Endgame-Analyzer/include/game_state.hpp

#include <algorithm>
#include <iostream>

#include "myassert.h"
#include "game_state.h"

/**
 * Compiling with -DINTEGRITY_CHECK_ON will enable exhaustive integrity check while backtracking.
 * These significantly slow down performance, so they are deactivated by default.
 */
#ifdef INTEGRITY_CHECK_ON
#define CHECK_DRAW_PILE_INTEGRITY check_draw_pile_integrity()
#else
#define CHECK_DRAW_PILE_INTEGRITY
#endif

namespace Hanabi
{

  template<size_t num_suits>
  std::ostream & operator<<(std::ostream & os, const Stacks<num_suits> & stacks)
  {
    for (size_t i = 0; i < stacks.size(); i++)
    {
      os << suit_initials[i] << starting_card_rank - stacks[i];
      if (i < stacks.size() - 1)
      {
        os << ", ";
      }
    }
    return os;
  }

  template<suit_t num_suits, typename T>
  void CardArray<num_suits, T>::fill(T val)
  {
    for (size_t suit = 0; suit < num_suits; suit++)
    {
      for (rank_t rank = 0; rank < starting_card_rank; rank++)
      {
        _array[suit][rank] = val;
      }
    }
  }

  template<suit_t num_suits, typename T>
  CardArray<num_suits, T>::CardArray(T default_val)
  {
    fill(default_val);
  }

  template<suit_t num_suits, typename T>
  const T & CardArray<num_suits, T>::operator[](const Card & card) const
  {
    return _array[card.suit][card.rank];
  };

  template<suit_t num_suits, typename T>
  T & CardArray<num_suits, T>::operator[](const Card & card)
  {
    return _array[card.suit][card.rank];
  };

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  HanabiState<num_suits, num_players, hand_size>::BacktrackAction::BacktrackAction(
        Hanabi::ActionType action_type
        , Hanabi::Card discarded_or_played
        , Hanabi::hand_index_t index
        , bool was_on_8_clues
        , bool strike
  ):
        action_type(action_type), discarded(discarded_or_played), index(index), was_on_8_clues(was_on_8_clues), strike(
        strike)
  {
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  HanabiState<num_suits, num_players, hand_size>::HanabiState(const std::vector<Card> & deck, uint8_t score_goal, clue_t num_clues_gained_on_discard_or_stack_finished):
        _clues_gained_on_discard_or_stack_finished(num_clues_gained_on_discard_or_stack_finished)
        , _score_goal(score_goal), _turn(0), _num_clues(max_num_clues), _weighted_draw_pile_size(deck.size()), _stacks(), _hands(), _draw_pile()
        , _endgame_turns_left(no_endgame), _pace(deck.size() - score_goal - num_players * (hand_size - 1)), _score(0)
        , _actions_log(), _relative_representation(), _position_tablebase()
        , _enumerated_states(0)
  {
    std::ranges::fill(_stacks, starting_card_rank);
    for (const Card & card: deck)
    {
      _draw_pile.push_back({card, 1});
    }
    for (player_t player = 0; player < num_players; player++)
    {
      for (std::uint8_t index = 0; index < hand_size; index++)
      {
        draw(index);
      }
      incr_turn();
    }
    ASSERT(_turn == 0);

    // Prepare card counting
    CardArray<num_suits, unsigned> card_multiplicities (0);
    for (auto const hand: _hands) {
      for (Card const card: hand) {
        _num_copies_left[card] += 1;
      }
    }
    for (CardMultiplicity const card_mult : _draw_pile) {
      _num_copies_left[card_mult.card] += card_mult.multiplicity;
    }
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  void HanabiState<num_suits, num_players, hand_size>::give_clue()
  {
    ASSERT(_num_clues >= clue_t(1));
    --_num_clues;

