/**
 ** Ansi C source code for Life starts here.
 ** Author Jawed Karim
 **/

#include <stdio.h>
#include <math.h>
#include <keys.h>

#define ALIVE 1
#define DEAD  0
#define LR_SIZE 21
#define UD_SIZE 21

void fill_zero ( int [][LR_SIZE] );
void display_contents ( int [][LR_SIZE] );
void input_values ( int [][LR_SIZE] );
void check_nayburs ( int [][LR_SIZE] );
void copy_array ( int [][LR_SIZE], int [][LR_SIZE] );

int generation = 0;

void main()
{
        int life[UD_SIZE][LR_SIZE], kbinput;
                
        clrscr();
        fill_zero ( life );             /* kill all cells */
        display_contents ( life );      /* display contents of cells */
        input_values ( life );          /* turn on/off cells */

        while (1)
        {
                clrscr();
                check_nayburs ( life );
                display_contents ( life );
                
                kbinput = getkey();
                
                if (kbinput == K_Escape)
                        exit(1);
        }
}

void copy_array ( int source[][LR_SIZE], int dest[][LR_SIZE] )
{
        int a, b;

        for (a = 0; a < UD_SIZE; a++)
        {
                for (b = 0; b < LR_SIZE; b++)
                {
                        dest[a][b] = source[a][b];
                }
        }
}

void check_nayburs ( int temp[][LR_SIZE] )
{
        int a, b, nayburs, original[UD_SIZE][LR_SIZE];

        ++generation;

        copy_array ( temp, original );

        for (a = 0; a < UD_SIZE; a++)
        {
                for (b = 0; b < LR_SIZE; b++)
                {
                        /* ====== Counting of neighbors ====== */
                        
                        nayburs = 0;
                        
                        if (b != LR_SIZE)
                        {
                                if (original[a][b+1] == ALIVE) /* check right */
                                        nayburs++;
                        }

                        if (b != 0)
                        {
                                if (original[a][b-1] == ALIVE) /* check left  */
                                        nayburs++;
                        }

                        if (a  != UD_SIZE)
                        {
                                if (original[a+1][b] == ALIVE) /* check down  */
                                        nayburs++;
                        }

                        if (a != 0)
                        {       
                                if (original[a-1][b] == ALIVE) /* check up    */
                                        nayburs++;
                        }
                        
                        if ( (a != UD_SIZE) && (b != LR_SIZE) )
                        {       
                                if (original[a+1][b+1] == ALIVE) /* check down-right */
                                        nayburs++;
                        }
                        
                        if ( (a != UD_SIZE) && (b != 0) )
                        {
                                if (original[a+1][b-1] == ALIVE) /* check down-left  */
                                        nayburs++;
                        }

                        if ( (a != 0) && (b != LR_SIZE) )
                        {       
                                if (original[a-1][b+1] == ALIVE) /* check up-right   */
                                        nayburs++;
                        }

                        if ( (a != 0) && (b != 0) )
                        {
                                if (original[a-1][b-1] == ALIVE) /* check up-left    */
                                        nayburs++;
                        }
                
                        /* ====== Life / Death Decision making ====== */

                        if ( (original[a][b] == DEAD) && (nayburs == 3) )
                        {
                                temp[a][b] = ALIVE;
                        }

                        if ( (nayburs > 3) || (nayburs < 2) )
                        {
                                temp[a][b] = DEAD;
                        }

                        nayburs = 0;
                }
        }
}


void fill_zero ( int temp[][LR_SIZE] )
{
        int a, b;

        for (a = 0; a < UD_SIZE; a++)
        {
                for (b = 0; b < LR_SIZE; b++)
                {
                        temp[a][b] = DEAD;
                }
        }
}

void display_contents ( int temp[][LR_SIZE] )
{
        int a, b;

        for (a = 0; a < UD_SIZE; a++)
        {
                for (b = 0; b < LR_SIZE; b++)
                {
                        if ( temp[a][b] == DEAD )
                                printf("_ ");
                        if ( temp[a][b] == ALIVE)
                                printf("X ");
                }

                if ( (a == 3) && (b == LR_SIZE) )
                {
                        if (generation <= 0)
                                printf("\tGeneration: initial");
                        else
                                printf("\tGeneration: %d", generation);
                }

                if ( (a == floor (UD_SIZE / 2)) && (b == LR_SIZE) )
                {
                        printf("\t\tGOF v1.0");
                }

                if ( (a == floor (UD_SIZE / 2) + 1) && (b == LR_SIZE) )
                {
                        printf("\t(C) 1996 by Jawed Karim");
                }

                if ( (a == floor (UD_SIZE / 2) + 6) && (b == LR_SIZE) )
                {
                        if (generation >= 1) 
                                printf("\tPress [ESC] to quit");
                }

                printf("\n");
        }
}

void input_values ( int temp[][LR_SIZE] )
{
        int a, b, value;
        
        printf("\nEnter COORDINATES and VALUE: (value != 1 && != 0 to start): ");
        scanf("%d %d %d", &a, &b, &value);

        if ( (value != 1) && (value != 0) )
                return;
        
        if ( ((a <= UD_SIZE) && (b <= LR_SIZE)) &&
        ((value == DEAD) || (value == ALIVE)) )
        {        
                temp[a][b] = value;
                clrscr();
                display_contents ( temp );
                input_values ( temp );
        }
}