#include <algorithm>
#include <cstdint>
#include <iostream>
#include <numeric>
#include <sstream>
#include <stdexcept>
#include <string>
#include <tuple>
#include <vector>

#include <doctest.h>

#include <aocpp/Startup.hpp>

namespace {

using Input = std::vector<std::vector<std::int64_t>>;

/// @brief Parse the input stream as a newline-delimited list of lists of integers
/// @param in input file parsed until EOF
/// @return outer list of elves, inner lists of calories
auto Parse(std::istream & in) -> Input
{
  Input result {{}};
  std::string line;
  while (std::getline(in, line)) {
    if (line.empty()) {
      result.push_back({});
    } else {
      result.back().emplace_back(std::stoll(line));
    }
  }
  return result;
}

/// @brief Compute the top calorie carrying elves
/// @param input List of elves each with a list of calories
/// @return top 1 and sum of top 3 calorie counts
auto Solve(Input const& input) -> std::pair<std::int64_t, std::int64_t>
{
  if (input.size() < 3) { throw std::runtime_error{"bad input"}; }

  std::vector<std::int64_t> elves;
  for (auto const& elf : input) {
    elves.push_back(std::reduce(elf.begin(), elf.end()));
  }

  std::partial_sort(elves.begin(), std::next(elves.begin(), 3), elves.end(), std::greater());

  return {elves.front(), std::reduce(elves.begin(), std::next(elves.begin(), 3))};
}

} // namespace

TEST_SUITE("2022-01 examples") {
  TEST_CASE("example") {
    std::istringstream in {
      "1000\n"
      "2000\n"
      "3000\n"
      "\n"
      "4000\n"
      "\n"
      "5000\n"
      "6000\n"
      "\n"
      "7000\n"
      "8000\n"
      "9000\n"
      "\n"
      "10000\n"};
    auto entries = Parse(in);
    auto [p1,p2] = Solve(entries);
    CHECK(p1 == 24000);
    CHECK(p2 == 45000);
  }
}

auto main(int argc, char** argv) -> int {
  auto [p1,p2] = Solve(Parse(*aocpp::Startup(argc, argv)));
  std::cout << "Part 1: " << p1 << std::endl;
  std::cout << "Part 2: " << p2 << std::endl;
}