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

#include <stdio.h>

#include "types.h"

main (int argc, char *argv[]) {
   personnel_rec e1, e2;
   int eof1, eof2;
   FILE *fp1, *fp2, *fp3;

   if (argc<4) {
      printf("You should provide:\n1. the name of the existing master file");
      printf("\n2. the name of the file with the new records\n3. the new master file.");
      exit(1);
   }
   fp1=fopen(argv[1],"rb");
   if (fp1==NULL) {
      printf("Can not open [%s] for reading.\n",argv[1]);
      exit(2);
   }
   fp2=fopen(argv[2],"rb");
   if (fp2==NULL) {
      printf("Can not open [%s] for reading.\n",argv[2]);
      fclose(fp1);
      exit(3);
   }
   fp3=fopen(argv[3],"wb");
   if (fp3==NULL) {
      printf("Can not open [%s] for writing.\n",argv[3]);
      fclose(fp1);
      fclose(fp2);
      exit(4);
   }

   eof1=fread(&e1,sizeof(personnel_rec),1,fp1)<1;
   eof2=fread(&e2,sizeof(personnel_rec),1,fp2)<1;
   while ((!eof1) && (!eof2))
      if (strcmp(e1.key, e2.key)<0) {
         fwrite(&e1,sizeof(personnel_rec),1,fp3);
         eof1=fread(&e1,sizeof(personnel_rec),1,fp1)<1;
      }
      else if (strcmp(e1.key, e2.key)>0) {
         fwrite(&e2,sizeof(personnel_rec),1,fp3);
         eof2=fread(&e2,sizeof(personnel_rec),1,fp2)<1;
      }
      else /* strcmp(e1.key, e2.key)==0 */ {
         /* abnormal case, in case that the new master file should have unique keys */
         printf("Already exist a record with key [%s] in the existing master file [%s]. ", e2.key, argv[1]);
         printf("The record of the file with the new records [%s] is discarded.\n", argv[2]);
         eof2=fread(&e2,sizeof(personnel_rec),1,fp2)<1;
      }
   while (!eof1) {
      fwrite(&e1,sizeof(personnel_rec),1,fp3);
      eof1=fread(&e1,sizeof(personnel_rec),1,fp1)<1;
   }
   while (!eof2) {
      fwrite(&e2,sizeof(personnel_rec),1,fp3);
      eof2=fread(&e2,sizeof(personnel_rec),1,fp2)<1;
   }

   fclose(fp1);
   fclose(fp2);
   fclose(fp3);
}