#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <stdlib.h>
#include <string.h>


void childProcess(int currentProcess);
void parentProcess(int numProcesses);
int atoi( const char *str );

int numLines; //number of lines in each  file
int numProcesses; //number of processes entered by the user
int numLinesPerFile;
pid_t pid; //process ID so we know whether it's a child or parent processs
int status; 
char fileNames[] = "abcdefghijklmnopqrstuvwxyz"; //this program can handle up to 26 processes
int main(int argc, char *argv[])
{
                  
    //get the information from the command line
    numLines = atoi(argv[2]);
	numProcesses = atoi(argv[3]);
	numLinesPerFile = numLines / numProcesses;
	//check to make sure the user entered the correct number of arguments. If they didn't, 
	//print an error message and quit     
	if(argc != 4)
	{ 
		printf("\nERROR! Wrong number of arguments.\n\n");
		return 0;
	}
	//print out the parameters the user entered for verification
    //this prints out the filename entered
	fprintf(stdout,"\n");
	fprintf(stdout, argv[1]);
	
	printf("\nNumber of lines: %d\n", numLines);
	printf("Number of processes: %d\n", numProcesses);
	printf("\n\nNumber of lines per file: %d\n", numLinesPerFile);
	
	//arbitrary buffer size of 200 to be sure that the string will fit
	//this will split the file up according to the number of processes
	char buff[200];
	sprintf(buff, "split -l %d %s ", numLinesPerFile, argv[1]);
	system(buff); 
    
	int extraLines = numLines - numLinesPerFile*numProcesses;
	//printf("\n\nThe number of extra lines is: %d", extraLines);
	if(extraLines != 0)
	{		
		char buff[200];
		sprintf(buff, "sort -o xa%c -m xa%c xa%c", fileNames[numProcesses-1], fileNames[numProcesses-1], fileNames[numProcesses] );
		system(buff); 	
		
		sprintf(buff, "rm xa%c", fileNames[numProcesses]);
		system(buff);
	}
	
	
	//this portion of the code will use the fork() to create new processes											                                            
	int i;
	for(i = 0; i < numProcesses; i++)
	{
		//keep up with the current process so we know which file to sort
		int currentProcess = i;
		//fork the current process
		pid = fork();
		if(pid == 0) //i am a child!
		{
			childProcess(currentProcess);
		}
		else //i am your parent!
		{
			//pass the number of processes so the parent knows how many files to merge
			parentProcess(numProcesses);
		}
	}
	
	return 0;      
}//end of main function

	void childProcess(int currentProcess)
	{
		//this portion will sort the file of the child we are on
		char buff[200];
		sprintf(buff, "sort xa%c -n -o xa%c", fileNames[currentProcess], fileNames[currentProcess]);
		system(buff);
		return;
	}//end child function
	
	void parentProcess(int numProcesses)
	{
		printf("\nI AM YOUR FATHER!\n");
		int l;
		//for(l = 0; l < numProcesses; l++)
		//{
			//wait for all of the children to catch up
			wait(&status);
		//}
		int j;
		//arbitrary buffer sizeto hold the entire merge
		char buffer[2000];
		for(j = 0; j < numProcesses; j++)
		{
			//if we are on the first item just take the name xaa
			if(j == 0)
			{
				
				sprintf(buffer, "xa%c ", fileNames[j]);
			}
			//if we aren't on the first file we have to do some concatenation with 
			//the new file name and the old ones
			else
			{
				char newBuffer[200];
				sprintf(newBuffer, "xa%c ", fileNames[j]);
				strcat(buffer, newBuffer);
			}
		}

		//this part actually merges the sorted children's files
		char string[20000];
		sprintf(string, "sort -o outfile -m -n %s", buffer);
		system(string);	
		//remove all of the intermediate files
		//sprintf(string, "rm %s", buffer);
		//system(string);
		return;
	}//end parent function

P1: Beginning.o
	gcc Beginning.o -o P1
Beginning.o:Beginning.c
	gcc -c Beginning.c