#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <EEPROM.h>

// OLED display settings
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET    -1
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

// Pin definitions
#define LM35_PIN A0    // LM35 connected to analog pin A0
#define UP_BUTTON 3
#define DOWN_BUTTON 4

// EEPROM address for setpoint
#define EEPROM_ADDRESS 0

float currentTemp = 0.0;
float setpoint = 25.0;  // Default setpoint

void setup() {
  // Initialize serial communication
  Serial.begin(9600);
  
  // Initialize OLED display
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD1306 allocation failed"));
    for(;;);
  }
  display.clearDisplay();
  
  // Initialize pins
  pinMode(LM35_PIN, INPUT);
  pinMode(UP_BUTTON, INPUT_PULLUP);
  pinMode(DOWN_BUTTON, INPUT_PULLUP);
  
  // Read stored setpoint from EEPROM
  EEPROM.get(EEPROM_ADDRESS, setpoint);
  if (isnan(setpoint) || setpoint < 0 || setpoint > 100) {
    setpoint = 25.0;  // Default value if EEPROM is empty or invalid
  }
}

float readTemperature() {
  // Read analog value and convert to temperature
  int sensorValue = analogRead(LM35_PIN);
  // Convert to voltage (5V reference, 10-bit ADC)
  float voltage = sensorValue * (5.0 / 1023.0);
  // LM35 outputs 10mV per °C
  float temperature = voltage * 100.0;
  return temperature;
}

void loop() {
  // Read temperature
  currentTemp = readTemperature();
  
  // Handle button presses
  if (digitalRead(UP_BUTTON) == LOW) {
    setpoint += 0.5;
    if (setpoint > 999.9) setpoint = 999.9;
    EEPROM.put(EEPROM_ADDRESS, setpoint);
    delay(200);  // Debounce
  }
  
  if (digitalRead(DOWN_BUTTON) == LOW) {
    setpoint -= 0.5;
    if (setpoint < 0) setpoint = 0;
    EEPROM.put(EEPROM_ADDRESS, setpoint);
    delay(200);  // Debounce
  }
  
  // Update display
  display.clearDisplay();
  display.setTextColor(SSD1306_WHITE);
  
  // Display current temperature
  display.setTextSize(1);
  display.setCursor(0, 0);
  display.print("Current Temp:");
  
  display.setTextSize(2);
  display.setCursor(0, 20);
  // Format temperature to always show two digits before decimal
  if (currentTemp < 0) display.print("0");
  display.print(currentTemp, 2);  // Display with 1 decimal place
  display.print(" C");
  
  // Display setpoint
  display.setTextSize(1);
  display.setCursor(0, 50);
  display.print("Setpoint: ");
  if (setpoint < 0) display.print("0");
  display.print(setpoint, 1);
  display.print(" C");
  
  display.display();
  
  delay(100);  // Update rate
}