eval.cpp

#include "eval.h"
#include "Weights.h"
#include "tune.h"
#include <iostream>
#include <position.h>
using namespace chess;
using namespace engine::eval;

namespace engine::eval {
static Bitboard passedMask[2][64];
struct PassedMaskInit {
    PassedMaskInit() {
        for (int sq = 0; sq < 64; sq++) {
            File f = file_of(Square(sq));
            Rank r = rank_of(Square(sq));
            for (int adjF = std::max(0, (int)f - 1); adjF <= std::min(7, (int)f + 1); adjF++) {
                for (int r2 = (int)r + 1; r2 <= 7; r2++)
                    passedMask[WHITE][sq] |= attacks::MASK_FILE[adjF] & attacks::MASK_RANK[r2];
                for (int r2 = (int)r - 1; r2 >= 0; r2--)
                    passedMask[BLACK][sq] |= attacks::MASK_FILE[adjF] & attacks::MASK_RANK[r2];
            }
        }
    }
};
static PassedMaskInit passedMaskInit;

Value *mgPst[] = { nullptr, mg_pawn_table, mg_knight_table, mg_bishop_table, mg_rook_table, mg_queen_table, mg_king_table };

Value *egPst[] = { nullptr, eg_pawn_table, eg_knight_table, eg_bishop_table, eg_rook_table, eg_queen_table, eg_king_table };

