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

// Pin Definitions
const int Thermostat_pin = A0; // Pin for the NTC temperature sensor output
const int buttonUp = 2;        // Pin for button to go up in the menu
const int buttonDown = 3;      // Pin for button to go down in the menu
const int buttonSelect = 4;    // Pin for button to select menu item

// RTC Object
RTC_DS1307 rtc;

// LCD Object
LiquidCrystal_I2C lcd(0x27, 20, 4); // Change address if needed

// Menu items
String MenuItems[] = {
    "Time & Date",
    "Set Time & Date",
    "Temperature",
    "Submenu 4",
    "Submenu 5",
    "Submenu 6",
    "Submenu 7",
    "Submenu 8"
};

// Current menu state
int currentMenuItem = 0;
int selectedMenu = -1; // -1 means no menu selected
int totalMenuItems = sizeof(MenuItems) / sizeof(MenuItems[0]);

// Variables for scrolling
int firstMenuIndex = 0; // Index of the first menu item to display

// Timing for button hold detection
unsigned long buttonHoldStartTime = 0;
bool buttonHeld = false;
const unsigned long holdDuration = 2000; // 2 seconds to detect hold

void setup() {
    Serial.begin(9600); // Initialize serial communication for output

    // Initialize buttons
    pinMode(buttonUp, INPUT_PULLUP);
    pinMode(buttonDown, INPUT_PULLUP);
    pinMode(buttonSelect, INPUT_PULLUP);

    // Initialize RTC
    if (!rtc.begin()) {
        Serial.println("RTC not found!"); // Inform if RTC is not found
        while (1); // Halt if RTC is not found
    }

    // Initialize LCD
    lcd.begin(20, 4);
    lcd.backlight(); // Turn on the backlight
    lcd.clear();

    // Welcome Animation
    String welcomeMessage = "                             Welcome!................"; // Add spaces for smoother scrolling
    int messageLength = welcomeMessage.length();
    int displayWidth = 20; // Width of the display
    int scrollLength = messageLength + displayWidth; // Total length to scroll

    // Scroll the message across the LCD
    for (int pos = 0; pos < scrollLength; pos++) {
        lcd.setCursor(0, 1); // Set cursor position on the second row
        lcd.print(welcomeMessage.substring(pos, pos + displayWidth)); 
        delay(50); // Adjust delay for speed of scrolling
    }
    
    delay(1000); // Pause before proceeding
}

void loop() {
    handleMenuNavigation(); // Call function to handle menu navigation

    // Read and display the temperature
    int Thermostat = analogRead(Thermostat_pin); // Read the NTC sensor value
    float temperature = calculateTemperature(Thermostat); // Calculate temperature

    // Get current time from RTC
    DateTime currentTime = rtc.now();

    // Clear LCD and update based on current menu or submenu
    lcd.clear();

    if (selectedMenu == -1) {
        // Show Main Menu with cursor and scroll if needed
        displayMainMenu();
    } else {
        // Display the selected submenu's information
        lcd.setCursor(0, 0);
        lcd.print(MenuItems[selectedMenu]); // Print the current submenu item

        if (selectedMenu == 0) {
            // Submenu 1: Display time
            lcd.setCursor(0, 1);
            lcd.print("Time: ");
            lcd.print(currentTime.hour());
            lcd.print(":");
            lcd.print(currentTime.minute());
            lcd.print(":");
            lcd.print(currentTime.second());
            lcd.setCursor(0, 2);
            lcd.print("Date: ");
            lcd.print(currentTime.day());
            lcd.print("/");
            lcd.print(currentTime.month());
            lcd.print("/");
            lcd.print(currentTime.year());
        } else if (selectedMenu == 1) {
            // Submenu 2: Set Time & Date
            setTimeAndDate();
            selectedMenu = -1; // Return to main menu after setting
        } else if (selectedMenu == 2) {
            // Submenu 3: Display temperature
            lcd.setCursor(0, 1);
            lcd.print("Temp: ");
            lcd.print(temperature);
            lcd.print(" C");
        } else {
            // For other submenus
            lcd.setCursor(0, 1);
            lcd.print("No data");
        }

