#include <Wire.h> // This library is used for communication between devices using the I2C protocol
#include <LiquidCrystal_I2C.h> // This library helps control an LCD that communicates using I2C

// Define the LCD address and its size (16 columns and 2 rows)
#define LCD_ADDRESS 0x27
#define LCD_COLUMNS 16
#define LCD_ROWS 2

// Define pins for the ultrasonic sensors (used to measure distance)
#define TRIG_PIN 2
#define ECHO_PIN 3
#define TRIG_PIN2 4
#define ECHO_PIN2 5
#define TRIG_PIN3 6
#define ECHO_PIN3 7

// Define the relay pin (used to control the pump) and switches for manual/auto modes
#define RELAY_PIN 13
#define AUTO_MANUAL_SWITCH_PIN 11
#define MANUAL_SWITCH_PIN 10

// Define pins for LEDs that indicate Auto and Manual modes
#define AUTO_LED_PIN 8
#define MANUAL_LED_PIN 9

// Define pins for the solenoid valves and their indicator LEDs
#define SOLENOID_VALVE1_PIN 12
#define SOLENOID_VALVE2_PIN 14
#define SOLENOID_VALVE1_LED_PIN 15
#define SOLENOID_VALVE2_LED_PIN 16

// Define a pin for the Pump's status LED
#define PUMP_LED_PIN 17

// Define constants for the tank's physical properties and control percentages
#define TANK_HEIGHT 200 // The height of the tank in centimeters
#define START_PUMP_PERCENTAGE 45 // Pump starts when the water is 45% full
#define STOP_PUMP_PERCENTAGE 88 // Pump stops when the water is 88% full

// Define a debounce delay (helps prevent switch bouncing issues)
#define DEBOUNCE_DELAY 200

// Define how frequently (in milliseconds) the sensors should check the water level
#define SENSOR_INTERVAL 500

// Create an LCD object (to control the LCD)
LiquidCrystal_I2C lcd(LCD_ADDRESS, LCD_COLUMNS, LCD_ROWS);

// Variables for keeping track of time and switch states
unsigned long previousSensorMillis = 0;
unsigned long previousDebounceMillis = 0;
bool lastManualSwitchState = LOW; // Tracks the last state of the manual switch
bool pumpManualState = LOW; // Keeps track of whether the pump is on in manual mode

void setup() {
  // Set up pin modes for the ultrasonic sensors (output for trigger, input for echo)
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(TRIG_PIN2, OUTPUT);
  pinMode(ECHO_PIN2, INPUT);
  pinMode(TRIG_PIN3, OUTPUT);
  pinMode(ECHO_PIN3, INPUT);
  
  // Set up pin modes for relay and switches
  pinMode(RELAY_PIN, OUTPUT);
  pinMode(AUTO_MANUAL_SWITCH_PIN, INPUT_PULLUP); // Pull-up means the switch is normally high
  pinMode(MANUAL_SWITCH_PIN, INPUT_PULLUP); 

  // Set up pin modes for the mode LEDs (Auto/Manual)
  pinMode(AUTO_LED_PIN, OUTPUT);
  pinMode(MANUAL_LED_PIN, OUTPUT);
  
  // Set up pin modes for the solenoid valves and their LEDs
  pinMode(SOLENOID_VALVE1_PIN, OUTPUT);
  pinMode(SOLENOID_VALVE2_PIN, OUTPUT);
  pinMode(SOLENOID_VALVE1_LED_PIN, OUTPUT);
  pinMode(SOLENOID_VALVE2_LED_PIN, OUTPUT);
  
  // Set up pin mode for the Pump LED
  pinMode(PUMP_LED_PIN, OUTPUT);

  // Initialize everything to OFF at the start
  digitalWrite(RELAY_PIN, LOW);
  digitalWrite(SOLENOID_VALVE1_PIN, LOW);
  digitalWrite(SOLENOID_VALVE2_PIN, LOW);
  digitalWrite(PUMP_LED_PIN, LOW);

  // Initialize the LCD and turn on its backlight
  lcd.begin(LCD_COLUMNS, LCD_ROWS);
  lcd.backlight(); 

  // Display a welcome message on the LCD
  lcd.setCursor(0, 0);
  lcd.print("GOD IS MY LIGHT");

  lcd.setCursor(0, 1);
  lcd.print("SmartPumpCrtSys");

  // Wait for 1 second to show the welcome message
  delay(1000);

  // Clear the LCD to prepare it for further use
  lcd.clear();
}

void loop() {
  unsigned long currentMillis = millis(); // Get the current time

  // Check if it's time to read the sensors again
  if (currentMillis - previousSensorMillis >= SENSOR_INTERVAL) {
    previousSensorMillis = currentMillis;

    // Measure the distance from each ultrasonic sensor (in cm)
    int distance1 = getDistance(TRIG_PIN, ECHO_PIN);
    int distance2 = getDistance(TRIG_PIN2, ECHO_PIN2);
    int distance3 = getDistance(TRIG_PIN3, ECHO_PIN3);

    // If any sensor fails, display an error message
    if (distance1 < 0 || distance2 < 0 || distance3 < 0) {
      lcd.setCursor(0, 0);
      lcd.print("Sensor Error    ");
      return;
    }