    _actions_log.emplace(ActionType::clue, Cards::unknown, 0);
    incr_turn();
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  void HanabiState<num_suits, num_players, hand_size>::incr_turn()
  {
    _turn = (_turn + 1) % num_players;
    if (_endgame_turns_left != no_endgame)
    {
      _endgame_turns_left--;
    }
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  void HanabiState<num_suits, num_players, hand_size>::decr_turn()
  {
    _turn = (_turn + num_players - 1) % num_players;
    if (_endgame_turns_left != no_endgame)
    {
      _endgame_turns_left++;
    }
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  void HanabiState<num_suits, num_players, hand_size>::check_draw_pile_integrity() const
  {
    if (not _relative_representation.initialized)
    {
      return;
    }
    if (_draw_pile.size() >= 2)
    {
      auto copy = _draw_pile;
      copy.sort([](CardMultiplicity const & card1, CardMultiplicity const & card2) {
        return card1.card.rank < card2.card.rank or
               (card1.card.rank == card2.card.rank and card1.card.suit < card2.card.suit);
      });
      auto before = copy.begin();
      for (auto it = std::next(copy.begin()); it != copy.end(); ++it)
      {
        ASSERT(before->card != it->card);
        ++before;
      }
    }
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  bool HanabiState<num_suits, num_players, hand_size>::is_playable(const Hanabi::Card & card) const
  {
    return card.rank == _stacks[card.suit] - 1;
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  bool HanabiState<num_suits, num_players, hand_size>::is_critical(Card const & card) const
  {
    return _num_copies_left[card] == 1;
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  std::uint64_t HanabiState<num_suits, num_players, hand_size>::enumerated_states() const
  {
    return _enumerated_states;
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  bool HanabiState<num_suits, num_players, hand_size>::is_trash(const Hanabi::Card & card) const
  {
    return card.rank >= _stacks[card.suit];
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  void HanabiState<num_suits, num_players, hand_size>::play(Hanabi::hand_index_t index)
  {
    play_and_potentially_update(index);
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  unsigned long
  HanabiState<num_suits, num_players, hand_size>::play_and_potentially_update(hand_index_t index, bool cycle)
  {
    CHECK_DRAW_PILE_INTEGRITY;
    ASSERT(index < _hands[_turn].size());
    const Card played_card = _hands[_turn][index];

    bool const strike = !is_playable(played_card);

    _actions_log.emplace(ActionType::play, played_card, index, _num_clues == 8, strike);

    if (!strike)
    {
      --_stacks[played_card.suit];
      _score++;
      if (played_card.rank == 0 and _num_clues < max_num_clues)
      {
        // update clues if we played the last played_card of a stack
        _num_clues += _clues_gained_on_discard_or_stack_finished;
      }
    } else {
      _num_copies_left[played_card]--;
    }

    const unsigned long multiplicity = draw(index, cycle, !strike);

    incr_turn();
    CHECK_DRAW_PILE_INTEGRITY;
    return multiplicity;
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  void HanabiState<num_suits, num_players, hand_size>::discard(hand_index_t index)
  {
    discard_and_potentially_update(index);
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  unsigned long
  HanabiState<num_suits, num_players, hand_size>::discard_and_potentially_update(hand_index_t index, bool cycle)
  {
    CHECK_DRAW_PILE_INTEGRITY;
    ASSERT(index < _hands[_turn].size());
    ASSERT(_num_clues != max_num_clues);

    const Card discarded_card = _hands[_turn][index];
    _num_clues += _clues_gained_on_discard_or_stack_finished;
    _pace--;

    _num_copies_left[discarded_card]--;

    unsigned long multiplicity = draw(index, cycle, false);
    _actions_log.emplace(ActionType::discard, discarded_card, index);

    incr_turn();
    CHECK_DRAW_PILE_INTEGRITY;
    return multiplicity;
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  std::uint8_t HanabiState<num_suits, num_players, hand_size>::find_card_in_hand(
        const Hanabi::Card & card
  ) const
  {
    auto it = std::find_if(_hands[_turn].begin(), _hands[_turn].end(), [&card, this](Card const & card_in_hand) {
      return card_in_hand == card or (is_trash(card) and is_trash(card_in_hand));
    });
    if (it != _hands[_turn].end())
    {
      return std::distance(_hands[_turn].begin(), it);
    }
    return -1;
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  void HanabiState<num_suits, num_players, hand_size>::print(std::ostream & os) const
  {
    os << "Stacks: " << _stacks << " (score " << +_score << ")";
    os << ", clues: " << +_num_clues << ", turn: " << +_turn;
    if (_endgame_turns_left != no_endgame)
    {
      os << ", " << +_endgame_turns_left << " turns left";
    }
    os << std::endl;
    os << "Draw pile: ";
    unsigned num_trash = 0;
    for (const auto & [card, mul]: _draw_pile)
    {
      if (is_trash(card))
      {
        num_trash += mul;
        continue;
      }
      os << card;
      if (mul > 1)
      {
        os << " (" << +mul << ")";
      }
      os << ", ";
    }
    if (num_trash > 0)
    {
      os << Cards::trash << " (" << num_trash << ") ";
    }
    os << "[size " << +_weighted_draw_pile_size << "]" << std::endl;
    os << "Hands: ";
    for (const auto & hand: _hands)
    {
      os << "[";
      for (hand_index_t index = 0; index < hand.size(); index++)
      {
        if (is_trash(hand[index])) {
          os << "kt";
        } else {
          os << hand[index];
        }
        if (is_critical(hand[index])) {
          os << "!";
        }
        if (index < hand.size() - 1)
        {
          os << " ";
        }
      }
      os << "] ";
    }
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  unsigned HanabiState<num_suits, num_players, hand_size>::draw(uint8_t index, bool cycle, bool played)
  {
    ASSERT(index < _hands[_turn].size());

