#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>

#include <chrsplit_doc.h>

typedef int bool_t;

int main(int argc, char *argv[]);
FILE *openfile(char *name, char *mode);
char *txtcat(char *a, char *b);
void error(char *msg);

#ifdef MSDOS

#include <process.h> 
#define RMODE "rb"
#define WMODE "wb"

#else

#define RMODE "r"
#define WMODE "w"

int fclose(FILE *);
int fflush(FILE *);
int _flsbuf(unsigned char, FILE*);
int _filbuf(FILE *);

#endif

int main(int argc, char *argv[])
{
  long unsigned chunksize;
  char *outname;
  char *tail;
  int chunk;
  long unsigned nchars;
  FILE *infile, *outfile;
  int c;
  if ((argc != 5) | (strcmp(argv[1], "-c") != 0))
    { error("usage: charsplit -c nnnnnn infile outname"); }
  chunksize = atoi(argv[2]);
  infile = openfile(argv[3], RMODE);
  c = getc(infile);
  outname = txtcat(argv[4], ".saa");
  tail = outname + strlen(argv[4])+2; 
  for (chunk = 0; (c != EOF) && (chunk < 26*26); chunk++)
    { tail[0] = 'a' + (chunk / 26);
      tail[1] = 'a' + (chunk % 26);
      assert(tail[2] == '\0');
      outfile = openfile(outname, WMODE);
      nchars = 0;
      while((c != EOF) && (nchars < chunksize))
        { putc(c, outfile);
          nchars++;
          c = getc(infile);
        }
      fprintf(stderr, "%8ld %s\n", nchars, outname);
      fclose(outfile);
    }
  if(c != EOF) error("too many chunks!");
  if(ferror(infile)) perror("read error on input file");
  fclose(infile);
  return(0);
}

FILE *openfile(char *name, char *mode)
  { FILE *f; 
    fprintf(stderr, "opening %s  mode = %s\n", name, mode);
    f = fopen(name, mode);
    if(f == NULL) error(txtcat("unable to open ", name));
    return(f);
  }
 
char *txtcat(char *a, char *b)
  { char *r = malloc(strlen(a) + strlen(b) + 1);
    if(r == NULL) error("memory exhausted");
    strcpy(r, a); strcat(r, b); 
    return(r);
  }

void error(char *msg)
  { fprintf(stderr, "** %s\n", msg); exit(1); }