    // Convert distance to water level as a percentage (0-100%)
    int waterLevel1 = map(distance1, 0, TANK_HEIGHT, 100, 0);
    int waterLevel2 = map(distance2, 0, TANK_HEIGHT, 100, 0);
    int waterLevel3 = map(distance3, 0, TANK_HEIGHT, 100, 0);

    // Display water levels of tank 1 and tank 2 on the LCD
    lcd.setCursor(0, 0);
    lcd.print("L1:");
    lcd.print(waterLevel1);
    lcd.print("% L2:");
    lcd.print(waterLevel2);
    lcd.print("%");

    // Display water level of tank 3 and the mode on the LCD
    lcd.setCursor(0, 1);
    lcd.print("L3:");
    lcd.print(waterLevel3);
    lcd.print("%");

    // Check if the system is in Auto mode (switch is HIGH)
    if (digitalRead(AUTO_MANUAL_SWITCH_PIN) == HIGH) {
      // Turn on the Auto LED and turn off the Manual LED
      digitalWrite(AUTO_LED_PIN, HIGH);
      digitalWrite(MANUAL_LED_PIN, LOW);

      // Indicate Auto mode on the LCD
      lcd.setCursor(6, 1);
      lcd.print("Auto   "); // Add spaces to clear leftover characters

      // In Auto mode, control the solenoid valves and pump automatically
      controlSolenoidValve(waterLevel2, SOLENOID_VALVE1_PIN, SOLENOID_VALVE1_LED_PIN);
      controlSolenoidValve(waterLevel3, SOLENOID_VALVE2_PIN, SOLENOID_VALVE2_LED_PIN);
      controlPump(waterLevel1);

    } else { // System is in Manual mode
      // Turn on the Manual LED and turn off the Auto LED
      digitalWrite(AUTO_LED_PIN, LOW);
      digitalWrite(MANUAL_LED_PIN, HIGH);

      // Indicate Manual mode on the LCD
      lcd.setCursor(6, 1);
      lcd.print("Manual "); // Add spaces to clear leftover characters

      // Turn off the solenoid valves in Manual mode
      digitalWrite(SOLENOID_VALVE1_PIN, LOW);
      digitalWrite(SOLENOID_VALVE1_LED_PIN, LOW);
      digitalWrite(SOLENOID_VALVE2_PIN, LOW);
      digitalWrite(SOLENOID_VALVE2_LED_PIN, LOW);

      // Handle manual pump control
      if (currentMillis - previousDebounceMillis >= DEBOUNCE_DELAY) {
        bool manualSwitchState = digitalRead(MANUAL_SWITCH_PIN);
        if (manualSwitchState != lastManualSwitchState) {
          previousDebounceMillis = currentMillis;
          lastManualSwitchState = manualSwitchState;

          if (manualSwitchState == HIGH) {
            pumpManualState = !pumpManualState; // Toggle pump state
          }
        }
      }

      // Display pump status based on manual switch
      if (pumpManualState) {
        lcd.setCursor(13, 1);
        lcd.print("ON ");
        digitalWrite(RELAY_PIN, HIGH);
        digitalWrite(PUMP_LED_PIN, HIGH);
      } else {
        lcd.setCursor(13, 1);
        lcd.print("OFF");
        digitalWrite(RELAY_PIN, LOW);
        digitalWrite(PUMP_LED_PIN, LOW);
      }
    }
  }
}

// Function to get the distance measured by an ultrasonic sensor
int getDistance(int trigPin, int echoPin) {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Measure the time it takes for the ultrasonic signal to return
  long duration = pulseIn(echoPin, HIGH, 25000); // Timeout after 25ms
  if (duration == 0) {
    return -1; // Return error if no signal is received
  }

  // Convert the time to distance (in cm)
  int distance = (duration * 0.0343) / 2;
  if (distance < 0 || distance > TANK_HEIGHT) {
    return -1; // Return error if the distance is out of range
  }
  return distance;
}

// Function to control the pump based on water level
void controlPump(int waterLevel) {
  if (waterLevel < START_PUMP_PERCENTAGE) {
    lcd.setCursor(13, 1); // Show pump status at the end of the second row
    lcd.print("ON ");
    digitalWrite(RELAY_PIN, HIGH);
    digitalWrite(PUMP_LED_PIN, HIGH); // Turn on the pump and its LED
  } else if (waterLevel > STOP_PUMP_PERCENTAGE) {
    lcd.setCursor(13, 1);
    lcd.print("OFF");
    digitalWrite(RELAY_PIN, LOW);
    digitalWrite(PUMP_LED_PIN, LOW); // Turn off the pump and its LED
  }
}

// Function to control a solenoid valve based on water level
void controlSolenoidValve(int waterLevel, int valvePin, int ledPin) {
  if (waterLevel < START_PUMP_PERCENTAGE) {
    digitalWrite(valvePin, HIGH);
    digitalWrite(ledPin, HIGH); // Open the valve and turn on its LED
  } else if (waterLevel > STOP_PUMP_PERCENTAGE) {
    digitalWrite(valvePin, LOW);
    digitalWrite(ledPin, LOW); // Close the valve and turn off its LED
  }
}