// tuning slop here

TUNE(SetRange(5, 30),
     tempo,
     SetRange(80, 150),
     PawnValueMG,
     SetRange(160, 260),
     PawnValueEG,
     SetRange(650, 850),
     KnightValueMG,
     SetRange(750, 950),
     KnightValueEG,
     SetRange(700, 900),
     BishopValueMG,
     SetRange(800, 1000),
     BishopValueEG,
     SetRange(1100, 1400),
     RookValueMG,
     SetRange(1200, 1500),
     RookValueEG,
     SetRange(2200, 2800),
     QueenValueMG,
     SetRange(2400, 3000),
     QueenValueEG);
TUNE(SetRange(-50, 70), mgMobilityCnt, egMobilityCnt);
TUNE(SetRange(0, 30), fianchettoBonus, SetRange(0, 100), trappedBishopPenalty);
TUNE(SetRange(-20, 20), kingTropismMg, kingTropismEg);
TUNE(SetRange(0, 30),
     centerWeight,
     SetRange(0, 20),
     mopUpKingDistWeight,
     SetRange(0, 20),
     mopUpEdgeDistWeight,
     SetRange(1, 30),
     spaceWeight);
TUNE(SetRange(0, 50), bishopPairMg, SetRange(0, 50), bishopPairEg);
TUNE(SetRange(1, 20), developedMg);
TUNE(SetRange(0, 30),
     rookOpenFileMg,
     SetRange(0, 30),
     rookOpenFileEg,
     SetRange(0, 20),
     rookSemiOpenFileMg,
     SetRange(0, 20),
     rookSemiOpenFileEg);
TUNE(SetRange(0, 30),
     doubledPawnMg,
     SetRange(0, 30),
     doubledPawnEg,
     SetRange(0, 40),
     isolatedPawnMg,
     SetRange(0, 40),
     isolatedPawnEg);
TUNE(SetRange(0, 400),
     passedBonusMg[1],
     passedBonusMg[2],
     passedBonusMg[3],
     passedBonusMg[4],
     passedBonusMg[5],
     passedBonusMg[6],
     passedBonusEg[1],
     passedBonusEg[2],
     passedBonusEg[3],
     passedBonusEg[4],
     passedBonusEg[5],
     passedBonusEg[6]);
TUNE(SetRange(1, 30),
     kingShelterBaseMg,
     SetRange(1, 30),
     kingShelterBaseEg,
     SetRange(1, 10),
     kingShelterDecayMg,
     SetRange(1, 10),
     kingShelterDecayEg);
TUNE(SetRange(-70, 200),
     mg_knight_table,
     mg_bishop_table,
     mg_rook_table,
     mg_king_table,
     mg_queen_table,
     eg_knight_table,
     eg_bishop_table,
     eg_rook_table,
     eg_king_table,
     eg_queen_table,
     mg_pawn_table[8],
     eg_pawn_table[8],
     mg_pawn_table[9],
     eg_pawn_table[9],
     mg_pawn_table[10],
     eg_pawn_table[10],
     mg_pawn_table[11],
     eg_pawn_table[11],
     mg_pawn_table[12],
     eg_pawn_table[12],
     mg_pawn_table[13],
     eg_pawn_table[13],
     mg_pawn_table[14],
     eg_pawn_table[14],
     mg_pawn_table[15],
     eg_pawn_table[15],
     mg_pawn_table[16],
     eg_pawn_table[16],
     mg_pawn_table[17],
     eg_pawn_table[17],
     mg_pawn_table[18],
     eg_pawn_table[18],
     mg_pawn_table[19],
     eg_pawn_table[19],
     mg_pawn_table[20],
     eg_pawn_table[20],
     mg_pawn_table[21],
     eg_pawn_table[21],
     mg_pawn_table[22],
     eg_pawn_table[22],
     mg_pawn_table[23],
     eg_pawn_table[23],
     mg_pawn_table[24],
     eg_pawn_table[24],
     mg_pawn_table[25],
     eg_pawn_table[25],
     mg_pawn_table[26],
     eg_pawn_table[26],
     mg_pawn_table[27],
     eg_pawn_table[27],
     mg_pawn_table[28],
     eg_pawn_table[28],
     mg_pawn_table[29],
     eg_pawn_table[29],
     mg_pawn_table[30],
     eg_pawn_table[30],
     mg_pawn_table[31],
     eg_pawn_table[31],
     mg_pawn_table[32],
     eg_pawn_table[32],
     mg_pawn_table[33],
     eg_pawn_table[33],
     mg_pawn_table[34],
     eg_pawn_table[34],
     mg_pawn_table[35],
     eg_pawn_table[35],
     mg_pawn_table[36],
     eg_pawn_table[36],
     mg_pawn_table[37],
     eg_pawn_table[37],
     mg_pawn_table[38],
     eg_pawn_table[38],
     mg_pawn_table[39],
     eg_pawn_table[39],
     mg_pawn_table[40],
     eg_pawn_table[40],
     mg_pawn_table[41],
     eg_pawn_table[41],
     mg_pawn_table[42],
     eg_pawn_table[42],
     mg_pawn_table[43],
     eg_pawn_table[43],
     mg_pawn_table[44],
     eg_pawn_table[44],
     mg_pawn_table[45],
     eg_pawn_table[45],
     mg_pawn_table[46],
     eg_pawn_table[46],
     mg_pawn_table[47],
     eg_pawn_table[47],
     mg_pawn_table[48],
     eg_pawn_table[48],
     mg_pawn_table[49],
     eg_pawn_table[49],
     mg_pawn_table[50],
     eg_pawn_table[50],
     mg_pawn_table[51],
     eg_pawn_table[51],
     mg_pawn_table[52],
     eg_pawn_table[52],
     mg_pawn_table[53],
     eg_pawn_table[53],
     mg_pawn_table[54],
     eg_pawn_table[54],
     mg_pawn_table[55],
     eg_pawn_table[55]);
TUNE(SetRange(0, 30),
     kqkDistWeight,
     SetRange(0, 20),
     kqkEdgeWeight,
     SetRange(0, 20),
     krkDistWeight,
     SetRange(0, 20),
     krkEdgeWeight,
     SetRange(0, 30),
     kpkWeight);

TUNE(SetRange(1, 100), outpostBonusKnight, outpostBonusBishop);
TUNE(SetRange(-20, 20), kingProtector);
TUNE(SetRange(-50, 100),
     threatByMinor[1],
     threatByMinor[2],
     threatByMinor[3],
     threatByMinor[4],
     threatByMinor[5],
     threatByMinor[6]);
TUNE(SetRange(-50, 100), threatByRook[1], threatByRook[2], threatByRook[3], threatByRook[4], threatByRook[5], threatByRook[6]);
TUNE(SetRange(1, 100), hangingScore, overloadScore, threatByRankScore);
TUNE(SetRange(10, 100), minorImWt, SetRange(5, 50), bishopImWt, SetRange(10, 100), rookImWt, SetRange(20, 150), queenImWt);
TUNE(SetRange(1, 50), rammedPawnPenalty);
TUNE(SetRange(1, 100), rookOnSeventhBonus);
TUNE(SetRange(1, 50), earlyQueenPenalty);