    // update card position of the card we are about to discard
    if (_relative_representation.initialized)
    {
      const Card discarded = _hands[_turn][index];
      if (!discarded.initial_trash)
      {
        if (discarded.in_starting_hand)
        {
          ASSERT(_relative_representation.card_positions_hands[discarded.local_index] ==
                 RelativeRepresentationData::hand);
          if (played)
          {
            _relative_representation.card_positions_hands[discarded.local_index] = RelativeRepresentationData::played;
          }
          else
          {
            _relative_representation.card_positions_hands[discarded.local_index] = RelativeRepresentationData::discarded;
          }
        }
        else
        {
          auto replaced_card_it = std::ranges::find(_relative_representation.card_positions_draw[discarded.local_index]
                                                    , _turn);
          ASSERT(replaced_card_it != _relative_representation.card_positions_draw[discarded.local_index].end());
          if (played)
          {
            *replaced_card_it = RelativeRepresentationData::play_stack;
          }
          else
          {
            *replaced_card_it = RelativeRepresentationData::discard_pile;
          }
          std::ranges::sort(_relative_representation.card_positions_draw[discarded.local_index]);
        }
      }
    }

    // draw a new card if the draw pile is not empty
    if (!_draw_pile.empty())
    {
      --_weighted_draw_pile_size;

      const CardMultiplicity draw = _draw_pile.front();
      _draw_pile.pop_front();
      ASSERT(draw.multiplicity > 0);

      if (draw.multiplicity > 1)
      {
        if (cycle)
        {
          _draw_pile.push_back(draw);
          _draw_pile.back().multiplicity--;
        }
        else
        {
          _draw_pile.push_front(draw);
          _draw_pile.front().multiplicity--;
        }
      }

      if (_relative_representation.initialized)
      {
        // update card position of the drawn card
        if (!draw.card.initial_trash)
        {
          ASSERT(draw.card.in_starting_hand == false);
          auto new_card_it = std::ranges::find(_relative_representation.card_positions_draw[draw.card.local_index]
                                               , RelativeRepresentationData::draw_pile);
          ASSERT(new_card_it != _relative_representation.card_positions_draw[draw.card.local_index].end());
          *new_card_it = _turn;
          std::ranges::sort(_relative_representation.card_positions_draw[draw.card.local_index]);
        }
      }

      _hands[_turn][index] = draw.card;

      if (_draw_pile.empty())
      {
        // Note the +1, since we will immediately decrement this when moving to the next player
        _endgame_turns_left = num_players + 1;
      }
      return draw.multiplicity;
    }
    return 1;
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  void HanabiState<num_suits, num_players, hand_size>::revert_draw(
        std::uint8_t index
        , Card discarded_card
        , bool cycle
        , bool played
  )
  {
    // Put the card that is currently in hand back into the draw pile (this does not happen in the last round!)
    if (_endgame_turns_left == num_players + 1 || _endgame_turns_left == no_endgame)
    {
      ASSERT(index < _hands[_turn].size());
      const Card & drawn = _hands[_turn][index];

      if (cycle)
      {
        // put discarded_card back into draw pile (at the back)
        if (!_draw_pile.empty() and _draw_pile.back().card.suit == drawn.suit and
            _draw_pile.back().card.rank == drawn.rank)
        {
          _draw_pile.back().multiplicity++;
        }
        else
        {
          _draw_pile.push_back({drawn, 1});
        }
      }
      else
      {
        // We don't know where the card came from (between the card having been removed from the draw pile
        // and re-adding it now, the user may have arbitrarily permuted the draw pile implicitly)
        // so we have to check if it is already contained in the draw pile somewhere
        auto it = std::find_if(_draw_pile.begin(), _draw_pile.end(), [&drawn](CardMultiplicity const & mult) {
          return mult.card == drawn;
        });
        if (it != _draw_pile.end())
        {
          it->multiplicity++;
        }
        else
        {
          _draw_pile.push_front({drawn, 1});
        }
      }

      if (_relative_representation.initialized && !drawn.initial_trash)
      {
        ASSERT(drawn.in_starting_hand == false);
        auto drawn_card_it = std::ranges::find(_relative_representation.card_positions_draw[drawn.local_index], _turn);
        ASSERT(drawn_card_it != _relative_representation.card_positions_draw[drawn.local_index].end());
        *drawn_card_it = RelativeRepresentationData::draw_pile;
        std::ranges::sort(_relative_representation.card_positions_draw[drawn.local_index]);
      }

