#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <NewPing.h>

#define TRIGGER_PIN   5
#define ECHO_PIN      18
#define MAX_DISTANCE  30 // in cm
#define BUZZER_PIN    4
#define SWITCH_PIN    19

LiquidCrystal_I2C lcd(0x27, 16, 2);  // I2C address 0x27, 16 columns, 2 rows
NewPing sonar(TRIGGER_PIN, ECHO_PIN, MAX_DISTANCE);

unsigned long lastDisconnectTime = 0;
bool switchState = true;
bool wasConnected = true;

float containerHeight = 30.0; // Adjust based on your container size

void setup() {
  pinMode(SWITCH_PIN, INPUT_PULLUP);
  pinMode(BUZZER_PIN, OUTPUT);
  Serial.begin(115200);

  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("System Starting...");
  delay(2000);
  lcd.clear();
}

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

  if (!switchState) {
    if (wasConnected) {
      lastDisconnectTime = millis();
      wasConnected = false;
    }

    if (millis() - lastDisconnectTime >= 30000) {
      while (digitalRead(SWITCH_PIN) == HIGH) {
        digitalWrite(BUZZER_PIN, HIGH);
        delay(1000);
        digitalWrite(BUZZER_PIN, LOW);
        delay(1000);

        switchState = digitalRead(SWITCH_PIN) == LOW;
        if (switchState) {
          wasConnected = true;
          return;
        }
      }
    }

    return;
  }

  wasConnected = true;

  delay(100);
  float distance = sonar.ping_cm();

  if (distance == 0 || distance > containerHeight) {
    Serial.println("Invalid distance");
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Distance Error");
    return;
  }

  float fillLevel = ((containerHeight - distance) / containerHeight) * 100.0;

  // Display fill level on LCD
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Fill Level:");
  lcd.setCursor(0, 1);
  lcd.print(fillLevel, 1);
  lcd.print(" %");

  // Sound buzzer if over 80%
  if (fillLevel >= 80.0) {
    digitalWrite(BUZZER_PIN, HIGH);
    delay(1000);
    digitalWrite(BUZZER_PIN, LOW);
  }

  delay(2000); // Update rate
}