Class Knights_Tour < Object

# File ext/tk/sample/demos-en/knightstour.rb, line 264
def initialize(parent = nil)
  create_gui(parent)
end

# File ext/tk/sample/demos-en/knightstour.rb, line 77
def _N(square)
  '%c%d' % [(97 + square % 8), (square.div(8) + 1)]
end

# File ext/tk/sample/demos-en/knightstour.rb, line 125
def _exit
  _stop
  $knightstour.destroy
end

# File ext/tk/sample/demos-en/knightstour.rb, line 121
def _stop
  Tk.after_cancel(@after_id) rescue nil
end

# File ext/tk/sample/demos-en/knightstour.rb, line 44
def check_square(square)
  valid_moves(square).find_all{|pos| ! @visited.include?(pos)}.length
end

# File ext/tk/sample/demos-en/knightstour.rb, line 173
def create_gui(parent = nil)
  $knightstour.destroy rescue nil
  $knightstour = Tk::Toplevel.new(parent, :title=>"Knight's tour")
  $knightstour.withdraw
  base_f = Ttk::Frame.new($knightstour)
  @board = Tk::Canvas.new(base_f, :width=>240, :height=>240)
  @log = Tk::Text.new(base_f, :width=>12, :height=>1,
                      :font=>'Arial 8', :background=>'white')
  scr = @log.yscrollbar(Ttk::Scrollbar.new(base_f))

  @visited = []
  @delay = TkVariable.new(600)
  @continuous = TkVariable.new(false)

  tool_f = Ttk::Frame.new($knightstour)
  label = Ttk::Label.new(tool_f, :text=>'Speed')
  scale = Ttk::Scale.new(tool_f, :from=>8, :to=>2000, :variable=>@delay,
                         :command=>proc{|n| set_delay(n)})
  check = Ttk::Checkbutton.new(tool_f, :text=>'Repeat',
                               :variable=>@continuous)
  @start_btn = Ttk::Button.new(tool_f, :text=>'Start',
                               :command=>proc{tour()})
  @exit_btn = Ttk::Button.new(tool_f, :text=>'Exit',
                              :command=>proc{_exit()})

  7.downto(0){|row|
    0.upto(7){|col|
      if ((col & 1) ^ (row & 1)).zero?
        fill  = 'bisque'
        dfill = 'bisque3'
      else
        fill  = 'tan3'
        dfill = 'tan4'
      end
      coords = [col * 30 + 4, row * 30 + 4, col * 30 + 30, row * 30 + 30]
      @board.create(TkcRectangle, coords,
                    :fill=>fill, :disabledfill=>dfill,
                    :width=>2, :state=>:disabled)
    }
  }

  @knight_font = TkFont.new(:size=>-24)
  @knight = TkcText.new(@board, 0, 0, :font=>@knight_font,
                        :text=>Tk::UTF8_String.new('\u265e'),
                        :anchor=>'nw', # :tags=>'knight',
                        :fill=>'black', :activefill=>'#600000')
  @knight.coords(@board.coords(rand(64)+1)[0..1])
  @knight.bind('ButtonPress-1', '%W %x %y'){|w,x,y| drag_start(w,x,y)}
  @knight.bind('Motion', '%W %x %y'){|w,x,y| drag_motion(w,x,y)}
  @knight.bind('ButtonRelease-1', '%W %x %y'){|w,x,y| drag_end(w,x,y)}

  Tk.grid(@board, @log, scr, :sticky=>'news')
  base_f.grid_rowconfigure(0, :weight=>1)
  base_f.grid_columnconfigure(0, :weight=>1)

  Tk.grid(base_f, '-', '-', '-', '-', '-', :sticky=>'news')
  widgets = [label, scale, check, @start_btn]
  sg = nil
  unless $RubyTk_WidgetDemo
    widgets << @exit_btn
    if Tk.windowingsystem != 'aqua'
      #widgets.unshift(Ttk::SizeGrip.new(tool_f))
      Ttk::SizeGrip.new(tool_f).pack(:side=>:right, :anchor=>'se')
    end
  end
  Tk.pack(widgets, :side=>:right)
  if Tk.windowingsystem == 'aqua'
    TkPack.configure(widgets, :padx=>[4, 4], :pady=>[12, 12])
    TkPack.configure(widgets[0], :padx=>[4, 24])
    TkPack.configure(widgets[-1], :padx=>[16, 4])
  end

  Tk.grid(tool_f, '-', '-', '-', '-', '-', :sticky=>'ew')

  if $RubyTk_WidgetDemo
    Tk.grid(make_SeeDismiss(), '-', '-', '-', '-', '-', :sticky=>'ew')
  end

  $knightstour.grid_rowconfigure(0, :weight=>1)
  $knightstour.grid_columnconfigure(0, :weight=>1)