      _weighted_draw_pile_size++;
      _endgame_turns_left = no_endgame;
    }
    else
    {
      ASSERT(_hands[_turn][index] == discarded_card);
    }

    if (_relative_representation.initialized && !discarded_card.initial_trash)
    {
      if (discarded_card.in_starting_hand)
      {
        ASSERT(_relative_representation.card_positions_hands[discarded_card.local_index] !=
               RelativeRepresentationData::hand);
        _relative_representation.card_positions_hands[discarded_card.local_index] = RelativeRepresentationData::hand;
      }
      else
      {
        player_t const old_position = [&played] {
          if (played)
          {
            return RelativeRepresentationData::play_stack;
          }
          else
          {
            return RelativeRepresentationData::discard_pile;
          }
        }();
        auto hand_card_it = std::ranges::find(_relative_representation.card_positions_draw[discarded_card.local_index]
                                              , old_position);
        ASSERT(hand_card_it != _relative_representation.card_positions_draw[discarded_card.local_index].end());
        *hand_card_it = _turn;
        std::ranges::sort(_relative_representation.card_positions_draw[discarded_card.local_index]);
      }
    }

    _hands[_turn][index] = discarded_card;
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  void HanabiState<num_suits, num_players, hand_size>::init_backtracking_information()
  {
    ASSERT(not _relative_representation.initialized);
    // Note that this function does not have to be particularly performant, we only call it once to initialize.
    const Card trash = [this]() -> Card {
      for (suit_t suit = 0; suit < num_suits; suit++)
      {
        if (_stacks[suit] < starting_card_rank)
        {
          return {suit, starting_card_rank - 1, 0, false, true};
        }
      }
      return {0, 0};
    }();

    CardArray<num_suits, std::uint8_t> nums_in_draw_pile;
    for (const auto [card, multiplicity]: _draw_pile)
    {
      if (_stacks[card.suit] > card.rank)
      {
        nums_in_draw_pile[card] += multiplicity;
      }
      else
      {
        nums_in_draw_pile[trash] += multiplicity;
      }
    }

    // Prepare draw pile
    _draw_pile.clear();
    for (suit_t suit = 0; suit < num_suits; suit++)
    {
      for (rank_t rank = 0; rank < starting_card_rank; rank++)
      {
        Card card{suit, rank, static_cast<uint8_t>(_relative_representation.card_positions_draw.size()), false
                  , is_trash(card)
        };
        if (nums_in_draw_pile[card] > 0)
        {
          _draw_pile.push_back({card, nums_in_draw_pile[card]});
          if (!is_trash(card))
          {
            _relative_representation.card_positions_draw.push_back({});
            _relative_representation.card_positions_draw
                                    .back()
                                    .resize(nums_in_draw_pile[card], RelativeRepresentationData::draw_pile);
            _relative_representation.good_cards_draw.push_back(card);
          }
        }
      }
    }
    _relative_representation.initial_draw_pile_size = _weighted_draw_pile_size;

    size_t num_useful_cards_in_starting_hands = 0;

    // Prepare cards in hands
    for (player_t player = 0; player < num_players; player++)
    {
      for (Card & card: _hands[player])
      {
        card.initial_trash = is_trash(card);
        card.in_starting_hand = true;
        // Needed to check for dupes in same hand
        boost::container::static_vector<Card, hand_size> good_cards_in_hand;
        if (!is_trash(card))
        {
          if (std::count(good_cards_in_hand.begin(), good_cards_in_hand.end(), card) > 0)
          {
            // This card is already in hand, so just replace the second copy by some trash
            card = trash;
          }
          else
          {
            card.local_index = num_useful_cards_in_starting_hands;
            num_useful_cards_in_starting_hands++;

            good_cards_in_hand.push_back(card);
          }
        }
      }
    }

    _relative_representation.card_positions_hands.clear();
    _relative_representation.card_positions_hands
                            .resize(num_useful_cards_in_starting_hands, RelativeRepresentationData::hand);

    _relative_representation.initialized = true;
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  void
  HanabiState<num_suits, num_players, hand_size>::revert_play(bool cycle)
  {
    CHECK_DRAW_PILE_INTEGRITY;
    const BacktrackAction last_action = _actions_log.top();
    _actions_log.pop();
    ASSERT(last_action.action_type == ActionType::play);
    ASSERT(!last_action.was_on_8_clues or _num_clues == 8);

    decr_turn();
    if (last_action.discarded.rank == 0 and not last_action.was_on_8_clues and not last_action.strike)
    {
      _num_clues -= _clues_gained_on_discard_or_stack_finished;
    }
    revert_draw(last_action.index, last_action.discarded, cycle, !last_action.strike);
    if (not last_action.strike)
    {
      _stacks[last_action.discarded.suit]++;
      _score--;
    } else {
      // If we misplayed, then we lost the card and have to regain it now
      _num_copies_left[last_action.discarded]++;
    }
    CHECK_DRAW_PILE_INTEGRITY;
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  void HanabiState<num_suits, num_players, hand_size>::revert_discard(bool cycle)
  {
    CHECK_DRAW_PILE_INTEGRITY;
    const BacktrackAction last_action = _actions_log.top();
    _actions_log.pop();

