#include <SPI.h>
#include <SD.h>

const int lm35Pin = A0;  // LM35 output connected to analog pin A0
const int SDCard = 4; // CS pin

//Array variables 
const int totalReads = 10;  // Number of readings to take for averaging
float readings[totalReads];  // Array to store the readings
int readIndex = 0;  // Index of the current reading
float total = 0;  // Total of the readings
float ftime = 0; 
const float BETA = 3950;


void setup() {
  Serial.begin(9600);  // Start the serial communication

  Serial.println("Reading for card...");

  if (!SD.begin(SDCard)) {
    Serial.println("Card failed, or not present");
  }
  else{
    Serial.println("Card Found!"); 
    File dataFile = SD.open("data.csv", FILE_WRITE);
    if (dataFile) {
      dataFile.println("Time,Temperature (°F)");
      dataFile.close();
    }
  }
}

void loop() {

  // Read the analog value from sensor
  
  //adc analoge digital converter into voltage (5.0 / 1023.0) turned to Celsius (voltage * 100.0) finally turned to Fereignheigt (C * 9.0 / 5.0)
  int adcValue = analogRead(lm35Pin);  
  float celsius = 1 / (log(1 / (1023.0 / adcValue - 1)) / BETA + 1.0 / 298.15) - 273.15;
  float temperatureF = (celsius * (1.8)) + 32;

  // Add the new reading to the total
  total = total + temperatureF;

  // Store the reading in the array
  readings[readIndex] = temperatureF;

  // next position of array
  readIndex++;

  //fake "time" to figure out how many repititions it had gone through the night. 
  Serial.println(temperatureF) ;

  // If we're at the end of the array, wrap around to the beginning
  if (readIndex >= totalReads) {
    readIndex = 0;
    float average = total / totalReads;
    Serial.print("Average Temperature: ");
    Serial.print(average);
    Serial.println("°F");
    writeToFile("data.csv", ftime, average);
    total = 0;
    ftime++; 
  }

  delay(1000);  // Wait for a second before reading again
}

void writeToFile(const char* filename, float time, float data) {
  // Open a file for writing
  File dataFile = SD.open(filename, FILE_WRITE);

  // If the file is available, write to it 
  if (dataFile) {
    dataFile.print(time);
    dataFile.print(",");
    dataFile.println(data);
    dataFile.close();
    Serial.println("Data written to file.");
  } else {
    // If the file didn't open, print an error
    Serial.println("Error opening file for writing.");
  }
}