#include <stdio.h>
#include <stdlib.h>

static char *look(char *board, unsigned pitch, unsigned x, unsigned y) {
    return &board[x+y*pitch];
}

static void display(char *board, unsigned rows, unsigned cols, unsigned pitch, unsigned x, unsigned y) {
    int i;
    while(y<rows) {
        printf("%3u ", y+1);
        i=x;
        while(i<cols) {
            printf(" %c", board[i+y*pitch]);
            i++;
            if(i!=cols) printf(" |");
        }

        y++;

        printf("\n");

        if(y!=rows) {
            printf("    ");
            for(i=x;i<cols;i++) {
                printf("---+");
                i++;
            }
            printf("---\n");
        }
    }
}

static void clear(char *board, unsigned rows, unsigned cols, unsigned pitch, unsigned x, unsigned y, char value) {
    int i;
    for(;y<rows;y++) {
        i=x;
        for(i=x;i<cols;i++) {
            board[i+y*pitch]=value;
        }
    }
}

static void play(char *board, unsigned rows, unsigned cols, unsigned pitch, char player) {
    unsigned x, y;

    /* TODO: look for a possible three in a row */
    for(y=0;y<rows;y++) {
        for(x=0;x<cols;x++) {
            switch(*look(board, pitch, rows/2, cols/2)) {
                case 'X':
                    p_x+=1;
                    break;
                case 'O':
                    p_o+=1;
                    break;
                case ' ':
                    p_s+=1;
            }
        }
    }

    /* TODO: look for possible blocks */
    /* TODO: threaten a win with two possible completions in two rows */
    /* TODO: avoid configuration in which opponent can force a win */
    /* TODO: threaten a win with a possible completion */

    /* get the center space, if not already taken */
    if(' '==*look(board, pitch, rows/2, cols/2)) {
        return;
    }

    /* TODO: prevent opponent from getting two in a row */
}

int main() {
    char *board;
    unsigned rows=3, cols=3;
    
    board=malloc(rows*cols*sizeof *board);
    clear(board, rows, cols, cols, 0, 0, ' '); 
    display(board, rows, cols, cols, 0, 0);

    printf("----- after X -----\n");
    play(board, rows, cols, cols, 'X');
    display(board, rows, cols, cols, 0, 0);
    return 0;
}