#include "../moves.h"

void __forloop_rook_moves_gen(
  moves_t* moves,
  bitboard_t friendly_type,
  bitboard_t friendly_pieces,
  bitboard_t enemy_pieces
) {
  while (friendly_type) {
    int from = __builtin_ctzll(friendly_type);
    friendly_type &= friendly_type - 1;

    int og_rank = from / 8; // range: [0, 7]
    int og_file = from % 8; // range: [0, 7]
    int rank = og_rank + 1, file = og_file, index = rank * 8 + file;


    while (rank < 8 && !occupied_by(friendly_pieces, index)) {
      add_move(moves, from, index);
      if (occupied_by(enemy_pieces, index)) {
        break;
      }
      index = ++rank * 8 + file;
    }

    rank = og_rank - 1, file = og_file, index = rank * 8 + file;
    while (rank >= 0 && !occupied_by(friendly_pieces, index)) {
      add_move(moves, from, index);
      if (occupied_by(enemy_pieces, index)) {
        break;
      }
      index = --rank * 8 + file;
    }

    rank = og_rank, file = og_file + 1, index = rank * 8 + file;
    while (file < 8 && !occupied_by(friendly_pieces, index)) {
      add_move(moves, from, index);
      if (occupied_by(enemy_pieces, index)) {
        break;
      }
      index = rank * 8 + ++file;
    }
    
    rank = og_rank, file = og_file - 1, index = rank * 8 + file;
    while (file >= 0 && !occupied_by(friendly_pieces, index)) {
      add_move(moves, from, index);
      if (occupied_by(enemy_pieces, index)) {
        break;
      }
      index = rank * 8 + --file;
    }
  }
}

void get_rook_moves(moves_t* moves, position_t position) {
  assert_valid_position(position);

  bitboard_t friendly_rooks;
  bitboard_t friendly_pieces;
  bitboard_t enemy_pieces;
  if (position.turn == WHITE_TURN) {
    friendly_pieces = whites(position);
    enemy_pieces = blacks(position);
    friendly_rooks = position.bitboards[WHITE_ROOK];
  } else {
    friendly_pieces = blacks(position);
    enemy_pieces = whites(position);
    friendly_rooks = position.bitboards[BLACK_ROOK];
  }
  
  __forloop_rook_moves_gen(
    moves,
    friendly_rooks,
    friendly_pieces,
    enemy_pieces
  );
}