/*
    This vets the legal moves for human vs human play.
    It does not contain a game engine.

    It should make a good test for the sprite library...

    Need to check for, and probably add, en passant, castling,
    and pawn promotion (arbitrary, don't assume queen)

    Detect Check, Check Mate, and Resign.

    This code came from https://programology.wordpress.com/2015/09/13/c-code-for-chess-game/
    which looks like one of those sites for Indian students to cheat on their class
    exercises. 
    Other sources at: https://www.google.com/search?q=%22setposrw(rookw,bishopw,knightw,%26kingw,%26queenw)%3B//sets+position%22&sxsrf=ALeKk00aRCuR66bNmJ3PquEABtOeep-ggw:1621755519918&filter=0&biw=1517&bih=730
 */

#include <stdio.h>
#ifdef __DOS86__
#include <conio.h>
#include <graphics.h>
#include <conio.h>
#include <dos.h>
#else
extern void clrscr(void);
#define WHITE 1
extern void setcolor(int c);
extern void outtextxy(int x, int y, char *prompt);
extern void gotoxy(int x, int y);
extern void send(char id, char c);
extern void bottom(void);
extern int kbhit(void);
extern int getch(void);
extern void exit(int rc);
extern void delay(int ticks);
extern void sound(int ticks);
extern void nosound(void);
extern int relposx(int x);
extern int relposy(int y);
void pawndraw(int x, int y, int colour);   // 0 for white.
void rookdraw(int x, int y, int colour);   // 0 for white.
void drawknight(int x, int y, int colour);   // 0 for white.
void drawbishop(int x, int y, int colour);   // 0 for white.
void drawking(int x, int y, int colour);   // 0 for white.
void drawqueen(int x, int y, int colour);   // 0 for white.
static inline int abs(int x) {
  if (x >= 0) return x;
  return -x;
}
#endif


void blk (int, int);
void display (void);
//void assign (char (*)[8], char (*)[8]);
void checkpwn (int, int);
void getmousepos (int *button, int *x, int *y);  // gets mouse position.
void showmouseptr (void);        // shows pointer in graphics mode.
void hidemouseptr (void);            // hides pointer
void restrictmouseptr (int x1, int y1, int x2, int y2);  // restrict pointer
void assign (char *post, char *col);
void checkpwn (int x3, int y3);
char getblkcolor (int, int, int, int, char);    // functions prototype

//enum bool {TRUE,FALSE};

void display (void)             // DISPLAY TO SHOW THE BOARD
{
#ifdef __DOS86__
  int gd = DETECT, gm, i, j, l, m, b;
  char pattern[] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
  int arrodd[32][2] = {
    {0, 0}, {100, 0}, {200, 0}, {300, 0}, {50, 50}, {150, 50},
    {250, 50}, {350, 50}, {0, 100}, {100, 100}, {200, 100}, {300, 100},
    {50, 150}, {150, 150}, {250, 150}, {350, 150}, {0, 200}, {100, 200},
    {200, 200}, {300, 200}, {50, 250}, {150, 250}, {250, 250}, {350, 250},
    {0, 300}, {100, 300}, {200, 300}, {300, 300}, {50, 350}, {150, 350},
    {250, 350}, {350, 350}
  };
  int arrevn[33][2] = {
    {50, 0}, {150, 0}, {250, 0}, {350, 0}, {0, 50}, {100, 50}, {200, 50},
    {300, 50}, {50, 100}, {150, 100}, {250, 100}, {350, 100}, {0, 150},
    {100, 150}, {200, 150}, {300, 150}, {50, 200}, {150, 200}, {250, 200},
    {350, 200}, {0, 250}, {100, 250}, {200, 250}, {300, 250}, {50, 300},
    {150, 300}, {250, 300}, {350, 300}, {0, 350}, {100, 350}, {200, 350},
    {300, 350}
  };
  clrscr ();
  initgraph (&gd, &gm, "");
  for (i = 0; i <= 400; i = i + 50) {   // to draw vertical lines of the chess board.
    line (i, 0, i, 400);
  }
  for (j = 0; j <= 400; j = j + 50) {   // to draw the horizontal lines of the chess board.
    line (0, j, 400, j);
  }
  blk (420, 0);
  blk (420, 250);
  line (0, 430, 0, 460);        // to draw the display at the bottom
  line (0, 430, 400, 430);
  line (0, 460, 400, 460);
  line (400, 430, 400, 460);
  settextstyle (7, HORIZ_DIR, 3);
  setfillpattern (&pattern, GREEN);
  for (b = 0; b <= 31; b++) {
    bar (arrodd[b][0], arrodd[b][1], arrodd[b][0] + 50, arrodd[b][1] + 50);
    rectangle (arrodd[b][0], arrodd[b][1], arrodd[b][0] + 50, arrodd[b][1] + 50);
  }
  setfillpattern (&pattern, DARKGRAY);
  for (m = 0; m <= 31; m++) {
    bar (arrevn[m][0], arrevn[m][1], arrevn[m][0] + 50, arrevn[m][1] + 50);
    rectangle (arrevn[m][0], arrevn[m][1], arrevn[m][0] + 50, arrevn[m][1] + 50);
  }
#endif
}
void blk (int q, int r) {
  int y, z;
#ifdef __DOS86__
  for (y = q; y <= (q + 200); y = y + 50) {
    line (y, r, y, r + 200);
  }
  for (z = r; z <= (r + 200); z = z + 50) {
    line (q, z, q + 200, z);
  }
#endif
}

