src/chess/pgn.c

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 2016 Mike Becker. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *
 *   2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include "pgn.h"

#include <stdlib.h>
#include <ctype.h>
#include <string.h>
#include <sys/time.h>
#include <time.h>

static const char* pgn_error_strings[] = {
    "No Error.",
    "Tag values must be enclosed in double-quotes.",
    "Missing closing brace '}' for comment.",
    "Tags must be enclosed in square brackets: '[Key \"Value\"]'.",
    "Move numbers must be terminated with a dot (e.g. '13.' - not '13').",
    "Result syntax is incorrect. Expected 1-0, 0-1, 1/2-1/2, or *.",
    "Result at end of move text does not match result in tag roster.",
    "Unexpected end of data.",
    "Invalid move.",
};

const char* pgn_error_str(int code) {
    return pgn_error_strings[code];
}

static const char *pgn_game_result(const GameState *gamestate) {
    if (is_game_drawn(gamestate)) {
        return "1/2-1/2";
    } else if (gamestate->wresign) {
        return "0-1";
    } else if (gamestate->bresign) {
        return "1-0";
    } else if (gamestate->checkmate) {
        if (current_color(gamestate) == BLACK) {
            return "1-0";
        } else {
            return "0-1";
        }
    } else {
        return "*";
    }
}

static pgn_result create_pgn_result(
        const char *datastart, const char *datacur,
        enum pgn_error_code code, unsigned move_half_number) {
    return (pgn_result) {
        .position = (size_t)(datacur - datastart),
        .code = code,
        .move_half_number = move_half_number
    };
}

static pgn_result create_pgn_move_error(
        const char *datastart, const char *datacur,
        int move_error_code, unsigned move_half_number) {
    return (pgn_result) {
        .position = (size_t)(datacur - datastart),
        .code = pgn_error_move,
        .move_error = move_error_code,
        .move_half_number = move_half_number
    };
}

pgn_result parse_pgn(const char *pgndata, GameState *gamestate) {
    const char * const pgndata0 = pgndata;
    int i;
    char c;
    
    char result[8] = {0};
    
    char tagkey[32];
    char tagvalue[128];
    
    /* read tag pairs */
    while (true) {
        while (isspace(c = *(pgndata++)));
        if (c == '1') {
            break;
        }
        if (c != '[') {
            return create_pgn_result(pgndata0, pgndata,
                pgn_error_missing_bracket, 0);
        }
        while (isspace(c = *(pgndata++)));
        i = 0;
        do {
            tagkey[i++] = c;
        } while (!isspace(c = *(pgndata++)));
        tagkey[i] = '\0';
        while (isspace(c = *(pgndata++)));
        if (c != '"') {
            return create_pgn_result(pgndata0, pgndata,
                pgn_error_missing_quote, 0);
        }
        i = 0;
        while ((c = *(pgndata++)) != '"') {
            if (c == '\n' || c == 0) {
                return create_pgn_result(pgndata0, pgndata,
                    pgn_error_missing_quote, 0);
            }
            tagvalue[i++] = c;
        }
        tagvalue[i] = '\0';
        if (*(pgndata++) != ']') {
            return create_pgn_result(pgndata0, pgndata,
                pgn_error_missing_bracket, 0);
        }

        // TODO: read clock info

        if (strcmp("Result", tagkey) == 0) {
            memcpy(result, tagvalue, 8);
        }
    }
    
    /* read moves */
    if (*(pgndata++) != '.') {
        return create_pgn_result(pgndata0, pgndata,
            pgn_error_missing_dot, 1);
    }
    
    char movestr[10];
    Move move;
    Color curcol = WHITE;
    bool movetext_ends_with_result = false;
    unsigned move_half_number = 1;
    
    while (true) {
        /* move */
        while (isspace(c = *(pgndata++)));
        i = 0;
        do {
            movestr[i++] = c;
            if (i >= 10) {
                return create_pgn_move_error(pgndata0, pgndata,
                    INVALID_MOVE_SYNTAX, move_half_number);
            }
        } while (!isspace(c = *(pgndata++)));
        movestr[i] = '\0';
        int move_result = eval_move_strict(gamestate, movestr, curcol, &move);
        if (!move_result) {
            move_result = validate_move(gamestate, &move);
        }
        if (move_result) {
            return create_pgn_move_error(pgndata0, pgndata,
                move_result, move_half_number);
        }
        format_move(gamestate, &move);
        apply_move(gamestate, &move);
        
