//==========================================================================================================
// Date and time functions using a DS1307 RTC connected via I2C and Wire lib
//
//  Logger    Description    Arduino
//  D1          SCL            A5   (remember to use 4.7K pullup resistor)
//  D2          SDA            A4   (remember to use 4.7K pullup resistor)
// Also required: GND, 5V, and V(bat)
//    V(bat): 2.0 - 3.5V (this is the CR1220 that goes on the back of the RTC/Logger board; "+" side out)
//
// This sketch is based on the one found in this thread: https://forum.arduino.cc/index.php?topic=128928.0...
// with minor modifications by me.
//
//  NOTES: 
//  - When I tried to replace the backup battery with 3.3V from the arduino it didn't work.  
//    But when I gave it 3V from my external power supply, it did.
//  - The module I have, "Wifi D1 Mini" or "Wemos D1 Mini", has a diode and resistor added to the 
//    circuit to protect against reverse polarity if the battery is inserted the wrong way.
//    But that increases the battery drain tremendously.  So I removed those components and plan
//    to be careful when inserting the battery (positive side outward).
//    The problem and the solution are described here:  https://sharedinventions.com/?p=663
//               
//==========================================================================================================
#include <Arduino.h>
#include "RTClib.h"  // Adafruit RTClib version 1.12.5 (and its dependencies). Install this through the library manager in this IDE
#include <SPI.h>
#include <SD.h>

RTC_DS1307 rtc;


char daysOfTheWeek[7][12] = {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};

int loop_counter;
File dataFile;


void setup ()
  { 
  Serial.begin(57600);

  pinMode(10, OUTPUT);
  digitalWrite(10, HIGH);  //-3- I may have to set Arduino Pin 10 HIGH here to keep the logger selected (slave-select)


  Serial.println("Looking for Real Time Clock...");
  
  if (! rtc.begin())
    {
    Serial.println("Could NOT find RTC");
    Serial.flush();
    abort();
    }
  else
    {
    Serial.println("Found RTC");
    }

  if (! rtc.isrunning())
    {
    Serial.println("\nReal Time Clock is NOT running, Setting the time now...");
    // When time needs to be set on a new device, or after a power loss, the
    // following line sets the RTC to the date & time this sketch was compiled
    rtc.adjust(DateTime(F(__DATE__), F(__TIME__)));
    Serial.println("Time has been set");
    // This line sets the RTC with an explicit date & time, for example to set
    // January 21, 2014 at 3am you would call:
    // rtc.adjust(DateTime(2014, 1, 21, 3, 0, 0));
    }
  else
    {
    Serial.println("\nReal Time Clock is already running - NOT setting the time now.");
    }

   // See if the card is present and can be initialized
  Serial.print("Initializing SD card...");
  while(1)
    {
    if (SD.begin()) break;
    Serial.println("Failed to initialize, or card not present.  Trying again...");
    delay(1000);
    }
  Serial.println("card initialized.");
  loop_counter = 0;

    // Open the file. Note that only one file can be open at a time.
  // To close this file:  dataFile.close();
  // FILE_READ: open the file for reading, starting at the BEGINNING of the file.
  // FILE_WRITE: open the file for reading and writing, starting at the END of the file.
  // The SD card library uses 8.3 format filenames and is case-insensitive.
  // So "datalog.txt" is the same as "DATALOG.txt"
  Serial.println("Chceck if the file exists ");

  if(SD.exists("datalog.txt")){
    Serial.println("Of coure, it exists");
  }
  else{
    SD.mkdir("datalog.txt");
    Serial.println("The datalog has been created");
    }
  
  // Serial.println("Opening datalog.txt...");
  // while(1)
  //    {
  //    dataFile = SD.open("datalog.txt", FILE_WRITE); 
  //    if (dataFile) break;
  //    Serial.println("Failed to open datalog.txt.  Trying again...");
  //    delay(1000);
  //    }
  // Serial.println("Opened datalog.txt");
  //  }
  }
   
void loop (){
    //  Serial.println("Checking time...");
    Serial.flush();
    dataFile.flush();
    DateTime now = rtc.now();
    //Serial.println("Got the time");

    Serial.print(now.year(), DEC);
    Serial.print('/');
    Serial.print(now.month(), DEC);
    Serial.print('/');
    Serial.print(now.day(), DEC);
    Serial.print(" | ");
    Serial.print(now.hour(), DEC);
    Serial.print(':');
    Serial.print(now.minute(), DEC);
    Serial.print(':');
    Serial.print(now.second(), DEC);
    Serial.println();

    dataFile.print(now.year(), DEC);
    dataFile.print('/');
    dataFile.print(now.month(), DEC);
    dataFile.print('/');
    dataFile.print(now.day(), DEC);
    dataFile.print(" | ");
    dataFile.print(now.hour(), DEC);
    dataFile.print(':');
    dataFile.print(now.minute(), DEC);
    dataFile.print(':');
    dataFile.print(now.second(), DEC);
    dataFile.println();
    
    // Serial.print(" since midnight 1/1/1970 = ");
    // Serial.print(now.unixtime());
    // Serial.print("s = ");
    // Serial.print(now.unixtime() / 86400L);
    // Serial.println("d");

    // // calculate a date which is 7 days, 12 hours, 30 minutes, and 6 seconds into the future
    // DateTime future (now + TimeSpan(7,12,30,6));

    // Serial.print(" now + 7d + 12h + 30m + 6s: ");
    // Serial.print(future.year(), DEC);
    // Serial.print('/');
    // Serial.print(future.month(), DEC);
    // Serial.print('/');
    // Serial.print(future.day(), DEC);
    // Serial.print(' ');
    // Serial.print(future.hour(), DEC);
    // Serial.print(':');
    // Serial.print(future.minute(), DEC);
    // Serial.print(':');
    // Serial.print(future.second(), DEC);
    // Serial.println();

    // Serial.println();

  // char my_string[100];
  // String dataString = "";  // NOTE: dataFile.println() can take char * or String;  Strings might be easier to format.
  
  //sprintf(my_string, "My Test %d", loop_counter);
  
  // If the log file is available, write to it:
  if (!dataFile)
    {
    // If the file isn't open, print an error, and try again to open the file.
    Serial.println(" Error opening datalog.txt");
    dataFile = SD.open("datalog.txt", FILE_WRITE); 
    }
    
  loop_counter++;

    
  delay(1000);
  }