char pos[8][8], color[8][8];
//void assign (char *, char *);

struct block {                  // structure for every block
  int curx, cury;
  char clr, blkcolor;
};

// union REGS i, o;                // for hardware interaction

void setposw (struct block *pawnw);    // sets each white pawn.
void setposb (struct block *pawnb);    // sets each black pawn.
void setposrw (struct block *rookw, struct block *bishopw,
               struct block *knightw, struct block *kingw,
	       struct block *queenw);  // it sets the white rook,knight,bishop etc.
     
void setposrb (struct block *rookb, struct block *bishopb,
	       struct block *knightb, struct block *kingb,
	       struct block *queenb);   // it sets the current coords of black
                                        // rook,bishop,knight etc.
void draw (int x3, int y3, struct block *selected, char nwblkclr, char id1);
char getblkcolor (int, int, int, int, char);    // functions prototype
char chkpawnmov (struct block *selected, int x3, int y3);
char chkrookmov (struct block *selected, int x3, int y3);
char chkknightmov (struct block *selected, int x3, int y3);
char chkbishopmov (struct block *selected, int x3, int y3);
char chkqueenmov (struct block *selected, int x3, int y3);
char chkkingmov (struct block *selected, int x3, int y3);
void checkpwn (int, int);

int main (void) {
  int i1, j1, button, x, y, x1, y1, x2, y2, x3, y3, ch, i = 0, j = 0, z = 1, turn = 0;
  struct block *selected, pw[8], pb[8], rookw[2], rookb[2], bishopw[2], bishopb[2];
  struct block kingw, kingb, queenw, queenb, knightw[2], knightb[2];
  char id, nwblkclr, move = 'i';