        /* skip spaces */
        while (isspace(c = *(pgndata++)));
        
        /* parse possible comment */
        if (c == '{') {
            // TODO: interpret comment (may contain clock info)
            do {
                c = *(pgndata++);
            } while (c != '}' && c != 0);
            if (c == 0) {
                return create_pgn_result(pgndata0, pgndata,
                    pgn_error_missing_brace, move_half_number);
            }
            /* skip spaces */
            while (isspace(c = *(pgndata++)));
        }
        
        /* end of game data encountered */
        if (c == 0) {
            break;
        }
        if (c == '1' || c == '0') {
            c = *(pgndata++);
            if (c == '-') {
                if (!gamestate->checkmate) {
                    c = *(pgndata++);
                    if (c == '1') {
                        gamestate->wresign = true;
                    } else if (c == '0') {
                        gamestate->bresign = true;
                    } else {
                        return create_pgn_result(pgndata0, pgndata,
                            pgn_error_result_syntax, 0);
                    }
                }
                movetext_ends_with_result = true;
                break;
            } else if (c == '/') {
                /* only set remis flag if the game was not drawn otherwise */
                gamestate->remis = !is_game_drawn(gamestate);
                movetext_ends_with_result = true;
                break;
            } else {
                /* oops, it was a move number, go back! */
                pgndata--;
            }
        }
        
        /* we have eaten the next valuable byte, so go back */
        pgndata--;
        
        /* skip move number after black move */
        if (curcol == BLACK) {
            while (isdigit(c = *(pgndata++)));
            if (c != '.') {
                return create_pgn_result(pgndata0, pgndata,
                    pgn_error_missing_dot, move_half_number + 1);
            }
        }
        curcol = opponent_color(curcol);
        move_half_number++;
    }

    /* sanity check result - if it was specified */
    if (movetext_ends_with_result && result[0]) {
        if (strncmp(result, pgn_game_result(gamestate), 8) != 0) {
            return create_pgn_result(pgndata0, pgndata,
                pgn_error_result_mismatch, 0);
        }
    }
    
    return create_pgn_result(pgndata0, pgndata, pgn_no_error, 0);
}

#undef return

pgn_result read_pgn(FILE *stream, GameState *gamestate) {
    fseek(stream, 0, SEEK_END);
    size_t size = ftell(stream);
    fseek(stream, 0, SEEK_SET);
    char *data = malloc(size + 1);
    memset(data, 0, size + 1);
    size_t read = 0;
    do {
        size_t r = fread(data + read, 1, size - read, stream);
        if (r == 0) {
            return (pgn_result) {
                .position = read,
                .code = pgn_error_unexpected_eof
            };
        }
        read += r;
    } while (read < size);
    pgn_result result = parse_pgn(data, gamestate);
    free(data);
    return result;
}

static void pgn_insert_newlines(char *block) {
    size_t pos = 0;
    size_t last_space_pos = 0;
    size_t line_len = 0;
    while (block[pos] != '\0') {
        if (block[pos] == 0x1f) {
            block[pos++] = ' ';
            continue;
        }
        if (block[pos] == ' ') {
            last_space_pos = pos;
        }
        line_len++;
        if (line_len > 80) {
            block[last_space_pos] = '\n';
            line_len = pos - last_space_pos;
        }
        pos++;
    }
}

