#include "quicksort.hpp"
#include "utils.hpp"
#include <iostream>
#include <vector>
#include <cassert>
#include <algorithm>

namespace
{

template <std::random_access_iterator T>
T quicksort_partition(T begin, T end, const std::function<bool(decltype(*std::declval<T>()), decltype(*std::declval<T>()))> comparer)
{
    std::cout << "part: " << *begin << std::endl;
    assert(begin != end);
    // using difftype = decltype(std::declval<T>() - std::declval<T>());
    const T piv = std::next(end, -1);
    T swapIfLesser = begin;
    while (swapIfLesser != piv && comparer(*swapIfLesser, *piv))
    {
        swapIfLesser = std::next(swapIfLesser);
    }
    swapIfLesser = std::next(swapIfLesser);
    T active = std::next(swapIfLesser);
    while (active != piv)
    {
        if (comparer(*active, *piv))
        {
            std::iter_swap(swapIfLesser, active);
            swapIfLesser = std::next(swapIfLesser);
        }
        active = std::next(active);
    }
    const T pivFinal = std::next(swapIfLesser);
    std::iter_swap(pivFinal, piv);
    return pivFinal;
}

}

template <std::random_access_iterator T>
void quicksort(T begin, T end, std::function<bool(decltype(*std::declval<T>()), decltype(*std::declval<T>()))> comparer)
{
    if (begin != end)
    {
        auto pivot = quicksort_partition(begin, end, comparer);
        quicksort(begin, pivot);
        quicksort(std::next(pivot), end);
    }
}

template <std::random_access_iterator T>
void quicksort(T begin, T end)
{
    const auto comparer = [](decltype(*std::declval<T>()) f, decltype(*std::declval<T>()) s){ return f < s; };
    quicksort(begin, end, comparer);
}

int main()
{
    //last value is to find OOB
    std::vector<int32_t> vec{12345, 1,5,3,2,5,7,9,-3,12,0, 9999};
    arrayprint(vec.begin()+1, vec.end()-1);
    std::cout << std::endl;
    quicksort(vec.begin()+1, vec.end()-1);
    arrayprint(vec.begin()+1, vec.end()-1);
    std::cout << std::endl;
    std::cout << std::endl;
    std::vector<int32_t> vec2;
    arrayprint(vec2.begin(), vec2.end());
    std::cout << std::endl;
    quicksort(vec2.begin(), vec2.end());
    arrayprint(vec2.begin(), vec2.end());
    std::cout << std::endl;
    return 0;
}