  assign ((char *)pos, (char *)color);
  clrscr ();
  display ();                   // for showing chess board
#ifdef NEVER
  design ();
  setspare ();                  // for drawing rook etc.
#endif
  setposw (pw);                 // sets position of black and
  setposb (pb);                 // white pawns with color
  setposrw (rookw, bishopw, knightw, &kingw, &queenw);  // sets position of whites
  setposrb (rookb, bishopb, knightb, &kingb, &queenb);  // sete position of blacks
  //restricts pointer of mouse in  the area specified there:
  //restrictmouseptr(0,0,400,400);
  showmouseptr ();
  while (z) {
    i = i + 1;
    setcolor (WHITE);
    if (turn % 2 == 0)          // means white's turn
      outtextxy (100, 430, "white's turn");
    else if (turn % 2 != 0)     // means black's turn
      outtextxy (100, 430, "black's turn");
    while (i) {
      if (kbhit ()) {
        ch = getch ();
        if (ch == '\n')         // escape at pressing enter.
          exit (0);
      }
      getmousepos (&button, &x, &y);    // gets click position of mouse
      if ((button == 001)) {
        sound (1000);
        i = i - 1;
        delay (50);
        nosound ();
        delay (500);
      }
    }
    x1 = relposx (x) / 50;
    y1 = relposy (y) / 50;
    gotoxy (6, 28);
    if (x1 == pw[0].curx && y1 == pw[0].cury) {
      selected = &pw[0];
      id = 'p';
    } else if (x1 == pw[1].curx && y1 == pw[1].cury) {
      selected = &pw[1];
      id = 'p';
    } else if (x1 == pw[2].curx && y1 == pw[2].cury) {
      selected = &pw[2];
      id = 'p';
    } else if (x1 == pw[3].curx && y1 == pw[3].cury) {
      selected = &pw[3];
      id = 'p';
    } else if (x1 == pw[4].curx && y1 == pw[4].cury) {
      selected = &pw[4];
      id = 'p';
    } else if (x1 == pw[5].curx && y1 == pw[5].cury) {
      selected = &pw[5];
      id = 'p';
    } else if (x1 == pw[6].curx && y1 == pw[6].cury) {
      selected = &pw[6];
      id = 'p';
    } else if (x1 == pw[7].curx && y1 == pw[7].cury) {
      selected = &pw[7];
      id = 'p';
    } else if (x1 == pb[0].curx && y1 == pb[0].cury) {
      selected = &pb[0];
      id = 'p';
    } else if (x1 == pb[1].curx && y1 == pb[1].cury) {
      selected = &pb[1];
      id = 'p';
    } else if (x1 == pb[2].curx && y1 == pb[2].cury) {
      selected = &pb[2];
      id = 'p';
    } else if (x1 == pb[3].curx && y1 == pb[3].cury) {
      selected = &pb[3];
      id = 'p';
    } else if (x1 == pb[4].curx && y1 == pb[4].cury) {
      selected = &pb[4];
      id = 'p';
    } else if (x1 == pb[5].curx && y1 == pb[5].cury) {
      selected = &pb[5];
      id = 'p';
    } else if (x1 == pb[6].curx && y1 == pb[6].cury) {
      selected = &pb[6];
      id = 'p';
    } else if (x1 == pb[7].curx && y1 == pb[7].cury) {
      selected = &pb[7];
      id = 'p';
    } else if (x1 == rookw[0].curx && y1 == rookw[0].cury) {
      selected = &rookw[0];
      id = 'r';
    } else if (x1 == rookw[1].curx && y1 == rookw[1].cury) {
      selected = &rookw[1];
      id = 'r';
    } else if (x1 == rookb[0].curx && y1 == rookb[0].cury) {
      selected = &rookb[0];
      id = 'r';
    } else if (x1 == rookb[1].curx && y1 == rookb[1].cury) {
      selected = &rookb[1];
      id = 'r';
    } else if (x1 == bishopw[0].curx && y1 == bishopw[0].cury) {
      selected = &bishopw[0];
      id = 'b';
    } else if (x1 == bishopw[1].curx && y1 == bishopw[1].cury) {
      selected = &bishopw[1];
      id = 'b';
    } else if (x1 == bishopb[0].curx && y1 == bishopb[0].cury) {
      selected = &bishopb[0];
      id = 'b';
    } else if (x1 == bishopb[1].curx && y1 == bishopb[1].cury) {
      selected = &bishopb[1];
      id = 'b';
    } else if (x1 == kingw.curx && y1 == kingw.cury) {
      selected = &kingw;
      id = 'g';
    } else if (x1 == queenw.curx && y1 == queenw.cury) {
      selected = &queenw;
      id = 'q';
    } else if (x1 == kingb.curx && y1 == kingb.cury) {
      selected = &kingb;
      id = 'g';
    } else if (x1 == queenb.curx && y1 == queenb.cury) {
      selected = &queenb;
      id = 'q';
    } else if (x1 == knightw[0].curx && y1 == knightw[0].cury) {
      selected = &knightw[0];
      id = 'k';
    } else if (x1 == knightw[1].curx && y1 == knightw[1].cury) {
      selected = &knightw[1];
      id = 'k';
    } else if (x1 == knightb[0].curx && y1 == knightb[0].cury) {
      selected = &knightb[0];
      id = 'k';
    } else if (x1 == knightb[1].curx && y1 == knightb[1].cury) {
      selected = &knightb[1];
      id = 'k';
    }
    if ((turn % 2 == 0 && selected->clr == 'b') || (turn % 2 != 0 && selected->clr == 'w'))
      exit (1);
    turn = turn + 1;
    j = j + 1;
    while (j) {
      if (kbhit ()) {
        ch = getch ();
        if (ch == '\n')         // escape at pressing enter.
          exit (0);
      }
      getmousepos (&button, &x2, &y2);  // gets click position of mouse
      if ((button == 001)) {
        sound (500);
        j = j - 1;
        delay (100);
        nosound ();
        delay (500);
      }
    }
    x3 = relposx (x2) / 50;     // gives standard x coordinate
    y3 = relposy (y2) / 50;     // gives standard y coordinate
    // get destination block 's color;
    nwblkclr = getblkcolor (x1, y1, x3, y3, selected->blkcolor);
    gotoxy (6, 28);
    bottom ();                  // clears bottom display
    if (id == 'p') {          // whether pawn?
      move = chkpawnmov (selected, x3, y3);
      if (move == 'v') {
        draw (x3, y3, selected, nwblkclr, 'p');
        checkpwn (x3, y3);
      }
    } else if (id == 'r') {   // whether rook?
      move = chkrookmov (selected, x3, y3);
      if (move == 'v') {
        draw (x3, y3, selected, nwblkclr, 'r');
      }
    } else if (id == 'k') {   // whether knight?
      move = chkknightmov (selected, x3, y3);
      if (move == 'v') {
        draw (x3, y3, selected, nwblkclr, 'k');
      }
    } else if (id == 'b') {   // whether bishop?
      move = chkbishopmov (selected, x3, y3);
      if (move == 'v') {
        draw (x3, y3, selected, nwblkclr, 'b');
      }
    } else if (id == 'q') {   // whether queen?
      move = chkqueenmov (selected, x3, y3);
      if (move == 'v')
        draw (x3, y3, selected, nwblkclr, 'q');
    } else if (id == 'g') {   // whether king?
      move = chkkingmov (selected, x3, y3);
      if (move == 'v')
        draw (x3, y3, selected, nwblkclr, 'g');
    }
    if (move == 'i')
      turn = turn - 1;
  }
  getch ();
  exit (0);
  return 0;
}

