chess_board_sim/src/game_logic/fen_strings.c

#include "fen_strings.h"
#include "game_state.h"
#include "string.h"
#include "assert.h"

char fen_string[200];
int fen_idx = 0;

static void fen_append(char val)
{
    assert(fen_idx < (int)sizeof(fen_string));
    fen_string[fen_idx] = val;
    fen_idx++;
}

char * fen_string_get_state(void)
{
    memset(fen_string, (int)' ', sizeof(fen_string));
    fen_idx = 0;
    Game_State_t * state = Board_get_game_state();
    for (int row = 0; row < 8; row++)
    {
        int consec_empty = 0;
        for (int column = 0; column < 8; column++)
        {
            if((state->board_pieces[row * 8 + column] == SQUARE_EMPTY))
            {
                consec_empty++;
                if (column == 7) {
                    fen_append((char)('0' + consec_empty));
                }
            }
            else
            {
                char ret_val;
                if (consec_empty != 0)
                {
                    fen_append((char)('0' + consec_empty));
                    consec_empty = 0;
                }
                switch (state->board_pieces[row * 8 + column])
                {
                    case PAWN_WHITE:
                        fen_append('P');
                        break;
                    case PAWN_BLACK:
                        fen_append('p');
                        break;
                    case KING_WHITE:
                        fen_append('K');
                        break;
                    case KING_BLACK:
                        fen_append('k');
                        break;
                    case ROOK_WHITE:
                        fen_append('R');
                        break;
                    case ROOK_BLACK:
                        fen_append('r');
                        break;
                    case KNIGHT_WHITE:
                        fen_append('N');
                        break;
                    case KNIGHT_BLACK:
                        fen_append('n');
                        break;
                    case BISHOP_WHITE:
                        fen_append('B');
                        break;
                    case BISHOP_BLACK:
                        fen_append('b');
                        break;
                    case QUEEN_WHITE:
                        fen_append('Q');
                        break;
                    case QUEEN_BLACK:
                        fen_append('q');
                        break;
                }
            }
        }
        fen_append('/');
    }
    fen_append(' ');
    if (state->player_turn) {
        fen_append('w');
    }
    else{
        fen_append('b');
    }
    fen_append(' ');
    char options[2][2] = {{'K', 'Q'}, {'k', 'q'}};
    bool castle = false;
    for(int color = 0; color < 2; color++){
        for(int k_q = 0; k_q < 2; k_q++){
            if(state->castling_allowed[color][k_q])
            {
                castle = true;
                fen_append(options[color][k_q]);
            }
        }
    }
    if (!castle) {
        fen_append('-');
    }


    fen_append(' ');
    fen_append('\0');
    return fen_string;
}