#define LEDPIN 1

// where the controller should send the message to this device -- can be anywhere from 8 - 127
#define I2CADDRESS 25 // what's funnier than 24?

#include <Wire.h>

// tells us if this 412 received an 'h' or an 'f' from the controller via I2C
bool hReceived = false;
bool fReceived = false;

void setup() {
  pinMode(LEDPIN, OUTPUT);
  Wire.begin(I2CADDRESS); // enable as peripheral at I2CADDRESS -- 0x25
  Wire.onReceive(readMessage); // function called when a message over I2C is received
  digitalWrite(LEDPIN,LOW); // ensure LED is off at start
}

// read the message, and decode whether or not an 'f' or 'h' is received
void readMessage(int bytes){
  if(Wire.available()) { // go through each character in the message -- for this test case there should only be 1 char
    char c = Wire.read(); // read received byte
    if(c=='h') hReceived = true; // received 'h'
    if(c=='f') fReceived = true; // received 'f'
  }
}

// main loop
void loop() {
  // 'h' is received from controller
  if(hReceived){
    // blink LED once
    digitalWrite(LEDPIN, HIGH);
    delay(100);
    digitalWrite(LEDPIN, LOW);
    hReceived = false;
  }

  // 'f' is received from controller
  if(fReceived){
    // blink LED twice
    digitalWrite(LEDPIN, HIGH);
    delay(100);
    digitalWrite(LEDPIN, LOW);
    delay(100);
    digitalWrite(LEDPIN, HIGH);
    delay(100);
    digitalWrite(LEDPIN, LOW);
    fReceived = false;
  }
  
  delay(100);
  digitalWrite(LEDPIN, LOW); // make sure the LED is off when a message is not received
}