EvalComponents eval_components(const chess::Position &board) {
    constexpr int KnightPhase = 1;
    constexpr int BishopPhase = 1;
    constexpr int RookPhase = 2;
    constexpr int QueenPhase = 4;
    constexpr int TotalPhase = KnightPhase * 4 + BishopPhase * 4 + RookPhase * 4 + QueenPhase * 2;
    int mgScore = 0;
    int egScore = 0;
    int phase = 0;
    // Precompute pawn attacks (needed for outpost, threats, etc.)
    Bitboard pawnBB[2] = { board.pieces(PAWN, WHITE), board.pieces(PAWN, BLACK) };
    Bitboard pawnAtks[2] = { attacks::pawn<WHITE>(pawnBB[WHITE]), attacks::pawn<BLACK>(pawnBB[BLACK]) };
#if 1
    // Development bonus: penalize undeveloped knights/bishops in middlegame
    int devCount[2] = { 0, 0 };
    for (Color c : { WHITE, BLACK }) {
        Bitboard homeRank = c == WHITE ? attacks::MASK_RANK[0] : attacks::MASK_RANK[7];
        Bitboard knights = board.pieces(KNIGHT, c);
        Bitboard bishops = board.pieces(BISHOP, c);
        Bitboard knightsHome = knights & homeRank;
        Bitboard bishopsHome = bishops & homeRank;
        devCount[c] = popcount(knightsHome) + popcount(bishopsHome);
    }
    mgScore += (devCount[BLACK] - devCount[WHITE]) * developedMg;
    // EG development term intentionally disabled

    // Early queen development penalty: queen moved but minors still on back rank
    for (Color c : { WHITE, BLACK }) {
        int s = (c == WHITE) ? 1 : -1;
        Square qStart = c == WHITE ? SQ_D1 : SQ_D8;
        if (board.pieces(QUEEN, c) && !(board.pieces(QUEEN, c) & (1ULL << qStart))) {
            Bitboard backRank = c == WHITE ? attacks::MASK_RANK[0] : attacks::MASK_RANK[7];
            int undeveloped = popcount((board.pieces(KNIGHT, c) | board.pieces(BISHOP, c)) & backRank);
            if (undeveloped >= 2) {
                mgScore -= s * earlyQueenPenalty;
                // disabled intentionally in endgames
                // egScore -= s * earlyQueenPenalty;
            }
        }
    }
#endif
    {
        Bitboard pinMask = board.pin_mask();
        Bitboard occ = board.occ(), occ2 = occ;
        while (occ) {
            Square sq = Square(pop_lsb(occ));
            auto p = board.at(sq);
            Color pc = color_of(p);
            int _sign = pc == WHITE ? 1 : -1;
            Square _sq = _sign == 1 ? sq : square_mirror(sq);
            auto pt = piece_of(p);
            if (pt == NO_PIECE_TYPE)
                continue;
            mgScore += _sign * mgPst[pt][_sq];
            egScore += _sign * egPst[pt][_sq];
            mgScore += _sign * piece_value_mg(pt);
            egScore += _sign * piece_value_eg(pt);
            if (pt == KNIGHT)
                phase += KnightPhase;
            else if (pt == BISHOP)
                phase += BishopPhase;
            else if (pt == ROOK)
                phase += RookPhase;
            else if (pt == QUEEN)
                phase += QueenPhase;
            Bitboard attacks = 0;
            if (pt == KNIGHT)
                attacks = chess::attacks::knight(sq);
            else if (pt == BISHOP)
                attacks = chess::attacks::bishop(sq, occ2);
            else if (pt == ROOK)
                attacks = chess::attacks::rook(sq, occ2);
            else if (pt == QUEEN)
                attacks = chess::attacks::queen(sq, occ2);
            attacks &= ~board.us(pc);
            int mobility = popcount(attacks);
            int clampedMobility = std::min(mobility, 7);
            if ((1ULL << sq) & pinMask)
                clampedMobility = std::min(clampedMobility / 4, 7);
            mgScore += _sign * mgMobilityCnt[pt][clampedMobility];
            egScore += _sign * egMobilityCnt[pt][clampedMobility];
            if (pt != PAWN && pt != KING) {
                int kd = square_distance(sq, board.kingSq(~pc));
                mgScore += _sign * (7 - kd) * kingTropismMg[pt];
                egScore += _sign * (7 - kd) * kingTropismEg[pt];
            }
#if 1
            // King protector: bonus for pieces close to own king
            if (pt != PAWN && pt != KING) {
                int kdist = square_distance(sq, board.kingSq(pc));
                int ki = std::min(kdist, 5);
                mgScore += _sign * kingProtector[pt][0] / (1 + ki);
                egScore += _sign * kingProtector[pt][1] / (1 + ki);
            }
            // Outpost bonus for knights and bishops
            if (pt == KNIGHT || pt == BISHOP) {
                Rank r = rank_of(sq);
                bool onOutpost = (pc == WHITE && r >= RANK_5) || (pc == BLACK && r <= RANK_4);
                if (onOutpost && !(pawnAtks[~pc] & (1ULL << sq))) {
                    bool defended = (pawnAtks[pc] & (1ULL << sq)) != 0;
                    int idx = defended ? 1 : 0;
                    if (pt == KNIGHT) {
                        mgScore += _sign * outpostBonusKnight[idx];
                        egScore += _sign * outpostBonusKnight[idx];
                    } else {
                        mgScore += _sign * outpostBonusBishop[idx];
                        egScore += _sign * outpostBonusBishop[idx];
                    }
                }
            }
#endif
        }
    }
    // Bishop pair bonus
    for (Color c : { WHITE, BLACK }) {
        if (board.count(BISHOP, c) >= 2) {
            int s = (c == WHITE) ? 1 : -1;
            mgScore += s * bishopPairMg;
            egScore += s * bishopPairEg;
        }
    }

