#include <SD.h>

const int baudRate = 9600; 
#define chipSelect 10
unsigned int fileCounter = 1;               
#define ANALOG0 A0              
unsigned long interval = 1000; 
File root;
unsigned long startTime = 0;          // Micros and Milis requires unsigned long


struct Date {
  int day;
  int month; 
};

Date date = {10, 10};


void setup() {
  SPI_initialization();
  SD_initialization();

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

  // Ask for date 
  Serial.println("Enter date in format: MM/DD");
  date = extractDateFromInput();
  Serial.print("Date entered: ");
  Serial.print(date.month);
  Serial.print("/");
  Serial.println(date.day);

  // Ask for Desired File interval
  Serial.println("Enter desired file interval (ms): ");
  interval = extractIntervalFromInput();
  Serial.print("Interval per file: ");
  Serial.println(interval);


  root = open_SD_tmp_File(fileCounter, date); // Create first file
  Serial.print("File Created: ");
  Serial.println(root.name());
  // root.close();

  startTime = millis();


}

void loop() {
  unsigned long startTime = millis();
  // unsigned long interval = 60000; //30s
  Serial.print("----------Start Time");
  Serial.println(startTime);
  int count = 0; 

  while (millis() - startTime < interval)
  {
   
    int sensorValue = analogRead(ANALOG0);
    String timeStamp = getTimeStamp_MMSSXXXX(millis());
    
    // if (millis() % 100 == 0) {
    //   Serial.println(timeStamp);
    //   root.print(timeStamp);
    //   root.print(",");
    //   root.println(sensorValue);
    //   Serial.println("writing to file");
    // }
    // delay(5); // Wait for stability
    
    root.print(timeStamp);
    root.print(",");
    root.println(sensorValue);
    count ++ ;

  }
  
  root.close();
  Serial.print("---------------Count:");
  Serial.println(count);
  Serial.print("---------------End Time:");
  Serial.println(millis()- startTime);
  // change the extension
  // while written .tmp
  // when closed .txt

  // root = open_SD_tmp_File(fileCounter, date);
  // if (root) {
  //   Serial.print(root.name());
  //   while (root.available()) {
  //     Serial.write(root.read());
  //     }
  //   root.close();
  //   } 
  // else {
  //   Serial.println("error opening!");
  //   }    

  fileCounter++;

  if (fileCounter >= 1)
  {
    Serial.println("\nMaximum number of files created. Data logging stopped.");
    Serial.print("file count... ");
    Serial.println(fileCounter);

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

    // Example of reading file from the card:------------------
    // File textFile = SD.open(root.name);
    // if (textFile) {
    //   Serial.print("wokwi.txt: ");
    //   while (textFile.available()) {
    //     Serial.write(textFile.read());
    //   }
    //   textFile.close();
    // } else {
    //   Serial.println("error opening wokwi.txt!");
    // }    
    //-----------------------------------------------------
    while (1)
      ;
  }  }

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();
  }
}

unsigned long extractIntervalFromInput() {
  unsigned long interval_ms = 1000; 

  while (true) {
    if (Serial.available() > 0) {
      String userInput = Serial.readStringUntil('\n');

      if (sscanf(userInput.c_str(), "%d", &interval_ms) == 1) {
        // Successfully extracted interval
        break;
      } else {
        Serial.println("Invalid");
      }
    }
    // Add a small delay between checks to avoid excessive processor load
    delay(100);
  }
  return interval_ms;
}

// Initialize SPI communication ------------------------------------------------------------------
void SPI_initialization()
{
  // Open serial communications by initializing serial obj @ baudRate
  //  - Standard baudRate = 9600
  Serial.begin(baudRate);

  // Wait wait up to 15 seconds for Arduino Serial Monitor / serial port to connect
  //  - Needed for native USB port only
  //  - Ensure only one monitor is open
  while (!Serial && millis() < 15000)
  {
    ;
  }
  Serial.println("Serial Communication Secured");
}

// Initialize SD communication ------------------------------------------------------------------
void SD_initialization()
{
  Serial.print("Initializing SD card... ");

  // Check access to SD card "Initialize the SD card"
  //  - Chipselect pin is different per board
  if (!SD.begin(chipSelect))
  {
    Serial.println("initialization failed!");
    while (1)
      ; // endless loop which "stops" any useful function
        // this may need to be changed to a user controlled break later
  }
  Serial.println("initialization done.");
}

Date extractDateFromInput() {
  Date extractedDate = {0, 0};

  while (true) {
    if (Serial.available() > 0) {
      String userInput = Serial.readStringUntil('\n');

      if (sscanf(userInput.c_str(), "%d/%d", &extractedDate.month, &extractedDate.day) == 2) {
        // Successfully extracted both month and day, break the loop
        // setTime(0,0,0,extractedDate.day, extractedDate.month,2023); 
        break;
      } else {
        Serial.println("Invalid input format. Please enter in format: MM/DD");
      }
    }
    // Add a small delay between checks to avoid excessive processor load
    delay(100);
  }
  return extractedDate;
}

File open_SD_tmp_File(int fileIndex, Date date)
{
  // Serial.print("\nInitilizing write to file... "); 

  //.tmp
  String fileName = twoDigits(date.month) + twoDigits(date.day) + fourDigits(fileIndex) + ".txt";

  File newFile = SD.open(fileName, FILE_WRITE);
  if (newFile)
  {
    // Serial.println("File created successfully!");
    return newFile;
  }
  else
  {
    Serial.println("Error creating file!");
    while(1); // Stop recording if the file creation fails 
  }
  return newFile;
}

String getTimeStamp_MMSSXXXX(unsigned long now) 
{
  /*
  This function uses modulo to compute values 
     ** 1 min = 60_000 ms 
     ** 1 sec = 1_000  ms 
     ** ms range: [0 - 1000]
  */
  unsigned long minutes = (now / 60000 ) % 60; 
  unsigned long seconds = (now / 1000 ) % 60; 
  unsigned long milliseconds = now % 1000; 

  String timeStamp = "";
  // timeStamp += "(MM:SS:XXXX): ";
  timeStamp += twoDigits(minutes);
  timeStamp += ":";
  timeStamp += twoDigits(seconds);
  timeStamp += ":"; 
  timeStamp += fourDigits(milliseconds);
  timeStamp += "\tRaw(ms):";
  timeStamp += String(now);

  return timeStamp;
}

String twoDigits(int digits)
{
  if (digits < 10)
  {
    return "0" + String(digits);
  }
  else
  {
    return String(digits);
  }
}

String fourDigits(int digits)
{
  if (digits < 10)
  {
    return "000" + String(digits);
  }
  else if (digits < 100)
  {
    return "00" + String(digits);
  }
  else if (digits < 1000)
  {
    return "0" + String(digits);
  }
  else
  {
    return String(digits);
  }
}