/*
 * animate.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 <stdlib.h>
#include <stdio.h>
#include <GL/glut.h>
#include "chess.h"

#define MOVE_FRAC 8

int frac;
int stage;
int piece;
int piece2;
int X, Y, NX, NY, XD, YD;
GLfloat CX1, CY1;
GLfloat CX2, CY2, CZ2;

FILE *inpf = NULL;

extern int path[10][10];
extern int board[10][10];
extern int cycle[10][10], cyclem, cycle2;
extern int stunt[10][10], stuntm, stunt2;

void read_move(void) {
  char buf[256];
  if (!inpf)
    inpf = fopen("chess.inp", "r");
  if (!inpf) {
    fprintf(stderr, "Could not open file chess.inp for reading.\n");
    exit(1); }
  if (feof(inpf))
    return;
  fgets(buf, 200, inpf);
  CX1 = NX = X = buf[0]-'a'+1;
  CY1 = NY = Y = buf[1]-'0';
  CX2 = XD = buf[2]-'a'+1;
  CY2 = YD = buf[3]-'0';
  piece = board[X][Y];
  piece2 = board[XD][YD];
  board[X][Y] = 0;
  board[XD][YD] = 0;
  solve_path(X, Y, XD, YD);
  stage = 0;
  frac = 0;
  cyclem = cycle[X][Y];
  cycle2 = cycle[XD][YD];
  stuntm = stunt[X][Y];
  stunt2 = stunt[XD][YD];
  switch(path[X][Y]) {
        case NORTH      : NY--; 
                          break;
        case SOUTH      : NY++; 
                          break;
        case WEST       : NX--; 
                          break;
        case EAST       : NX++; 
                          break;
        case NORTHWEST  : NX--; 
                          NY--; 
                          break;
        case NORTHEAST  : NX++; 
                          NY--; 
                          break;
        case SOUTHWEST  : NX--; 
                          NY++; 
                          break;
        case SOUTHEAST  : NX++; 
                          NY++; 
                          break; }
  if (NY == YD && NX == XD)
    stage = 1;
}

void proceed(void) {
  frac ++;
  if (stage == 1) {
    if (piece2 && frac <= MOVE_FRAC * 2) {
      CZ2 = -((GLfloat) frac)/MOVE_FRAC/1.8;
      return; }
    frac = 0;
    piece2 = 0;
    stage ++;
    return; }
    else
    if (stage == 3)
      return;
      else
      CZ2 = 0.0;
  if (frac >= MOVE_FRAC) {
    frac = 0;
    X = NX;
    Y = NY;
    if (NX == XD && NY == YD) {
      board[XD][YD] = piece;
      cycle[XD][YD] = cyclem;
      stunt[XD][YD] = stuntm;
      piece = 0;
      read_move();
      return; }
    switch(path[X][Y]) {
      case NORTH      : NY--; 
                        break;
      case SOUTH      : NY++; 
                        break;
      case WEST       : NX--; 
                        break;
      case EAST       : NX++; 
                        break;
      case NORTHWEST  : NX--; 
                        NY--; 
                        break;
      case NORTHEAST  : NX++; 
                        NY--; 
                        break;
      case SOUTHWEST  : NX--; 
                        NY++; 
                        break;
      case SOUTHEAST  : NX++; 
                        NY++; 
                        break; }
    if (NX == XD && NY == YD)
      stage ++; }
  CX1 = ((GLfloat) (X*(MOVE_FRAC-frac) + NX*frac))/ MOVE_FRAC;
  CY1 = ((GLfloat) (Y*(MOVE_FRAC-frac) + NY*frac))/ MOVE_FRAC;
}