// Pins for 74HC595 
const int latchPin = 10; // Latch pin
const int clockPin = 9;  // Clock pin
const int dataPin = 8;   // Data pin

// Digit selection pins (common cathode)
const int digitPins[] = {11, 12, 13, 14}; // Control pins for 4 digits

// Traffic light pins (grouped by direction)
const int redNorth = 22, yellowNorth = 23, greenNorth = 24;
const int redSouth = 22, yellowSouth = 23, greenSouth = 24; // Synced with North
const int redEast = 25, yellowEast = 26, greenEast = 27;
const int redWest = 25, yellowWest = 26, greenWest = 27; // Synced with East

// Digit patterns for 7-segment display (common cathode)
const byte digits[] = {
  0b00111111, // 0
  0b00000110, // 1
  0b01011011, // 2
  0b01001111, // 3
  0b01100110, // 4
  0b01101101, // 5
  0b01111101, // 6
  0b00000111, // 7
  0b01111111, // 8
  0b01101111  // 9
};

void setup() {
  // Setup pins for 74HC595
  pinMode(latchPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  pinMode(dataPin, OUTPUT);

  // Setup pins for digit selection
  for (int i = 0; i < 4; i++) {
    pinMode(digitPins[i], OUTPUT);
    digitalWrite(digitPins[i], LOW); // Ensure all digits are off initially
  }

  // Setup traffic light pins
  pinMode(greenNorth, OUTPUT);
  pinMode(yellowNorth, OUTPUT);
  pinMode(redNorth, OUTPUT);
  pinMode(greenEast, OUTPUT);
  pinMode(yellowEast, OUTPUT);
  pinMode(redEast, OUTPUT);

  // Start with all lights off
  turnOffAllLights();
}

void loop() {
  // Execute traffic light cycle with countdown
  fullCycle(
    greenNorth, yellowNorth, redNorth, 
    greenEast, yellowEast, redEast,
    digitPins[0], digitPins[1], digitPins[2], digitPins[3]
  );
}

// Turn off all traffic lights
void turnOffAllLights() {
  digitalWrite(greenNorth, LOW);
  digitalWrite(yellowNorth, LOW);
  digitalWrite(redNorth, LOW);
  digitalWrite(greenEast, LOW);
  digitalWrite(yellowEast, LOW);
  digitalWrite(redEast, LOW);
}

void fullCycle(
  int greenPrimary, int yellowPrimary, int redPrimary,
  int greenOpposite, int yellowOpposite, int redOpposite,
  int displayPrimary1, int displayPrimary2, int displayOpposite1, int displayOpposite2) {

  // Phase 1: N-S Green, E-W Red
  digitalWrite(greenPrimary, HIGH);   // N-S Green ON
  digitalWrite(redPrimary, LOW);     // N-S Red OFF
  digitalWrite(redOpposite, HIGH);   // E-W Red ON
  digitalWrite(yellowPrimary, LOW);  // N-S Yellow OFF
  countdown(9, displayPrimary1, displayPrimary2); // 10 seconds for N-S Green
  digitalWrite(greenPrimary, LOW);   // Turn OFF N-S Green

  // Phase 2: N-S Yellow, E-W Red
  digitalWrite(yellowPrimary, HIGH); // N-S Yellow ON
  countdown(2, displayPrimary1, displayPrimary2);  // 3 seconds for N-S Yellow
  digitalWrite(yellowPrimary, LOW);  // Turn OFF N-S Yellow
  digitalWrite(redPrimary, HIGH);    // Turn ON N-S Red

  // Phase 3: E-W Yellow, N-S Red
  digitalWrite(yellowOpposite, HIGH); // E-W Yellow ON
  digitalWrite(redOpposite, LOW);     // Turn OFF E-W Red
  countdown(2, displayOpposite1, displayOpposite2);  // 3 seconds for E-W Yellow
  digitalWrite(yellowOpposite, LOW);  // Turn OFF E-W Yellow

  // Phase 4: E-W Green, N-S Red
  digitalWrite(greenOpposite, HIGH);  // E-W Green ON
  countdown(9, displayOpposite1, displayOpposite2); // 10 seconds for E-W Green
  digitalWrite(greenOpposite, LOW);   // Turn OFF E-W Green

  // Phase 5: E-W Yellow, N-S Red
  digitalWrite(yellowOpposite, HIGH); // E-W Yellow ON
  countdown(2, displayOpposite1, displayOpposite2);  // 3 seconds for E-W Yellow
  digitalWrite(yellowOpposite, LOW);  // Turn OFF E-W Yellow
  digitalWrite(redOpposite, HIGH);    // Turn ON E-W Red

  // Phase 6: N-S Yellow, E-W Red
  digitalWrite(yellowPrimary, HIGH);  // N-S Yellow ON
  digitalWrite(redPrimary, LOW);
  countdown(2, displayPrimary1, displayPrimary2);  // 3 seconds for N-S Yellow
  digitalWrite(yellowPrimary, LOW);   // Turn OFF N-S Yellow
  digitalWrite(redPrimary, LOW);      // Turn OFF N-S Red

  // Back to Phase 1: N-S Green
}


// Function to display countdown on 7-segment displays
void countdown(int seconds, int digit1, int digit2) {
  for (int i = seconds; i >= 0; i--) {
    int digitValues[] = {i / 10, i % 10}; // Extract tens and ones digits

    // Multiplex the 7-segment display for both digits
    for (int j = 0; j < 2; j++) {
      activateDigit(j == 0 ? digit1 : digit2);
      sendToShiftRegister(digits[digitValues[j]]);
      delay(5); // Short delay for persistence of vision
      deactivateAllDigits();
    }
    delay(995); // 1-second delay minus multiplexing time
  }
}

// Function to send data to the 74HC595 shift register
void sendToShiftRegister(byte data) {
  digitalWrite(latchPin, LOW);        // Prepare to send data
  shiftOut(dataPin, clockPin, MSBFIRST, data);
  digitalWrite(latchPin, HIGH);       // Latch the data to output pins
}

// Function to activate a specific digit
void activateDigit(int digitPin) {
  digitalWrite(digitPin, HIGH); // Turn on the specific digit
}

// Function to deactivate all digits
void deactivateAllDigits() {
  for (int i = 0; i < 4; i++) {
    digitalWrite(digitPins[i], LOW); // Turn off all digits
  }
}