Someone

/*
    chess.c

    A simple chess table.  Needs rule checking and a better looking
    'GUI' but its a start.
*/

// Base object
inherit BASE;

// Player whos turn it is, 0 - white, 1 - black
private nosave int pturn;

// Players
private nosave object white;
private nosave object black;

// The table display, only changes when the table changes.
nosave private string current_table;

// Inital stat of the table.
nosave private mixed array b = ({
    ({ "R","P","","","","","p","r" }),
    ({ "N","P","","","","","p","n" }),
    ({ "B","P","","","","","p","b" }),
    ({ "K","P","","","","","p","k" }),
    ({ "Q","P","","","","","p","q" }),
    ({ "B","P","","","","","p","b" }),
    ({ "N","P","","","","","p","n" }),
    ({ "R","P","","","","","p","r" })
});

// Prototype functions.
string compile_table();
string invalid_move(object p,int x1, int y1, int x2, int y2);
int move_piece(string arg);
int join_game(string side);
int part_game();
int player_index(object obj);
int same_color(string a, string b);

void create() {
    if(!clonep()) {
        return;
    }

    base::create();

    pturn = 0;

    set_id( ({ "table", "chess table" }) );
    set_short( "a chess table" );
    set_long( "\
This is a small chess table, thank Azhag.

chess           display the current state of the chess table
join <color>    join the <white> or <black> side
part            leave the chess table
move FF TT      where FF and TT are ordered pairs (XY)

Note:  At the moment the table doenst check for valid moves
so you can move any piece anywhere.  Just play by the rules
until I fix it.\n");

    current_table = compile_table();
}

void init() {
    add_action("move_piece", "place");
    add_action("draw_table", "chess");

    add_action("join_game", "join");
    add_action("part_game", "part");
}

int draw_table() {
    message("", current_table, this_player());
    return 1;
}

string compile_table() {
    int x,y;
    string line;
    string result;

    result =
    "White: " + (white ? white->query_name(1) : "") + "\n"+
    "Black: " + (black ? black->query_name(1) : "") + "\n"+
    "--It is " + ((pturn == 0) ? "White" : "Black") + "'s turn--\n\n";

    for(y = 7; y >= 0; y--) {
        line = y + "  ";
        for(x = 0; x < 8; x++) {
            line += sprintf("%-1s ",((b[x][y] == "") ? "." : b[x][y]));
        }
        result += "  "+line+"\n";
    }

    result += "\n     0 1 2 3 4 5 6 7\n\n--Chess table v0.1b--\n";

    return result;
}

string invalid_move(object p,int x1, int y1, int x2, int y2) {
    int calling_player = player_index(p) - 1;

    if(pturn != calling_player) {
        return "its not your turn";
    }

    if(b[x1][y1] == "") {
        return "there is no piece at the source location "+x1+":"+y1;
    }

    if((x2 < 0 || x2 > 7) || (y2 < 0 || y2 > 7)) {
        return "you cannot move a piece off the table.";
    }

    if((b[x1][y1] != "") && (b[x2][y2] !="")) {
        if(same_color(b[x1][y1],b[x2][y2])) {
            return "you cannot capture your own piece";
        }
    }

    return;
}

int move_piece(string arg) {
    int x1,y1;
    int x2,y2;

    string array args = explode(arg, " ");

    string iv_move;

    if(!player_index(this_player())) {
        return notify_fail("You're not currently playing chess.\n");
    }

    if(sizeof(args) != 2) {
        return notify_fail("move: invalid ordered pairs.\n");
    }

    if(strlen(args[0]) != 2) {
        return notify_fail("move: ordered pair #1 is invalid.\n");
    }

    if(strlen(args[1]) != 2) {
        return notify_fail("move: ordered pair #2 is invalid.\n");
    }

    x1 = atoi(args[0][0..0]); y1 = atoi(args[0][1..1]);
    x2 = atoi(args[1][0..0]); y2 = atoi(args[1][1..1]);

    iv_move = invalid_move(this_player(),x1,y1,x2,y2);

    if(iv_move != "") {
        return notify_fail("invalid move: "+iv_move+".\n");
    }

    (pturn == 0?pturn = 1:pturn = 0);

    b[x2][y2] = b[x1][y1];
    b[x1][y1] = "";

    current_table = compile_table();

    if(black) { message("",current_table,black); }
    if(white) { message("",current_table,white); }

    tell_room(environment(this_player()),
    sprintf(this_player()->query_name()+" moves from %s to %s\n",
    x1+":"+y1,x2+":"+y2),this_player());

    return 1;
}

int join_game(string side) {
    notify_fail("Syntax: join < white | black >\n");

    if(player_index(this_player())) {
        return notify_fail("You're already playing. You must part first.\n");
    }

    if(side == "white") {
        if(!white) {
            white = this_player();
            current_table = compile_table();

            message("",current_table,this_player());

            tell_room(environment(this_player()),this_player()->query_name(1)+
            " sits down on the white side of the chess table.\n",
            this_player());
        } else {
            message("","Someone is already sitting there.\n",this_player());
        }
    } else if(side == "black") {
        if(!black) {
            black = this_player();
            current_table = compile_table();

            message("",current_table,this_player());

            tell_room(environment(this_player()),this_player()->query_name(1)+
            " sits down on the black side of the chess table.\n",
            this_player());
        } else {
            message("","Someone is already sitting there.\n",this_player());
        }
    } else {
        return 0;
    }

    return 1;
}

int part_game() {
    int i = player_index(this_player());

    if(i) {
        if(i == 1) { white = 0; }
        if(i == 2) { black = 0; }

        message("","You are no longer playing chess.\n",this_player());

        tell_room(environment(this_player()),this_player()->query_name(1)+
        " stands up from the chess table.\n",this_player());

        current_table = compile_table();

        return 1;
    }
}

int player_index(object obj) {
    if(white == obj) { return 1; }
    if(black == obj) { return 2; }
}

// Determine if a and b are the same case.
int same_color(string a, string b) {
    int a_is_lower;
    int b_is_lower;

    a_is_lower = (a == lower_case(a)) ?  1 : 0;
    b_is_lower = (b == lower_case(b)) ?  1 : 0;

    return (a_is_lower == b_is_lower) ? 1 : 0;
}