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

// Define the LCD address and dimensions
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Define pins for the ultrasonic sensor
const int trigPin = 9;
const int echoPin = 10;

// Define pin for the relay module
const int relayPin = 8;

// Define pin for the pushbutton
const int buttonPin = 7;

// Define pin for the buzzer
const int buzzerPin = 6;

// Variables for duration and distance
long duration;
int distance;
const float minDistance = 2;  // Minimum distance for 100% water level in cm
const float maxDistance = 400; // Maximum distance for 0% water level in cm

// Configurable pump control thresholds
const int turnOnPercentage = 15;  // Turn on the pump when water level is at or below this percentage
const int cutOffPercentage = 99;  // Turn off the pump when water level is at or above this percentage

// Variables for dry run detection
unsigned long pumpStartTime = 0;
bool pumpRunning = false;
bool dryRunDetected = false;
int previousWaterLevelPercent = 0;
int lastWaterLevelPercent = 0;
unsigned long lastCheckTime = 0;

void setup() {
  // Initialize the Serial Monitor
  Serial.begin(9600);
  
  // Initialize the LCD
  lcd.begin(16, 2);
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("Water Level:");

  // Set the ultrasonic sensor pins as output and input
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  
  // Set the relay pin as output
  pinMode(relayPin, OUTPUT);
  
  // Set the button pin as input with internal pull-up resistor
  pinMode(buttonPin, INPUT_PULLUP);
  
  // Set the buzzer pin as output
  pinMode(buzzerPin, OUTPUT);
  
  // Initially turn off the pump and buzzer
  digitalWrite(relayPin, LOW);
  digitalWrite(buzzerPin, LOW);
}

void loop() {
  // Clear the trigPin
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  
  // Set the trigPin on HIGH state for 10 microseconds
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  
  // Read the echoPin and calculate the distance
  duration = pulseIn(echoPin, HIGH);
  distance = duration * 0.034 / 2;
  
  // Calculate water level percentage
  int waterLevelPercent = map(distance, maxDistance, minDistance, 0, 100);
  waterLevelPercent = constrain(waterLevelPercent, 0, 100);

  // Print the water level percentage to the Serial Monitor
  Serial.print("Water Level: ");
  Serial.print(waterLevelPercent);
  Serial.println("%");

  // Display the water level percentage on the LCD if no dry run is detected
  if (!dryRunDetected) {
    lcd.setCursor(0, 1);
    lcd.print("Lvl:");
    lcd.print(waterLevelPercent);
    lcd.print("%   "); // Add spaces to ensure old values are overwritten
  }

  // Control the pump based on water level percentage and dry run state
  if (waterLevelPercent <= turnOnPercentage && !pumpRunning && !dryRunDetected) {
    // Turn on the pump
    digitalWrite(relayPin, HIGH);
    pumpStartTime = millis();
    pumpRunning = true;
    lastWaterLevelPercent = waterLevelPercent;
    lastCheckTime = millis();
  } else if (waterLevelPercent >= cutOffPercentage && pumpRunning) {
    // Turn off the pump
    digitalWrite(relayPin, LOW);
    pumpRunning = false;
  }

  // Check for dry run condition
  if (pumpRunning && (millis() - lastCheckTime > 10000)) { // 10 seconds
    if (waterLevelPercent <= lastWaterLevelPercent) {
      // Turn off the pump
      digitalWrite(relayPin, LOW);
      pumpRunning = false;
      dryRunDetected = true;
      
      // Turn on the buzzer
      digitalWrite(buzzerPin, HIGH);

      // Display dry run warning message
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Dry Run");
    } else {
      // Update last water level percent if the water level has increased
      lastWaterLevelPercent = waterLevelPercent;
    }
    lastCheckTime = millis(); // Reset the check timer
  }

  // Check if the button is pressed to reset dry run state
  if (digitalRead(buttonPin) == LOW) {
    dryRunDetected = false;
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Dry Run Reset  "); // Clear the message after reset
    // Turn off the buzzer
    digitalWrite(buzzerPin, LOW);
    delay(1000);  // Display the reset message for 1 second
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Water Level:");
  }

  // Add a delay before the next reading
  delay(1000);
}