#include <iostream>
#include <future>
#include <chrono>
#include <condition_variable>
#include <iostream>
#include <mutex>
#include <string>
#include <thread>
#include <cstdio>
#include <fstream>
#include <algorithm>

using namespace std ;

string dataFileName ;
int indexG = 1 ;
const int blockSize = 2  ;
ifstream dataFile ;
char ch1 ;

int countNoLines( string filename )
{
    ifstream inputFile(filename);       // Open the file for reading

      if (!inputFile.is_open()) { // Check if the file was opened successfully
          cerr << "Error: Could not open the file \"" << filename << "\"" << endl;
          return 1; // Indicate an error
      }

      int lineCount = 0;
      string line;

      // Read the file line by line until the end of the file is reached
      while (getline(inputFile, line))
      {

		  if ( line.length() > 0 && line[0] != 10 &&
		    line[0] != 13  )
		   {
            lineCount++; // Increment the line counter for each line read
            cout << "Line:" << line.length() << " " << (int)line[0] << endl ;
		   }
      }

    inputFile.close();
    return  lineCount ;
}

void readIntoArray( int  tempArr1[], int size )
{
  static bool hasBeenOpened = false ;
  cout << " readIntoArray: Step1" << endl ;
  if ( !hasBeenOpened )
   {
     dataFile.open( dataFileName ) ;
     hasBeenOpened = true  ;
   }


       int x1 ;
       cout << "readIntoArray size: " << size << endl ;
       for( int i1=0 ; i1<size ; i1++ )
        {
           dataFile >> x1 ;
           cout << "x1:" << x1 << endl ;
           tempArr1[i1] = x1 ;
		} //for




}

void writeArrayIntoFile( int  tempArr1[], int size , string fileName )
{
  ofstream outputFile ;
  outputFile.open( fileName );
  for( int i1=0 ; i1 < size ; i1++ )
   {
      outputFile <<  tempArr1[i1] << endl ;
   }

  outputFile.close() ;
}

void printArray( int arr1[] , int size )
{
	cout << "Printing the array1." << endl ;
	for( int i1=0 ; i1<size ; i1++ )
	 {
        cout << "i1:" << arr1[i1] << " " ;
	 }
   cout << "\nPrinting the array2." << endl ;
}

void   merge( string file1 , string file2 , string outputFile )
{
  ifstream file1InputStream( file1 )  ;
  ifstream file2InputStream( file2 ) ;
  ofstream outputFileStream( outputFile )  ;
  int x1, x2 ;
  bool file1IsDone = false ; bool file2IsDone = false ;
  string line ;
          getline( file1InputStream, line )  ;
          x1 = stoi(line) ;
          cout << "line1:" << line << endl ;
          getline( file2InputStream, line )  ;
          cout << "line2:" << line << endl ;
          x2 = stoi(line) ;


  while ( true )
   {
	  cout << "Step1" << endl ;
      if ( x1 < x2 )
       {
          outputFileStream << x1 << endl ;
	   }
	  else
	   {
		  outputFileStream << x2 << endl ;
	   }

			  if ( x1 < x2 )
			   {
				            getline( file1InputStream, line )  ;

				            cout << "line5:" << line << ":" << endl ;
				            if (  line.length() == 0 ||
				               file1InputStream.eof() )
				              {
                                file1IsDone = true ; break ;
						      }
				            x1 = stoi(line) ;


			   }
			  else
			   {
						  getline( file2InputStream, line )  ;
				            if (  line.length() == 0 ||
				               file2InputStream.eof() )
				              {
                                file2IsDone = true ; break ;
						      }

						  cout << "line6:" << line << endl ;
						  x2 = stoi(line) ;

			   }


       cout << "Inside while:" << endl ;
       cin >> ch1 ;
   } //while



	  //if (  file1InputStream.eof() )
	  if ( file1IsDone )
	    {
			cout << "Reached end of file1." << endl ;
              outputFileStream << x2 << endl ;
             while( getline( file2InputStream, line )  )
               {
				   cout << "line 3." << line << endl ;
				   if ( line.length() > 0 )
				    {
                      x2 = stoi(line) ;
                      outputFileStream << x2 << endl ;
				    }
			   } //while


		}
	 else
	    {
		  cout << "Reached end of file2." << endl ;
           outputFileStream << x1 << endl ;
             while( getline( file1InputStream, line )  )
               {
				   cout << "line 4." << line << endl ;
				   if ( line.length() > 0 )
				    {
                     x1 = stoi(line) ;
                     outputFileStream << x1 << endl ;
				    }
			   } //while


		}

   file1InputStream.close() ;
   file2InputStream.close() ;
   outputFileStream.close() ;


}


void mergeSort( int start , int end , string outputFile )
{
	cout << "mergeSort: " << start << " " << end  << endl ;
    if (  (end-start) < blockSize )
      {
          cout << "Working on block. " << start << " "  <<
          end << ":outputFile: " <<
          outputFile << endl ;

          int sizeOfArray = (end-start) + 1 ;
          int tempArr1[ sizeOfArray ] ;
          readIntoArray(  tempArr1 , sizeOfArray) ;
          sort( tempArr1 , (tempArr1 + sizeOfArray)  ) ;
          printArray( tempArr1 , sizeOfArray ) ;
          writeArrayIntoFile(tempArr1, sizeOfArray , outputFile) ;
	  }
	else
	  {

		  int middle = start + ( end  - start ) / 2 ;
          string file1 = "file" + to_string(indexG++) + ".txt" ;
          string file2 = "file" + to_string(indexG++) + ".txt" ;
		  cout << "Splitting the file. middle:" <<  middle << endl ;
          mergeSort( start , middle , file1 ) ;
          mergeSort( middle+1 , end , file2 ) ;
          merge( file1 , file2 , outputFile ) ;
	  }

}


int main()
{

    cout << "Enter the name of input file: "  << endl ;
    //cin >> dataFileName ;
    dataFileName = "input.txt"  ;
    int noOfLines  = countNoLines( dataFileName )  ;
    cout << "noOfLines: " << noOfLines <<  endl ;
    mergeSort( 0 , noOfLines-1, "result.txt" )  ;
   // merge( "file1.txt" , "file2.txt" , "outputFile.txt" ) ;
    return 0;
}