#include <SPI.h>
#include <Adafruit_GFX.h>
#include <Adafruit_PCD8544.h>

// Pin definitions for Nokia 5110 display
#define PIN_RST  3
#define PIN_CE   4
#define PIN_DC   5
#define PIN_DIN  6
#define PIN_CLK  7

// Temperature sensor pin
#define TEMP_PIN A0

// Initialize display
Adafruit_PCD8544 display = Adafruit_PCD8544(PIN_CLK, PIN_DIN, PIN_DC, PIN_CE, PIN_RST);

// NTC thermistor parameters
const float BETA = 3950;        // Beta coefficient (adjust based on your sensor)
const float SERIES_RESISTOR = 10000;  // 10k ohm series resistor
const float THERMISTOR_NOMINAL = 10000; // 10k ohm at 25°C
const float NOMINAL_TEMP = 25;   // Nominal temperature in Celsius

// Variables for temperature reading
float temperature = 0;
float previousTemp = 0;
unsigned long lastReadTime = 0;
const unsigned long readInterval = 1000; // Read temperature every 1 second

void setup() {
  Serial.begin(9600);
  
  // Initialize display
  display.begin();
  
  // Set contrast (adjust as needed for best visibility)
  display.setContrast(50);
  
  // Clear the buffer
  display.clearDisplay();
  
  // Display startup message
  display.setTextSize(1);
  display.setTextColor(BLACK);
  display.setCursor(0, 0);
  display.println("Nokia 5110");
  display.println("Temperature");
  display.println("Monitor");
  display.println("");
  display.println("Initializing...");
  display.display();
  
  delay(2000);
  
  // Draw initial interface
  updateDisplay();
}

void loop() {
  // Read temperature every second
  if (millis() - lastReadTime >= readInterval) {
    lastReadTime = millis();
    readTemperature();
    updateDisplay();
    
    // Print to serial monitor for debugging
    Serial.print("Temperature: ");
    Serial.print(temperature);
    Serial.println(" °C");
  }
  
  // Small delay to prevent overwhelming the display
  delay(50);
}

void readTemperature() {
  // Read analog value (0-1023)
  int analogValue = analogRead(TEMP_PIN);
  
  // Convert analog reading to resistance
  float resistance = SERIES_RESISTOR / ((1023.0 / analogValue) - 1.0);
  
  // Calculate temperature using the Beta equation
  float steinhart;
  steinhart = resistance / THERMISTOR_NOMINAL;           // (R/Ro)
  steinhart = log(steinhart);                            // ln(R/Ro)
  steinhart /= BETA;                                     // 1/B * ln(R/Ro)
  steinhart += 1.0 / (NOMINAL_TEMP + 273.15);            // + (1/To)
  steinhart = 1.0 / steinhart;                           // Invert
  temperature = steinhart - 273.15;                      // Convert to Celsius
  
  // Optional: Convert to Fahrenheit
  // float temperatureF = (temperature * 9.0/5.0) + 32.0;
}

void updateDisplay() {
  display.clearDisplay();
  
  // Draw border
  display.drawRect(0, 0, 84, 48, BLACK);
  
  // Title
  display.setTextSize(1);
  display.setCursor(2, 2);
  display.println("Temperature:");
  
  // Temperature value (large font)
  display.setTextSize(2);
  display.setCursor(2, 16);
  
  // Format temperature with 1 decimal place
  char tempStr[10];
  dtostrf(temperature, 4, 1, tempStr);
  display.print(tempStr);
  display.print(" C");
  
  // Add a simple bar graph to show temperature visually
  int barHeight = map(constrain(temperature, 0, 40), 0, 40, 0, 30);
  display.fillRect(60, 35 - barHeight, 20, barHeight, BLACK);
  display.drawRect(60, 5, 20, 30, BLACK);
  
  // Draw temperature icon (thermometer)
  display.drawRect(72, 38, 4, 8, BLACK);
  display.fillRect(73, 40, 2, 4, BLACK);
  
  // Add a simple indicator for temperature trend
  if (temperature > previousTemp + 0.2) {
    display.fillTriangle(78, 42, 82, 42, 80, 38, BLACK);
  } else if (temperature < previousTemp - 0.2) {
    display.fillTriangle(78, 44, 82, 44, 80, 48, BLACK);
  }
  
  previousTemp = temperature;
  
  // Show reading indicator
  display.setTextSize(1);
  display.setCursor(68, 1);
  display.print("*");
  
  // Display last update time
  display.setCursor(2, 42);
  display.print("Updated");
  
  display.display();
}

// Optional: Add a simple menu system or button handling
// You can expand this to show min/max temperatures, etc.