    // Fianchetto bonus
    for (Color c : { WHITE, BLACK }) {
        int s = (c == WHITE) ? 1 : -1;
        Square fianchettoSq[2] = { relative_square(c, SQ_B2), relative_square(c, SQ_G2) };
        Square pawnSq[2] = { relative_square(c, SQ_B3), relative_square(c, SQ_G3) };
        for (int i = 0; i < 2; i++) {
            if (board.at<PieceType>(fianchettoSq[i]) == BISHOP && board.at<Color>(fianchettoSq[i]) == c &&
                board.at<PieceType>(pawnSq[i]) == PAWN && board.at<Color>(pawnSq[i]) == c) {
                mgScore += s * fianchettoBonus;
                egScore += s * fianchettoBonus;
            }
        }
    }
#if 1
    // Trapped bishop penalty
    for (Color c : { WHITE, BLACK }) {
        int s = (c == WHITE) ? 1 : -1;
        Square trapSq[2] = { relative_square(c, SQ_A2), relative_square(c, SQ_H2) };
        Square kingAdj[2] = { relative_square(c, SQ_B1), relative_square(c, SQ_G1) };
        for (int i = 0; i < 2; i++) {
            if (board.at<PieceType>(trapSq[i]) == BISHOP && board.at<Color>(trapSq[i]) == c && board.kingSq(c) == kingAdj[i]) {
                mgScore -= s * trappedBishopPenalty;
                egScore -= s * trappedBishopPenalty;
            }
        }
    }
#endif
    // Rook on open/semi-open file
    for (Color c : { WHITE, BLACK }) {
        int s = (c == WHITE) ? 1 : -1;
        Bitboard rooks = board.pieces(ROOK, c);
        while (rooks) {
            Square sq = Square(pop_lsb(rooks));
            File f = file_of(sq);
            Bitboard fileMask = attacks::MASK_FILE[f];
            bool hasOwnPawn = (board.pieces(PAWN, c) & fileMask) != 0;
            bool hasEnemyPawn = (board.pieces(PAWN, ~c) & fileMask) != 0;
            if (!hasOwnPawn && !hasEnemyPawn) {
                mgScore += s * rookOpenFileMg;
                egScore += s * rookOpenFileEg;
            } else if (!hasOwnPawn) {
                mgScore += s * rookSemiOpenFileMg;
                egScore += s * rookSemiOpenFileEg;
            }
        }
    }
#if 1
    // Rook on seventh rank bonus (endgame, x-raying >=2 undefended pawns)
    for (Color c : { WHITE, BLACK }) {
        int s = (c == WHITE) ? 1 : -1;
        Bitboard rooks = board.pieces(ROOK, c);
        while (rooks) {
            Square sq = Square(pop_lsb(rooks));
            Rank r7 = c == WHITE ? RANK_7 : RANK_2;
            if (rank_of(sq) != r7)
                continue;
            Bitboard ep = board.pieces(PAWN, ~c) & attacks::MASK_RANK[r7];
            int cnt = 0;
            Bitboard tmp = ep;
            while (tmp) {
                Square psq = Square(pop_lsb(tmp));
                if (!board.is_attacked_by(~c, psq))
                    cnt++;
            }
            if (cnt >= 2) {
                mgScore += s * rookOnSeventhBonus / 2;
                egScore += s * rookOnSeventhBonus;
            }
        }
    }
#endif
    // Pawn structure: doubled, isolated, passed in one pass per color
    for (Color c : { WHITE, BLACK }) {
        int s = (c == WHITE) ? 1 : -1;
        Bitboard pawns = pawnBB[c];
        Bitboard enemyPawns = pawnBB[~c];