void getmousepos (int *button, int *x, int *y)  // gets mouse position.
{
#ifdef __DOS86__
  i.x.ax = 3;
  int86 (0x33, &i, &o);
  *button = o.x.bx;
  *x = o.x.cx;
  *y = o.x.dx;
#else
  *button = 0;
  *x = 0; *y = 0;
#endif
  return;
}

void showmouseptr (void)        // shows pointer in graphics mode.
{
#ifdef __DOS86__
  i.x.ax = 1;
  int86 (0x33, &i, &o);
#endif
  return;
}

void hidemouseptr (void)            // hides pointer
{
#ifdef __DOS86__
  i.x.ax = 0;
  int86 (0x33, &i, &o);
#endif
  return;
}

void restrictmouseptr (int x1, int y1, int x2, int y2)  // restrict pointer
{
#ifdef __DOS86__
  i.x.ax = 7;
  i.x.cx = x1;
  i.x.dx = x2;
  int86 (0x33, &i, &o);
  i.x.ax = 8;
  i.x.cx = y1;
  i.x.dx = y2;
  int86 (0x33, &i, &o);
#endif
  return;
}

void setposw (struct block *pawnw) {    // sets each white pawn.
  int count, togl;

  for (count = 0, togl = 0; count <= 7; count++, togl++) {
    pawnw->curx = count;
    pawnw->cury = 6;
    pawnw->clr = 'b';
    if (togl % 2 == 0)
      pawnw->blkcolor = 'g';
    else if (togl % 2 == 1)
      pawnw->blkcolor = 'm';
    pawnw++;
  }
  return;
}

void setposb (struct block *pawnb) {    // sets each black pawn.
  int count, togl;

  for (count = 0, togl = 0; count <= 7; count++, togl++) {
    pawnb->curx = count;
    pawnb->cury = 1;
    pawnb->clr = 'w';
    if (togl % 2 == 0)
      pawnb->blkcolor = 'm';
    else if (togl % 2 == 1)
      pawnb->blkcolor = 'g';
    pawnb++;
  }
  return;
}

char chkpawnmov (struct block *selected, int x3, int y3) {
  char mov, id, c;              // checks each pawn (black and white) move.

