/*------------------------------------------------------*
 | Author: Maurizio Loreti, aka MLO or (HAM) I3NOO      |
 | Work:   University of Padova - Department of Physics |
 |         Via F. Marzolo, 8 - 35131 PADOVA - Italy     |
 | Phone:  +39 (049) 827-7216   FAX: +39 (049) 827-7102 |
 | EMail:  loreti@padova.infn.it                        |
 | WWW:    http://wwwcdf.pd.infn.it/~loreti/mlo.html    |
 *------------------------------------------------------*

 The five procedures i_strchr, i_strrchr, i_strstr, i_strcmp
 and i_strncmp behave exactly as their counterparts (without
 the leading i_) as defined in <string.h>; but the comparison
 is case insensitive.  l_strlcpy and l_strlcat behave as strcpy
 and strcat, but the copied string is converted to lowercase.

 Compile with -DTEST to have a (quick and dirty) test program.

 *------------------------------------------------------*/

#include <ctype.h>              /* tolower */
#include <stdlib.h>             /* size_t  */

#ifdef TEST
  #include <stdio.h>
  #include <string.h>

  #define BUFFER_LENGTH 128
#endif /* TEST */

/**
 | Prototypes
**/

char *i_strchr(const char *,  const int);
char *i_strrchr(const char *, const int);
char *i_strstr(const char *,  const char *);
int   i_strcmp(const char *,  const char *);
int   i_strncmp(const char *, const char *, size_t);
char *l_strcpy(char *, const char *);
char *l_strcat(char *, const char *);

char *i_strchr(
  const char *s,
  const int   c
) {
  register int sc;
  register int cc;

  for (cc = tolower((unsigned char) c);
       (sc = tolower((unsigned char) *s)) != 0;  s++) {
    if (sc == cc) return ((char *) s);
  }

  return 0;
}

char *i_strrchr(
  const char *s,
  const int   c
) {
  register int         sc;
  register int         cc;
  register const char *pc = 0;

  for (cc = tolower((unsigned char) c);
       (sc = tolower((unsigned char) *s)) != 0;  s++) {
    if (sc == cc) pc = s;
  }

  return ((char *) pc);
}

char *i_strstr(
  const char *s1,
  const char *s2
) {
  register char sc1;
  register char sc2;

  if ((sc2 = tolower((unsigned char) *s2)) == '\0') return ((char *) s1);

  for ( ;  (sc1 = tolower((unsigned char) *s1)) != '\0';  s1++) {
    if (sc1 == sc2) {
      register const char *p1 = s1;
      register const char *p2 = s2;

      while (1) {
        if (*++p2 == '\0') {
          return ((char *) s1);
        } else {
          if (tolower((unsigned char) *++p1) !=
              tolower((unsigned char) *p2)) break;
        }
      }
    }
  }

  return 0;
}

int i_strcmp(
  const char   *s1,
  const char   *s2
){
  while (1) {
    register int i;

    i = tolower((unsigned char) *s1) - tolower((unsigned char) *s2);
    if (i  ||  *s2 == '\0') return i;
    s1++;
    s2++;
  }

  return 0;
}

int i_strncmp(
  const char   *s1,
  const char   *s2,
        size_t  n
){
  for ( ;  n--;  s1++, s2++) {
    register int i;

    i = tolower((unsigned char) *s1) - tolower((unsigned char) *s2);
    if (i  ||  *s2 == '\0') return i;
  }

  return 0;
}

char *l_strcpy(
  char *to,
  const char *from
) {
  register const char *pc = from;

  while ((*to++ = tolower((unsigned char) *pc)) != 0)   pc++;
  return ((char *) from);
}

char *l_strcat(
  char *to,
  const char *from
) {
  register const char *pc = from;

  while (*to != '\0') to++;
  while ((*to++ = tolower((unsigned char) *pc)) != '\0') pc++;
  return ((char *) from);
}

