/*
# txt-image-sub.c
# (C) 2016 Luca Barion (License GNU GPL v3)
# Sottrae 2 immagini .txt e scrive in out.txt
# Last modified: 2016-08-18 12:04
*/

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

#define MAX_RIGA 32768
#define XMAX 2048

int main(int argc, char *argv[])
{
 gzFile fp1, fp2;
 int fp_out;
 int x, s1, s2, y=0;
 char stringa[16];
 char linea1[MAX_RIGA], linea2[MAX_RIGA];
 char *ptr1, *ptr2, *sptr1, *sptr2;
 char *f1, *f2;
 float val1, val2, val;
 
 printf("Text image subtract - (C) 2016 Luca Barion\n");
 
 if (argc!=3)
 {
  printf(" usage: txt-image-sub <image1.txt.gz> <image2.txt.gz>\n");
  printf(" result written to out.txt\n");
  return 1;
 }
 
 // File 1
 fp1=gzopen(argv[1], "r");
 if (fp1==NULL)
  {
   printf("Error opening %s!\n", argv[1]);
   return -1;
  }
 
 // File 2
 fp2=gzopen(argv[2], "r");
 if (fp1==NULL)
  {
   printf("Error opening %s!\n", argv[2]);
   return -1;
  }
 
 // File out
 fp_out=open("out.txt", O_WRONLY | O_TRUNC | O_CREAT, 0644);
 if (fp_out==-1)
  {
   printf("Error opening out.txt!\n");
   return -1;
  }
 
 printf("%s - %s => out.txt\n", argv[1], argv[2]);
 
 while (1)
  {
   y++;
   f1=gzgets(fp1, linea1, MAX_RIGA);
   if(f1==NULL) break;
 
   //printf("%s\n", linea1); exit(2);
   f2=gzgets(fp2, linea2, MAX_RIGA);
   if(f2==NULL) break;
 
   ptr1 = strtok_r (linea1, " ", &sptr1);
   ptr2 = strtok_r (linea2, " ", &sptr2);
 
   //printf("#");
   for (x=0; x<XMAX; x++)
    {
     s1=sscanf(ptr1, "%f", &val1);
     s2=sscanf(ptr2, "%f", &val2);
     //printf("(%s)", ptr2);
     val=val1-val2;
     sprintf(stringa, " %.2f", val);
     write(fp_out, stringa, strlen(stringa) );
     ptr1 = strtok_r(NULL, " ", &sptr1);
     ptr2 = strtok_r(NULL, " ", &sptr2);
     if (ptr1==NULL || ptr2==NULL || s1!=1 || s2!=1) break;
    }
   
   write(fp_out, "\n", 1);
   printf("\rline: %5d", y);
   fflush(stdout);
  }
 
 gzclose(fp1);
 gzclose(fp2);
 close(fp_out);
 
 printf("\n");
 
 return 0;
}