From fadfab165a805fd2a970999e11b1032480b069dc Mon Sep 17 00:00:00 2001
From: Arthur Bols <arthur@bols.dev>
Date: Thu, 22 Dec 2022 18:31:13 +0100
Subject: [PATCH] [MoveGenerator] Add MoveGenerator

---
 CMakeLists.txt    |  1 +
 MoveGenerator.cpp | 62 +++++++++++++++++++++++++++++++++++++++++++++++
 MoveGenerator.hpp | 36 +++++++++++++++++++++++++++
 3 files changed, 99 insertions(+)
 create mode 100644 MoveGenerator.cpp
 create mode 100644 MoveGenerator.hpp

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 2eb28ef..491d0c1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -36,6 +36,7 @@ add_library(cplchess_lib OBJECT
     EngineFactory.cpp
     Uci.cpp
     BitBoard.cpp
+    MoveGenerator.cpp
 )
 
 target_include_directories(cplchess_lib PUBLIC .)
diff --git a/MoveGenerator.cpp b/MoveGenerator.cpp
new file mode 100644
index 0000000..40c0dcc
--- /dev/null
+++ b/MoveGenerator.cpp
@@ -0,0 +1,62 @@
+#include <iostream>
+#include "MoveGenerator.hpp"
+#include "Board.hpp"
+
+MoveGenerator::MoveGenerator(const std::shared_ptr<BitBoard[]> &pieceBB,
+                             const std::shared_ptr<BitBoard> &occupiedBB)
+        : mPieceBBs(pieceBB), mOccupiedBB(occupiedBB) {
+
+}
+
+void MoveGenerator::generatePawnMoves(const Square &from, const std::optional<Square> &eps,
+                                      PieceColor color, MoveVec &moves) const {
+
+    BitBoard targets = 0;
+    if (eps.has_value()) {
+        targets |= BitBoard::fromIndex(eps.value().index());
+    }
+
+    generatePawnMoves(from, targets, color, moves);
+}
+void MoveGenerator::generatePawnMoves(const Square &from, PieceColor color, MoveVec &moves) {
+    generatePawnMoves(from, BitBoard(0), color, moves);
+}
+
+void MoveGenerator::generatePawnMoves(const Square &from, BitBoard targets, PieceColor color, MoveVec &moves) const {
+
+    auto fromBB = BitBoard::fromIndex(from.index());
+    targets |= mPieceBBs[Board::toIndex(!color)];
+
+    BitBoard movesBB;
+    if (color == PieceColor::White) {
+        movesBB = BitBoard::pawnNorthAttacks(fromBB, targets) & ~mPieceBBs[Board::toIndex(color)];
+        movesBB |= BitBoard::pawnNorthMoves(fromBB, ~*mOccupiedBB);
+    } else {
+        movesBB = BitBoard::pawnSouthAttacks(fromBB, targets) & ~mPieceBBs[Board::toIndex(color)];
+        movesBB |= BitBoard::pawnSouthMoves(fromBB, ~*mOccupiedBB);
+    }
+
+    bool isPromotion = movesBB & (Rank1 | Rank8);
+    if (isPromotion) {
+        generateMovesWithPromotion(from, movesBB, moves);
+    } else {
+        generateMoves(from, movesBB, moves);
+    }
+}
+
+void MoveGenerator::generateMoves(const Square &from, BitBoard movesBB, MoveGenerator::MoveVec &moves) {
+    while (movesBB) {
+        auto to = Square(movesBB.pop());
+        moves.emplace_back(from, to, std::nullopt);
+    }
+}
+
+void MoveGenerator::generateMovesWithPromotion(const Square &from, BitBoard movesBB, MoveGenerator::MoveVec &moves) {
+    while (movesBB) {
+        auto to = Square(movesBB.pop());
+        for (const auto &kItem : Piece::PromotionTypes) {
+            moves.emplace_back(from, to, static_cast<PieceType>(kItem));
+        }
+    }
+}
+
diff --git a/MoveGenerator.hpp b/MoveGenerator.hpp
new file mode 100644
index 0000000..c9ae940
--- /dev/null
+++ b/MoveGenerator.hpp
@@ -0,0 +1,36 @@
+#ifndef CHESS_ENGINE_MOVEGENERATOR_HPP
+#define CHESS_ENGINE_MOVEGENERATOR_HPP
+
+#include "Piece.hpp"
+#include "Square.hpp"
+#include "Move.hpp"
+#include "CastlingRights.hpp"
+#include "BitBoard.hpp"
+
+#include <optional>
+#include <iosfwd>
+#include <vector>
+#include <memory>
+
+class MoveGenerator {
+public:
+    using MoveVec = std::vector<Move>;
+
+    MoveGenerator(const std::shared_ptr<BitBoard[]>& pieceBB, const std::shared_ptr<BitBoard>& occupiedBB);
+    MoveGenerator(MoveGenerator &) = delete;
+    MoveGenerator &operator=(MoveGenerator const &) = delete;
+
+    void generatePawnMoves(const Square &from, const std::optional<Square> &eps, PieceColor color, MoveVec &moves) const;
+    void generatePawnMoves(const Square &from, PieceColor color, MoveVec &moves);
+
+private:
+    const std::shared_ptr<const BitBoard[]> mPieceBBs;
+    const std::shared_ptr<const BitBoard> mOccupiedBB;
+
+    void generatePawnMoves(const Square &from, BitBoard targets, PieceColor color, MoveVec &moves) const;
+
+    static void generateMoves(const Square &from, BitBoard movesBB, MoveVec &moves);
+    static void generateMovesWithPromotion(const Square &from, BitBoard movesBB, MoveVec &moves);
+};
+
+#endif //CHESS_ENGINE_MOVEGENERATOR_HPP