    ASSERT(last_action.action_type == ActionType::discard);

    decr_turn();

    _num_clues -= _clues_gained_on_discard_or_stack_finished;
    ASSERT(_num_clues >= clue_t(0));

    _pace++;

    _num_copies_left[last_action.discarded]++;

    revert_draw(last_action.index, last_action.discarded, cycle, false);
    CHECK_DRAW_PILE_INTEGRITY;
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  void HanabiState<num_suits, num_players, hand_size>::revert_clue()
  {
    const BacktrackAction last_action = _actions_log.top();
    _actions_log.pop();

    ASSERT(last_action.action_type == ActionType::clue);

    decr_turn();
    ASSERT(_num_clues < max_num_clues);

    _num_clues++;
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  void HanabiState<num_suits, num_players, hand_size>::revert()
  {
    switch (_actions_log.top().action_type)
    {
      case ActionType::clue:
        revert_clue();
        break;
      case ActionType::discard:
        revert_discard();
        break;
      case ActionType::play:
        revert_play();
        break;
      default:
        return;
    }
  }


  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  void HanabiState<num_suits, num_players, hand_size>::modify_clues(Hanabi::clue_t change)
  {
    _num_clues += change;
    if (_num_clues > 8)
    {
      _num_clues = 8;
    }
    if (_num_clues < 0)
    {
      _num_clues = 0;
    }
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  void HanabiState<num_suits, num_players, hand_size>::set_clues(Hanabi::clue_t clues)
  {
    ASSERT(clue_t(0) <= clues);
    ASSERT(clues <= clue_t(8));
    _num_clues = clues;
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  player_t HanabiState<num_suits, num_players, hand_size>::turn() const
  {
    return _turn;
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  clue_t HanabiState<num_suits, num_players, hand_size>::num_clues() const
  {
    return _num_clues;
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  unsigned HanabiState<num_suits, num_players, hand_size>::score() const
  {
    return _score;
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  std::vector<std::vector<Card>> HanabiState<num_suits, num_players, hand_size>::hands() const
  {
    std::vector<std::vector<Card>> hands;
    for (player_t player = 0; player < num_players; player++)
    {
      hands.push_back({});
      for (const Card & card: _hands[player])
      {
        hands.back().push_back(card);
      }
    }
    return hands;
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  std::vector<Card> HanabiState<num_suits, num_players, hand_size>::cur_hand() const
  {
    std::vector<Card> hand;
    for (const Card & card: _hands[_turn])
    {
      hand.push_back(card);
    }
    return hand;
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  std::vector<std::pair<CardMultiplicity, std::optional<probability_t>>>
  HanabiState<num_suits, num_players, hand_size>::possible_next_states(hand_index_t index, bool play)
  {
    std::vector<std::pair<CardMultiplicity, std::optional<probability_t>>> next_states;
    do_for_each_potential_draw(index, play, [this, &next_states, &index](unsigned multiplicity) {
      auto prob = lookup();

      // bit hacky to get drawn card here
      decr_turn();
      const CardMultiplicity drawn_card = {_hands[_turn][index], multiplicity};
      incr_turn();

      next_states.emplace_back(drawn_card, prob);
    });
    return next_states;
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  std::vector<std::pair<Action, std::optional<probability_t>>>
  HanabiState<num_suits, num_players, hand_size>::get_reasonable_actions()
  {
    std::vector<std::pair<Action, std::optional<probability_t>>> reasonable_actions{};

    if (_score == _score_goal or _pace < 0 or _endgame_turns_left == 0)
    {
      return reasonable_actions;
    }

    const std::array<Card, hand_size> & hand = _hands[_turn];
    // First, check for playable cards
    for (std::uint8_t index = 0; index < hand_size; index++)
    {
      if (is_playable(hand[index]))
      {
        const Action action = {ActionType::play, hand[index]};
        bool known = true;
        probability_t sum_of_probabilities = 0;

        do_for_each_potential_draw(index, true, [this, &sum_of_probabilities
                                                 , &known](const unsigned long multiplicity) {
          const std::optional<probability_t> prob = lookup();
          if (prob.has_value())
          {
            sum_of_probabilities += prob.value() * multiplicity;
          }
          else
          {
            known = false;
          }
        });

        if (known)
        {
          const unsigned long total_weight = std::max(static_cast<unsigned long>(_weighted_draw_pile_size), 1ul);
          const probability_t probability_play = sum_of_probabilities / total_weight;
          reasonable_actions.emplace_back(action, probability_play);
        }
        else
        {
          reasonable_actions.emplace_back(action, std::nullopt);
        }
      }
    }

