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

// LCD setup: I2C address 0x27, 16 columns and 2 rows
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Pin Definitions
const int sensorPin = A0;  // RT1000 temperature sensor
const int relay1Pin = 7;   // Relay 1
const int relay2Pin = 8;   // Relay 2
const int modeButtonPin = 2;
const int upButtonPin = 3;
const int downButtonPin = 4;

// Variables
float temperature = 0.0;
float setpoint = 20.0;     // Default setpoint
int mode = 0;
unsigned long lastSwitchTime = 0;
const unsigned long switchInterval = 5000; // Toggle screen every 5 seconds
unsigned long lastInteractionTime = 0;
const unsigned long returnToDefaultInterval = 5000; // 5 seconds return to default
bool screenToggle = true;  // Toggle between screens
int currentUnit = 1;       // Unit 1 or Unit 2 (starting with unit 1)
bool isBelowSetpoint = false; // Flag to indicate temperature below setpoint

// Function to read RT1000 temperature sensor
float readTemperature() {
  int sensorValue = analogRead(sensorPin);
  return map(sensorValue, 0, 1023, 0, 50);  // Assuming the sensor range is 0-50°C
}

// Function to display welcome message
void displayWelcomeMessage() {
  lcd.clear();
  lcd.setCursor(4, 0);
  lcd.print("Welcome");
  lcd.setCursor(5, 1);
  lcd.print("Syncro");
  delay(5000);  // Show for 5 seconds
}

// Function to show temperature and setpoint
void displayTempSetpointScreen() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Temp: ");
  lcd.print(temperature);
  lcd.setCursor(0, 1);
  lcd.print("Set P: ");
  lcd.print(setpoint, 1);  // Show setpoint with 1 decimal
}

// Function to show unit statuses
void displayUnitStatusScreen() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("UNIT-1: ");
  lcd.print(digitalRead(relay1Pin) == HIGH ? "ON" : "OFF");
  lcd.setCursor(0, 1);
  lcd.print("UNIT-2: ");
  lcd.print(digitalRead(relay2Pin) == HIGH ? "ON" : "OFF");
}

// Function to show device info
void displayDeviceInfo() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("ID: 1 Baud:9600");
  lcd.setCursor(0, 1);
  lcd.print("Parity: 8N1");
  delay(1000);  // Show for 2 seconds
}

// Function to show vendor info
void displayVendorInfo() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Make: Syncro");
  delay(1000);  // Show for 2 seconds
}

// Function to check button press
void checkButtons() {
  if (digitalRead(modeButtonPin) == LOW) {
    mode++;
    if (mode > 2) mode = 0;
    screenToggle = false;  // Stop screen toggling
    lastInteractionTime = millis();
    delay(100); // Debounce delay
  }

  if (digitalRead(upButtonPin) == LOW) {
    if (mode == 0) {  // Adjust setpoint only in temperature mode
      setpoint += 0.5;
      if (setpoint > 30) setpoint = 30;  // Max setpoint is 30
    }
    screenToggle = false;  // Stop screen toggling
    lastInteractionTime = millis();
    delay(200);  // Debounce delay
  }

  if (digitalRead(downButtonPin) == LOW) {
    if (mode == 0) {  // Adjust setpoint only in temperature mode
      setpoint -= 0.5;
      if (setpoint < 15) setpoint = 15;    // Min setpoint is 15
    }
    screenToggle = false;  // Stop screen toggling
    lastInteractionTime = millis();
    delay(200);  // Debounce delay
  }
}

// Function to manage relay control
void manageRelay() {
  unsigned long thirtyMinutes = 5000; // 30 minutes in milliseconds

  if (temperature > setpoint) {
    // Turn ON both units if above setpoint
    digitalWrite(relay1Pin, HIGH);
    digitalWrite(relay2Pin, HIGH);
    isBelowSetpoint = false;  // Reset flag
  } 
  // If below setpoint, turn on one unit and auto-sequence every 30 minutes
  else if (temperature <= setpoint - 0.5) {
    if (!isBelowSetpoint) {
      // If first time below setpoint, turn on only one unit
      digitalWrite(relay1Pin, HIGH);  // Relay 1 ON
      digitalWrite(relay2Pin, LOW);   // Relay 2 OFF
      currentUnit = 1;  // Start with unit 1
      lastSwitchTime = millis();  // Reset the switch timer
      isBelowSetpoint = true;  // Set flag to indicate temperature is below setpoint
    }

    if (millis() - lastSwitchTime > thirtyMinutes) {
      // Auto-sequence switching
      if (currentUnit == 1) {
        digitalWrite(relay1Pin, LOW);   // Relay 1 OFF
        digitalWrite(relay2Pin, HIGH);  // Relay 2 ON
        currentUnit = 2;
      } else {
        digitalWrite(relay1Pin, HIGH);  // Relay 1 ON
        digitalWrite(relay2Pin, LOW);   // Relay 2 OFF
        currentUnit = 1;
      }
      lastSwitchTime = millis(); // Reset the timer for the next 30-minute cycle
    }
  }
}

// Setup function
void setup() {
  lcd.begin(16, 2);  // Initialize with 16 columns and 2 rows
  lcd.backlight();
  displayWelcomeMessage();
  
  // Pin modes
  pinMode(sensorPin, INPUT);
  pinMode(relay1Pin, OUTPUT);
  pinMode(relay2Pin, OUTPUT);
  pinMode(modeButtonPin, INPUT_PULLUP);
  pinMode(upButtonPin, INPUT_PULLUP);
  pinMode(downButtonPin, INPUT_PULLUP);
  
  // Initialize relays: Ensure one relay is on
  digitalWrite(relay1Pin, HIGH);  // Relay 1 ON at startup
  digitalWrite(relay2Pin, LOW);   // Relay 2 OFF
  
  // Read setpoint from EEPROM
  EEPROM.get(0, setpoint);
  if (isnan(setpoint) || setpoint < 15 || setpoint > 30) {
    setpoint = 20.0;  // Set default setpoint if EEPROM value is invalid
  }
}

// Main loop function
void loop() {
  // Read temperature
  temperature = readTemperature();

  // Check button presses
  checkButtons();

  // Return to default screen after inactivity
  if (millis() - lastInteractionTime > returnToDefaultInterval) {
    screenToggle = true;
    mode = 0;  // Reset to temperature screen mode
  }

  // Display temperature or unit status based on time interval
  if (screenToggle) {
    if (millis() - lastSwitchTime >= switchInterval) {
      displayTempSetpointScreen();
      lastSwitchTime = millis();
    } else {
      displayUnitStatusScreen();
    }
  }

  // Display the mode screen if button pressed
  if (!screenToggle) {
    switch (mode) {
      case 0:
        displayTempSetpointScreen();
        break;
      case 1:
        displayDeviceInfo();
        break;
      case 2:
        displayVendorInfo();
        break;
    }
  }

  // Manage relay based on temperature and setpoint
  manageRelay();

  // Save the setpoint to EEPROM if it has changed
  static float lastSetpoint = -1;
  if (setpoint != lastSetpoint) {
    EEPROM.put(0, setpoint);
    lastSetpoint = setpoint;
  }
  
  delay(1000);
}