  id = pos[x3][y3];             // anybody?
  c = color[x3][y3];            // color?
  if (selected->clr == 'w') { // white pawn?
    if (x3 == selected->curx && y3 == selected->cury + 1) {     // move 1
      if (id == 'n')          // id is none when nobody is there
        mov = 'v';
    } else if ((x3 == selected->curx + 1 || x3 == selected->curx - 1) && y3 == selected->cury + 1) {
      if (id != 'n' && c == 'b') {  // black present?
        mov = 'v';
        send (id, c);
      }
    }
  } else if (selected->clr == 'b') {
    if (x3 == selected->curx && y3 == selected->cury - 1) {     // black and white both not there?
      if (id == 'n')
        mov = 'v';
    } else if ((x3 == selected->curx - 1 || x3 == selected->curx + 1) && y3 == selected->cury - 1) {
      if (id != 'n' && c == 'w') {  // white there
        mov = 'v';            // valid move
        send (id, c);
      }
    }
  } else {                      // no action at invalid move.
    mov = 'i';
  }
  return (mov);
}

void setposrw (struct block *rookw, struct block *bishopw,
	       struct block *knightw, struct block *kingw,
	       struct block *queenw) {  // it sets the white rook,knight,bishop etc.
  int i;

  rookw->curx = rookw->cury = 7;
  rookw->clr = 'w';
  rookw->blkcolor = 'm';
  rookw++;
  rookw->curx = 7;
  rookw->cury = 7;
  rookw->clr = 'w';
  rookw->blkcolor = 'g';
  bishopw->curx = 2;
  bishopw->cury = 7;
  bishopw->clr = 'w';
  bishopw->blkcolor = 'm';
  bishopw++;
  bishopw->curx = 5;
  bishopw->cury = 7;
  bishopw->clr = 'w';
  bishopw->blkcolor = 'g';
  knightw->curx = 1;
  knightw->cury = 7;
  knightw->clr = 'w';
  knightw->blkcolor = 'g';
  knightw++;
  knightw->curx = 6;
  knightw->cury = 7;
  knightw->clr = 'w';
  knightw->blkcolor = 'm';
  kingw->curx = 3;
  kingw->cury = 7;
  kingw->clr = 'w';
  kingw->blkcolor = 'm';
  queenw->curx = 4;
  queenw->cury = 7;
  queenw->clr = 'w';
  queenw->blkcolor = 'g';
  return;
}

void setposrb (struct block *rookb, struct block *bishopb,
	       struct block *knightb, struct block *kingb,
	       struct block *queenb) {  // it sets the current coords of black
                                        // rook,bishop,knight etc.
  int i;

  rookb->curx = 0;
  rookb->cury = 0;
  rookb->clr = 'b';
  rookb->blkcolor = 'g';
  rookb++;
  rookb->curx = 7;
  rookb->cury = 0;
  rookb->clr = 'b';
  rookb->blkcolor = 'm';
  bishopb->curx = 2;
  bishopb->cury = 0;
  bishopb->clr = 'b';
  bishopb->blkcolor = 'g';
  bishopb++;
  bishopb->curx = 5;
  bishopb->cury = 0;
  bishopb->clr = 'b';
  bishopb->blkcolor = 'm';
  knightb->curx = 1;
  knightb->cury = 0;
  knightb->clr = 'b';
  knightb->blkcolor = 'm';
  knightb++;
  knightb->curx = 6;
  knightb->cury = 0;
  knightb->clr = 'b';
  knightb->blkcolor = 'g';
  kingb->curx = 3;
  kingb->cury = 0;
  kingb->clr = 'b';
  kingb->blkcolor = 'm';
  queenb->curx = 4;
  queenb->cury = 0;
  queenb->clr = 'b';
  queenb->blkcolor = 'g';
  return;
}