        // Check if "select" button is held down to return to main menu
        if (digitalRead(buttonSelect) == LOW) {
            if (!buttonHeld) {
                buttonHoldStartTime = millis(); // Start timing the button hold
                buttonHeld = true;
            } else if (millis() - buttonHoldStartTime > holdDuration) {
                // Button held for more than 2 seconds, go back to main menu
                selectedMenu = -1;
                buttonHeld = false; // Reset button hold flag
            }
        } else {
            buttonHeld = false; // Reset if the button is released
        }
    }

    delay(1000); // Delay for 1 second before the next read
}

// Handle menu navigation with buttons and scrolling
void handleMenuNavigation() {
    if (selectedMenu == -1) {
        // Main Menu Navigation
        if (digitalRead(buttonUp) == LOW) {
            if (currentMenuItem > 0) { // Prevent moving above the first item
                currentMenuItem--; // Move up in the menu
            }

            if (currentMenuItem < firstMenuIndex) {
                firstMenuIndex = currentMenuItem; // Scroll up if necessary
            }
            delay(200); // Debounce delay
        }

        if (digitalRead(buttonDown) == LOW) {
            if (currentMenuItem < totalMenuItems - 1) { // Prevent moving below the last item
                currentMenuItem++; // Move down in the menu
            }

            if (currentMenuItem >= firstMenuIndex + 4) { // If it goes out of the display
                firstMenuIndex = currentMenuItem - 3; // Scroll down
            }
            delay(200); // Debounce delay
        }

        if (digitalRead(buttonSelect) == LOW) {
            selectedMenu = currentMenuItem; // Select the current menu item
            delay(200); // Debounce delay
        }
    } else {
        // In a submenu: allow the "select" button to go back to the main menu
        if (digitalRead(buttonSelect) == LOW) {
            selectedMenu = -1; // Go back to the main menu
            delay(200); // Debounce delay
        }
    }
    
}

// Display the main menu with a cursor and handle scrolling
void displayMainMenu() {
    for (int i = 0; i < 4; i++) {
        lcd.setCursor(0, i); // Set cursor position on each line
        int menuIndex = firstMenuIndex + i; // Adjust the menu index based on scrolling
        if (menuIndex < totalMenuItems) {
            if (menuIndex == currentMenuItem) {
                lcd.print(">"); // Display cursor (>)
            } else {
                lcd.print(" "); // Blank space when not selected
            }
            lcd.print(MenuItems[menuIndex]); // Print menu item
        }
    }
}

// Thermostat to temperature
float calculateTemperature(int sensorValue) {
    float resistance = (1023.0 / sensorValue) - 1.0; // Calculate resistance
    resistance = 10000.0 / resistance; // Convert to temperature
    return (1.0 / (log(resistance / 10000.0) / 3950 + (1.0 / 298.15))) - 273.15; // Return Celsius
}

// Function to set time and date
void setTimeAndDate() {
    int newHour = rtc.now().hour();
    int newMinute = rtc.now().minute();
    int newDay = rtc.now().day();
    int newMonth = rtc.now().month();
    int newYear = rtc.now().year();

    int settingMode = 0;  // 0: Hour, 1: Minute, 2: Day, 3: Month, 4: Year
    bool settingComplete = false;

    while (!settingComplete) {
        lcd.clear();
        lcd.setCursor(0, 0);
        lcd.print("Set Time & Date");

        lcd.setCursor(0, 1);
        lcd.print("Hour:   ");
        lcd.print(newHour);
        lcd.setCursor(0, 2);
        lcd.print("Minute: ");
        lcd.print(newMinute);
        lcd.setCursor(0, 3);
        lcd.print("Day:    ");
        lcd.print(newDay);
        lcd.setCursor(10, 3);
        lcd.print("Month:  ");
        lcd.print(newMonth);
        lcd.setCursor(0, 4);
        lcd.print("Year:   ");
        lcd.print(newYear);

        // Handle navigation with buttons
        if (digitalRead(buttonUp) == LOW) {
            if (settingMode == 0) newHour = (newHour + 1) % 24;
            else if (settingMode == 1) newMinute = (newMinute + 1) % 60;
            else if (settingMode == 2) newDay = (newDay % 31) + 1;
            else if (settingMode == 3) newMonth = (newMonth % 12) + 1;
            else if (settingMode == 4) newYear++;
            delay(200); // Debounce delay
        }
        if (digitalRead(buttonDown) == LOW) {
            if (settingMode == 0) newHour = (newHour == 0) ? 23 : newHour - 1;
            else if (settingMode == 1) newMinute = (newMinute == 0) ? 59 : newMinute - 1;
            else if (settingMode == 2) newDay = (newDay == 1) ? 31 : newDay - 1;
            else if (settingMode == 3) newMonth = (newMonth == 1) ? 12 : newMonth - 1;
            else if (settingMode == 4) newYear--;
            delay(200); // Debounce delay
        }

        if (digitalRead(buttonSelect) == LOW) {
            settingMode++;
            if (settingMode > 4) {
                settingMode = 0;
                settingComplete = true;
            }
            delay(200); // Debounce delay
        }
    }

    // Set the new time and date
    rtc.adjust(DateTime(newYear, newMonth, newDay, newHour, newMinute, 0)); // Set seconds to 0
    lcd.clear();
    lcd.print("Time & Date Set!");
    delay(1000);  // Delay before returning to the menu
}