/*
  3-bit Binary Input with Pushbuttons, LEDs and LED Bar Graph
  - LED1 (digital pin 22) represents the least-significant bit.
  - LED2 (digital pin 23) represents the middle bit.
  - LED3 (digital pin 24) represents the most-significant bit.
  - Pushbuttons on digital pins 2, 3, and 4 toggle the corresponding bits.
  - The binary value is displayed on an 8-segment LED bar graph connected to digital pins 30..37.
  - Button presses shorter than 0.15 sec (150ms) are ignored.
*/

const int btn1Pin = 2;      // btn1 toggles bit0 & led1
const int btn2Pin = 3;      // btn2 toggles bit1 & led2
const int btn3Pin = 4;      // btn3 toggles bit2 & led3

const int led1Pin = 22;     // LSB
const int led2Pin = 23;     // Middle bit
const int led3Pin = 24;     // MSB

// Bar graph: we'll use 8 segments (0 to 7) mapped to digital pins 30-37 (segment N maps to binary value N)
const int numSegments = 8;
const int barGraphPins[numSegments] = {30, 31, 32, 33, 34, 35, 36, 37};

unsigned long debounceDelay = 150;  // 150ms debounce threshold

// For debouncing each button
unsigned long lastDebounceTime1 = 0;
unsigned long lastDebounceTime2 = 0;
unsigned long lastDebounceTime3 = 0;

bool lastBtn1State = HIGH;
bool lastBtn2State = HIGH;
bool lastBtn3State = HIGH;

// Current state of each LED (and corresponding bit)
bool led1State = false;   // LSB
bool led2State = false;   // Middle bit
bool led3State = false;   // MSB

// Function to update the bar graph according to current binary value
void updateBarGraph() {
  // Calculate binary value from bits: bit2 bit1 bit0
  int binaryValue = (led3State << 2) | (led2State << 1) | led1State;
  
  // Turn off all segments first
  for (int i = 0; i < numSegments; i++) {
    digitalWrite(barGraphPins[i], LOW);
  }
  // Light the segment corresponding to binaryValue
  // (Assuming that the correct segment is connected to the pin mapped as:
  // binary value 0 --> barGraphPins[0] (i.e., segment A1),
  // binary value 1 --> barGraphPins[1] (i.e., segment A2), etc.)
  if (binaryValue >= 0 && binaryValue < numSegments) {
    digitalWrite(barGraphPins[binaryValue], HIGH);
  }
}

void setup() {
  // Initialize LED pins as outputs; start with off.
  pinMode(led1Pin, OUTPUT);
  digitalWrite(led1Pin, LOW);
  
  pinMode(led2Pin, OUTPUT);
  digitalWrite(led2Pin, LOW);
  
  pinMode(led3Pin, OUTPUT);
  digitalWrite(led3Pin, LOW);
  
  // Initialize pushbutton pins as inputs with internal pullup resistor.
  pinMode(btn1Pin, INPUT_PULLUP);
  pinMode(btn2Pin, INPUT_PULLUP);
  pinMode(btn3Pin, INPUT_PULLUP);
  
  // Initialize bar graph segment pins as outputs; ensure all off.
  for (int i = 0; i < numSegments; i++) {
    pinMode(barGraphPins[i], OUTPUT);
    digitalWrite(barGraphPins[i], LOW);
  }
}

void loop() {
  unsigned long currentTime = millis();
  
  // Read the current state of each button (LOW means pressed)
  bool currentBtn1State = digitalRead(btn1Pin);
  bool currentBtn2State = digitalRead(btn2Pin);
  bool currentBtn3State = digitalRead(btn3Pin);
  
  // Check btn1: toggle bit0 & led1 if button pressed and debounce time passed.
  if (lastBtn1State == HIGH && currentBtn1State == LOW) { // Button press detected (transition HIGH->LOW)
    if (currentTime - lastDebounceTime1 > debounceDelay) {
      led1State = !led1State;  // toggle the state
      digitalWrite(led1Pin, led1State ? HIGH : LOW);
      lastDebounceTime1 = currentTime;
      updateBarGraph(); // update bar graph display after a state change
    }
  }
  lastBtn1State = currentBtn1State;
  
  // Check btn2: toggle bit1 & led2
  if (lastBtn2State == HIGH && currentBtn2State == LOW) {
    if (currentTime - lastDebounceTime2 > debounceDelay) {
      led2State = !led2State;
      digitalWrite(led2Pin, led2State ? HIGH : LOW);
      lastDebounceTime2 = currentTime;
      updateBarGraph();
    }
  }
  lastBtn2State = currentBtn2State;
  
  // Check btn3: toggle bit2 & led3
  if (lastBtn3State == HIGH && currentBtn3State == LOW) {
    if (currentTime - lastDebounceTime3 > debounceDelay) {
      led3State = !led3State;
      digitalWrite(led3Pin, led3State ? HIGH : LOW);
      lastDebounceTime3 = currentTime;
      updateBarGraph();
    }
  }
  lastBtn3State = currentBtn3State;
  
  // (Optional small delay so the loop does not run too fast)
  delay(10);
}