#include <LiquidCrystal.h>

// Constants for LCD Pins
const int rs = 7;     // Register Select pin
const int en = 8;     // Enable pin
const int d4 = 12;    // Data pin 4
const int d5 = 11;    // Data pin 5
const int d6 = 10;    // Data pin 6
const int d7 = 9;     // Data pin 7

// Constants for Time
const long hour = 3600000;  // 3600000 milliseconds in an hour
const long minute = 60000;  // 60000 milliseconds in a minute
const long second = 1000;   // 1000 milliseconds in a second

// Push buttons
int pbA = 6;    // SWITCH BETWEEN CLOCK AND TEMPERATURE MODE
int pbB = 5;    // Increments hours & switches between C and F
int pbC = 4;    // Decrements hours
int pbD = 3;    // Increments minutes
int pbE = 2;    // Decrements minutes

// LCD setup
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);

// Variables
int g = 1;       // a variable that toggles between Celsius & Fahrenheit
int i = 0;       // a variable to toggle between clock and temp
long addition = 0;  // this will be used as an addition to add the time

// Enums for Mode and Unit
enum Mode { CLOCK, TEMPERATURE };
enum Unit { CELSIUS, FAHRENHEIT };

Mode currentMode = CLOCK;
Unit currentUnit = CELSIUS;

// Variable to indicate display mode (0 for clock, 1 for temperature)
int displayMode = 0;

// Constants for NTC Thermistor
const int thermistorPin = A0;  // Analog pin connected to thermistor
const float seriesResistor = 10000.0;  // Resistance of series resistor (10k ohm)
const float thermistorNominal = 10000.0;  // Resistance at 25 degrees C
const float temperatureNominal = 25.0;  // Nominal temperature
const int bValue = 3950;  // Beta value for the thermistor

// Setting up push buttons as INPUT_PULLUP
void setup() {
  pinMode(pbA, INPUT_PULLUP);
  pinMode(pbB, INPUT_PULLUP);
  pinMode(pbC, INPUT_PULLUP);
  pinMode(pbD, INPUT_PULLUP);
  pinMode(pbE, INPUT_PULLUP);
  Serial.begin(57600);
  lcd.begin(16, 2); // Set the lcd column and row
}

// Function to display fixed temperature value
void temp() {
  if (digitalRead(pbB) == LOW) {
    currentUnit = (currentUnit == CELSIUS) ? FAHRENHEIT : CELSIUS; // Toggle temperature unit
    delay(100);
  }

  int adcValue = analogRead(thermistorPin);
  float resistance = seriesResistor / ((1023.0 / adcValue) - 1);
  float steinhart;
  steinhart = resistance / thermistorNominal;     // (R/Ro)
  steinhart = log(steinhart);                     // ln(R/Ro)
  steinhart /= bValue;                            // 1/B * ln(R/Ro)
  steinhart += 1.0 / (temperatureNominal + 273.15); // + (1/To)
  steinhart = 1.0 / steinhart;                    // Invert
  steinhart -= 273.15;                            // Convert to Celsius

  float tempC = steinhart;
  float tempF = (tempC * 9.0) / 5.0 + 32.0;

  printTemperature(tempC, tempF); // Display temperature on LCD
  delay(500);
}

// Function to handle time
void time() {
  long timeNow = millis() + hour; // Get current time in milliseconds and add the initial offset
  Serial.print(addition); // Print the current time adjustment
  Serial.println();

  timeNow = timeNow + addition; // Adjust the current time with the accumulated addition
  Serial.print(timeNow); // Print the adjusted time
  Serial.println();

  int hours = timeNow / hour; // Calculate the hours from the adjusted time
  Serial.println(hours);
  Serial.println(hours * hour);

  if (hours >= 24) {
    hours = hours % 24; // Ensure hours are within 24-hour format
  } else if (hours < 0) {
    addition = 3600000 * 24; // Reset the addition to keep time positive
    Serial.print("hello");
  }

  if (digitalRead(pbB) == LOW) {
    addition = addition + hour; // Increment hours if button B is pressed
  } else if (digitalRead(pbC) == LOW) {
    addition = addition - hour; // Decrement hours if button C is pressed
  }

  timeNow = timeNow + addition; // Adjust the time again based on button input
  Serial.print(timeNow);
  Serial.println();

  if (digitalRead(pbD) == LOW) {
    addition = addition + minute; // Increment minutes if button D is pressed
  } else if (digitalRead(pbE) == LOW) {
    addition = addition - minute; // Decrement minutes if button E is pressed
  }

  int minutes = (timeNow % hour) / minute; // Calculate the minutes from the adjusted time
  int seconds = (timeNow % minute) / second; // Calculate the seconds from the adjusted time

  printTime(hours, minutes, seconds); // Display time on LCD
  delay(500);
}

// Function to print temperature on LCD
void printTemperature(float tempC, float tempF) {
  lcd.clear(); // Clear the LCD screen
  if (displayMode == 1) { // Check if the display mode is set to temperature
    lcd.setCursor(0, 0);
    if (currentUnit == CELSIUS) {
      lcd.print("TempC ");
      lcd.setCursor(6, 0);
      lcd.print(tempC); // Print the temperature in Celsius
      Serial.print("TempC ");
      Serial.print(tempC);
    } else {
      lcd.print("TempF ");
      lcd.setCursor(6, 0);
      lcd.print(tempF); // Print the temperature in Fahrenheit
      Serial.print("TempF ");
      Serial.print(tempF);
    }
  }
}

// Function to print time on LCD
void printTime(int hours, int minutes, int seconds) {
  lcd.clear(); // Clear the LCD screen
  if (displayMode == 0) { // Check if the display mode is set to time
    lcd.setCursor(0, 0);
    lcd.print("HH:MM:SS ");

    lcd.setCursor(0, 1);
    if (hours < 10) {
      lcd.print("0");
    }
    lcd.print(hours);
    lcd.print(":");
    if (minutes < 10) {
      lcd.print("0");
    }
    lcd.print(minutes);
    lcd.print(":");
    if (seconds < 10) {
      lcd.print("0");
    }
    lcd.print(seconds); // Print hours, minutes, and seconds on LCD
  }
}

// Main loop
void loop() {
  if (digitalRead(pbA) == LOW) {
    if (i == 1) {
      i = 0;
      currentMode = CLOCK; // Toggle between clock and temperature modes
    } else if (i == 0) {
      i = 1;
      currentMode = TEMPERATURE;
    }
    delay(100);
  }

  if (currentMode == CLOCK) {
    time(); // Execute time-related functionality
    displayMode = 0; // Set display mode to clock
  } else if (currentMode == TEMPERATURE) {
    temp(); // Execute temperature-related functionality
    displayMode = 1; // Set display mode to temperature
  }

  delay(1000);
}