static const char *pgn_date(const GameState *gamestate) {
    static char date[16];
    time_t dateseconds;
    if (gamestate->movecount == 0) {
        struct timeval curtimestamp;
        gettimeofday(&curtimestamp, NULL);
        dateseconds = curtimestamp.tv_sec;
    } else {
        dateseconds = (time_t) gamestate->moves[0].timestamp.sec;
    }
    struct tm *tm = gmtime(&dateseconds);
    if (tm == NULL) {
        /* fallback - should never happen in reality */
        strncpy(date, "????.??.??", sizeof(date));
    } else {
        int year = tm->tm_year + 1900;
        int month = tm->tm_mon + 1;
        int day = tm->tm_mday;
#ifdef __GNUC__
        /* this is required to tell GCC that it does not need to warn
         * about the small buffer size of the date string.
         */
        if (year < 1900 || year > 9999) __builtin_unreachable();
        if (month < 1 || month > 12) __builtin_unreachable();
        if (day < 1 || day > 31) __builtin_unreachable();
#endif
        snprintf(date, sizeof(date), "%04d.%02d.%02d",
            year, month, day);
    }
    return date;
}

const char *pgn_player_name(const GameState *gamestate, Color color) {
    const char *name = color == WHITE ? gamestate->wname : gamestate->bname;
    return name[0] != '\0' ? name : "Anonymous";
}

int write_pgn(FILE* stream, const GameState *gamestate, bool export_comments) {
    char *pgn = create_pgn(gamestate, export_comments);
    if (pgn == NULL) return 1;
    fputs(pgn, stream);
    free(pgn);
    return 0;
}

char *create_pgn(const GameState *gamestate, bool export_comments) {
    size_t resultcap = 4096;
    char *result = malloc(resultcap);
    if (result == NULL) return NULL;
    char *resp = result;

    /* STR tag pairs */
    resp += sprintf(resp, "[Event \"%s\"]\n", "terminal-chess game");
    resp += sprintf(resp, "[Site \"%s\"]\n", "Somewhere on Earth");
    resp += sprintf(resp, "[Date \"%s\"]\n", pgn_date(gamestate));
    resp += sprintf(resp, "[Round \"%s\"]\n", "-");
    resp += sprintf(resp, "[White \"%s\"]\n", pgn_player_name(gamestate, WHITE));
    resp += sprintf(resp, "[Black \"%s\"]\n", pgn_player_name(gamestate, BLACK));
    const char *gameresult = pgn_game_result(gamestate);
    resp += sprintf(resp, "[Result \"%s\"]\n\n", gameresult);

    // TODO: add optional clock info
    
    /* moves */
    char *moveblk = resp; /* remember where the move block starts */

    for (unsigned i = 0 ; i < gamestate->movecount ; i++) {
        /* reallocate buffer if needed */
        {
            size_t rsize = resp - result;
            if (rsize + 128 > resultcap) {
                resultcap *= 2;
                char *newresult = realloc(result, resultcap);
                if (newresult == NULL) {
                    free(result);
                    return NULL;
                }
                result = newresult;
                resp = result + rsize;
            }
        }

        if (i % 2 == 0) {
            resp += snprintf(resp, 16, "%d.\x1f%s",
                1+i/2, gamestate->moves[i].string);
        } else {
            resp += snprintf(resp, 16, "%s",
                gamestate->moves[i].string);
        }

        if (!export_comments) {
            *(resp++) = ' ';
            continue;
        }

        /* add clock times when the game was under time control */
        if (gamestate->info.timecontrol) {
            memcpy(resp, " {[%clk ", 8);
            resp += 8;
            unsigned clkmv = i + 2; /* time for the next move! */
            uint16_t clk = remaining_movetime2(gamestate, clkmv);
            resp += print_clk(clk, resp, true);
            *(resp++) = ']';
            *(resp++) = '}';
            
            /* elapsed move time */
            memcpy(resp, " {[%emt ", 8);
            resp += 8;
            uint16_t emt = gamestate->moves[i].movetime / 1000000ull;
            resp += print_clk(emt, resp, true);
            *(resp++) = ']';
            *(resp++) = '}';
        }
        
        *(resp++) = ' ';
    }
    
    if (gameresult[0] != '*') {
        size_t rlen = strlen(gameresult);
        memcpy(resp, gameresult, rlen);
        resp += rlen;
    }
    *(resp++) = '\n';
    *resp = 0;

    /* post-process move block and format it nicely */
    pgn_insert_newlines(moveblk);

    return result;
}