changes

1 files changed, 189 insertions, 0 deletions

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
new file mode 100644
index 0000000..c53e64e
--- /dev/null
+++ b/src/evaluate.cpp
@@ -0,0 +1,189 @@
+#include "evaluate.hpp"
+#include "moves.hpp"
+#include <cstdlib>
+
+constexpr int PAWN_VALUE = 100;
+constexpr int KNIGHT_VALUE = 320;
+constexpr int BISHOP_VALUE = 400;
+constexpr int ROOK_VALUE = 500;
+constexpr int QUEEN_VALUE = 900;
+constexpr int MATE = 10000;
+
+static int PAWN_TABLE[64] = {
+    0,  0,  0,   0,   0,   0,   0,  0,  // last rank promotes to a quuen
+    50, 50, 50,  50,  50,  50,  50, 50, // comments to stop formating to ruin it
+    10, 10, 20,  35,  35,  20,  10, 10, //
+    5,  5,  10,  30,  30,  10,  5,  5,  //
+    0,  0,  0,   25,  25,  0,   0,  0,  //
+    5,  -5, -10, 0,   0,   -10, -5, 5,  //
+    5,  10, 10,  -20, -20, 10,  10, 5,  //
+    0,  0,  0,   0,   0,   0,   0,  0   //
+};
+
+static int KNIGHT_TABLE[64] = {
+    -50, -40, -30, -30, -30, -30, -40, -50, //
+    -40, -20, 0,   0,   0,   0,   -20, -40, //
+    -30, 0,   10,  15,  15,  10,  0,   -30, //
+    -30, 5,   15,  20,  20,  15,  5,   -30, //
+    -30, 0,   15,  20,  20,  15,  0,   -30, //
+    -30, 5,   10,  15,  15,  10,  5,   -30, //
+    -40, -20, 0,   5,   5,   0,   -20, -40, //
+    -50, -40, -30, -30, -30, -30, -40, -50, //
+};
+
+static int BISHOP_TABLE[64] = {
+    -20, -10, -10, -10, -10, -10, -10, -20, //
+    -10, 5,   0,   0,   0,   0,   5,   -10, //
+    -10, 10,  10,  10,  10,  10,  10,  -10, //
+    -10, 0,   10,  15,  15,  10,  0,   -10, //
+    -10, 5,   5,   10,  10,  5,   5,   -10, //
+    -10, 0,   5,   10,  10,  5,   0,   -10, //
+    -10, 0,   0,   0,   0,   0,   0,   -10, //
+    -20, -10, -10, -10, -10, -10, -10, -20, //
+};
+
+static int ROOK_TABLE[64] = {
+    0,  0,  5,  10, 10, 5,  0,  0,  //
+    5,  10, 10, 10, 10, 10, 10, 5,  //
+    -5, 0,  0,  0,  0,  0,  0,  -5, //
+    -5, 0,  0,  5,  5,  0,  0,  -5, //
+    -5, 0,  0,  5,  5,  0,  0,  -5, //
+    -5, 0,  0,  0,  0,  0,  0,  -5, //
+    5,  10, 10, 10, 10, 10, 10, 5,  //
+    0,  0,  5,  10, 10, 5,  0,  0,  //
+};
+
+static int QUEEN_TABLE[64] = {
+    -20, -10, -10, -5, -5, -10, -10, -20, //
+    -10, 0,   0,   0,  0,  0,   0,   -10, //
+    -10, 0,   5,   5,  5,  5,   0,   -10, //
+    -5,  0,   5,   5,  5,  5,   0,   -5,  //
+    0,   0,   5,   5,  5,  5,   0,   -5,  //
+    -10, 5,   5,   5,  5,  5,   0,   -10, //
+    -10, 0,   5,   0,  0,  0,   0,   -10, //
+    -20, -10, -10, -5, -5, -10, -10, -20, //
+};
+
+static int KING_TABLE_EARLY[64] = {
+    -30, -40, -40, -50, -50, -40, -40, -30, //
+    -30, -40, -40, -50, -50, -40, -40, -30, //
+    -30, -40, -40, -50, -50, -40, -40, -30, //
+    -30, -40, -40, -50, -50, -40, -40, -30, //
+    -20, -30, -30, -40, -40, -30, -30, -20, //
+    -10, -20, -20, -20, -20, -20, -20, -10, //
+    20,  20,  0,   0,   0,   0,   20,  20,  //
+    20,  30,  10,  0,   0,   10,  30,  20,  //
+};
+
+/*
+ * i cound some up with better name
+ * this function just takes square and if color is black rotate it
+ */
+static int RotateBoardForBlack(const int square, const bool color) {
+  return color ? square : (56 ^ square);
+}
+
+static int ForceKingToEdgeBonus(const Position enemyKing,
+                                const Position myKing) {
+  int bonus = 0;
+
+  // Push enemy king toward edge
+  const int distToCenter =
+      std::abs(enemyKing.file - 3) + std::abs(enemyKing.rank - 3);
+
+  bonus += distToCenter * 10;
+
+  // Bring own king closer
+  const int kingDistance = std::abs(myKing.file - enemyKing.file) +
+                           std::abs(myKing.rank - enemyKing.rank);
+
+  bonus += (14 - kingDistance) * 5;
+
+  return bonus;
+}
+
+static bool IsEndgame(Game *g) {
+  int queens = 0;
+  int rooks = 0;
+
+  for (const Piece &piece : g->pieces) {
+    switch (piece.type) {
+    case QUEEN:
+      queens++;
+      break;
+    case ROOK:
+      rooks++;
+      break;
+    default:
+      break;
+    }
+  }
+
+  return queens == 0 || (queens == 2 && rooks <= 1);
+}
+
+int EvaluateBoardForWhite(Game *g) {
+  switch (GetNewGameState(g)) {
+  case WHITE_WON:
+    return MATE;
+  case BLACK_WON:
+    return -MATE;
+  case DRAW:
+    return 0;
+  case TURN:
+    break;
+  }
+
+  int score = 0;
+
+  for (int i = 0; i < 64; i++) {
+    const Piece piece = g->pieces[i];
+    if (piece.type == NONEPIECE)
+      continue;
+
+    int value = 0;
+
+    switch (piece.type) {
+    case PAWN:
+      value = PAWN_VALUE;
+      value += PAWN_TABLE[RotateBoardForBlack(i, piece.color)];
+      break;
+    case KNIGHT:
+      value = KNIGHT_VALUE;
+      value += KNIGHT_TABLE[RotateBoardForBlack(i, piece.color)];
+      break;
+    case BISHOP:
+      value = BISHOP_VALUE;
+      value += BISHOP_TABLE[RotateBoardForBlack(i, piece.color)];
+      break;
+    case ROOK:
+      value = ROOK_VALUE;
+      value += ROOK_TABLE[RotateBoardForBlack(i, piece.color)];
+      break;
+    case QUEEN:
+      value = QUEEN_VALUE;
+      value += QUEEN_TABLE[RotateBoardForBlack(i, piece.color)];
+      break;
+    case KING:
+      value = KING_TABLE_EARLY[RotateBoardForBlack(i, piece.color)];
+      break;
+    default:
+      break;
+    }
+
+    if (piece.color) {
+      score += value;
+    } else {
+      score -= value;
+    }
+  }
+
+  Position whiteKing = FindKing(g, true);
+  Position blackKing = FindKing(g, false);
+
+  if (IsEndgame(g)) {
+    score += ForceKingToEdgeBonus(blackKing, whiteKing);
+    score -= ForceKingToEdgeBonus(whiteKing, blackKing);
+  }
+  return score;
+}