        bool fileHasPawn[8] = { false };
        int fileCount[8] = { 0 };
        Bitboard tmp = pawns;
        while (tmp) {
            Square sq = Square(pop_lsb(tmp));
            File f = file_of(sq);
            fileCount[f]++;
            fileHasPawn[f] = true;
        }

        for (int f = 0; f < 8; f++)
            if (fileCount[f] >= 2) {
                mgScore -= s * (fileCount[f] - 1) * doubledPawnMg;
                egScore -= s * (fileCount[f] - 1) * doubledPawnEg;
            }

        tmp = pawns;
        while (tmp) {
            Square sq = Square(pop_lsb(tmp));
            File f = file_of(sq);
            Rank relRank = relative_rank(c, sq);

            bool isolated = true;
            if (f > FILE_A && fileHasPawn[f - 1])
                isolated = false;
            if (f < FILE_H && fileHasPawn[f + 1])
                isolated = false;
            if (isolated) {
                mgScore -= s * isolatedPawnMg;
                egScore -= s * isolatedPawnEg;
            }

            if (relRank >= RANK_2 && (passedMask[c][sq] & enemyPawns) == 0) {
                mgScore += s * passedBonusMg[relRank];
                egScore += s * passedBonusEg[relRank];
            }
        }
    }
#if 1
    // Pawn rams: blocked pawn penalty
    for (Color c : { WHITE, BLACK }) {
        int s = (c == WHITE) ? 1 : -1;
        Bitboard pawns = pawnBB[c];
        while (pawns) {
            Square sq = Square(pop_lsb(pawns));
            Square forward = sq + pawn_push(c);
            if (forward >= SQ_A1 && forward <= SQ_H8 && (pawnBB[~c] & (1ULL << forward))) {
                mgScore -= s * rammedPawnPenalty;
                egScore -= s * rammedPawnPenalty;
            }
        }
    }
#endif
    // Center control (using precomputed pawn attacks)
    {
        Bitboard centerMask = (1ULL << SQ_D4) | (1ULL << SQ_E4) | (1ULL << SQ_D5) | (1ULL << SQ_E5);
        int wc = popcount(pawnAtks[WHITE] & centerMask);
        int bc = popcount(pawnAtks[BLACK] & centerMask);
        mgScore += (wc - bc) * centerWeight;
        egScore += (wc - bc) * centerWeight;
    }

    // Space evaluation
    for (Color c : { WHITE, BLACK }) {
        int s = (c == WHITE) ? 1 : -1;
        Bitboard safe = ~pawnAtks[~c];
        Bitboard enemyCamp = c == WHITE ? (attacks::MASK_RANK[4] | attacks::MASK_RANK[5] | attacks::MASK_RANK[6])
                                        : (attacks::MASK_RANK[3] | attacks::MASK_RANK[2] | attacks::MASK_RANK[1]);
        int space = popcount(pawnAtks[c] & safe & enemyCamp);
        mgScore += s * space * spaceWeight;
        egScore += s * space * spaceWeight;
    }