void draw (int x3, int y3, struct block *selected, char nwblkclr, char id1) {
  int nx3, ny3, ncx, ncy;
  nx3 = x3 * 50;
  ny3 = y3 * 50;
  ncx = (selected->curx) * 50;
  ncy = (selected->cury) * 50;
#ifdef __DOS86__
  if (nwblkclr == 'g')        // CLEAR NEW POSITION
    setfillpattern (pattern, GREEN);
  else if (nwblkclr == 'm')
    setfillpattern (pattern, MAGENTA);
  hidemouseptr ();              // necessary to avoid the effect of mouse pointer.
  bar (nx3, ny3, nx3 + 50, ny3 + 50);
  setcolor (WHITE);
  rectangle (nx3, ny3, nx3 + 50, ny3 + 50);
  if (selected->blkcolor == 'g')      // CLEAR PREVIOUS POSITION
    setfillpattern (pattern, GREEN);
  else if (selected->blkcolor == 'm')
    setfillpattern (pattern, MAGENTA);  // clear the previous pos.
  bar (ncx, ncy, ncx + 50, ncy + 50);
  setcolor (WHITE);
  rectangle (ncx, ncy, ncx + 50, ncy + 50);
#endif
  if (id1 == 'p') {           // if pawn was selected then draw the pawn at new position.
    if (selected->clr == 'w')
      pawndraw (nx3, ny3, 0);   // 0 for white.
    else if (selected->clr == 'b')
      pawndraw (nx3, ny3, 1);
  } else if (id1 == 'r') {    // if rook was selected
    if (selected->clr == 'w')
      rookdraw (nx3, ny3, 0);   // 0 for white.
    else if (selected->clr == 'b')
      rookdraw (nx3, ny3, 1);
  } else if (id1 == 'k') {    // if knight was selected
    if (selected->clr == 'w')
      drawknight (nx3, ny3, 0);  // 0 for white.
    else if (selected->clr == 'b')
      drawknight (nx3, ny3, 1);
  } else if (id1 == 'b') {    // if bishop was selected
    if (selected->clr == 'w')
      drawbishop (nx3, ny3, 0); // 0 for white.
    else if (selected->clr == 'b')
      drawbishop (nx3, ny3, 1);
  } else if (id1 == 'g') {
    if (selected->clr == 'w')
      drawking (nx3, ny3, 0);   // 0 for white.
    else if (selected->clr == 'b')
      drawking (nx3, ny3, 1);
  } else if (id1 == 'q') {
    if (selected->clr == 'w')
      drawqueen (nx3, ny3, 0);  // 0 for white.
    else if (selected->clr == 'b')
      drawqueen (nx3, ny3, 1);
  }

  showmouseptr ();
  pos[selected->curx][selected->cury] = 'n';
  color[selected->curx][selected->cury] = 'n';        // welcome back mr.
#ifdef __DOS86__
  pointer.selected->curx = x3;
#endif
  selected->cury = y3;
  selected->blkcolor = nwblkclr;
  pos[x3][y3] = id1;
  color[x3][y3] = selected->clr;
  return;
}

char chkrookmov (struct block *selected, int x3, int y3) {
  // checks rook move for black and white as both have same moves.
  int i;
  char id, c, mov = 'v';

  if ((x3 == selected->curx) || (y3 == selected->cury)) {
    if (x3 > selected->curx && y3 == selected->cury) {
      for (i = selected->curx + 1; i < x3; i++) {
        id = pos[i][y3];
        // c=color[i][y3];
        if (id != 'n') {       // if black or white present move is invalid
          mov = 'i';
        }
      }
    } else if (x3 < selected->curx && y3 == selected->cury) {
      for (i = selected->curx - 1; i > x3; i--) {
        id = pos[i][y3];
        // c=color[i][y3];
        if (id != 'n')        // if black or white
        {
          mov = 'i';
        }
      }
    } else if (x3 == selected->curx && y3 > selected->cury) {
      for (i = selected->cury + 1; i < y3; i++) {
        id = pos[x3][i];
        // c=color[x3][i];
        if (id != 'n')        // if black or white
        {
          mov = 'i';
        }
      }
    } else if (x3 == selected->curx && y3 < selected->cury) {
      for (i = selected->cury - 1; i > y3; i--) {
        id = pos[x3][i];
        // c=color[x3][i];
        if (id != 'n')        // if black or white
        {
          mov = 'i';
        }
      }
    }
    if (mov == 'v') {
      id = pos[x3][y3];
      c = color[x3][y3];
      if (id != 'n' && c == 'b' && selected->clr == 'w') {        // means black at x3,y3
        mov = 'v';
        send (id, c);
      } else if (id != 'n' && c == 'w' && selected->clr == 'b') { // means white there
        mov = 'v';
        send (id, c);
      } else if (id == 'n')   // none of the white or black even at x3 & y3?
        mov = 'v';
      else
        mov = 'i';
    }
  } else
    mov = 'i';
  return (mov);
}

char chkknightmov (struct block *selected, int x3, int y3) {
  // knight' s moves are not affected if some entity lies in the way.
  // it just jumps over them.Atmost only eight moves are possible.
  int i, posk[8][2];
  char id, c, mov = 'i';

