#include <cassert>
#include <iostream>
#include <iterator>
#include <vector>

template <typename InputIt, typename OutputIt, typename Pred>
std::pair<InputIt, OutputIt> copy_while(InputIt first, InputIt last,
                                        OutputIt out, Pred p) {
    // Iterate through the input range
    while (first != last && p(*first)) {
        *out = *first; // Copy the value to the output
        ++first;       // Move to the next input element
        ++out;         // Move to the next output element
    }
    // Return the pair of iterators
    return {first, out};
}

std::vector<int> take_while_sum_less_than(std::vector<int> &invec, int n) {
    std::vector<int> out;
    int sum = 0;
    copy_while(invec.begin(), invec.end(), std::back_inserter(out),
               [&](int &x) -> bool { return (sum += x) < n; });
    return out;
}

int main() {
    // Sample data
    std::vector<int> input = {1, 2, 3, 6,
                              7, 8}; // We will stop copying when we encounter 6
    std::vector<int> output;

    // Define the predicate: copy while the value is <= 5
    auto pred = [](int n) { return n <= 5; };

    // Call copy_while with the test data
    auto [new_first, new_out] = copy_while(input.begin(), input.end(),
                                           std::back_inserter(output), pred);

    // Assert that the copied elements are correct (only the first three
    // elements)
    std::vector<int> test = std::vector<int>{1, 2, 3};
    assert(output == test);

    // Assert that the iterator returned points to the element that did not
    // match the predicate (6)
    assert(*new_first == 6);

    std::vector<int> v{1, 2, 3};
    auto w = take_while_sum_less_than(v, 10);
    std::cout << "Hello" << std::endl;
    std::for_each(w.begin(), w.end(),
                  [](int &a) { std::cout << a << " " << std::endl; });
}