    // Check for discards
    if (_pace > 0 and _num_clues < max_num_clues)
    {
      for (std::uint8_t index = 0; index < hand_size; index++)
      {
        if (is_trash(hand[index]))
        {
          const Action action = {ActionType::discard, hand[index]};
          bool known = true;
          probability_t sum_of_probabilities = 0;

          do_for_each_potential_draw(index, false, [this, &sum_of_probabilities
                                                    , &known](const unsigned long multiplicity) {
            const std::optional<probability_t> prob = lookup();
            if (prob.has_value())
            {
              sum_of_probabilities += prob.value() * multiplicity;
            }
            else
            {
              known = false;
            }
          });

          if (known)
          {
            const unsigned long total_weight = std::max(static_cast<unsigned long>(_weighted_draw_pile_size), 1ul);
            const probability_t probability_discard = sum_of_probabilities / total_weight;
            reasonable_actions.emplace_back(action, probability_discard);
          }
          else
          {
            reasonable_actions.emplace_back(action, std::nullopt);
          }

          // All discards are equivalent, do not continue searching for different trash
          break;
        }
      }
    }

    if (_num_clues >= clue_t(1))
    {
      give_clue();
      const std::optional<probability_t> prob = lookup();
      const Action action = {ActionType::clue, Cards::unknown};
      reasonable_actions.emplace_back(action, prob);
      revert_clue();
    }
    return reasonable_actions;
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  std::optional<probability_t> HanabiState<num_suits, num_players, hand_size>::lookup() const
  {
    if (_score == 5 * num_suits)
    {
      return 1;
    }
    if (_pace < 0 or _endgame_turns_left == 0)
    {
      return 0;
    }
    const auto id = unique_id();
    if (_position_tablebase.contains(id))
    {
      return _position_tablebase.at(id);
    }
    else
    {
      return std::nullopt;
    }
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  void HanabiState<num_suits, num_players, hand_size>::rotate_next_draw(const Card & card)
  {
    auto card_it = std::find_if(_draw_pile.begin()
                                , _draw_pile.end()
                                , [&card, this](const CardMultiplicity & card_multiplicity) {
            return (is_trash(card) and is_trash(card_multiplicity.card)) or
                   (card_multiplicity.card.rank == card.rank and card_multiplicity.card.suit == card.suit);
          });
    ASSERT(card_it != _draw_pile.end());
    std::swap(*card_it, _draw_pile.front());
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  ActionType HanabiState<num_suits, num_players, hand_size>::last_action_type() const
  {
    ASSERT(not _actions_log.empty());
    return _actions_log.top().action_type;
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  probability_t HanabiState<num_suits, num_players, hand_size>::evaluate_state()
  {
    ASSERT(_relative_representation.initialized);
    _enumerated_states++;
    const unsigned long id_of_state = unique_id();

    const unsigned id = 55032;
    if (id_of_state == id)
    {
      std::cout << "Found state with id of " << id << "\n" << *this << std::endl;
    }

    if (_score == _score_goal)
    {
      return 1;
    }
    if (_pace < 0 || _endgame_turns_left == 0)
    {
      return 0;
    }
#ifndef GAME_STATE_NO_TABLEBASE_LOOKUP
    if (_position_tablebase.contains(id_of_state)) {
        return _position_tablebase[id_of_state];
    }
#endif

    // TODO: Have some endgame analysis here?

    probability_t best_probability = 0;
    const std::array<Card, hand_size> & hand = _hands[_turn];

    // First, check for playables
    for (std::uint8_t index = 0; index < hand_size; index++)
    {
      if (is_playable(hand[index]))
      {
        probability_t const probability_play = check_play_or_discard(index, true);

        best_probability = std::max(best_probability, probability_play);
        if (best_probability == 1)
        {
          update_tablebase(id_of_state, best_probability);
          return best_probability;
        };
      }
    }

    // Check for discards now
    if (_pace > 0 and _num_clues < max_num_clues)
    {
      // This will hold the index of trash to discard
      std::uint8_t const invalid_index = std::numeric_limits<std::uint8_t>::max();
      std::uint8_t discard_index = invalid_index;

      for (hand_index_t index = 0; index < hand_size; index++)
      {
        if (is_trash(hand[index]))
        {
          discard_index = index;

