//See TextBase Layer.

#define ATTR (BLACK<<12+WHITE<<8)

U32 text[TEXT_ROWS][TEXT_COLS];

U0 DrawIt(CTask *task,CDC *)
{//gr.text_basegets clear 30fps, so we must use our own permanent text array.
  MemCpy(gr.text_base+TEXT_COLS,text,(TEXT_ROWS-1)*TEXT_COLS*sizeof(U32));
  // You can copy it this way, if you like:
  //  I64 i,j;
  //  for (j=0;j<TEXT_ROWS;j++)
  //    for (i=0;i<TEXT_COLS;i++)
  //     TextChar(task,,i,j,text[j][i]);
  TextPrint(task,0,0,ATTR>>8,"Draw a maze with left bttn.");
  TextPrint(task,0,1,ATTR>>8,"Solve maze starting at right click.");
}

#define STK_SIZE 2048
//We would put these as local vars
//in SolveMaze() but the system stk size
//is limited, so it's a bad habit.  The heap
//is the normal TempleOS technique, but
//it's a pain in this case.
I64     stk_ptr,
    stk_x  [STK_SIZE],
    stk_y  [STK_SIZE],
    stk_dir[STK_SIZE];

//Four directions:
//  0=Up,1=right,2=down,3=left
I64     dir_x[4]= { 0,+1, 0,-1}, // Could use gr_x_offsets2,gr_y_offsets2
              dir_y[4]= {+1, 0,-1, 0};

U0 SolveMaze(I64 x,I64 y)
{
  I64 dir=0;
  stk_ptr=0;
  stk_x[stk_ptr]=x;
  stk_y[stk_ptr]=y;
  stk_dir[stk_ptr++]=dir;
  while (TRUE)
  {
    if (!(0<=x<MinI64(Fs->win_width,TEXT_COLS)) ||
        !(0<=y<MinI64(Fs->win_height,TEXT_ROWS)) )
    {
      Beep;
      Beep;
      break;
    }
    if (!text[y][x].u8[0])
      text[y][x]='.'+ATTR;
    x+=dir_x[dir];
    y+=dir_y[dir];
//u8.[0] is the ASCII
    if (text[y][x].u8[0])
    {
      x-=dir_x[dir];
      y-=dir_y[dir];
      if (++dir==4)
      {
        if (--stk_ptr<0) return;
        x=stk_x[stk_ptr];
        y=stk_y[stk_ptr];
        dir=stk_dir[stk_ptr];
      }
    }
    else
    {
      dir=0;
      stk_x[stk_ptr]=x;
      stk_y[stk_ptr]=y;
      stk_dir[stk_ptr++]=dir;
      if (stk_ptr==STK_SIZE) return;
      Sleep(100);
      if (ScanChar)
        throw;
    }
  }
}

U0 Maze()
{
  I64 ch,x,y;
  SettingsPush; //See SettingsPush
  AutoComplete;
  WinBorder;
  WinMax;
  DocCursor;
  DocClear;
  Fs->draw_it=&DrawIt;
  Fs->win_inhibit=WIG_TASK_DFT-WIF_SELF_FOCUS-WIF_SELF_BORDER;
  try
    do
    {
      MemSet(text,0,sizeof(text));
      while (!(ch=ScanChar))
      {
        x=ms.pos_text.x-Fs->win_left-Fs->scroll_x/FONT_WIDTH;
        y=ms.pos_text.y-Fs->win_top-Fs->scroll_y/FONT_HEIGHT;
        if (ms.lb&&!winmgr.grab_scroll)
          text[y][x]=CH_SPACE+ATTRF_INVERT+ATTR;
        if (ms.rb&&!winmgr.grab_scroll)
        {
          text[y][x]='*'+ATTR;
          SolveMaze(x,y);
          ch=GetChar;
          break;
        }
        Refresh;
      }
    }
    while (ch!=CH_SHIFT_ESC && ch!=CH_ESC);
  catch
    PutExcept;
  SettingsPop;
}

Maze;