  posk[0][0] = selected->curx + 1;
  posk[0][1] = selected->cury - 2;
  posk[1][0] = selected->curx - 1;
  posk[1][1] = selected->cury - 2;
  posk[2][0] = selected->curx + 1;
  posk[2][1] = selected->cury + 2;
  posk[3][0] = selected->curx - 1;
  posk[3][1] = selected->cury + 2;
  posk[4][0] = selected->curx + 2;
  posk[4][1] = selected->cury - 1;
  posk[5][0] = selected->curx + 2;
  posk[5][1] = selected->cury + 1;
  posk[6][0] = selected->curx - 2;
  posk[6][1] = selected->cury + 1;
  posk[7][0] = selected->curx - 2;
  posk[7][1] = selected->cury - 1;
  for (i = 0; i <= 7; i++) {
    if (x3 == posk[i][0] && y3 == posk[i][1]) {
      id = pos[x3][y3];
      c = color[x3][y3];
      if (id != 'n' && c == 'b' && selected->clr == 'w') {
        mov = 'v';              // means black is there.
        send (id, c);
      } else if (id != 'n' && c == 'w' && selected->clr == 'b') {
        mov = 'v';              // means white is there.
        send (id, c);
      } else if (id == 'n')
        mov = 'v';              // means it is blank.
    }
  }
  return (mov);
}

char chkbishopmov (struct block *selected, int x3, int y3) {
  int m, n, m1, n1, i, j;
  char mov, id, c;

  m = x3 - selected->curx;
  n = y3 - selected->cury;
  if (abs (m) == abs (n)) {
    if (m > 0 && n < 0) {       // move 1

      // warning: operation on ‘i’ may be undefined [-Wsequence-point]
      // for (i = selected->curx + 1, j = selected->cury - 1; (i < x3 && j > y3); i = i++, j--) {
      //                                                                          ^^^^^^^

      for (i = selected->curx + 1, j = selected->cury - 1; (i < x3 && j > y3); i++, j--) {
        id = pos[i][j];
        // c=color[i][j];
        if (id != 'n')
          mov = 'i';
      }
    }
    if (m > 0 && n > 0) {       // move 2
      for (i = selected->curx + 1, j = selected->cury + 1; (i < x3 && j < y3); i++, j++) {
        id = pos[i][j];
        // c=color[i][j];
        if (id != 'n')
          mov = 'i';
      }
    }
    if (m < 0 && n < 0) {       // move 3
      for (i = selected->curx - 1, j = selected->cury - 1; (i != x3 && j != y3); i--, j--) {
        id = pos[i][j];
        // c=color[i][j];
        if (id != 'n')
          mov = 'i';
      }
    }
    if (m < 0 && n > 0) {       // move 4
      for (i = selected->curx - 1, j = selected->cury + 1; (i > x3 && j < y3); i--, j++) {
        id = pos[i][j];
        // c=color[i][j];
        if (id != 'n')
          mov = 'i';
      }
    }
    if (mov != 'i') {           // ..that nobody is in the way, now at x3 y3?
      id = pos[x3][y3];
      c = color[x3][y3];
      if (id != 'n' && c == 'b') {      // means black at x3,y3
        if (selected->clr == 'w') {
          mov = 'v';
          send (id, c);
        } else mov = 'i';
      } else if (id != 'n' && c == 'w') { // means white there
        if (selected->clr == 'b') {
          mov = 'v';
          send (id, c);
        } else mov = 'i';
      } else if (id == 'n') mov = 'v';    // none of the white or black even at x3 & y3?
    }
  } else mov = 'i';             // means not at the x cross.
  return (mov);
}

char chkqueenmov (struct block *selected, int x3, int y3) {
  char mov1, mov2, mov3 = 'i', id, c;

  mov1 = chkrookmov (selected, x3, y3);
  mov2 = chkbishopmov (selected, x3, y3);
  if (mov1 == 'v' || mov2 == 'v') mov3 = 'v';    // move is valid and color is checked already.
  return (mov3);
}

char chkkingmov (struct block *selected, int x3, int y3) {
  char id, c, mov = 'i';

