/*
 * pathplan.c - part of the chess demo in the glut distribution.
 *
 * (C) Henk Kok (kok@wins.uva.nl)
 *
 * This file can be freely copied,changed,redistributed,etc. as long as
 * this copyright notice stays intact.
 */

#include "chess.h"

extern int board[10][10];

int path[10][10];
int hops[10][10];

int steps;
int cur_hops;

void init_board(void) {
  int i,j;
  for (i=0;i<10;i++) {
    for(j=0;j<10;j++) {
      hops[i][j] = 0;
      path[i][j] = (board[i][j]?-1:0); } }
}

void test_exit(int i,int j,int dir) {
  if (i<0 || i>9 || j<0 || j>9)
    return;
  if (path[i][j])
    return;
  steps ++;
  path[i][j] = dir;
  hops[i][j] = cur_hops + 1;
}

int solve_path(int x1,int y1,int x2,int y2) {
  int i,j;
  init_board();
  path[x2][y2] = 9;
  hops[x2][y2] = 1;
  path[x1][y1] = 0;
  cur_hops = 1;
  for (;;) {
    steps = 0;
    for (i=0;i<10;i++) {
      for (j=0;j<10;j++) {
        if (hops[i][j] != cur_hops)
          continue;
        test_exit(i,j-1,SOUTH);
        test_exit(i,j+1,NORTH);
        test_exit(i-1,j,EAST);
        test_exit(i+1,j,WEST); } }
    for (i=0;i<10;i++) {
      for (j=0;j<10;j++) {
        if (hops[i][j] != cur_hops)
          continue;
      test_exit(i-1,j-1,SOUTHEAST);
      test_exit(i+1,j-1,SOUTHWEST);
      test_exit(i-1,j+1,NORTHEAST);
      test_exit(i+1,j+1,NORTHWEST); } }
    cur_hops++;
    if (path[x1][y1])
      return 1;
    if (steps == 0)
      return 0; }
}