          // All discards are equivalent, do not continue searching for different trash
          break;
        }
      }

      // If no trivial trash found, check for duplicates next
      if (discard_index == invalid_index) {
        for (std::uint8_t index = 0; index < hand_size; index++) {
          Card const card = _hands[_turn][index];
          auto it = std::find_if(_hands[_turn].begin() + index + 1, _hands[_turn].end(), [&card, this](Card const & card_in_hand) {
            return card_in_hand == card;
          });
          if (it != _hands[_turn].end()) {
            // found a duplicate to discard
            discard_index = index;
            // Since we are discarding essentially trash, we do not have to consider further actions
            break;
          }
        }
      }

      // Discard if we found trash now
      if (discard_index != invalid_index) {
        probability_t const probability_discard = check_play_or_discard(discard_index, false);

        best_probability = std::max(best_probability, probability_discard);
        if (best_probability == 1)
        {
          update_tablebase(id_of_state, best_probability);
          return best_probability;
        };
      } else {
        // If we reach this state, then there are no dupes in hand, so we need to check if we want to
        // sacrifice cards in hand
        for(hand_index_t index = 0; index < hand_size; ++index) {
          if(!is_critical(hand[index])) {
            probability_t const probability_sacrifice = check_play_or_discard(index, false);

            best_probability = std::max(best_probability, probability_sacrifice);
            if (best_probability == 1)
            {
              update_tablebase(id_of_state, best_probability);
              return best_probability;
            };
          }
        }
      }
    }

    // Last option is to stall
    if (_num_clues >= clue_t(1))
    {
      give_clue();
      const probability_t probability_stall = evaluate_state();
      revert_clue();
      best_probability = std::max(best_probability, probability_stall);
      if (best_probability == 1)
      {
        update_tablebase(id_of_state, best_probability);
        return best_probability;
      };
    }

    update_tablebase(id_of_state, best_probability);
    return best_probability;
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  probability_t HanabiState<num_suits, num_players, hand_size>::check_play_or_discard(hand_index_t index, bool play) {
    probability_t sum_of_probabilities = 0;

    do_for_each_potential_draw(index, play, [this, &sum_of_probabilities](const unsigned long multiplicity) {
      sum_of_probabilities += evaluate_state() * multiplicity;
    });

    const unsigned long total_weight = std::max(static_cast<unsigned long>(_weighted_draw_pile_size), 1ul);
    return sum_of_probabilities / total_weight;
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  template<class Function>
  void
  HanabiState<num_suits, num_players, hand_size>::do_for_each_potential_draw(hand_index_t index, bool play, Function f)
  {
    auto copy = _draw_pile;
    auto do_action = [this, index, play]() {
      if (play)
      {
        return play_and_potentially_update(index, true);
      }
      else
      {
        return discard_and_potentially_update(index, true);
      }
    };

    auto revert_action = [this, play]() {
      if (play)
      {
        revert_play(true);
      }
      else
      {
        revert_discard(true);
      }
    };

    if (_draw_pile.empty())
    {
      do_action();
      f(1);
      revert_action();
    }
    else
    {
      unsigned sum_of_multiplicities = 0;
      for (size_t i = 0; i < _draw_pile.size(); i++)
      {
        const unsigned long multiplicity = do_action();
        sum_of_multiplicities += multiplicity;
        f(multiplicity);
        revert_action();
      }
      ASSERT(sum_of_multiplicities == _weighted_draw_pile_size);
    }
    ASSERT(_draw_pile == copy);
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  std::uint64_t HanabiState<num_suits, num_players, hand_size>::unique_id() const
  {
    unsigned long id = 0;

    // encode all positions of cards that started in draw pile
    ASSERT(_relative_representation.card_positions_draw.size() == _relative_representation.good_cards_draw.size());
    for (size_t i = 0; i < _relative_representation.card_positions_draw.size(); i++)
    {
      for (player_t player: _relative_representation.card_positions_draw[i])
      {
        id *= num_players + 3;
        // We normalize here: If a card is already played, then the positions of its other copies
        // do not matter, so we can just pretend that they are all in the trash already.
        // The resulting states will be equivalent.
        if (!is_trash(_relative_representation.good_cards_draw[i]))
        {
          id += player;
        }
        else
        {
          id += RelativeRepresentationData::discard_pile;
        }
      }
    }

    // encode number of clues
    clue_t const scaled_clues = clue_t(2) * _num_clues;
    assert(scaled_clues.denominator() == 1);
    id *= (max_num_clues * clue_t(2)).numerator() + 1;
    id += scaled_clues.numerator();

