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

#include <doctest.h>

#include <aocpp/Startup.hpp>

namespace {

auto Parse(std::istream & in) -> std::vector<std::string>
{
  std::vector<std::string> result;
  std::string line;
  while (std::getline(in, line)) {
    result.emplace_back(std::move(line));
  }
  return result;
}

auto Priority(char const c) -> std::int64_t
{
  return c < 'a' ? c-'A'+27 : c-'a'+1;
}

auto Intersect(std::string const& a, std::string const& b) {
  std::string common;
  std::set_intersection(a.begin(), a.end(), b.begin(), b.end(),
    std::back_inserter(common));
  return common;
}

auto Part1(std::vector<std::string> const& input) -> std::int64_t
{
  std::int64_t n {0};
  for (auto const& line : input) {
    auto m = line.size() / 2;

    auto elf1 {line.substr(0, m)};
    std::sort(elf1.begin(), elf1.end());

    auto elf2 {line.substr(m)};
    std::sort(elf2.begin(), elf2.end());

    n += Priority(Intersect(elf1, elf2).at(0));
  }
  return n;
}

auto Part2(std::vector<std::string> input) -> std::int64_t
{
  std::int64_t n {0};

  for (auto & line : input) {
    std::sort(line.begin(), line.end());
  }

  for (std::size_t i = 0; i + 2 < input.size(); i += 3) {
    n += Priority(Intersect(Intersect(input[i], input[i+1]), input[i+2]).at(0));
  }
  return n;
}

} // namespace

TEST_SUITE("2022-03 examples") {
  TEST_CASE("example") {
    std::istringstream in {
      "vJrwpWtwJgWrhcsFMMfFFhFp\n"
      "jqHRNqRjqzjGDLGLrsFMfFZSrLrFZsSL\n"
      "PmmdzqPrVvPwwTWBwg\n"
      "wMqvLMZHhHMvwLHjbvcjnnSBnvTQFn\n"
      "ttgJtRGJQctTZtZT\n"
      "CrZsJsPPZsGzwwsLwLmpwMDw\n"};
    auto input = Parse(in);
    CHECK(Part1(input) == 157);
    CHECK(Part2(std::move(input)) == 70);
  }
}

auto main(int argc, char** argv) -> int {
  auto input = Parse(*aocpp::Startup(argc, argv));
  std::cout << "Part 1: " << Part1(input) << std::endl;
  std::cout << "Part 2: " << Part2(std::move(input)) << std::endl;
}