#include <LiquidCrystal.h>
#include <SPI.h>
#include "SdFat.h"
#include <EEPROM.h> // Include EEPROM library

const int rs = 13;         // RS pin of LCD to Arduino digital pin 13
const int en = 12;         // EN pin of LCD to Arduino digital pin 12
const int d4 = 11;         // D4 pin of LCD to Arduino digital pin 11
const int d5 = 10;         // D5 pin of LCD to Arduino digital pin 10
const int d6 = 9;          // D6 pin of LCD to Arduino digital pin 9
const int d7 = 8;          // D7 pin of LCD to Arduino digital pin 8
const int buttonPin = 2;   // the number of the pushbutton pin
const int ledHigh = 3;     // the number of the high LED pin
const int ledLow = 4;      // the number of the low LED pin
const int pwmPin = 5;      // PWM pin for heater control
const int chipSelect = 6;  // CS pin of the SD card module
const int dataInPin = 7;   // DI pin of the SD card module
const int clockPin = 1;    // SCK pin of the SD card module

const float BETA = 3950;   // Beta Coefficient of the thermistor
const float desiredTemp = 40.0; // Desired temperature
const float tolerance = 5.0;    // Tolerance for temperature range

LiquidCrystal lcd(rs, en, d4, d5, d6, d7);
SdFat SD;
SdFile file;
int buttonState = 0;

void setup() {
  lcd.begin(16, 2); // Initialize the LCD with 16 columns and 2 rows
  Serial.begin(115200);

  pinMode(buttonPin, INPUT);
  pinMode(ledHigh, OUTPUT);
  pinMode(ledLow, OUTPUT);
  pinMode(pwmPin, OUTPUT); // Set PWM pin as output

  if (!SD.begin(chipSelect, SPI_HALF_SPEED)) {
    Serial.println("SD initialization failed!");
    return;
  }
}

void loop() {
  // Read button state
  buttonState = digitalRead(buttonPin);

  // Measure temperature
  int analogValue = analogRead(A0);
  float celsius = 1 / (log(1 / (1023. / analogValue - 1)) / BETA + 1.0 / 298.15) - 273.15;

  // Display live temperature on LCD
  lcd.setCursor(0, 0);
  lcd.print("Temperature: ");
  lcd.print(celsius, 2);
  delay(100); // Add a small delay
  lcd.print(" C");

  // Print temperature to Serial Monitor only when button is pressed
  if (buttonState == HIGH) {
    // Save current temperature to EEPROM
    int address = 0; // EEPROM address to store temperature
    float savedTemp = celsius;
    EEPROM.put(address, savedTemp);
    Serial.println("Temperature saved to EEPROM.");
    Serial.print("Current Temp: ");
    Serial.print(celsius, 2);
    Serial.println(" C");
  }

  // Control LEDs and heater based on temperature
  if (celsius > (desiredTemp + tolerance)) {
    digitalWrite(ledHigh, HIGH);
    digitalWrite(ledLow, LOW);
    analogWrite(pwmPin, 0); // Turn off PWM (heater)
  } else if (celsius < (desiredTemp - tolerance)) {
    digitalWrite(ledHigh, LOW);
    digitalWrite(ledLow, HIGH);
    // Calculate PWM duty cycle to heat up
    int dutyCycle = map(celsius, desiredTemp - tolerance, desiredTemp, 255, 0); // Inverted for proportional control
    dutyCycle = constrain(dutyCycle, 0, 255); // Ensure duty cycle is within valid range
    analogWrite(pwmPin, dutyCycle); // Adjust PWM duty cycle
  } else {
    digitalWrite(ledHigh, LOW);
    digitalWrite(ledLow, LOW);
    analogWrite(pwmPin, 0); // Turn off PWM (heater)
  }

  delay(1000); // Delay for readability
}