  id = pos[x3][y3];
  c = pos[x3][y3];
  if (x3 == selected->curx + 1 && y3 == selected->cury - 1) {   // move 1
    if (id == 'n') mov = 'v';
    else if (selected->clr == 'w' && id != 'n' && c == 'b') {   // means black there.
      mov = 'v';
      send (id, c);
    } else if (selected->clr == 'b' && id != 'n' && c == 'w') { // means white there.
      mov = 'v';
      send (id, c);
    }
  } else if (x3 == selected->curx - 1 && y3 == selected->cury - 1) {    // move 2
    if (id == 'n') mov = 'v';
    else if (selected->clr == 'w' && id != 'n' && c == 'b') {   // means black there.
      mov = 'v';
      send (id, c);
    } else if (selected->clr == 'b' && id != 'n' && c == 'w') { // means white there.
      mov = 'v';
      send (id, c);
    }
  } else if (x3 == selected->curx - 1 && y3 == selected->cury + 1) {    // move 3
    if (id == 'n') mov = 'v';
    else if (selected->clr == 'w' && id != 'n' && c == 'b') {   // means black there.
      mov = 'v';
      send (id, c);
    } else if (selected->clr == 'b' && id != 'n' && c == 'w') { // means white there.
      mov = 'v';
      send (id, c);
    }
  } else if (x3 == selected->curx + 1 && y3 == selected->cury + 1) {    // move 4
    if (id == 'n') mov = 'v';
    else if (selected->clr == 'w' && id != 'n' && c == 'b') {   // means black there.
      mov = 'v';
      send (id, c);
    } else if (selected->clr == 'b' && id != 'n' && c == 'w') { // means white there.
      mov = 'v';
      send (id, c);
    }
  } else if (x3 == selected->curx + 1 && y3 == selected->cury) { // move 5
    if (id == 'n') mov = 'v';
    else if (selected->clr == 'w' && id != 'n' && c == 'b') {   // means black there.
      mov = 'v';
      send (id, c);
    } else if (selected->clr == 'b' && id != 'n' && c == 'w') { // means white there.
      mov = 'v';
      send (id, c);
    }
  } else if (x3 == selected->curx && y3 == selected->cury - 1) { // move 6
    if (id == 'n') mov = 'v';
    else if (selected->clr == 'w' && id != 'n' && c == 'b') {   // means black there.
      mov = 'v';
      send (id, c);
    } else if (selected->clr == 'b' && id != 'n' && c == 'w') { // means white there.
      mov = 'v';
      send (id, c);
    }
  } else if (x3 == selected->curx - 1 && y3 == selected->cury) { // move 7
    if (id == 'n') mov = 'v';
    else if (selected->clr == 'w' && id != 'n' && c == 'b') {   // means black there.
      mov = 'v';
      send (id, c);
    } else if (selected->clr == 'b' && id != 'n' && c == 'w') { // means white there.
      mov = 'v';
      send (id, c);
    }
  } else if (x3 == selected->curx && y3 == selected->cury + 1) { // move 8
    if (id == 'n') mov = 'v';
    else if (selected->clr == 'w' && id != 'n' && c == 'b') {   // means black there.
      mov = 'v';
      send (id, c);
    } else if (selected->clr == 'b' && id != 'n' && c == 'w') { // means white there.
      mov = 'v';
      send (id, c);
    }
  } else mov = 'i';                 // means move is not valid
  return (mov);
}

void assign (char *post, char *col) {
  int i;
  char val1[64] = { "rpnnnnprkpnnnnpkbpnnnnpbgpnnnnpqqpnnnnpgbpnnnnpbkpnnnnpkrpnnnnpr" };
  char val2[64] = { "wwnnnnbbwwnnnnbbwwnnnnbbwwnnnnbbwwnnnnbbwwnnnnbbwwnnnnbbwwnnnnbb" };
  for (i = 0; i <= 63; i++, post++, col++) {
    *post = val1[i];
    *col = val2[i];
  }
}

void checkpwn (int x3, int y3) {
  char a;

  a = color[x3][y3];            // whether pawn is white or black?
  bottom ();
  setcolor (WHITE);
  if (a == 'w' && (x3 >= 0 && x3 <= 7) && y3 == 7) {
    outtextxy (100, 430, "well done white..press w");
    getch ();
    bottom ();
  } else if (a == 'b' && (x3 >= 0 && x3 <= 7) && y3 == 0) {
    outtextxy (100, 430, "well done black..press b");
    getch ();
    bottom ();
  }
  return;
}