#include <stdio.h>
#include <string.h>
#include "board.h"

int pop_count(Bitboard bb){
  if (bb == 0) return 0;
  return pop_count(bb >> 1) + (bb & 1);
}

void print_bitboard(Bitboard bb) {
  for (U64 index = 0; index < 64; index++) {
    printf("%lu", (bb >> index) & 1);
    if ((index + 1) % 8 == 0) printf("\n");
  }
  printf("\n\n");
}


void precompute_knight_attack_table(Bitboard attacks[64]) {
  for (int index = 0; index < 64; index++) {
    U64 position = (U64)1 << index;

    attacks[index] =
      ((position & notAFile & notBFile) << 6) |
      ((position & notGFile & notHFile) << 10) |
      ((position & notAFile) << 15) |
      ((position & notHFile) << 17) |
      ((position & notGFile & notHFile) >> 6) |
      ((position & notAFile & notBFile) >> 10) |
      ((position & notHFile) >> 15) |
      ((position & notAFile) >> 17);
  }
}

Board parse_FEN(char* FEN) {
  Board board;
  for (int i = 0; i < 12; i++) board.pieces[i] = 0;

  int rank = 7;
  int file = 0;

  for (int k = 0; k < strlen(FEN); k++) {
    int c = FEN[k];
    int index = rank * 8 + file;
    Bitboard position = (Bitboard)1 << index;

    if (c > '0' && c <= '8') file += c - '0';
    else {
      switch (c) {
        case 'R':
          board.pieces[ROOK] |= position;
          break;
        case 'N':
          board.pieces[KNIGHT] |= position;
          break;
        case 'B':
          board.pieces[BISHOP] |= position;
          break;
        case 'Q':
          board.pieces[QUEEN] |= position;
          break;
        case 'K':
          board.pieces[KING] |= position;
          break;
        case 'P':
          board.pieces[PAWN] |= position;
          break;
        case 'r':
          board.pieces[ROOK | BLACK] |= position;
          break;
        case 'n':
          board.pieces[KNIGHT | BLACK] |= position;
          break;
        case 'b':
          board.pieces[BISHOP | BLACK] |= position;
          break;
        case 'q':
          board.pieces[QUEEN | BLACK] |= position;
          break;
        case 'k':
          board.pieces[KING | BLACK] |= position;
          break;
        case 'p':
          board.pieces[PAWN | BLACK] |= position;
          break;
        case '/':
          rank--;
          file = -1; // So that it becomes 0
          break;
        case ' ': // TODO: parse everything after
          return board;
      }
      file++;
    }
  }
  return board;
}


void print_board(Board board) {
  printf("\n");
  for (int rank = 7; rank >= 0; rank--) {
    printf("%i|", rank + 1);
    for (int file = 0; file < 8; file++) {
      int index = rank * 8 + file;
      Bitboard position = (Bitboard)1 << index;

      int found = 0;
      for (int piece = 0; piece < 12; piece++) {

        if (board.pieces[piece] & position) {
          found = 1;
          printf("%s ", pieces[piece]);
          break;
        }
      }
      if (!found) printf(". ");
    }
    printf("\n");
  }
  printf("  a b c d e f g h\n");
}