#include <LiquidCrystal_I2C.h>

// Define LCD settings
#define LCD_ADDRESS 0x27
#define LCD_COLUMNS 16
#define LCD_ROWS 2

// Define pin connections
#define TRIG_PIN 2
#define ECHO_PIN 3
#define RELAY_PIN 13
#define AUTO_MANUAL_SWITCH_PIN 7
#define MANUAL_SWITCH_PIN 6

// Define thresholds (in cm) for a standard tank
#define TANK_HEIGHT 200  // Standard tank height in cm
#define PUMP_ON_LEVEL 160  // 80% distance from the ultrasonic sensor (20% below the tank)
#define PUMP_OFF_LEVEL 20   // 90% of the tank height

// Define delays
#define PUMP_DELAY 2000

// Initialize the LCD
LiquidCrystal_I2C lcd(LCD_ADDRESS, LCD_COLUMNS, LCD_ROWS);

// Variables for non-blocking operations
unsigned long previousPumpMillis = 0;
bool pumpState = false;
bool isAutoMode = true;
int lastWaterLevel = -1;
bool lastPumpState = false;
bool lastIsAutoMode = true;

void setup() {
  // Configure pin modes
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(RELAY_PIN, OUTPUT);
  pinMode(AUTO_MANUAL_SWITCH_PIN, INPUT_PULLUP);
  pinMode(MANUAL_SWITCH_PIN, INPUT_PULLUP);

  // Initialize relay as OFF
  digitalWrite(RELAY_PIN, LOW);

  // Initialize the LCD
  lcd.begin(LCD_COLUMNS, LCD_ROWS);
  lcd.backlight();

  // Display initial message
  lcd.setCursor(0, 0);
  lcd.print("GOD IS MY LIGHT");
  lcd.setCursor(0, 1);
  lcd.print("Initializing...");
  delay(2000);
  lcd.clear();
}

void loop() {
  // Read the mode
  isAutoMode = digitalRead(AUTO_MANUAL_SWITCH_PIN) == HIGH;

  // Get water level
  int distance = getDistance();
  int waterLevel = map(distance, 0, TANK_HEIGHT, 100, 0); // Convert distance to percentage
  waterLevel = constrain(waterLevel, 0, 100);

  // Update pump state based on the mode
  if (isAutoMode) {
    handleAutoMode(distance, millis());
  } else {
    handleManualMode();
  }

  // Update the display only when there's a change
  if (shouldUpdateDisplay(waterLevel)) {
    updateDisplay(waterLevel);
  }
}

// Function to handle automatic mode
void handleAutoMode(int distance, unsigned long currentMillis) {
  if (distance > PUMP_ON_LEVEL && !pumpState && currentMillis - previousPumpMillis >= PUMP_DELAY) {
    pumpState = true;
    previousPumpMillis = currentMillis;
    digitalWrite(RELAY_PIN, HIGH);
  } else if (distance < PUMP_OFF_LEVEL && pumpState && currentMillis - previousPumpMillis >= PUMP_DELAY) {
    pumpState = false;
    previousPumpMillis = currentMillis;
    digitalWrite(RELAY_PIN, LOW);
  }
}

// Function to handle manual mode
void handleManualMode() {
  if (digitalRead(MANUAL_SWITCH_PIN) == HIGH) {
    pumpState = true;
    digitalWrite(RELAY_PIN, HIGH);
  } else {
    pumpState = false;
    digitalWrite(RELAY_PIN, LOW);
  }
}

// Function to update the LCD display
void updateDisplay(int waterLevel) {
  lcd.setCursor(0, 0);

  // Display mode
  if (isAutoMode) {
    lcd.print("Mode: Auto   ");
  } else {
    lcd.print("Mode: Manual ");
  }

  // Display pump status
  lcd.setCursor(0, 1);
  if (pumpState) {
    lcd.print("Pump: ON  ");
  } else {
    lcd.print("Pump: OFF ");
  }

  // Display water level
  lcd.setCursor(10, 1);
  lcd.print("Lvl:");
  if (waterLevel < 10) lcd.print(" "); // Ensure alignment for single digits
  lcd.print(waterLevel);
  lcd.print("%  ");

  // Save the last states
  lastWaterLevel = waterLevel;
  lastPumpState = pumpState;
  lastIsAutoMode = isAutoMode;
}

// Function to determine if the display needs to be updated
bool shouldUpdateDisplay(int waterLevel) {
  return waterLevel != lastWaterLevel || pumpState != lastPumpState || isAutoMode != lastIsAutoMode;
}

// Function to get the distance from the ultrasonic sensor
int getDistance() {
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  long duration = pulseIn(ECHO_PIN, HIGH, 30000); // Timeout after 30ms
  if (duration == 0) return TANK_HEIGHT + 1; // Return max distance if no reflection

  int distance = (duration * 0.0343) / 2;
  return distance > 0 ? distance : TANK_HEIGHT + 1; // Return max distance if invalid
}