    // we can encode draw pile size and extra turn in one metric, since we only have extra turns if draw pile is empty
    const std::uint8_t draw_pile_size_and_extra_turns = [this]() -> uint8_t {
      if (_endgame_turns_left == no_endgame)
      {
        return _weighted_draw_pile_size + num_players;
      }
      else
      {
        return _endgame_turns_left;
      }
    }();

    id *= _relative_representation.initial_draw_pile_size + num_players;
    id += draw_pile_size_and_extra_turns;

    // encode positions of cards that started in hands
    for (typename RelativeRepresentationData::CardPosition const & position: _relative_representation.card_positions_hands)
    {
      id *= 3;
      id += static_cast<std::underlying_type_t<typename RelativeRepresentationData::CardPosition>>(position);
    }

    id *= num_players;
    id += _turn;

    // The id is unique now, since for all relevant cards, we know their position (including if they are played),
    // the number of clues, the draw pile size and whose turn it is.
    // This already uniquely determines the current players position, assuming that we never discard good cards
    // (and only play them)

    return id;
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  std::pair<std::vector<std::uint64_t>, std::vector<Card>>
  HanabiState<num_suits, num_players, hand_size>::dump_unique_id_parts() const
  {
    std::vector<std::uint64_t> ret;
    std::vector<Card> cards;

    // encode all positions of cards that started in draw pile
    ASSERT(_relative_representation.card_positions_draw.size() == _relative_representation.good_cards_draw.size());
    for (size_t i = 0; i < _relative_representation.card_positions_draw.size(); i++)
    {
      for (player_t player: _relative_representation.card_positions_draw[i])
      {
        // We normalize here: If a card is already played, then the positions of its other copies
        // do not matter, so we can just pretend that they are all in the trash already.
        // The resulting states will be equivalent.
        if (!is_trash(_relative_representation.good_cards_draw[i]))
        {
          ret.push_back(player);
        }
        else
        {
          ret.push_back(RelativeRepresentationData::discard_pile);
        }
        cards.push_back(_relative_representation.good_cards_draw[i]);
      }
    }

    // encode number of clues
    clue_t const scaled_clues = clue_t(2) * _num_clues;
    assert(scaled_clues.denominator() == 1);
    ret.push_back(scaled_clues.numerator());

    // we can encode draw pile size and extra turn in one metric, since we only have extra turns if draw pile is empty
    const std::uint8_t draw_pile_size_and_extra_turns = [this]() -> uint8_t {
      if (_endgame_turns_left == no_endgame)
      {
        return _weighted_draw_pile_size + num_players;
      }
      else
      {
        return _endgame_turns_left;
      }
    }();

    ret.push_back(draw_pile_size_and_extra_turns);

    // encode positions of cards that started in hands
    for (typename RelativeRepresentationData::CardPosition const & position: _relative_representation.card_positions_hands)
    {
      ret.push_back(static_cast<std::underlying_type_t<typename RelativeRepresentationData::CardPosition>>(position));
    }

    ret.push_back(_turn);

    // The id is unique now, since for all relevant cards, we know their position (including if they are played),
    // the number of clues, the draw pile size and whose turn it is.
    // This already uniquely determines the current players position, assuming that we never discard good cards
    // (and only play them)

    return {ret, cards};
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  const std::unordered_map<unsigned long, probability_t> &
  HanabiState<num_suits, num_players, hand_size>::position_tablebase() const
  {
    return _position_tablebase;
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  size_t HanabiState<num_suits, num_players, hand_size>::draw_pile_size() const
  {
    return _weighted_draw_pile_size;
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  bool HanabiState<num_suits, num_players, hand_size>::is_relative_state_initialized() const
  {
    return _relative_representation.initialized;
  }

  template<suit_t num_suits, player_t num_players, hand_index_t hand_size>
  void HanabiState<num_suits, num_players, hand_size>::update_tablebase(
        unsigned long id, Hanabi::probability_t probability
  )
  {
    // This macro can be activated if we want to dump details on all game states visited for analysis purposes.
#ifdef DUMP_STATES
    std::cout << *this << std::endl;
    const auto [id_parts, cards] = dump_unique_id_parts();
    std::cout << "id is: " << id << ", id parts are: ";
    for (auto const & part: id_parts) {
      std::cout << part << " ";
    }
    std::cout << ", encoded cards are ";
    for (auto const & part: cards) {
      std::cout << part << " ";
    }
    std::cout << ", probability is ";
    print_probability(std::cout, probability);
    std::cout << "\n" << std::endl;
#endif
    if (_position_tablebase.contains(id))
    {
      ASSERT(_position_tablebase[id] == probability);
    }
    _position_tablebase[id] = probability;
  }

} // namespace Hanabi