#include "MoveGenerator.hpp"
#include "Board.hpp"
#include "BoardState.hpp"

void MoveGenerator::generatePawnMoves(const BoardState &bs, const Square &from, MoveVec &moves) {

    BitBoard targets = 0;
    if (bs.eps.has_value()) {
        targets |= BitBoard::fromIndex(bs.eps.value().index());
    }

    generatePawnMoves(bs, from, targets, moves);
}

void MoveGenerator::generatePawnMoves(const BoardState &bs, const Square &from, BitBoard targets, MoveVec &moves) {

    auto fromBB = BitBoard::fromIndex(from.index());
    targets |= (*bs.pieceBBs)[Board::toIndex(!bs.turn)];

    BitBoard movesBB;
    if (bs.turn == PieceColor::White) {
        movesBB = BitBoard::pawnNorthAttacks(fromBB, targets) & ~(*bs.pieceBBs)[Board::toIndex(bs.turn)];
        movesBB |= BitBoard::pawnNorthMoves(fromBB, ~bs.occupiedBB);
    } else {
        movesBB = BitBoard::pawnSouthAttacks(fromBB, targets) & ~(*bs.pieceBBs)[Board::toIndex(bs.turn)];
        movesBB |= BitBoard::pawnSouthMoves(fromBB, ~bs.occupiedBB);
    }

    bool isPromotion = movesBB & (Rank1 | Rank8);
    if (isPromotion) {
        generateMovesWithPromotion(from, movesBB, moves);
    } else {
        generateMoves(from, movesBB, moves);
    }
}

void MoveGenerator::generateBishopMoves(const BoardState &bs, const Square &from, MoveVec &moves) {
    auto fromBB = BitBoard::fromIndex(from.index());
    auto movesBB = BitBoard::bishopAttacks(fromBB, ~bs.occupiedBB) & ~(*bs.pieceBBs)[Board::toIndex(bs.turn)];

    generateMoves(from, movesBB, moves);
}

void MoveGenerator::generateMoves(const Square &from, BitBoard movesBB, MoveVec &moves) {
    while (movesBB) {
        auto to = Square(movesBB.pop());
        moves.emplace_back(from, to, std::nullopt);
    }
}

void MoveGenerator::generateMovesWithPromotion(const Square &from, BitBoard movesBB, MoveVec &moves) {
    while (movesBB) {
        auto to = Square(movesBB.pop());
        for (const auto &kItem : Piece::PromotionTypes) {
            moves.emplace_back(from, to, static_cast<PieceType>(kItem));
        }
    }
}
void MoveGenerator::generateKingMoves(const BoardState &bs, const Square &from, MoveGenerator::MoveVec &moves) {
    auto fromBB = BitBoard::fromIndex(from.index());
    auto movesBB = BitBoard::kingMoves(fromBB) & ~(*bs.pieceBBs)[Board::toIndex(bs.turn)];

    if ((bs.cr & CastlingRights::All) != CastlingRights::None) {

        auto checkCR = CastlingRights::White;
        auto castlingRank = WhiteCastlingRank;
        if (bs.turn == PieceColor::Black) {
            checkCR = CastlingRights::Black;
            castlingRank = BlackCastlingRank;
        }

        checkCR &= bs.cr;

        if (checkCR != CastlingRights::None) {
            // Generate attacked squares
            BitBoard target = CastlingRanks | bs.occupiedBB;
            auto attacked = generateAttackedSquares(bs, target, !bs.turn);

            movesBB |= BitBoard::castlingMoves(fromBB & ~attacked,
                                               (*bs.pieceBBs)[Board::toIndex(PieceType::Rook)],
                                               ~bs.occupiedBB) & castlingRank;

            if ((checkCR & CastlingRights::KingSide) == CastlingRights::None) {
                movesBB &= ~GFile;
            }
            if ((checkCR & CastlingRights::QueenSide) == CastlingRights::None) {
                movesBB &= ~CFile;
            }
        }
    }

    generateMoves(from, movesBB, moves);
}

void MoveGenerator::generateRookMoves(const BoardState &bs, const Square &from, MoveVec &moves) {
    auto fromBB = BitBoard::fromIndex(from.index());
    auto movesBB = BitBoard::rookAttacks(fromBB, ~bs.occupiedBB) & ~(*bs.pieceBBs)[Board::toIndex(bs.turn)];

    generateMoves(from, movesBB, moves);
}

void MoveGenerator::generateQueenMoves(const BoardState &bs, const Square &from, MoveVec &moves) {
    auto fromBB = BitBoard::fromIndex(from.index());
    auto movesBB = BitBoard::queenAttacks(fromBB, ~bs.occupiedBB) & ~(*bs.pieceBBs)[Board::toIndex(bs.turn)];

    generateMoves(from, movesBB, moves);
}

void MoveGenerator::generateKnightMoves(const BoardState &bs, const Square &from, MoveVec &moves) {

    auto fromBB = BitBoard::fromIndex(from.index());
    auto movesBB = BitBoard::knightMoves(fromBB) & ~(*bs.pieceBBs)[Board::toIndex(bs.turn)];
    generateMoves(from, movesBB, moves);
}

BitBoard MoveGenerator::generateAttackedSquares(const BoardState &bs, BitBoard target, PieceColor opColor) {
    auto opponentBB = (*bs.pieceBBs)[Board::toIndex(opColor)];
    BitBoard attacked = 0;

    // pawns
    if (opColor == PieceColor::White) {
        attacked |= BitBoard::pawnNorthAttacks((*bs.pieceBBs)[Board::toIndex(PieceType::Pawn)] & opponentBB, target);
    } else {
        attacked |= BitBoard::pawnSouthAttacks((*bs.pieceBBs)[Board::toIndex(PieceType::Pawn)] & opponentBB, target);
    }

    // knights
    attacked |= BitBoard::knightMoves((*bs.pieceBBs)[Board::toIndex(PieceType::Knight)] & opponentBB) & target;

    // Bishop
    attacked |= BitBoard::bishopAttacks((*bs.pieceBBs)[Board::toIndex(PieceType::Bishop)] & opponentBB, target);

    // Rook
    attacked |= BitBoard::rookAttacks((*bs.pieceBBs)[Board::toIndex(PieceType::Rook)] & opponentBB, target);

    // Queen
    attacked |= BitBoard::queenAttacks((*bs.pieceBBs)[Board::toIndex(PieceType::Queen)] & opponentBB, target);

    // King
    attacked |= BitBoard::kingMoves((*bs.pieceBBs)[Board::toIndex(PieceType::Queen)] & opponentBB) & target;

    return attacked;
}