// Motorcycle Tail Light Control

const int light = 7;           // output for brake light, digital pin
const int sw = 8;              // input for brake light switch, digital pin
const int flashpref = 9;       // input for flash number preference, digital pin (LOW = 2 flashes, HIGH = 3 flashes)
const int ontime = 75;        // flash duration ON time
const int offtime = 50;       // flash duration OFF time
const long delaytime = 3000;   // delay timeout (ms)
long releasetime;
long interval;

void setup()  {
  pinMode(light, OUTPUT);
  pinMode(sw, INPUT);
  pinMode(flashpref, INPUT);
  releasetime = -90000000;
  flash();                    // startup chime
}

void loop()  {
  interval = millis() - releasetime;                             // calculate how long the brake has been off
  if(digitalRead(sw) == HIGH && interval >= delaytime){          // flash + hold! (if more than 3sec elapsed)
      flash();
      while(digitalRead(sw) == HIGH){  //holds the brake light on
          digitalWrite(light, HIGH);
          releasetime = millis();
      }
  }
  else if(digitalRead(sw) == HIGH && interval < delaytime){      // turns the brake light on without flashing (if less than 3 sec)
    while(digitalRead(sw) == HIGH){
        digitalWrite(light, HIGH);
        releasetime = millis();
    }
  }
  else                                                           // turns the brake light off
  {
      digitalWrite(light, LOW);
  }
}

void flash(){                                                    // function for flashing
      digitalWrite(light, HIGH);
      delay(ontime);
      digitalWrite(light, LOW);
      delay(offtime);
      digitalWrite(light, HIGH);
      delay(ontime);
      digitalWrite(light, LOW);
      delay(offtime);
      if(digitalRead(flashpref) == HIGH){                        // flash once more if preference is set
          digitalWrite(light, HIGH);
          delay(ontime);
          digitalWrite(light, LOW);
          delay(offtime);
      }
}