#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define TRIG_PIN 9
#define ECHO_PIN 10
#define GREEN_LED 3
#define YELLOW_LED 4
#define RED_LED 5
#define BUZZER 6

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

void setup() {
    pinMode(GREEN_LED, OUTPUT);
    pinMode(YELLOW_LED, OUTPUT);
    pinMode(RED_LED, OUTPUT);
    pinMode(BUZZER, OUTPUT);
    pinMode(TRIG_PIN, OUTPUT);
    pinMode(ECHO_PIN, INPUT);
    Serial.begin(9600);
    
    if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
        Serial.println(F("SSD1306 allocation failed"));
        for (;;);
    }
    display.clearDisplay();
    display.setTextSize(1);
    display.setTextColor(WHITE);
}

long getDistance() {
    digitalWrite(TRIG_PIN, LOW);
    delayMicroseconds(2);
    digitalWrite(TRIG_PIN, HIGH);
    delayMicroseconds(10);
    digitalWrite(TRIG_PIN, LOW);
    return pulseIn(ECHO_PIN, HIGH) * 0.034 / 2;
}

void loop() {
    // Green Light
    digitalWrite(GREEN_LED, HIGH);
    digitalWrite(YELLOW_LED, LOW);
    digitalWrite(RED_LED, LOW);
    delay(10000);
    
    // Yellow Light
    digitalWrite(GREEN_LED, LOW);
    digitalWrite(YELLOW_LED, HIGH);
    delay(10000);
    
    // Red Light
    digitalWrite(YELLOW_LED, LOW);
    digitalWrite(RED_LED, HIGH);
    delay(500);
    
    for (int i = 0; i < 20; i++) {
        long distance = getDistance();
        Serial.print("Distance: ");
        Serial.print(distance);
        Serial.println(" cm");
        
        if (distance > 0 && distance < 10) {
            digitalWrite(BUZZER, HIGH);
            display.clearDisplay();
            display.setCursor(10, 30);
            display.print("Red Light Crossed");
            display.display();
            delay(2000);
            digitalWrite(BUZZER, LOW);
        }
        
        delay(500);
    }
}