentials/TelegramApi.credentials.ts

@@ -16,5 +16,25 @@ export class TelegramApi implements ICredentialType {
 			default: '',
 			description: 'Chat with the <a href="https://telegram.me/botfather">bot father</a> to obtain the access token.',
 		},
+		{
+			displayName: 'Advanced',
+			name: 'advanced',
+			type: 'boolean',
+			default: false,
+		},
+		{
+			displayName: 'APIEndpoint',
+			name: 'apiEndpoint',
+			type: 'string',
+			displayOptions: {
+				show: {
+					advanced: [
+						true,
+					],
+				},
+			},
+			default: 'https://api.telegram.org/bot{0}/{1}',
+			description: 'API endpoint. Use to redirect Telegram API calls to another server. First \'{0}\' is the \'accessToken\', second \'{1}\' is the endpoint method. See: <a href="https://core.telegram.org/bots">bot api</a>.',
+		},
 	];
 }

packages/nodes-base/nodes/Telegram/GenericFunctions.ts

@@ -150,12 +150,14 @@ export async function apiRequest(this: IHookFunctions | IExecuteFunctions | ILoa
 		throw new NodeOperationError(this.getNode(), 'No credentials got returned!');
 	}
 
+	const uri = formatString(`${credentials.apiEndpoint}`, `${credentials.accessToken}`, endpoint);
+
 	query = query || {};
 
 	const options: OptionsWithUri = {
 		headers: {},
 		method,
-		uri: `https://api.telegram.org/bot${credentials.accessToken}/${endpoint}`,
+		uri: uri,
 		body,
 		qs: query,
 		json: true,
@@ -196,3 +198,12 @@ export function getImageBySize(photos: IDataObject[], size: string): IDataObject
 export function getPropertyName(operation: string) {
 	return operation.replace('send', '').toLowerCase();
 }
+
+function formatString(s: string, ...args : string[]): string {
+	return s.replace(/{(\d+)}/g, function(match, number) {
+		return typeof args[number] != 'undefined'
+		  ? args[number]
+		  : match
+		;
+	  });
+}