    // King safety: pawn shelter
    for (Color c : { WHITE, BLACK }) {
        int s = (c == WHITE) ? 1 : -1;
        Square kingSq = board.kingSq(c);
        File kf = file_of(kingSq);
        Rank kr = rank_of(kingSq);
        Bitboard pawns = board.pieces(PAWN, c);
        int shelterMg = 0, shelterEg = 0;
        int startF = std::max(0, (int)kf - 1);
        int endF = std::min(7, (int)kf + 1);
        for (int adjF = startF; adjF <= endF; adjF++) {
            Bitboard fileMask = attacks::MASK_FILE[adjF];
            if (c == WHITE) {
                for (int r = (int)kr + 1; r <= std::min(7, (int)kr + 3); r++) {
                    if (pawns & (fileMask & attacks::MASK_RANK[r])) {
                        shelterMg += kingShelterBaseMg - (r - (int)kr - 1) * kingShelterDecayMg;
                        shelterEg += kingShelterBaseEg - (r - (int)kr - 1) * kingShelterDecayEg;
                    }
                }
            } else {
                for (int r = (int)kr - 1; r >= std::max(0, (int)kr - 3); r--) {
                    if (pawns & (fileMask & attacks::MASK_RANK[r])) {
                        shelterMg += kingShelterBaseMg - ((int)kr - r - 1) * kingShelterDecayMg;
                        shelterEg += kingShelterBaseEg - ((int)kr - r - 1) * kingShelterDecayEg;
                    }
                }
            }
        }
        mgScore += s * shelterMg;
        egScore += s * shelterEg;
    }

    // Endgame bonuses + mop-up in one pass per color
    for (Color c : { WHITE, BLACK }) {
        int s = (c == WHITE) ? 1 : -1;
        int oppCount = popcount(board.occ(~c));
        Square myKing = board.kingSq(c);
        Square oppKing = board.kingSq(~c);

        // KQK: queen vs lone king
        if (board.count(QUEEN, c) >= 1 && oppCount == 1) {
            int kingDist = std::max(std::abs((int)file_of(myKing) - (int)file_of(oppKing)),
                                    std::abs((int)rank_of(myKing) - (int)rank_of(oppKing)));
            File ef = file_of(oppKing);
            Rank er = rank_of(oppKing);
            int edgeDist = std::min(std::min((int)ef, 7 - (int)ef), std::min((int)er, 7 - (int)er));
            mgScore += s * ((14 - kingDist) * kqkDistWeight + (7 - edgeDist) * kqkEdgeWeight);
            egScore += s * ((14 - kingDist) * kqkDistWeight + (7 - edgeDist) * kqkEdgeWeight);
        }

        // KRK: rook vs lone king
        if (board.count(ROOK, c) >= 1 && oppCount == 1 && board.count(QUEEN, c) == 0 && board.count(BISHOP, c) == 0 &&
            board.count(KNIGHT, c) == 0 && board.count(PAWN, c) == 0) {
            int kingDist = std::max(std::abs((int)file_of(myKing) - (int)file_of(oppKing)),
                                    std::abs((int)rank_of(myKing) - (int)rank_of(oppKing)));
            File ef = file_of(oppKing);
            Rank er = rank_of(oppKing);
            int edgeDist = std::min(std::min((int)ef, 7 - (int)ef), std::min((int)er, 7 - (int)er));
            mgScore += s * ((14 - kingDist) * krkDistWeight + (7 - edgeDist) * krkEdgeWeight);
            egScore += s * ((14 - kingDist) * krkDistWeight + (7 - edgeDist) * krkEdgeWeight);
        }

        // KPK: king + pawn(s) vs lone king
        if (board.count(PAWN, c) >= 1 && oppCount == 1 && board.count(QUEEN, c) == 0 && board.count(ROOK, c) == 0 &&
            board.count(BISHOP, c) == 0 && board.count(KNIGHT, c) == 0) {
            Bitboard ps = pawnBB[c];
            while (ps) {
                Square psq = Square(pop_lsb(ps));
                Rank pr = relative_rank(c, psq);
                if (pr < RANK_4)
                    continue;

                File pf = file_of(psq);
                Square promSq = make_sq(pf, c == WHITE ? RANK_8 : RANK_1);
                int pawnDist = (c == WHITE) ? (7 - (int)rank_of(psq)) : (int)rank_of(psq);
                int pkDist =
                    std::max(std::abs((int)file_of(oppKing) - (int)pf), std::abs((int)rank_of(oppKing) - (int)rank_of(promSq)));
                int mkDist = std::max(std::abs((int)file_of(myKing) - (int)file_of(psq)),
                                      std::abs((int)rank_of(myKing) - (int)rank_of(psq)));

                bool winning = pkDist > pawnDist || mkDist <= pawnDist + 1 ||
                               (pr >= RANK_6 && file_of(myKing) == pf &&
                                ((c == WHITE && rank_of(myKing) >= RANK_6) || (c == BLACK && rank_of(myKing) <= RANK_3)));
                if ((pf == FILE_A || pf == FILE_H) && oppKing == promSq)
                    winning = false;

                if (winning) {
                    mgScore += s * kpkWeight * pawnDist;
                    egScore += s * kpkWeight * pawnDist;
                }
            }
        }

