#define NOMINMAX     // due to conflict with max()
#include <windows.h> // warning: no C++ standard!

#include "MyBigUnsigned.h" // http://henkessoft.de/Sonstiges/MyBigUnsigned.rar
                           // based on https://mattmccutchen.net/bigint/

#include <iostream>
#include <cstdint>
#include <vector>
#include <cassert>
#include <thread>
#include <mutex>

using namespace std;

const uint32_t numberOfThreads = 11;
const uint32_t DIVISOR_PRECHECK_MAX = 293;
uint64_t const primeLimit = 100000000;
uint64_t frequency;

mutex mutex0;

void textcolor(unsigned short color = 15)
{
    SetConsoleTextAttribute(::GetStdHandle(STD_OUTPUT_HANDLE), color);
}

uint64_t convertBigToU64(BigUnsigned num)
{
    BigUnsigned ZweiHochVierUndSechzig = stringToBigUnsigned("18446744073709551616");
    assert(num < ZweiHochVierUndSechzig);
    uint64_t jHi = num.getBlock(1);
    uint64_t jLo = num.getBlock(0);
    return (jHi << 32 | jLo);
}

void convertU64ToBig(uint64_t num, BigUnsigned& b)
{
    uint32_t numLo = (uint32_t)(num & 0xFFFFFFFF);
    uint32_t numHi = (uint32_t)((num >> 32) & 0xFFFFFFFF);
    b.setBlock(0, numLo);
    b.setBlock(1, numHi);
}

BigUnsigned calculateMersenneNumber(BigUnsigned p)
{
    BigUnsigned x = 2;

    for (BigUnsigned i = 1; i < p; ++i)
    {
        x <<= 1;
    }
    return (x - 1);
}

bool LucasLehmerTest(BigUnsigned m, BigUnsigned p)
{
    BigUnsigned s = 4;

    for (BigUnsigned i = 2; i < p; ++i)
        s = (s*s - 2) % m;

    return (s == 0);
}

// division test with first prime numbers
BigUnsigned divisionPrecheck(vector<bool>& primes, BigUnsigned m)
{
    for (BigUnsigned divisor = 7; divisor <= DIVISOR_PRECHECK_MAX; ++divisor)
    {
        if (primes[convertBigToU64(divisor)])
        {
            if (m % divisor == 0)
            {
                return divisor;
            }
        }
    }

    return 0; // No divisor found
}

void mersennePrimeCheck(vector<bool>& primes, uint64_t startCount, uint64_t lastCount, uint64_t startP, uint64_t limitP)
{
    BigUnsigned bigStartP, bigLimitP;
    convertU64ToBig(startP, bigStartP);
    convertU64ToBig(limitP, bigLimitP);

    for (BigUnsigned p = bigStartP; p < bigLimitP; ++p)
    {
        // primes lookup for p: in order for M(p) to be prime, p must itself be prime.
        if (!primes[convertBigToU64(p)])
            continue;

        // if p is prime, then we calculate the mersenne number
        BigUnsigned m = calculateMersenneNumber(p);

        // mersenne number with prime factors are no mersenne primes
        if (p > 19)
        {
            BigUnsigned divisor(0);
            divisor = divisionPrecheck(primes, m);
            if (divisor !=0)
            {
                mutex0.lock();
                textcolor(3);
                cout << ">>> divisionPrecheck finds " << divisor << " for p = " << p << " <<<" << endl;
                mutex0.unlock();
                continue;
            }
        }

        if (LucasLehmerTest(m, p))
        {
            QueryPerformanceCounter((LARGE_INTEGER*)&lastCount);
            uint64_t delta = lastCount - startCount;

            mutex0.lock();
            textcolor(15);
            cout << "p: " << p;
            textcolor(2);
            cout << "\ttime: " << 1000 * delta / frequency << " ms" << endl;
            mutex0.unlock();
        }
    }

    mutex0.lock();
    textcolor(11);
    cout << "work is done for " << bigStartP << " to " << bigLimitP-1 << endl;
    mutex0.unlock();
}

int main()
{
    uint64_t startCount = 0, lastCount = 0, delta = 0;
    QueryPerformanceFrequency((LARGE_INTEGER*)&frequency);
    cout << "cpu frequency: " << frequency << " Hz" << endl;
    cout << "DIVISOR_PRECHECK_MAX: " << DIVISOR_PRECHECK_MAX << endl;
    cout << "number of threads: " << numberOfThreads << endl;

    ////////////////////////// Generate primes lookup table /////////////////////////////////////////////////////////////

    vector<bool> primes(primeLimit + 1); // calculated primes (low values)

    primes[0] = primes[1] = false;
    for (uint64_t i = 2; i < primeLimit + 1; ++i) { primes[i] = true; }

    // Erastothenes sieving loop
    uint64_t iMax = (uint64_t)sqrt((double)primeLimit) + 1;
    for (uint64_t i = 2; i < iMax; ++i)
    {
        if (primes[i])
        {
            for (uint64_t j = 2 * i; j < primeLimit + 1; j += i)
            {
                primes[j] = false;
            }
        }
    }

    /////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

    cout << "Lucas Lehmer prime test for mersenne numbers" << endl; // https://de.wikipedia.org/wiki/Lucas-Lehmer-Test

    QueryPerformanceCounter((LARGE_INTEGER*)&startCount);

    vector<thread> t;
    uint64_t startP = 0;
    uint64_t limitP = 2400;

    for (int x = 0; x < numberOfThreads; ++x)
    {
        t.emplace_back(mersennePrimeCheck, primes, startCount, lastCount, startP + x * 2400, limitP + x * 2400);
    }

    for (int x = 0; x < numberOfThreads; ++x)
    {
        t[x].join(); // main has to wait for the results of the threads.
    }
}