#include "string_buffer.h"
#include "utils.h"

#include <stdlib.h>
#include <string.h>
#include <ctype.h>

#define VALID_FOR_USERNAME(c) (isalpha(c) || c == '_')

int
contain_special(const char *s)
{
    return strchr(s, '&') || strchr(s, '"') || strchr(s, '\'') || strchr(s, '<') || strchr(s, '>');
}

int
is_valid_username(const char *s)
{
    char c;
    while ((c = *s++)) {
        if (!VALID_FOR_USERNAME(c)) {
            return 0;
        }
    }
    return 1;
}

int
is_valid_password(const char *s)
{
    char c;
    unsigned char b;
    while ((c = *s++)) {
        b = (unsigned char) c;
        if (b < 32) {
            return 0;
        }
    }
    return 1;
}

char *
mk_specialchars(const char *input)
{
    StringBuffer _buffer, *buffer;
    char c;
    char *retval;
    
    buffer = &_buffer;
    sb_init_empty(buffer);

    while ((c = *(input++))) {
        switch (c) {
            case '&':
                sb_add_string(buffer, "&amp;");
                break;
            case '"':
                sb_add_string(buffer, "&quot;");
                break;
            case '\'':
                sb_add_string(buffer, "&#039;");
                break;
            case '<':
                sb_add_string(buffer, "&lt;");
                break;
            case '>':
                sb_add_string(buffer, "&gt;");
                break;
            default:
                sb_add_char(buffer, c);
        }
    }

    SB_MOVE(buffer, retval);
    return retval;
}