        // Mop-up: general endgame drive
        Bitboard ourMat = board.occ(c) & ~board.pieces(PAWN) & ~board.pieces(KING);
        Bitboard theirMat = board.occ(~c) & ~board.pieces(PAWN) & ~board.pieces(KING);
        if (ourMat && !theirMat && oppCount <= 2) {
            int kingDist = std::max(std::abs((int)file_of(myKing) - (int)file_of(oppKing)),
                                    std::abs((int)rank_of(myKing) - (int)rank_of(oppKing)));
            File ef = file_of(oppKing);
            Rank er = rank_of(oppKing);
            int edgeDist = std::min(std::min((int)ef, 7 - (int)ef), std::min((int)er, 7 - (int)er));
            mgScore += s * ((14 - kingDist) * mopUpKingDistWeight + (7 - edgeDist) * mopUpEdgeDistWeight);
            egScore += s * ((14 - kingDist) * mopUpKingDistWeight + (7 - edgeDist) * mopUpEdgeDistWeight);
        }
    }

// --- Threat evaluation ---
#if 1
    for (Color c : { WHITE, BLACK }) {
        int s = (c == WHITE) ? 1 : -1;
        Color opp = ~c;
        Bitboard ourPieces = board.occ(c) & ~board.pieces(PAWN) & ~board.pieces(KING);
        while (ourPieces) {
            Square sq = Square(pop_lsb(ourPieces));
            PieceType pt = piece_of(board.at(sq));
            bool attacked = board.is_attacked_by(opp, sq);
            if (!attacked)
                continue;
            bool defended = board.is_attacked_by(c, sq);
            Bitboard occ = board.occ();
            int attackers = popcount(board.attackers_mask(opp, sq, occ));
            int defenders = defended ? popcount(board.attackers_mask(c, sq, occ)) : 0;
            bool hanging = !defended;
            bool overloaded = defenders == 1 && attackers >= 2;
            bool attackedByMinor =
                (board.attackers_mask(opp, sq, occ) & (board.pieces(KNIGHT, opp) | board.pieces(BISHOP, opp))) != 0;
            bool attackedByRook = (board.attackers_mask(opp, sq, occ) & board.pieces(ROOK, opp)) != 0;

            int mgThreat = 0, egThreat = 0;
            if (hanging) {
                mgThreat += (pt == QUEEN ? hangingScore / 2 : hangingScore);
                egThreat += (pt == QUEEN ? hangingScore / 4 : hangingScore / 2);
            }
            if (overloaded) {
                mgThreat += overloadScore;
                egThreat += overloadScore / 2;
            }
            if (attackedByMinor && pt < KING) {
                mgThreat += threatByMinor[pt][0];
                egThreat += threatByMinor[pt][1];
            }
            if (attackedByRook && pt < KING) {
                mgThreat += threatByRook[pt][0];
                egThreat += threatByRook[pt][1];
            }
            // Rank-based threat bonus
            Rank relRank = relative_rank(c, sq);
            mgThreat += threatByRankScore * static_cast<int>(relRank);
            egThreat += threatByRankScore * static_cast<int>(relRank);

