#include <io.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include "system.h"

#include "GPU.h"

#define msleep(msec) usleep(1000*msec);

 
static void
gpu_write (unsigned int reg, unsigned int data)
{
  IOWR (GPU_0_BASE, reg << 2, data);
}

static void
load_sprite (void)
{
  const uint16_t sprite[16]={ 0x00C0, 0x03E0, 0x0FF8, 0x1FFE, 0x3FC7, 0x3F83, 0x3933, 0x3987, 0x3D37, 0x3D37, 0x3D87, 0x3FFF, 0x1FFE, 0x07F8, 0x01E0, 0x00C0 };
  const unsigned int n=sizeof(sprite)/sizeof(uint16_t);
  unsigned int i;

  //                      RRR GGG BBB
  // set the sprite color 111 010 000 - orange
  gpu_write (GPU_REG_SPRITE_COLOUR, 0x01D0);

  // squirt the bromium logo into the sprite
  for (i=0;i<n;++i) 
	  gpu_write (GPU_REG_SPRITE_BASE+i,sprite[i]);
}


static int
dir (int a, int b)
{
  if (a > b)
    return 1;
  if (a < b)
    return -1;
  return 0;
}

static void
move_bat (int *b, int db)
{
  *b += dir (db, *b);
}

static int
squish (int *v, int min, int max)
{
  if (*v < min)
    {
      *v = min;
      return 1;
    }
  if (*v >= max)
    {
      *v = max - 1;
      return 1;
    }
  return 0;
}

static int
find_intersection (int x, int y, int xd, int yd, int t)
{

  // super lazy - we should use the power of MATHS

  while (x != t)
    {
      x += xd;
      y += yd;

      if (squish (&y, 0, GPU_HEIGHT))
        yd = -yd;

      if (squish (&x, 0, GPU_WIDTH))
        xd = -xd;
    }

  return y;
}

int
main (void)
{
  int x, y, xd, yd;
  int bat0, dbat0;
  int bat1, dbat1;
  int missed = 0;

  printf ("Working...\n");
  msleep (500);
  srand (12392184);

  bat0 = 100;
  bat1 = 200;

  load_sprite ();

  while (1)
    {
      x = 1;
      y = 1;
      xd = 1;
      yd = 1;

      dbat0 = find_intersection (x + xd, y + yd, xd, yd, 0);
      dbat1 = find_intersection (x + xd, y + yd, xd, yd, GPU_WIDTH-1);

      while (!missed)
        {
          x += xd;
          y += yd;


          if (squish (&y, 0, GPU_HEIGHT))
            yd = -yd;

          if (squish (&x, 0, GPU_WIDTH))
            {
              xd = (rand () % 3) + 1;
              if (x)
                xd = -xd;
              yd = rand () % 7;
              yd -= 3;

              if (x)
                {
                  dbat0 = find_intersection (x + xd, y + yd, xd, yd, 0);
                  dbat1 = GPU_HEIGHT / 2;
                }
              else
                {
                  dbat0 = GPU_HEIGHT / 2;

                  dbat1 = find_intersection (x + xd, y + yd, xd, yd, GPU_WIDTH-1);
                }
            }

          move_bat (&bat0, dbat0);
          move_bat (&bat1, dbat1);


          gpu_write (1, x + GPU_OFFSET);
          gpu_write (2, y + GPU_OFFSET);
          gpu_write (3, bat0 + GPU_OFFSET);
          gpu_write (4, bat1 + GPU_OFFSET);

          gpu_write (0, 0);

          msleep (2);
        }
    }
}