  $knightstour.bind('Control-F2'){TkConsole.show}
  $knightstour.bind('Return'){@start_btn.invoke}
  $knightstour.bind('Escape'){@exit_btn.invoke}
  $knightstour.bind('Destroy'){ _stop }
  $knightstour.protocol('WM_DELETE_WINDOW'){ _exit }

  $knightstour.deiconify
  $knightstour.tkwait_destroy
end

# File ext/tk/sample/demos-en/knightstour.rb, line 146
def drag_end(w, x, y)
  square = w.find_closest(x, y, 0, 65)
  w.coords('selected', w.coords(square)[0..1])
  w.dtag('selected')
  @dragging = nil
end

# File ext/tk/sample/demos-en/knightstour.rb, line 140
def drag_motion(w, x, y)
  return unless @dragging
  w.move('selected', x - @dragging[0], y - @dragging[1])
  @dragging = [x, y]
end

# File ext/tk/sample/demos-en/knightstour.rb, line 134
def drag_start(w, x, y)
  w.dtag('selected')
  w.addtag('selected', :withtag, 'current')
  @dragging = [x, y]
end

# File ext/tk/sample/demos-en/knightstour.rb, line 68
def edgemost(nxt, pos)
  col_A = 3 - ((3.5 - nxt % 8).abs.to_i)
  col_B = 3 - ((3.5 - pos % 8).abs.to_i)
  row_A = 3 - ((3.5 - nxt.div(8)).abs.to_i)
  row_B = 3 - ((3.5 - pos.div(8)).abs.to_i)
  (col_A * row_A < col_B * row_B)? nxt : pos
end

# File ext/tk/sample/demos-en/knightstour.rb, line 153
def make_SeeDismiss
  ## See Code / Dismiss
  frame = Ttk::Frame.new($knightstour)
  sep = Ttk::Separator.new(frame)
  Tk.grid(sep, :columnspan=>4, :row=>0, :sticky=>'ew', :pady=>2)
  TkGrid('x',
         Ttk::Button.new(frame, :text=>'See Code',
                         :image=>$image['view'], :compound=>:left,
                         :command=>proc{showCode 'knightstour'}),
         Ttk::Button.new(frame, :text=>'Dismiss',
                         :image=>$image['delete'], :compound=>:left,
                         :command=>proc{
                           $knightstour.destroy
                           $knightstour = nil
                         }),
         :padx=>4, :pady=>4)
  frame.grid_columnconfigure(0, :weight=>1)
  frame
end

# File ext/tk/sample/demos-en/knightstour.rb, line 82
def move_piece(last, square)
  @log.insert(:end, "#{@visited.length}. #{_N last} -> #{_N square}\n", '')
  @log.see(:end)
  @board.itemconfigure(1+last, :state=>:normal, :outline=>'black')
  @board.itemconfigure(1+square, :state=>:normal, :outline=>'red')
  @knight.coords(@board.coords(1+square)[0..1])
  @visited << square
  if (nxt = next_square(square)) != -1
    @after_id = Tk.after(@delay.numeric){move_piece(square, nxt) rescue nil}
  else
    @start_btn.state :normal
    if @visited.length == 64
      if @initial == square
        @log.insert :end, 'Closed tour!'
      else
        @log.insert :end, "Success\n", {}
        Tk.after(@delay.numeric * 2){tour(rand(64))} if @continuous.bool
      end
    else
      @log.insert :end, "FAILED!\n", {}
    end
  end
end

# File ext/tk/sample/demos-en/knightstour.rb, line 50
def next_square(square)
  minimum = 9
  nxt = -1
  valid_moves(square).each{|pos|
    unless @visited.include?(pos)
      cnt = check_square(pos)
      if cnt < minimum
        minimum = cnt
        nxt = pos
      elsif cnt == minimum
        nxt = edgemost(nxt, pos)
      end
    end
  }
  nxt
end

# File ext/tk/sample/demos-en/knightstour.rb, line 130
def set_delay(new)
  @delay.numeric = new.to_i
end

# File ext/tk/sample/demos-en/knightstour.rb, line 107
def tour(square = nil)
  @visited.clear
  @log.clear
  @start_btn.state :disabled
  1.upto(64){|n|
    @board.itemconfigure(n, :state=>:disabled, :outline=>'black')
  }
  unless square
    square = @board.find_closest(*(@knight.coords << 0 << 65))[0].to_i - 1
  end
  @initial = square
  Tk.after_idle{ move_piece(@initial, @initial) rescue nil }
end

# File ext/tk/sample/demos-en/knightstour.rb, line 31
def valid_moves(square)
  moves = []
  [
    [-1,-2], [-2,-1], [-2,1], [-1,2], [1,2], [2,1], [2,-1], [1,-2]
  ].each{|col_delta, row_delta|
    col = (square % 8) + col_delta
    row = (square.div(8)) + row_delta
    moves << (row * 8 + col) if row > -1 && row < 8 && col > -1 && col < 8
  }
  moves
end