#define SWITCH_PIN 14    // Pin connected to the NO pin of the switch
#define LED_PIN 33       // Pin connected to the LED
#define BUZZER_PIN 32    // Pin connected to the buzzer
#define TRIG_PIN 25      // Ultrasonic sensor Trig pin
#define ECHO_PIN 26      // Ultrasonic sensor Echo pin

#define MAX_DISTANCE 300 // Maximum distance in cm (300 cm = 3 meters)
#define RESET_DISTANCE 50 // Reset distance in cm (50 cm = 0.5 meters)

// Function to measure distance using HC-SR04
float measureDistance() {
    digitalWrite(TRIG_PIN, LOW);
    delayMicroseconds(2);
    digitalWrite(TRIG_PIN, HIGH);
    delayMicroseconds(10);
    digitalWrite(TRIG_PIN, LOW);

    long duration = pulseIn(ECHO_PIN, HIGH);
    float distance = (duration * 0.034) / 2; // Convert to cm
    return distance;
}

void setup() {
    pinMode(SWITCH_PIN, INPUT_PULLUP); // Use pull-up for switch stability
    pinMode(LED_PIN, OUTPUT);
    pinMode(BUZZER_PIN, OUTPUT);
    pinMode(TRIG_PIN, OUTPUT);
    pinMode(ECHO_PIN, INPUT);

    digitalWrite(LED_PIN, LOW);    // Initially, turn off LED
    digitalWrite(BUZZER_PIN, LOW); // Initially, turn off buzzer

    Serial.begin(115200); // For debugging
}

void loop() {
    int switchState = digitalRead(SWITCH_PIN);

    // If the switch is OFF, turn off LED and buzzer, then skip the loop
    if (switchState == LOW) {
        digitalWrite(LED_PIN, LOW);
        digitalWrite(BUZZER_PIN, LOW);
        return; // Exit the loop
    }

    // If the switch is ON
    digitalWrite(LED_PIN, HIGH); // Turn on LED to indicate the system is active

    // Measure the distance
    float distance = measureDistance();
    Serial.print("Distance: ");
    Serial.println(distance);

    // Logic for the buzzer behavior
    if (distance >= MAX_DISTANCE) {
        // Dog is far away (300 cm or more), beep every second
        digitalWrite(BUZZER_PIN, HIGH);
        delay(500); // Buzzer ON for 500ms
        digitalWrite(BUZZER_PIN, LOW);
        delay(500); // Buzzer OFF for 500ms
    } else if (distance <= RESET_DISTANCE) {
        // Dog is close (50 cm or less), turn off the buzzer
        digitalWrite(BUZZER_PIN, LOW);
    } else {
        // Keep the buzzer off if the distance is between 50 and 300 cm
        digitalWrite(BUZZER_PIN, LOW);
    }
}