// A (over)simplified command line interpreter.
//
// Using the readStringUntil('\n') is dangerous,
// there could be a '\r' or both a '\r' and '\n',
// and care should be taken with a timeout.
// All of that is not possible with readStringUntil().
// That means that this example is not only
// (over)simplified, it is also bad code.

char *command = "";
int number = 0;

void setup() 
{
  Serial.begin(115200);
  Serial.println();
  Serial.println("type: help");
  Serial.setTimeout(100);
}

void loop() 
{
  if (Serial.available() > 0) 
  {
    String input = Serial.readStringUntil('\n');

    if(input.startsWith("delay"))
    {
      command = "delay";
      number = (int) input.substring(6).toInt();
    }
    else if(input.startsWith("blink"))
    {
      command = "blink";
      number = (int) input.substring(6).toInt();
    }
    else if(input.startsWith("test"))
    {
      command = "test";
      number = (int) input.substring(5).toInt();
    }
    else if(input.startsWith("led"))
    {
      command = "led";
      number = (int) input.substring(4).toInt();
    }
    else if(input.startsWith("help"))
    {
      Serial.println("-------------------------------------------------");
      Serial.println("Type a command, followed by a space and a number.");
      Serial.println("Available commands: delay, help, blink, test, led");
      Serial.println("-------------------------------------------------");
      command = "help";
      number = (int) input.substring(5).toInt();
    }
    else
    {
      command = "<unknown>";
      number = 0;
    }
    
    Serial.print("Command: \"");
    Serial.print(command);
    Serial.print("\", Number: ");
    Serial.println(number);
  }
  delay(10);  // slow down the sketch (for no reason)
}