#define RED_LIGHT 14
#define YELLOW_LIGHT 12
#define GREEN_LIGHT 13
#define PED_LIGHT 5
#define BUTTON 4
#define BUZZER 18

#define LATCH_PIN 23
#define CLOCK_PIN 22
#define DATA_PIN 21

volatile bool pedestrian_requested = false;
unsigned long last_interrupt_time = 0;

const byte numbers[] = {
  0b00111111, // 0
  0b00000110, // 1
  0b01011011, // 2
  0b01001111, // 3
  0b01100110, // 4
  0b01101101, // 5
  0b01111101, // 6
  0b00000111, // 7
  0b01111111, // 8
  0b01101111  // 9
};

// Interrupt Service Routine (ISR) for button press
void IRAM_ATTR pedestrian_request() {
  unsigned long interrupt_time = millis();
  if (interrupt_time - last_interrupt_time > 500) { // Debounce
    pedestrian_requested = true;
  }
  last_interrupt_time = interrupt_time;
}

// Function to update 7-segment display
void displayNumber(int num) {
  digitalWrite(LATCH_PIN, LOW);
  shiftOut(DATA_PIN, CLOCK_PIN, MSBFIRST, numbers[num]);
  digitalWrite(LATCH_PIN, HIGH);
}

void setup() {
  pinMode(RED_LIGHT, OUTPUT);
  pinMode(YELLOW_LIGHT, OUTPUT);
  pinMode(GREEN_LIGHT, OUTPUT);
  pinMode(PED_LIGHT, OUTPUT);
  pinMode(BUZZER, OUTPUT);
  pinMode(BUTTON, INPUT_PULLUP);

  pinMode(LATCH_PIN, OUTPUT);
  pinMode(CLOCK_PIN, OUTPUT);
  pinMode(DATA_PIN, OUTPUT);

  attachInterrupt(BUTTON, pedestrian_request, FALLING);

  Serial.begin(115200);
}

void loop() {
  if (!pedestrian_requested) {
    // Normal traffic light cycle
    digitalWrite(GREEN_LIGHT, HIGH);
    digitalWrite(YELLOW_LIGHT, LOW);
    digitalWrite(RED_LIGHT, LOW);
    digitalWrite(PED_LIGHT, LOW);
    digitalWrite(BUZZER, LOW);
    displayNumber(0); // Display 0 when in normal state
  } 
  else {
    // Handle pedestrian crossing
    digitalWrite(GREEN_LIGHT, LOW);
    digitalWrite(YELLOW_LIGHT, HIGH);
    delay(2000); // Yellow warning

    digitalWrite(YELLOW_LIGHT, LOW);
    digitalWrite(RED_LIGHT, HIGH);
    digitalWrite(PED_LIGHT, HIGH);
    Serial.println("Pedestrians may cross...");

    // Countdown from 5 to 0
    for (int i = 5; i >= 0; i--) {
      displayNumber(i);
      digitalWrite(BUZZER, HIGH);
      delay(250);
      digitalWrite(BUZZER, LOW);
      delay(750);
    }

    delay(1000); // Additional delay before resetting

    // Reset system
    digitalWrite(PED_LIGHT, LOW);
    digitalWrite(RED_LIGHT, LOW);
    pedestrian_requested = false;
  }

  delay(500);
}