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

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_ADDR 0x3C

// NTC Temperature Sensor Pin (use an analog pin on STM32, e.g., PA0)
#define NTC_PIN PA0

// NTC Parameters (from Wokwi reference)
const float BETA = 3950;           // Beta coefficient of the thermistor
const float SERIES_RESISTOR = 10000; // 10K series resistor
const float NOMINAL_RESISTANCE = 10000; // Resistance at 25°C
const float NOMINAL_TEMPERATURE = 298.15; // 25°C in Kelvin

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

// thermostat icon
const unsigned char temp_icon [] PROGMEM = {
	0x00, 0x3c, 0x00, 0x00, 0x7e, 0x00, 0x00, 0x42, 0x00, 0x00, 0x42, 0x00, 0x00, 0x42, 0x00, 0x00, 
	0x42, 0x00, 0x00, 0x5a, 0x00, 0x00, 0x5a, 0x00, 0x00, 0x5a, 0x00, 0x00, 0x5a, 0x00, 0x00, 0x5a, 
	0x00, 0x00, 0x5a, 0x00, 0x00, 0x5a, 0x00, 0x00, 0x5a, 0x00, 0x00, 0xdb, 0x00, 0x01, 0x99, 0x80, 
	0x01, 0x18, 0x80, 0x01, 0x3c, 0x80, 0x01, 0x3c, 0x80, 0x01, 0x3c, 0x80, 0x01, 0x18, 0x80, 0x01, 
	0x81, 0x80, 0x00, 0xe7, 0x00, 0x00, 0x3c, 0x00
};

// drop icon 
const unsigned char drop_icon[] PROGMEM = {
  0x01, 0x80, 0x01, 0x80, 0x03, 0xC0, 0x03, 0xC0, 0x07, 0xE0, 0x07, 0xE0,
  0x0F, 0xF0, 0x0F, 0xF0, 0x1F, 0xF8, 0x1F, 0xF8, 0x1F, 0xF8, 0x1F, 0xF8,
  0x0F, 0xF0, 0x0F, 0xF0, 0x07, 0xE0, 0x03, 0xC0, 0x01, 0x80, 0x00, 0x00
};

// Function to read temperature from NTC sensor
float readTemperature() {
  int analogValue = analogRead(NTC_PIN);
  
  // Prevent division by zero
  if (analogValue == 0) return -999; // Error value
  
  // Convert analog reading to temperature using Steinhart-Hart equation
  // Formula from Wokwi reference: celsius = 1 / (log(1 / (1023. / analogValue - 1)) / BETA + 1.0 / 298.15) - 273.15
  float celsius = 1.0 / (log(1.0 / (1023.0 / analogValue - 1.0)) / BETA + 1.0 / 298.15) - 273.15;
  
  return celsius;
}



void displayData(float temp, int hum) {
  display.clearDisplay();
  display.setTextColor(SSD1306_WHITE);

  // ===== TEMPERATURE =====
  display.drawBitmap(4, 4, temp_icon, 24, 24, SSD1306_WHITE);

  display.setTextSize(1);
  display.setCursor(32, 4);
  display.print("TEMPERATURE");

  display.setTextSize(2);
  display.setCursor(32, 16);
  
  // Check for sensor error
  if (temp < -100) {
    display.print("ERR");
  } else {
    display.print(temp, 1);
    display.print("C");
  }

  // Divider
  display.drawLine(0, 32, 127, 32, SSD1306_WHITE);

  // ===== HUMIDITY  =====
  display.drawBitmap(6, 40, drop_icon, 16, 16, SSD1306_WHITE);

  display.setTextSize(1);
  display.setCursor(32, 36);
  display.print("HUMIDITY");

  display.setTextSize(2);
  display.setCursor(32, 48);
  display.print(hum);
  display.print("%");

  display.display();
}

void setup() {
  Serial.begin(115200);
  
  // Initialize I2C for STM32 (PB7=SDA, PB6=SCL)
  Wire.begin(PB7, PB6);

  // Initialize OLED
  if (!display.begin(SSD1306_SWITCHCAPVCC, OLED_ADDR)) {
    Serial.println(F("SSD1306 allocation failed"));
    while (true);
  }
  
  // Set analog reference if needed (STM32 specific)
  analogReadResolution(10); // Set to 10-bit for Wokwi compatibility, use 12 for real STM32
  
  Serial.println("NTC Temperature Sensor Initialized");
}

void loop() {
  // Read real temperature from NTC sensor
  float temperature = readTemperature(); // or use readTemperatureSTM32() for hardware
  
  // Simulated humidity (add DHT11/22 if you want real humidity)
  int humidity = 60; // Placeholder - replace with actual sensor if needed
  
  // Debug output to Serial
  Serial.print("Temperature: ");
  Serial.print(temperature);
  Serial.println(" C");
  
  // Display on OLED
  displayData(temperature, humidity);
  
  delay(1000);
}