/* *******************************************************
   * Author: Nikitas N. Karanikolas, Assistant Professor *
   * Creation Date: February 21, 2009                    *
   ******************************************************* */

#include <stdio.h>

#include "types.h"

int partial_sort(FILE *fp1, FILE *fp2) {
   personnel_rec e1, e2;
   int howmany;
   int sorted=1; /* sorted <- true */
   howmany=fread(&e1,sizeof(personnel_rec),1,fp1);
   if (howmany<1)
      return sorted;
   do {
      howmany=fread(&e2,sizeof(personnel_rec),1,fp1);
      if (howmany<1) {
	 fwrite(&e1,sizeof(personnel_rec),1,fp2);
	 break;
      }
      if (strcmp(e1.key,e2.key)<=0) {
	 fwrite(&e1,sizeof(personnel_rec),1,fp2);
	 memcpy(&e1,&e2,sizeof(personnel_rec));
      }
      else {
	 fwrite(&e2,sizeof(personnel_rec),1,fp2);
         sorted=0; /* sorted <- false */
      }
   } while (1);
   return sorted;
}

main (int argc, char *argv[]) {
   int i=0;
   int sorted;
   FILE *fp1, *fp2;

   if (argc<2) {
      printf("You should provide the name of the file to be created.");
      exit(1);
   }

   do {
      if (i % 2 == 0) {
         fp1=fopen(argv[1],"rb");
         fp2=fopen("tmp$$.tmp","wb");
      }
      else {
         fp1=fopen("tmp$$.tmp","rb");
         fp2=fopen(argv[1],"wb");
      }
      sorted=partial_sort(fp1,fp2);
      fclose(fp1);
      fclose(fp2);
      i++;
   } while (!sorted);
   printf("\nNumber of file traverses: %d\n", i);
   if (i % 2 == 1) {
      unlink(argv[1]); /* delete the original file */
      rename("tmp$$.tmp",argv[1]); /* rename the temporary file to the original */
   }
   else {
      unlink("tmp$$.tmp"); /* delete temporary file */
   }
}