#include "fen.hpp"
#include "board.hpp"
#include <cassert>
#include <cctype>
#include <cstdlib>
#include <cstring>
#include <print>
#include <string>
#include <sys/types.h>

bool WHITE = true;
bool BLACK = false;

static void updateBitboards(Game *g) {
  g->PieceBitboard = 0;
  g->WhitePieceBitboard = 0;
  g->BlackPieceBitboard = 0;
  std::memset(g->PieceBitboards, 0, sizeof(g->PieceBitboards));
  for (uint8_t i = 0; i < 64; i++) {
    Piece piece = g->pieces[i];
    if (piece.type == NONEPIECE) {
      continue;
    }
    g->PieceBitboards[piece.color][piece.type] |= (1ULL << i);

    if (piece.color) {
      g->WhitePieceBitboard |= (1ULL << i);
    } else {
      g->BlackPieceBitboard |= (1ULL << i);
    }
  }
  g->PieceBitboard = g->WhitePieceBitboard | g->BlackPieceBitboard;
}
static void SetPiece(int i, PieceType type, bool color, Game *g) {
  if (i < 0 || i >= 64) {
    std::println("Fatal: piece outside board");
    assert(false && "Malformed board");
    exit(1);
  }
  g->pieces[i] = {.color = color, .type = type};
}
static void clearBoard(Game *g) {
  for (auto &piece : g->pieces) {
    piece = {.color = false, .type = NONEPIECE};
  }
  g->blackCastleKing = false;
  g->blackCastleQueen = false;
  g->whiteCastleKing = false;
  g->whiteCastleQueen = false;
}

void setBoardFen(const std::string &fen, Game *g) {
  clearBoard(g);
  // example fen rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1
  int file = 0;
  int rank = 7;

  Position enpassant = {};
  enum parserState : std::uint8_t {
    BOARD,
    PLAYER_TO_MOVE,
    CASTLE,
    ENPASSANT,
    HALF_MOVE_CLOCK,
    FULL_MOVE_CLOCK,
  };
  parserState parser_state = BOARD;

  for (uint i = 0; i < fen.length(); i++) {
    char c = fen[i];
    if (c == ' ') {
      if (parser_state == BOARD) {
        parser_state = PLAYER_TO_MOVE;
        continue;
      }
      if (parser_state == PLAYER_TO_MOVE) {
        parser_state = CASTLE;
        continue;
      }
      if (parser_state == CASTLE) {
        parser_state = ENPASSANT;
        continue;
      }
      if (parser_state == ENPASSANT) {
        parser_state = HALF_MOVE_CLOCK;
        continue;
      }
      if (parser_state == HALF_MOVE_CLOCK) {
        parser_state = FULL_MOVE_CLOCK;
        continue;
      }
    }
    if (parser_state == ENPASSANT) {
      continue;
    }
    if (parser_state == CASTLE) {
      if (c == '-') {
        g->blackCastleKing = false;
        g->blackCastleQueen = false;
        g->whiteCastleKing = false;
        g->whiteCastleQueen = false;
        continue;
      }
      if (c == 'K') {
        g->whiteCastleKing = true;
        continue;
      }
      if (c == 'Q') {
        g->whiteCastleQueen = true;
        continue;
      }
      if (c == 'k') {
        g->blackCastleKing = true;
        continue;
      }
      if (c == 'q') {
        g->blackCastleQueen = true;
        continue;
      }
    }
    if (parser_state == PLAYER_TO_MOVE) {
      if (toupper(c) == 'W') {
        g->turn = WHITE;
        continue;
      }
      if (toupper(c) == 'B') {
        g->turn = BLACK;
        continue;
      }
    }
    if (parser_state == BOARD) {
      if (isdigit(c) != 0) {
        int move = c - '0';
        file += move;
        if (file > 8) {
          std::println("Fatal: file was to big");
          assert(false && "Malformed file");
          exit(1);
          return; // malformed file
        }
        continue;
      }
      if (c == '/') {
        file = 0;
        rank--;
        if (rank < 0) {
          std::println("Fatal: rank was to big");
          assert(false && "Malformed rank");
          exit(1);
          return; // malformed rank
        }
        continue;
      };
      if (toupper(c) == 'N') {
        SetPiece((rank * 8) + file, KNIGHT, isupper(c) != 0, g);
        file++;
        continue;
      };
      if (toupper(c) == 'R') {
        SetPiece((rank * 8) + file, ROOK, isupper(c) != 0, g);
        file++;
        continue;
      }
      if (toupper(c) == 'Q') {
        SetPiece((rank * 8) + file, QUEEN, isupper(c) != 0, g);
        file++;
        continue;
      }
      if (toupper(c) == 'B') {
        SetPiece((rank * 8) + file, BISHOP, isupper(c) != 0, g);
        file++;
        continue;
      }
      if (toupper(c) == 'P') {
        SetPiece((rank * 8) + file, PAWN, isupper(c) != 0, g);
        file++;
        continue;
      }
      if (toupper(c) == 'K') {
        SetPiece((rank * 8) + file, KING, isupper(c) != 0, g);
        file++;
        continue;
      }
    }
    break;
  }
  g->enPassant = enpassant;
  updateBitboards(g);
}