/*
 * This taken from the source code of tgnet library v. 1.0
 * It is licensed under GNU GPL v. 2 or later.
 * You should have received a copy of the license in this archive (see LICENSE).
 *
 * Copyright Nikolai Kudashov, 2015.
 */

#include <phpcpp.h>


inline uint64_t gcd(uint64_t a, uint64_t b) {
    while (a != 0 && b != 0) {
        while ((b & 1) == 0) {
            b >>= 1;
        }
        while ((a & 1) == 0) {
            a >>= 1;
        }
        if (a > b) {
            a -= b;
        } else {
            b -= a;
        }
    }
    return b == 0 ? a : b;
}
inline Php::Value factorize(Php::Parameters &parameters)
{
    uint64_t what = (int64_t) parameters[0];
    int32_t it = 0, i, j;
    uint64_t g = 0;
    for (i = 0; i < 3 || it < 1000; i++) {
        uint64_t t = ((lrand48() & 15) + 17) % what;
        uint64_t x = (long long) lrand48() % (what - 1) + 1, y = x;
        int32_t lim = 1 << (i + 18);
        for (j = 1; j < lim; j++) {
            ++it;
            uint64_t a = x, b = x, c = t;
            while (b) {
                if (b & 1) {
                    c += a;
                    if (c >= what) {
                        c -= what;
                    }
                }
                a += a;
                if (a >= what) {
                    a -= what;
                }
                b >>= 1;
            }
            x = c;
            uint64_t z = x < y ? what + x - y : x - y;
            g = gcd(z, what);
            if (g != 1) {
                break;
            }
            if (!(j & (j - 1))) {
                y = x;
            }
        }
        if (g > 1 && g < what) {
            break;
        }
    }

    if (g > 1 && g < what) {
        return (int32_t) g;
    } else {
        throw Php::Exception("Factorization failed!");
        return false;
    }
}

extern "C" {
    PHPCPP_EXPORT void *get_module() {
        static Php::Extension extension("primemodule", "1.0");
        extension.add<factorize>("factorize", {
            Php::ByVal("pq")
        });
        return extension;
    }
}