            mgScore -= s * mgThreat;
            egScore -= s * egThreat;
        }
    }

    // --- Trapped bishop at a7/h7 ---
    for (Color c : { WHITE, BLACK }) {
        int s = (c == WHITE) ? 1 : -1;
        Color opp = ~c;
        Square aFileSq = relative_square(c, SQ_A7);
        Square hFileSq = relative_square(c, SQ_H7);
        Square bPawnSq = relative_square(c, SQ_B6);
        Square gPawnSq = relative_square(c, SQ_G6);
        // Bishop on a7/h7 trapped by b6/g6 pawn
        if (board.at<PieceType>(aFileSq) == BISHOP && board.at<Color>(aFileSq) == c) {
            if (board.at<PieceType>(bPawnSq) == PAWN && board.at<Color>(bPawnSq) == opp && !board.is_attacked_by(c, aFileSq)) {
                mgScore -= s * trappedBishopPenalty;
                egScore -= s * trappedBishopPenalty;
            }
        }
        if (board.at<PieceType>(hFileSq) == BISHOP && board.at<Color>(hFileSq) == c) {
            if (board.at<PieceType>(gPawnSq) == PAWN && board.at<Color>(gPawnSq) == opp && !board.is_attacked_by(c, hFileSq)) {
                mgScore -= s * trappedBishopPenalty;
                egScore -= s * trappedBishopPenalty;
            }
        }
    }
    // --- Material imbalance ---
    {
        int pieceCount[2][7] = { { 0 } };
        for (Color c : { WHITE, BLACK })
            for (PieceType pt : { PAWN, KNIGHT, BISHOP, ROOK, QUEEN, KING })
                pieceCount[c][pt] = board.count(pt, c);
        int ourMinors = pieceCount[WHITE][KNIGHT] + pieceCount[WHITE][BISHOP];
        int theirMinors = pieceCount[BLACK][KNIGHT] + pieceCount[BLACK][BISHOP];
        int imbalance = (ourMinors - theirMinors) * minorImWt                                  // minor piece imbalance
                        + (pieceCount[WHITE][BISHOP] - pieceCount[BLACK][BISHOP]) * bishopImWt // bishop vs knight
                        + (pieceCount[WHITE][ROOK] - pieceCount[BLACK][ROOK]) * rookImWt       // rook imbalance
                        + (pieceCount[WHITE][QUEEN] - pieceCount[BLACK][QUEEN]) * queenImWt;   // queen imbalance
        mgScore += imbalance;
        egScore += imbalance;
    }
#endif
    // Draw detection: score 0 for positions where neither side can force a win
    int totalPieces = popcount(board.occ());
    int pawnCount = board.count<PAWN>();
    if (board.is_insufficient_material())
        return { 0, 0, 0 };

    // KBKB same-colored bishops (no pawns) - drawn
    if (totalPieces == 4 && pawnCount == 0 && board.count<BISHOP>() == 2 && board.count<KNIGHT>() == 0 &&
        board.count<ROOK>() == 0 && board.count<QUEEN>() == 0 && board.count(BISHOP, WHITE) == 1 &&
        board.count(BISHOP, BLACK) == 1) {
        Bitboard wbBB = board.pieces(BISHOP, WHITE);
        Bitboard bbBB = board.pieces(BISHOP, BLACK);
        Square wb = Square(pop_lsb(wbBB));
        Square bb = Square(pop_lsb(bbBB));
        if (square_color(wb) == square_color(bb))
            return { 0, 0, 0 };
    }

    // KNNK (no pawns) - drawn
    if (totalPieces == 4 && pawnCount == 0 && board.count<KNIGHT>() == 2 && board.count<BISHOP>() == 0 &&
        board.count<ROOK>() == 0 && board.count<QUEEN>() == 0)
        return { 0, 0, 0 };

    phase = std::min((phase * 128 + TotalPhase / 2) / TotalPhase, 128);
    return { mgScore, egScore, phase };
}
Value score_from_components(const EvalComponents &comp, const chess::Position &board) {
    if (comp.mg == 0 && comp.eg == 0 && comp.phase == 0)
        return 0;

    int sf = 64;
    int total = chess::popcount(board.occ());
    int pawns = board.count<chess::PAWN>();
    if (total == 2 && pawns == 0)
        return 0;
    if (total <= 4 && pawns == 0)
        sf = 32;
    int eg = comp.eg * sf / 64;

    int v = (comp.mg * comp.phase + eg * (128 - comp.phase)) / 128;
    v = (v / 16) * 16;

    int rule50 = std::min(static_cast<int>(board.rule50_count()), 100);
    v = v * (100 - rule50) / 100;

    const int sign = board.side_to_move() == chess::WHITE ? 1 : -1;
    return v * sign + engine::eval::tempo;
}

Value eval(const chess::Position &board) { return score_from_components(eval_components(board), board); }
Value piece_value_mg(PieceType pt) {
    Value pieces[] = { 0, PawnValueMG, KnightValueMG, BishopValueMG, RookValueMG, QueenValueMG, 0 };
    return pieces[pt];
}
Value piece_value_eg(PieceType pt) {
    Value pieces[] = { 0, PawnValueEG, KnightValueEG, BishopValueEG, RookValueEG, QueenValueEG, 0 };
    return pieces[pt];
}
} // namespace engine::eval