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

#define alpha(x) (tolower((x))-'a'+1)

/*
 * Example:
 * $ ./vigenere "hi from somewhere" somekey e
 * zw jbsk gaqoafwfq
 * $ ./vigenere "zw jbsk gaqoafwfq" somekey d
 * hi from somewhere
 *
 * This code might be bugged.. I just coded it for fun a quite long time ago.
 */

char *square[] = {
                    "AABCDEFGHIJKLMNOPQRSTUVWXYZ",
                    "AABCDEFGHIJKLMNOPQRSTUVWXYZ",
                    "BBCDEFGHIJKLMNOPQRSTUVWXYZA",
                    "CCDEFGHIJKLMNOPQRSTUVWXYZAB",
                    "DDEFGHIJKLMNOPQRSTUVWXYZABC",
                    "EEFGHIJKLMNOPQRSTUVWXYZABCD",
                    "FFGHIJKLMNOPQRSTUVWXYZABCDE",
                    "GGHIJKLMNOPQRSTUVWXYZABCDEF",
                    "HHIJKLMNOPQRSTUVWXYZABCDEFG",
                    "IIJKLMNOPQRSTUVWXYZABCDEFGH",
                    "JJKLMNOPQRSTUVWXYZABCDEFGHI",
                    "KKLMNOPQRSTUVWXYZABCDEFGHIJ",
                    "LLMNOPQRSTUVWXYZABCDEFGHIJK",
                    "MMNOPQRSTUVWXYZABCDEFGHIJKL",
                    "NNOPQRSTUVWXYZABCDEFGHIJKLM",
                    "OOPQRSTUVWXYZABCDEFGHIJKLMN",
                    "PPQRSTUVWXYZABCDEFGHIJKLMNO",
                    "QQRSTUVWXYZABCDEFGHIJKLMNOP",
                    "RRSTUVWXYZABCDEFGHIJKLMNOPQ",
                    "SSTUVWXYZABCDEFGHIJKLMNOPQR",
                    "TTUVWXYZABCDEFGHIJKLMNOPQRS",
                    "UUVWXYZABCDEFGHIJKLMNOPQRST",
                    "VVWXYZABCDEFGHIJKLMNOPQRSTU",
                    "WWXYZABCDEFGHIJKLMNOPQRSTUV",
                    "XXYZABCDEFGHIJKLMNOPQRSTUVW",
                    "YYZABCDEFGHIJKLMNOPQRSTUVWX",
                    "ZZABCDEFGHIJKLMNOPQRSTUVWXY",
                };

int main(int ac, char **av)
{
    if (ac < 4) {
        fprintf(stderr, "Usage: %s txt key enc|dec\n", av[0]);
        return 0;
    }

    char *txt, *key, *what;
    txt = av[1];
    key = av[2];
    what = av[3];

    unsigned int keylen, textlen, i, kcount;
    keylen = strlen(key);
    textlen = strlen(txt);

    char done[50];
    memset(done,0,50);

    for (i = 0, kcount = 0; i < textlen; i++, kcount++) {
        if (kcount == keylen)
            kcount = 0;

        if (!isalpha(txt[i])) {
            done[i] = txt[i];
            continue;
        }

        if (*what == 'e')
            done[i] = tolower(square[alpha(key[kcount])][alpha(txt[i])]);
        else
            done[i] = tolower(square[0][(int)(strchr(square[alpha(key[kcount])],toupper(txt[i]))-square[alpha(key[kcount])])]);
    }

    printf("%s\n",done);
    return 0;
}