#include <avr/interrupt.h>
#include <TimeLib.h>

const int ledPin=5;
const int debounceTime=20;
unsigned long int currentTime0=0;
unsigned long int currentTime1=0;
volatile unsigned long int triggerTime0=0;
volatile unsigned long int triggerTime1=0;
volatile int luminosity=0;

void setup(){
 DDRB|=(1<<PB5|1<<PB4|1<<PB3|1<<PB2|1<<PB1|1<<PB0);//outputs for segments A B C D E F
 DDRD|=(1<<PD7|1<<PD5);//output for G segment and PWM output on pin5 for LED
 DDRD&=~(1<<PD2|1<<PD3);//configuring pin 2 and 3 as inputs
 PORTB=(1<<PB5|1<<PB4|1<<PB3|1<<PB2|1<<PB1|1<<PB0);//7 segment default will be 0
 PORTD&=~(1<<PD7|1<<PD5);//setting G segment and LED to 0   
 PORTD|=(1<<PD2|1<<PD3);//pullup resistor for both pins
 EIMSK|=0b00000011;//configuring both INT0 and INT1 interrupts
 EICRA|=0b00000000;//interrupt if low level is detected
 sei();
}

ISR(INT0_vect){

 currentTime0=millis();

 if(currentTime0-triggerTime0>debounceTime){
  if(luminosity>0)luminosity--;
  triggerTime0=millis();
 }
}

ISR(INT1_vect){

currentTime1=millis();

if(currentTime1-triggerTime1>debounceTime){
  if(luminosity<9)luminosity++;
  triggerTime1=millis();
  }
}

void updateLuminosity();

int main(){
  init();
  setup();
  while(true){
    updateLuminosity();
  }
}

void updateLuminosity(){
 switch (luminosity){
      case 0:
       PORTB=1<<PB5|1<<PB4|1<<PB3|1<<PB2|1<<PB1|1<<PB0;
       PORTD&=~(1<<PD7);
       break;
      case 1: 
       PORTB=1<<PB4|1<<PB3;
       PORTD&=~(1<<PD7);
       break;
      case 2: 
       PORTB=1<<PB5|1<<PB4|1<<PB2|1<<PB1;
       PORTD|=1<<PD7;
       break;
      case 3: 
       PORTB=1<<PB5|1<<PB4|1<<PB3|1<<PB2;
       PORTD|=1<<PD7;
       break;
      case 4: 
       PORTB=1<<PB4|1<<PB3|1<<PB0;
       PORTD|=1<<PD7;
       break;
      case 5: 
       PORTB=1<<PB5|1<<PB3|1<<PB2|1<<PB0;
       PORTD|=1<<PD7;
       break;
      case 6: 
       PORTB=1<<PB5|1<<PB3|1<<PB2|1<<PB1|1<<PB0;
       PORTD|=1<<PD7;
       break;
      case 7: 
       PORTB=1<<PB5|1<<PB4|1<<PB3;
       PORTD&=~(1<<PD7);
       break;
      case 8: 
       PORTB=1<<PB5|1<<PB4|1<<PB3|1<<PB2|1<<PB1|1<<PB0;
       PORTD|=1<<PD7;
       break;
      case 9: 
       PORTB=1<<PB5|1<<PB4|1<<PB3|1<<PB2|1<<PB0;
       PORTD|=1<<PD7;
       break;
    }
    analogWrite(ledPin,luminosity*28);
}