#define MOVES_INTERNAL
#include "engine/moves.h"

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

  bitboard_t friendly_king;
  int king_square;
  bitboard_t friendly_pieces;
  bitboard_t enemy_pieces;
  if (position.turn == WHITE_TURN) {
    friendly_pieces = whites(position);
    enemy_pieces = blacks(position);
    friendly_king = position.bitboards[WHITE_KING];
  } else {
    friendly_pieces = blacks(position);
    enemy_pieces = whites(position);
    friendly_king = position.bitboards[BLACK_KING];
  }
  king_square = __builtin_ctzll(friendly_king);

  bitboard_t movement;
  if (king_square >= 10) {
    movement = 920078ULL << (king_square - 10);
  } else {
    movement = 920078ULL >> -(king_square - 10);
  }
  if (friendly_king & BITMASK_FILE_A) {
    movement &= BITMASK_FILE_A | BITMASK_FILE_B;
  } else if (friendly_king & BITMASK_FILE_H) {
    movement &= BITMASK_FILE_G | BITMASK_FILE_H;
  }

  movement &= ~friendly_pieces;
  while (movement) {
    int to = __builtin_ctzll(movement);
    movement &= movement - 1;
    add_move(
      moves,
      king_square,
      to,
      .flags = ((enemy_pieces >> to) & 1) ? MOVE_CAPTURE : 0,
    );
  }

  bitboard_t all_occupied = friendly_pieces | enemy_pieces;
  if (position.turn == WHITE_TURN) {
    if ((position.castling & WHITE_SHORT_CASTLE) &&
        king_square == 4 &&
        !((all_occupied >> 5) & 1) &&
        !((all_occupied >> 6) & 1))
    {
      add_move(moves, 4, 6, .flags = MOVE_SHORT_CASTLE);
    }
    if ((position.castling & WHITE_LONG_CASTLE) &&
        king_square == 4 &&
        !((all_occupied >> 3) & 1) &&
        !((all_occupied >> 2) & 1) &&
        !((all_occupied >> 1) & 1))
    {
      add_move(moves, 4, 2, .flags = MOVE_LONG_CASTLE);
    }
  } else {
    if ((position.castling & BLACK_SHORT_CASTLE) &&
        king_square == 60 &&
        !((all_occupied >> 61) & 1) &&
        !((all_occupied >> 62) & 1))
    {
      add_move(moves, 60, 62, .flags = MOVE_SHORT_CASTLE);
    }
    if ((position.castling & BLACK_LONG_CASTLE) &&
        king_square == 60 &&
        !((all_occupied >> 59) & 1) &&
        !((all_occupied >> 58) & 1) &&
        !((all_occupied >> 57) & 1))
    {
      add_move(moves, 60, 58, .flags = MOVE_LONG_CASTLE);
    }
  }
}

#ifdef TEST_MOD
#include <stdbool.h>

bool test_white_king_corners() {
  moves_t moves;
  moves_init(&moves);
  position_t p = {0};
  p.bitboards[BLACK_KING] = 100;
  p.bitboards[WHITE_KING] = 1;
  p.turn = WHITE_TURN;
  get_king_moves(&moves, p);
  if (moves.length != 3) return false;
  if (moves.moves[0].from != 0) return false;
  if (moves.moves[0].to != 1) return false;
  if (moves.moves[1].from != 0) return false;
  if (moves.moves[1].to != 8) return false;
  if (moves.moves[2].from != 0) return false;
  if (moves.moves[2].to != 9) return false;
  moves.length = 0;
  p.bitboards[WHITE_KING] = 128;
  get_king_moves(&moves, p);
  if (moves.length != 3) return false;
  if (moves.moves[0].from != 7) return false;
  if (moves.moves[0].to != 6) return false;
  if (moves.moves[1].from != 7) return false;
  if (moves.moves[1].to != 14) return false;
  if (moves.moves[2].from != 7) return false;
  if (moves.moves[2].to != 15) return false;
  moves.length = 0;
  p.bitboards[WHITE_KING] = 72057594037927936ULL;
  get_king_moves(&moves, p);
  if (moves.length != 3) return false;
  if (moves.moves[0].from != 56) return false;
  if (moves.moves[0].to != 48) return false;
  if (moves.moves[1].from != 56) return false;
  if (moves.moves[1].to != 49) return false;
  if (moves.moves[2].from != 56) return false;
  if (moves.moves[2].to != 57) return false;

  moves_deinit(moves);
  return true;
}

bool test_black_king_corners() {
  moves_t moves;
  moves_init(&moves);

  position_t p = {0};
  p.bitboards[WHITE_KING] = 100;
  p.bitboards[BLACK_KING] = 1;
  p.turn = BLACK_TURN;
  get_king_moves(&moves, p);
  if (moves.length != 3) return false;
  if (moves.moves[0].from != 0) return false;
  if (moves.moves[0].to != 1) return false;
  if (moves.moves[1].from != 0) return false;
  if (moves.moves[1].to != 8) return false;
  if (moves.moves[2].from != 0) return false;
  if (moves.moves[2].to != 9) return false;
  moves.length = 0;
  p.bitboards[BLACK_KING] = 128;
  get_king_moves(&moves, p);
  if (moves.length != 3) return false;
  if (moves.moves[0].from != 7) return false;
  if (moves.moves[0].to != 6) return false;
  if (moves.moves[1].from != 7) return false;
  if (moves.moves[1].to != 14) return false;
  if (moves.moves[2].from != 7) return false;
  if (moves.moves[2].to != 15) return false;
  moves.length = 0;
  p.bitboards[BLACK_KING] = 72057594037927936ULL;
  get_king_moves(&moves, p);
  if (moves.length != 3) return false;
  if (moves.moves[0].from != 56) return false;
  if (moves.moves[0].to != 48) return false;
  if (moves.moves[1].from != 56) return false;
  if (moves.moves[1].to != 49) return false;
  if (moves.moves[2].from != 56) return false;
  if (moves.moves[2].to != 57) return false;

  moves_deinit(moves);
  return true;
}
#endif