add Telegram response to each command with display text

include/Telegram.h

@@ -6,7 +6,7 @@
 struct TelegramCommand
 {
     const String command;
-    void (*const functionPointer) (const String arguments);
+    String (*const functionPointer) (const String arguments);
 };
 
 class Telegram

src/Telegram.cpp

@@ -43,22 +43,32 @@ void Telegram::handleNewMessages(int numNewMessages)
                 String Arguments = "";
                 if (text.length() > cmdList[i].command.length() + 1)
                 {
-                    //Arguments are on space behind the command string
+                    // Arguments are on space behind the command string
                     Arguments = text.substring(cmdList[i].command.length() + 1);
                 }
 
                 if (cmdList[i].functionPointer != nullptr)
                 {
-                    cmdList[i].functionPointer(Arguments);
+                    String DisplayText = cmdList[i].functionPointer(Arguments);
+                    if (DisplayText.isEmpty())
+                    {
+                        bot.sendMessage(chat_id, "Display text is empty!!");
+                    }
+                    else
+                    {
+                        String Answer = "Display text is \"";
+                        Answer += DisplayText;
+                        Answer += "\".";
+                        bot.sendMessage(chat_id, "Display text is empty!!");
+                    }
+                    break;
                 }
-
-                break;
             }
         }
-        
-        if (text == "/display_start")
+
+        if ((text == "/display_start") || (text == "/start") || (text == "/help"))
         {
-            String welcome = "Willkommen beim Tür-Display-Bot," + from_name + ".\n";
+            String welcome = "Willkommen beim Tür-Display-Bot, " + from_name + ".\n\n";
             welcome += "Hier kommen die möglichen Kommandos, die ich verstehe:\n";
 
             for (uint32_t i = 0; i < cmdListCount; i++)

src/main.cpp

@@ -35,15 +35,15 @@ void displayText(const char *text, bool background, int16_t x = -1, int16_t y =
 // BearSSL::WiFiClientSecure secured_client;
 WiFiClientSecure secured_client;
 
-// TelegramCommand callbacks must fulfill a function pointer: void (*) (const String arguments)
-void printOpen(String Args);
-void printClose(String Args);
-void printText(String Args);
+// TelegramCommand callbacks must fulfill a function pointer: String (*) (const String arguments)
+String printOpen(String Args);
+String printClose(String Args);
+String printText(String Args);
 
 TelegramCommand myCmdList[]{
-    {"/display_open", printOpen},
-    {"/display_close", printClose},
-    {"/display_text", printText},
+    {"/open", printOpen},
+    {"/close", printClose},
+    {"/text", printText},
 };
 
 uint32_t myCmdListCnt = sizeof(myCmdList) / sizeof(myCmdList[0]);
@@ -288,20 +288,26 @@ void displayText(const char *text, bool background, int16_t x, int16_t y)
   canvas.print(text);
 }
 
-void printOpen(String Args)
+String printOpen(String Args)
 {
   Text = "offen";
+
+  return Text;
 }
 
-void printClose(String Args)
+String printClose(String Args)
 {
   Text = "leider zu";
+
+  return Text;
 }
 
-void printText(String Args)
+String printText(String Args)
 {
   Serial.print("Display would show '");
   Serial.print(Args);
   Serial.println("'");
   Text = Args;
+
+  return Text;
 }