#include <Toggle.h>

const byte but1 = 2;
const byte but2 = 3;
const byte but3 = 4;
const byte but4 = 5;
const byte led1 = 8;
const byte led2 = 9;
const byte led3 = 10;
const byte led4 = 11;
const byte ledUnlocked = 12;

byte butState = 0;

Toggle b1(but1);
Toggle b2(but2);
Toggle b3(but3);
Toggle b4(but4);

void setup() {
  pinMode(led1, OUTPUT);
  pinMode(led2, OUTPUT);
  pinMode(led3, OUTPUT);
  pinMode(led4, OUTPUT);
  pinMode(ledUnlocked, OUTPUT);
  b1.begin(but1);
  b2.begin(but2);
  b3.begin(but3);
  b4.begin(but4);
}

void loop() {
  b1.poll();
  b2.poll();
  b3.poll();
  b4.poll();

  if (b1.onRelease()) {
    if (butState == 0b00000000) {
      butState |= 0b00000001;
      digitalWrite(led1, HIGH);
    } else {
      clr();
    }
  }
  if (b2.onRelease()) {
    if (butState == 0b00000001) {
      butState |= 0b00000001;
      digitalWrite(led2, HIGH);
      butState |= 0b00000010;
    } else {
      clr();
    }
  }
  if (b3.onRelease()) {
    if (butState == 0b00000011) {
      butState |= 0b00000001;
      digitalWrite(led3, HIGH);
      butState |= 0b00000100;
    } else {
      clr();
    }
  }
  if (b4.onRelease()) {
    if (butState == 0b00000111) {
      butState |= 0b00000001;
      digitalWrite(led4, HIGH);
      butState |= 0b00001000;
    } else {
      clr();
    }
  }
  if (butState == 0b00001111) {
    digitalWrite(ledUnlocked, HIGH);
    butState = 0;
  }
}

void clr() {
  butState = 0;
  digitalWrite(ledUnlocked, LOW);
  digitalWrite(led1, LOW);
  digitalWrite(led2, LOW);
  digitalWrite(led3, LOW);
  digitalWrite(led4, LOW);
}