#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <openssl/sha.h>

const char *coin_err;
#define bail(s) { coin_err = s; return 0; }

int unbase58(const char *s, unsigned char *out) {
    static const char *tmpl = "123456789"
        "ABCDEFGHJKLMNPQRSTUVWXYZ"
        "abcdefghijkmnopqrstuvwxyz";
    int i, j, c;
    const char *p;

    memset(out, 0, 40);
    for (i = 0; s[i]; i++) {
        if (!(p = strchr(tmpl, s[i])))
            bail("bad char");

        c = p - tmpl;
        for (j = 37; j--; ) {
            c += 58 * out[j];
            out[j] = c % 256;
            c /= 256;
        }

        if (c) bail("address too long");
    }

    return 1;
}

int valid(const char *s) {
    unsigned char dec[40], d1[SHA256_DIGEST_LENGTH], d2[SHA256_DIGEST_LENGTH];

    coin_err = "";
    if (!unbase58(s, dec)) return 0;

    SHA256(SHA256(dec, 33, d1), SHA256_DIGEST_LENGTH, d2);

    if (memcmp(dec + 33, d2, 4))
        bail("bad digest");

    return 1;
}

#define C_1_INDEX 6
#define C_2_INDEX 11
#define C_3_INDEX 27
#define C_4_INDEX 34
#define C_5_INDEX 47

int main (void) {
    const char *chars = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
    char addr[100];
    strcpy(addr, "5HpHag-65TZ-G1PH3CSu63k8Dbp-D8s5ip-nEB3kEsreAnc-uDf");

    int i;
    for (i = 0; addr[i]; i++) {
        if (addr[i] == '-') printf("index: %d\n", i);
    }

    int c1 = 0, c2 = 0, c3 = 0, c4 = 0, c5 = 0, status;
    float startTime, endTime;
    for (c1 = 0; c1 < 58; c1++) {
        addr[C_1_INDEX] = chars[c1];
        for (c2 = 0; c2 < 58; c2++) {
            addr[C_2_INDEX] = chars[c2];
            printf("Test: %c%c...", chars[c1], chars[c2]);fflush(stdout);
            startTime = (float)clock()/CLOCKS_PER_SEC;
            for (c3 = 0; c3 < 58; c3++) {
                addr[C_3_INDEX] = chars[c3];
                for (c4 = 0; c4 < 58; c4++) {
                    addr[C_4_INDEX] = chars[c4];
                    for (c5 = 0; c5 < 58; c5++) {
                        addr[C_5_INDEX] = chars[c5];
                        status = valid(addr);
                        if (status) {
                            printf("\nFOUND: %s\n", addr);
                            return 1;
                        }
                    }
                }
            }
            endTime = (float)clock()/CLOCKS_PER_SEC;
            printf("%fs\n", (endTime-startTime));
        }
    }

    return 0;
}