#include <LiquidCrystal_I2C.h>
#include <SD.h>

#define LDR_PIN 2
#define CS_PIN 10

// LDR Characteristics
const float GAMMA = 0.7;
const float RL10 = 50;

String filename = "arduino.txt";
char MyCharArray[] = "Start";
byte myByteArray[] = {'1', '2', '3', '4', '5'};

LiquidCrystal_I2C lcd(0x27, 20, 4);

File root;
File myFile;

void setup() {
  pinMode(LDR_PIN, INPUT);

  lcd.init();
  lcd.backlight();

  Serial.begin(115200);

  Serial.print("Initializing SD card... ");

  if (!SD.begin(CS_PIN)) {
    Serial.println("Card initialization failed!");
    while (true);
  }

  Serial.println("initialization done.");

  Serial.println("Files in the card:");
  root = SD.open("/");
  printDirectory(root, 0);
  Serial.println("");

  //Reading file from the card:
  File textFile = SD.open("wokwi.txt");
  if (textFile) {
    Serial.print("wokwi.txt: ");
    while (textFile.available()) {
      Serial.write(textFile.read());
    }
    textFile.close();
  } else {
    Serial.println("error opening wokwi.txt!");
  }

  //Creating new file for writing:
  myFile = SD.open(filename, FILE_WRITE);

  if (myFile) {
    myFile.println("test of writing more text");
    Serial.println("file writing test complete");


    for (int i = 0; i < 5; i++) {
      myFile.write(myByteArray[i]);

      if (i < 4)
        myFile.write(",");

    }
    myFile.write("\n");

    for (int k = 1; k < 5; k++) {

      int analogValue = analogRead(A0);

      float voltage = analogValue / 1024. * 5;
      float resistance = 2000 * voltage / (1 - voltage / 5);
      float lux = pow(RL10 * 1e3 * pow(10, GAMMA) / resistance, (1 / GAMMA));

      myFile.println(analogValue);
      myFile.println(voltage);
      myFile.println(lux);
      Serial.print("Voltage ");
      Serial.println(voltage);
      Serial.print("Analog Value ");
      Serial.println(analogValue);
      Serial.print("Lux ");
      Serial.println(lux);

      lcd.setCursor(2, 0);
      lcd.print("Room: ");
      if (lux > 50) {
        lcd.print("Light!");
      } else {
        lcd.print("Dark  ");
      }

      lcd.setCursor(0, 1);
      lcd.print("Lux: ");
      lcd.print(lux);
      lcd.print("          ");

      delay(1000);
    }


    myFile.close();
  } else {
    Serial.println("error opening file to write!");
  }

  // Read the data on the new file
  myFile = SD.open(filename);

  if (myFile) {
    Serial.print(filename);
    Serial.println(": opened");

    while (myFile.available()) {
      Serial.write(myFile.read());
    }
    myFile.close();
  } else {
    Serial.println("error opening file for reading!");
  }
  Serial.println("file reading complete");
}

void loop() {

}

void printDirectory(File dir, int numTabs) {
  while (true) {

    File entry =  dir.openNextFile();
    if (! entry) {
      // no more files
      break;
    }
    for (uint8_t i = 0; i < numTabs; i++) {
      Serial.print('\t');
    }
    Serial.print(entry.name());
    if (entry.isDirectory()) {
      Serial.println("/");
      printDirectory(entry, numTabs + 1);
    } else {
      // files have sizes, directories do not
      Serial.print("\t\t");
      Serial.println(entry.size(), DEC);
    }
    entry.close();
  }
}