/******************************************************************************
 * This program implements the ACORN pseudo-random number generator.
 * 
 * Copyright © 2021 Richard Lesh.  All rights reserved.
 *****************************************************************************/

#undef NDEBUG

#include "Utils.hpp"
#include <cmath>
#include <fmt/format.h>
#include <iostream>
#include <memory>
#include <string>
#include <vector>

using namespace Utils;
using namespace std;

class AcornPrng {
private:
    long modulus;
    int order;
    vector<long> seeds = {};

public:
    AcornPrng(int order) noexcept {
        this->modulus = 4294967295L;
        this->order = order;
        for (auto m = 0; m <= order; ++m) {
            long s(modulus * rand()/(RAND_MAX + 1.0));
            if (s % 2 == 0) {
                ++s;
            }
            Utils::push(seeds, s);
        }
    }

    long next_int() noexcept {
        for (auto m = 1; m <= order; ++m) {
            seeds[m] = (m == 1 ? seeds[0] : seeds[m - 1]) + seeds[m];
            seeds[m] &= modulus;
        }
        return seeds[order];
    }

    double next_float() noexcept {
        return next_int() / (modulus + 1.0);
    }
};

int main(int argc, char **argv) {
    if (argc == 2 && string(argv[1]) == "-h") {
        cout << "Syntax: " << argv[0] << " [num_random] [int|float]" << endl;
        cout << "If no arguments are provided a random stream of bytes" << endl;
        cout << "are output." << endl;
        exit(1);
    }
    int num = argc >= 2 ? Utils::stoiWithDefault(string(argv[1]), 10) : -1;
    string type = argc == 3 ? string(argv[2]) : "int";

    cout << "type: " << (type == "int" ? "d" : "f") << endl;
    cout << "count: " << num << endl;
    cout << "numbit: 32" << endl;
    shared_ptr<ACORN_PRNG> generator(new AcornPrng(10));
    if (type == "int") {
        if (num < 1) {
            while (true) {
                int randint = int(generator->next_int());
                unsigned char b = (unsigned char)(randint & 0xFF);
                cout.put(b);
                randint >>= 8;
                b = (unsigned char)(randint & 0xFF);
                cout.put(b);
                randint >>= 8;
                b = (unsigned char)(randint & 0xFF);
                cout.put(b);
                randint >>= 8;
                b = (unsigned char)(randint & 0xFF);
                cout.put(b);
            }
        } else {
            for (auto i = 0; i < num; ++i) {
                cout << generator->next_int() << endl;
            }
        }
    } else {
        for (auto i = 0; i < num; ++i) {
            cout << fmt::format("{0:.10f}", generator->next_float()) << endl;
        }
    }
    return 0;
}