const int GREEN_PIN = 11;
const int YELLOW_PIN = 12;
const int RED_PIN = 13;
const int BUZZER_BUTTON = 10;
const int PUSH_BUTTON = 4;
const int TRIG = 6; //..We are setting the TRIG on the ultrasonic sensor to port 23
const int ECHO = 5;
long previousMillis = 0;
long interval = 500;        // First length of time I want the buzzer to stay on set tone

void setup() {
  // put your setup code here, to run once:
  pinMode(GREEN_PIN, OUTPUT);
  pinMode(YELLOW_PIN, OUTPUT);
  pinMode(RED_PIN, OUTPUT);
  pinMode(BUZZER_BUTTON, OUTPUT);
  pinMode(TRIG, OUTPUT);    // TRIG pin as output
  pinMode(ECHO, INPUT);     // ECHO pin as input
  Serial.begin(9600);
  Serial.println("Train Crossing Active!");
}

//define a function that is called get distance gets distance of ultrasonic wave that is sent
long getDistance()// #define a function that is called get distanc
{
  digitalWrite(TRIG, HIGH);  // Start the ultrasonic pulse
  delayMicroseconds(10);     // Send a 10-microsecond pulse
  digitalWrite(TRIG, LOW);   // Stop the pulse

  unsigned long startTime = 0;
  unsigned long endTime = 0;

  // Wait for ECHO to go HIGH and record the start time
  unsigned long timeout = millis();
  while (digitalRead(ECHO) == LOW) {
    startTime = micros();
    if (millis() - timeout > 50) return -1; // Exit if timeout (no response)
  }

  // Wait for ECHO to go LOW and record the end time
  timeout = millis();
  while (digitalRead(ECHO) == HIGH) {
    endTime = micros();
    if (millis() - timeout > 50) return -1; // Exit if timeout
  }

  // Calculate the duration in microseconds
  long duration = endTime - startTime;

  // Convert duration to distance in centimeters
  long distance_cm = duration / 58; // 58 us per cm for sound in air
  
  return distance_cm;
}


//This is what the output should be when the function green light is to be run 
void greenLight()
{
    digitalWrite(GREEN_PIN,  HIGH); //turn will turn on green light
    digitalWrite(YELLOW_PIN,  LOW); //turn the yellow led off
    digitalWrite(RED_PIN, LOW); //turn the red led off
    
}

void yellow_light() 
{
        
    digitalWrite(GREEN_PIN, LOW);   // Turn off green light
    digitalWrite(YELLOW_PIN, HIGH);  // Turn on yellow light
    digitalWrite(RED_PIN, LOW);      // Turn off red light
    
    
}


void red_light() 
{
    digitalWrite(GREEN_PIN, LOW);     // Turn off green light
    digitalWrite(YELLOW_PIN, LOW);    // Turn off yellow light
    digitalWrite(RED_PIN, HIGH);       // Turn on red light
    
    
}

void no_light() 
{
        // Ensure all lights and buzzer are off
    digitalWrite(GREEN_PIN, LOW);   
    digitalWrite(YELLOW_PIN, LOW);  
    digitalWrite(RED_PIN, LOW);     
  
}

bool buttonPressed = false;
// delay(flashDelay)
void loop() 
{
  if (digitalRead(PUSH_BUTTON) == HIGH && !buttonPressed) {
    buttonPressed = true; // Track that the button was pressed
  }
  if(buttonPressed)
  {
  // put your main code here, to run repeatedly:
    long distance = getDistance();
    // start the crossing guard actions
    if(distance >=90)
    {
      no_light();
      noTone(BUZZER_BUTTON); 
    }
    else if(distance > 23 && distance < 90)
    {
      greenLight();
      noTone(BUZZER_BUTTON); 

    }
    else if(distance > 16 && distance < 22)
    {
      yellow_light();
      noTone(BUZZER_BUTTON); 
    }
    else if(distance <=15)
    {
      red_light();
      if(millis() - previousMillis > interval)
      {
        tone(BUZZER_BUTTON, 500);
        previousMillis = millis(); // Reset the timer
      }
    }
    // Check if the buzzer should be turned off
  }

}