#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

unsigned char *utf8_check(unsigned char *s);

int all_lines = 0;

int scan_file(FILE *f, char *filename) {
  char s[2048], *s1, *s2, *s3;
  int error = 0;

  while (fgets(s, sizeof(s), f)) {
    if ((s1 = s2 = utf8_check(s)) || all_lines) {
      if (filename) {
	printf("%s:\n", filename);
	filename = NULL;
      }
      fputs(s, stdout);
    }
    s3 = s;
    while (s2) {
      while (s3++ < s2)
	putchar('-');
      putchar('^');
      s2 = utf8_check(s3);
    }
    if (s1) {
      putchar('\n');
      error = 1;
    }
  }

  return error;
}

int main(int argc, char **argv)
{
  int option, i, error = 0;
  FILE *f;

  while ((option = getopt(argc, argv, "a")) >= 0) {
    switch(option) {
    case 'a':
      all_lines = 1;
      break;
    default:
      printf("Usage: utf8_test [option] [files ...]\n"
	     "\nOptions:\n\n  -a   print all lines\n");
      exit(1);
    }
  }

  if (optind < argc)
    for (i = optind; i < argc; i++) {
      if ((f = fopen(argv[i], "r"))) {
	error |= scan_file(f, argv[i]);
	fclose(f);
      }	else {
	printf("Cannot read file '%s", argv[i]);
	perror("'");
      }
    }
  else
    error |= scan_file(stdin, NULL);

  return error;
}