#include <vector>
#include <fstream>
#include <expected>
#include <system_error>
#include <ranges>
#include <string>
#include <algorithm>
#include <numeric>

#include "aoc.hpp"
#include "aoc/utils.hpp"
#include "fmt/format.h"

namespace vfp {
using namespace aoc::types;
using order_rule = std::vector<i32>;
}

auto aoc24::day05([[maybe_unused]]std::span<char const*> const& args) -> std::expected<void, aoc::error> {
    using namespace std::string_view_literals;
    // auto txtres = aoc::read_text("./dat/24/ex/05.txt");
    auto txtres = aoc::read_text("./dat/24/re/05.txt");
    if (!txtres) return std::unexpected(txtres.error());
    auto const txt = *txtres;

    auto const not_empty = [](auto const& str) { return !str.empty(); };
    auto lines = txt | std::views::split("\n"sv)
                     | std::views::transform([](auto const& str) { return std::string_view(str); });

    auto rules_str = lines | std::views::take_while(not_empty)
                           | std::ranges::to<std::vector>();
    auto updates_str = lines | std::views::drop_while(not_empty)
                             | std::views::drop(1)
                             | std::views::take_while(not_empty)
                             | std::ranges::to<std::vector>();

    // fmt::print("rules:\n");
    // std::ranges::for_each(rules_str,  [](auto const& str) {
    //     fmt::print("  \"{}\"\n", str);
    // });
    // fmt::print("\n");
    //
    // fmt::print("updates:\n");
    // std::ranges::for_each(updates_str,  [](auto const& str) {
    //     fmt::print("  \"{}\"\n", str);
    // });

    auto order_rules = rules_str | std::views::transform([](auto const& str) {
        return str | std::views::split("|"sv)
                   | std::views::transform([](auto const& num_str) {
                         return std::stoi(std::string{std::begin(num_str), std::end(num_str)});
                   }) | std::ranges::to<std::vector>();
    }) | std::ranges::to<std::vector>();

    auto updates = updates_str | std::views::transform([](auto const& str) {
        return str | std::views::split(","sv)
                   | std::views::transform([](auto const& num_str) {
                         return std::stoi(std::string{std::begin(num_str), std::end(num_str)});
                   }) | std::ranges::to<std::vector>();
    }) | std::ranges::to<std::vector>();

    // std::ranges::for_each(order_rules, [](auto const& rule) {
    //     std::ranges::for_each(rule, [](auto const& page) {
    //         fmt::print("{} ", page);
    //     });
    //     fmt::print("\n");
    // });
    //
    // std::ranges::for_each(updates, [](auto const& update) {
    //     std::ranges::for_each(update, [](auto const& page) {
    //         fmt::print("{}, ", page);
    //     });
    //     fmt::print("\n");
    // });

    auto valid_updates = updates | std::views::filter([&](auto const& pages) {
        return std::ranges::all_of(order_rules, [&](auto const& rule) {
            auto const a = std::ranges::find(pages, rule[0]);
            auto const b = std::ranges::find(pages, rule[1]);
            return a < b || a == std::end(pages) || b == std::end(pages) || a == b;
        });
    });

    // std::ranges::for_each(valid_updates, [](auto const& update){
    //     std::ranges::for_each(update, [](auto const& page) {
    //         fmt::print("{}, ", page);
    //     });
    //     fmt::print("\n");
    // });

    auto mids = valid_updates | std::views::transform([](auto const& updates) {
        return *std::ranges::next(std::begin(updates), updates.size() / 2);
    });

    // std::ranges::for_each(mids, [](auto const& mid) {
    //     fmt::print("{}\n", mid);
    // });

    auto const sum = std::accumulate(std::begin(mids), std::end(mids), 0);
    fmt::print("Part A: {}\n", sum);
    return {};
}