#include <vector>
#include <random>
#include <ctime>
#include <functional>
#include <iostream>
#include <algorithm>
#include <memory>

template<class T>
struct trained {
    unsigned int id;
    T decider;
    
    double   monies;
    unsigned stock;
    double   wealth;
   
    void recalculate(double price)
    {
        wealth = monies + stock*price;
    }

    double score;
};

template <class T>
class trainer {
    std::vector<std::shared_ptr<trained<T>>> trainees;
    std::function<T()> factory;

    unsigned int id;

    std::default_random_engine random_engine;
    std::size_t n;

public:
    double money;
    unsigned stock;

    std::function<double(std::shared_ptr<trained<T>> x)> q;

    trainer(double money, unsigned stock, std::size_t n, std::function<T()> factory) 
        : factory(factory), id(0), money(money), stock(stock), n(n),
        q([](std::shared_ptr<trained<T>> x){ return x->wealth; }), random_engine(std::time(0))
    {
        add(n);
    }

    void add(std::size_t n, std::function<T()> factory)
    {
        for(std::size_t i = 0; i < n; i++) {
            add(factory());
        }
    }

    void add(std::size_t n) 
    {
        add(n, factory);
    }

    void add(const T& decider)
    {
        auto trainee = std::make_shared<trained<T>>();
        trainee->id = ++id;
        trainee->decider = decider;

        trainees.push_back(trainee);
    }

    int train(std::shared_ptr<trained<T>> trainee, double price)
    {
        auto decision   = trainee->decider.decide(price, trainee->monies, trainee->stock);
        auto current    = price*trainee->stock + trainee->monies;
        auto max_credit = std::max(current * 0.05, -1e4);

        /* std::cout << "D: " << decision << " C: " << current << " P: " << price << " MC: " << max_credit << std::endl; */ 
        if (decision > 0 && trainee->monies - decision*price < -max_credit) {
            decision = floor((trainee->monies + max_credit) / price);
        }

        if (decision < 0 && -decision > trainee->stock) {
            decision = -trainee->stock;
        }

        trainee->stock  += decision;
        trainee->monies -= price*decision;
        trainee->recalculate(price);

        return decision;
    }

    void test(std::istream& input)
    {
        for (auto trainee : trainees) {
            trainee->monies = money;
            trainee->stock  = stock;

            trainee->decider.start_money = money;
            trainee->decider.start_stock = stock;
            trainee->decider.reset();
        }

        double price, start;
        input >> price;
        start = price*stock + money;

        do {
            for (auto trainee : trainees) {
                train(trainee, price);
            }
        } while (input >> price);

        auto hodl = price * stock + money;
        std::cout << "Zakonczono testy " << trainees.size() << " przypadkow." << std::endl;
        std::cout << "HODL: " << hodl << " START: " << start << std::endl;
        std::cout << "-----------------------" << std::endl;

        normalize();

        for (auto trainee : trainees) {
            std::cout 
                << "#" << trainee->id << ": " << trainee->wealth 
                << " [" << trainee->wealth - hodl << "] (" << trainee->score << ") "
                << trainee->stock << " akcji, " 
                << trainee->monies << " gelda w banku. " << std::endl; 
        }

        filter();
        breed();
    }

    void normalize()
    {
        std::sort(trainees.begin(), trainees.end(), [=](std::shared_ptr<trained<T>> a, std::shared_ptr<trained<T>> b){
            return q(a) > q(b);
        });

        auto high = q(*trainees.begin());
        auto low  = q(*(trainees.end() - 1));

        // best = 1, worst = 0
        for (auto t : trainees) {
            t->score = (q(t) - low) / (high - low);
        };
    }

    void filter()
    {
        /* static std::exponential_distribution<double> distribution(0.50); */

        /* auto random = [=](){ return 1. - std::clamp(0., distribution(random_engine), 2.)/2.1; }; */
        /* auto iterator = std::remove_if(trainees.begin(), trainees.end(), [=](std::shared_ptr<trained<T>> t) { */
        /*     return random() > t->score; */
        /* }); */

        trainees.erase(trainees.begin() + 49, trainees.end());

        std::cout << "Przy życiu pozostają: ";
        for (auto trainee : trainees) {
            std::cout << "#" << trainee->id << " ";
        }
        std::cout << std::endl;
    }

    void breed()
    {   
        std::size_t diff = n - trainees.size();
        std::cout << "---------------------------------------" << std::endl;
        std::cout << "W populacji brakuje " << diff << " sieci, aktualnie " << trainees.size() << "." << std::endl;

        std::vector<double> probability;
        for (auto t : trainees) {
            probability.push_back(t->score);
        }

        std::discrete_distribution<unsigned> distribution(probability.begin(), probability.end());
        std::exponential_distribution<double> exponential(1.5);
        
        auto combiner = [=](const double& a, const double& b){
            auto mutation = (rand() % 2 ? -1 : 1) * exponential(random_engine);

            if (exponential(random_engine) < 1) {
                return .6 * a + .4 * b + mutation; 
            }

            return (rand() % 2 ? a : b) + mutation;
        };

        unsigned first, second;
        for (int i = 0; i < diff; i++) {
            first = distribution(random_engine);
            do { second = distribution(random_engine); } while (first == second);

            auto combined = trainees[first]->decider.combine(trainees[second]->decider, combiner);
            std::cout << "Łączenie #" << trainees[first]->id << " z #" << trainees[second]->id << " dało #" << (id+1) << std::endl;
            add(combined);
        }
    }

    void see_best(std::istream& stream)
    {
        std::shared_ptr<trained<T>> trainee = this->trainees[0];

        std::cout << "price,decision" << std::endl;
        double price;
        
        trainee->monies = money;
        trainee->stock  = stock;

        trainee->decider.reset();
        while (stream >> price) {
            int decision = train(trainee, price);
            std::cout << price << "," << decision << std::endl;
        }
    }
};