#ifdef TEST
int main()
{
  char buffer[BUFFER_LENGTH], string[BUFFER_LENGTH];
  char *pc;

  puts("Testing strchr...");
  for (;;) {
    char c;

    printf("String (\\ to exit) ? ");
    fgets(buffer, BUFFER_LENGTH, stdin);
    if (buffer[0] == '\\') break;
    if ((pc = strrchr(buffer, '\n')) != 0) *pc = '\0';
    strcpy(string, buffer);

    printf("Char ? ");
    fgets(buffer, BUFFER_LENGTH, stdin);
    c = buffer[0];
    if ((pc = i_strchr(string, c)) == 0) {
      puts("No match.");
    } else {
      size_t pos = pc - string;

      printf("Match at string[%u]\n", pos);
    }
  }

  puts("Testing strrchr...");
  for (;;) {
    char c;

    printf("String (\\ to exit) ? ");
    fgets(buffer, BUFFER_LENGTH, stdin);
    if (buffer[0] == '\\') break;
    if ((pc = strrchr(buffer, '\n')) != 0) *pc = '\0';
    strcpy(string, buffer);

    printf("Char ? ");
    fgets(buffer, BUFFER_LENGTH, stdin);
    c = buffer[0];
    if ((pc = i_strrchr(string, c)) == 0) {
      puts("No match.");
    } else {
      size_t pos = pc - string;

      printf("Match at string[%u]\n", pos);
    }
  }

  puts("Testing strstr...");
  for (;;) {
    printf("String (\\ to exit) ? ");
    fgets(buffer, BUFFER_LENGTH, stdin);
    if (buffer[0] == '\\') break;
    if ((pc = strrchr(buffer, '\n')) != 0) *pc = '\0';
    strcpy(string, buffer);

    printf("Substring ? ");
    fgets(buffer, BUFFER_LENGTH, stdin);
    if ((pc = strrchr(buffer, '\n')) != 0) *pc = '\0';
    if ((pc = i_strstr(string, buffer)) == 0) {
      puts("No match.");
    } else {
      size_t pos = pc - string;

      printf("Match at string[%u]\n", pos);
    }
  }

  puts("Testing strcmp...");
  for (;;) {
    int i;

    printf("String 1 (\\ to exit) ? ");
    fgets(buffer, BUFFER_LENGTH, stdin);
    if (buffer[0] == '\\') break;
    if ((pc = strrchr(buffer, '\n')) != 0) *pc = '\0';
    strcpy(string, buffer);

    printf("String 2 ? ");
    fgets(buffer, BUFFER_LENGTH, stdin);
    if ((pc = strrchr(buffer, '\n')) != 0) *pc = '\0';
    if ((i = i_strcmp(string, buffer)) == 0) {
      puts("String 1 == String 2");
    } else if (i < 0) {
      puts("String 1 < String 2");
    } else {
      puts("String 1 > String 2");
    }
  }

  puts("Testing strncmp...");
  for (;;) {
    int i;
    size_t n;
    char input[BUFFER_LENGTH];

    printf("String 1 (\\ to exit) ? ");
    fgets(buffer, BUFFER_LENGTH, stdin);
    if (buffer[0] == '\\') break;
    if ((pc = strrchr(buffer, '\n')) != 0) *pc = '\0';
    strcpy(string, buffer);

    printf("String 2 ? ");
    fgets(buffer, BUFFER_LENGTH, stdin);
    if ((pc = strrchr(buffer, '\n')) != 0) *pc = '\0';

    printf("N ? ");
    fgets(input, BUFFER_LENGTH, stdin);
    if ((pc = strrchr(input, '\n')) != 0) *pc = '\0';
    n = strtoul(input, 0, 10);

    if ((i = i_strncmp(string, buffer, n)) == 0) {
      puts("String 1 == String 2");
    } else if (i < 0) {
      puts("String 1 < String 2");
    } else {
      puts("String 1 > String 2");
    }
  }

  puts("Testing strcpy...");
  for (;;) {
    printf("String (\\ to exit) ? ");
    fgets(buffer, BUFFER_LENGTH, stdin);
    if (buffer[0] == '\\') break;
    if ((pc = strrchr(buffer, '\n')) != 0) *pc = '\0';
    l_strcpy(string, buffer);
    printf("Destination: \"%s\"\n", string);
  }

  puts("Testing strcat...");
  for (;;) {
    printf("Original string (\\ to exit) ? ");
    fgets(buffer, BUFFER_LENGTH, stdin);
    if (buffer[0] == '\\') break;
    if ((pc = strrchr(buffer, '\n')) != 0) *pc = '\0';

    printf("String to be appended ? ");
    fgets(string, BUFFER_LENGTH, stdin);
    if ((pc = strrchr(string, '\n')) != 0) *pc = '\0';
    l_strcat(buffer, string);
    printf("Result: \"%s\"\n", buffer);
  }

  return 0;
}
#endif /* TEST */