#include <Wire.h>
#include <EEPROM.h>
#include <LiquidCrystal.h>

// Create an LCD object with pins specified
LiquidCrystal lcd(2, 3, 4, 5, 6, 7);

long duration, inches;  // Variables for distance and water level
int set_val, percentage;  // Variables for set value and percentage
bool state, pump;  // Flags for button state and pump control

void setup() {
  // Initialize LCD and print initial messages
  lcd.begin(16, 2);
  lcd.print("WATER LEVEL:");
  lcd.setCursor(0, 1);
  lcd.print("PUMP:OFF MANUAL");

  // Set pin modes for sensor, pump, and buttons
  pinMode(8, OUTPUT);  // Trigger pin for ultrasonic sensor
  pinMode(9, INPUT);   // Echo pin for ultrasonic sensor
  pinMode(10, INPUT_PULLUP);  // Button for setting value
  pinMode(11, INPUT_PULLUP);  // Button for automatic/manual mode
  pinMode(12, OUTPUT);  // Pump control pin
  pinMode(13, OUTPUT);  // Buzzer control pin

  // Read set value from EEPROM (non-volatile memory)
  set_val = EEPROM.read(0);
  // Limit set value to a maximum of 150
  if (set_val > 150) set_val = 150;
}

void loop() {
  // Trigger the ultrasonic sensor and measure duration
  digitalWrite(8, LOW);
  delayMicroseconds(2);
  digitalWrite(8, HIGH);
  delayMicroseconds(10);
  digitalWrite(8, LOW);
  duration = pulseIn(9, HIGH);

  // Convert duration to inches
  inches = microsecondsToInches(duration);

  // Calculate water level percentage
  percentage = (set_val - inches) * 100 / set_val;
  // Ensure percentage is not negative
  if (percentage < 0) percentage = 0;

  // Display water level percentage on LCD
  lcd.setCursor(12, 0);
  lcd.print(percentage);
  lcd.print("%  ");

  // Control pump based on water level and mode
  if (percentage < 30 && digitalRead(11)) {  // If in auto mode and level low
    pump = 1;  // Turn on pump
  } else if (percentage > 99) {  // If level high
    pump = 0;  // Turn off pump
  }
  digitalWrite(12, !pump);  // Invert signal for pump control

  // Control buzzer based on water level
  if (percentage <= 20) {
    tone(13, 262, 250);  // Play a tone on the buzzer
  } else {
    noTone(13);  // Stop playing the tone
  }

  // Display pump status and mode on LCD
  lcd.setCursor(5, 1);
  lcd.print(pump ? "ON " : "OFF");  // Use ternary operator for conciseness
  lcd.setCursor(9, 1);
  lcd.print(digitalRead(11) ? "AUTO  " : "MANUAL");

  // Handle button presses for setting value and manual pump control
  if (!digitalRead(10) && !state && digitalRead(11)) {  // Set value button pressed in auto mode
    state = 1;
    set_val = inches;  // Set new value based on current water level
    EEPROM.write(0, set_val);  // Save new value to EEPROM
  } else if (!digitalRead(10) && !state && !digitalRead(11)) {  // Set value button pressed in manual mode
    state = 1;
    pump = !pump;  // Toggle pump manually
  }
  if (digitalRead(10))  // Button released
    state = 0;

  delay(500);  // Wait for 500 milliseconds before the next loop
}

// Function to convert microseconds to inches
long microsecondsToInches(long microseconds) {
  return microseconds / 74 / 2;  // Conversion factor for ultrasonic sensor
}