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// Copyright (C) 2007 EPITA Research and Development Laboratory
//
// This file is part of the Olena Library.  This library is free
// software; you can redistribute it and/or modify it under the terms
// of the GNU General Public License version 2 as published by the
// Free Software Foundation.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this library; see the file COPYING.  If not, write to
// the Free Software Foundation, 51 Franklin Street, Fifth Floor,
// Boston, MA 02111-1307, USA.
//
// As a special exception, you may use this file as part of a free
// software library without restriction.  Specifically, if other files
// instantiate templates or use macros or inline functions from this
// file, or you compile this file and link it with other files to
// produce an executable, this file does not by itself cause the
// resulting executable to be covered by the GNU General Public
// License.  This exception does not however invalidate any other
// reasons why the executable file might be covered by the GNU General
// Public License.

#ifndef MLN_LEVEL_MEDIAN_HH
# define MLN_LEVEL_MEDIAN_HH

/*! \file mln/level/median.hh
 *
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 * \brief Median filtering of an image.
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 */

# include <mln/core/concept/image.hh>
# include <mln/core/window2d.hh>
# include <mln/accu/median.hh>

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# include <mln/canvas/sbrowsing.hh>

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namespace mln
{

  namespace level
  {

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    /*! Compute in \p output the median filter of image \p input by
     *  the window \p win.
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     *
     * \param[in] input The image to be filtered.
     * \param[in] win The window.
     * \param[in,out] output The output image.
     *
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     * \pre \p input and \p output have to be initialized.
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     */
    template <typename I, typename W, typename O>
    void median(const Image<I>& input, const Window<W>& win,
		Image<O>& output);


# ifndef MLN_INCLUDE_ONLY


    namespace impl
    {

      template <typename I, typename W, typename O>
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      void median_as_procedure(const I& input,
			       const W& win,
			       O& output)
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      {
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	mln_precondition(input.has_data());
	mln_precondition(output.has_data());

	int
	  min_row = input.min_row(), max_row = input.max_row(),
	  min_col = input.min_col(), max_col = input.max_col();
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	window2d
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	  win_fwd_plus  = win - (win + left),
	  win_fwd_minus = (win + left) - win,
	  win_bkd_plus  = win - (win + right),
	  win_bkd_minus = (win + right) - win,
	  win_bot  = win - (win + up),
	  win_top = (win + up) - win;

	point2d p;
	mln_qiter(W)
	  q_fp(win_fwd_plus, p), q_fm(win_fwd_minus, p),
	  q_bp(win_bkd_plus, p), q_bm(win_bkd_minus, p),
	  q_top(win_top, p), q_bot(win_bot, p);
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	accu::median_on<mln_value(I)> med;

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	// initialization

	p = input.domain().pmin() + up;
	med.init();
	{
	  mln_qiter(W) q(win, p);
	  for_all(q) if (input.has(q))
	    med.take(input(q));
	}

	int& row = p.row();
	int& col = p.col();
	bool fwd = true;

	mln_assertion(p.col() == min_col);
	mln_assertion(p.row() == min_row - 1);
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	for (row = min_row; row <= max_row; ++row)
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	  {
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	    // "go down"
	    for_all(q_top) if (input.has(q_top))
	      med.untake(input(q_top));
	    for_all(q_bot) if (input.has(q_bot))
	      med.take(input(q_bot));
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	    output(p) = med;

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	    if (fwd)
	      // browse line fwd
	      while (col < max_col)
		{
		  ++col;
		  for_all(q_fm) if (input.has(q_fm))
		    med.untake(input(q_fm));
		  for_all(q_fp) if (input.has(q_fp))
		    med.take(input(q_fp));
		  output(p) = med;
		}
	    else
	      // browse line bkd
	      while (col > min_col)
		{
		  --col;
		  for_all(q_bm) if (input.has(q_bm))
		    med.untake(input(q_bm));
		  for_all(q_bp) if (input.has(q_bp))
		    med.take(input(q_bp));
		  output(p) = med;
		}

	    // change browsing
	    fwd = ! fwd;
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	  }
      }

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      template <typename I, typename W, typename O>
      struct median_functor
      { 
	// i/o

	const I& input;
	const W& win;
	O& output;

	// aux data

	mln_point(I) p;
	window2d     win_fp, win_fm, win_bp, win_bm, win_dp, win_dm;
	mln_qiter(W)   q_fp,   q_fm,   q_bp,   q_bm,   q_dp,   q_dm;
	accu::median_on<mln_value(I)> med;

	// ctor

	median_functor(I& input_, const W& win_, O& output_)
	  :
	  // i/o
	  input(exact(input_)),
	  win(exact(win_)),
	  output(exact(output_)),
	  // aux data
	  p(),
	  win_fp(win - (win + left)),   win_fm((win + left)  - win),
	  win_bp(win - (win + right)),  win_bm((win + right) - win),
	  win_dp(win - (win + up)),     win_dm((win + up)    - win),
	  q_fp(win_fp, p),  q_fm(win_fm, p),
	  q_bp(win_bp, p),  q_bm(win_bm, p),
	  q_dp(win_dp, p),  q_dm(win_dm, p)
	{
	}

	// parts

	void init()
	{
	  med.init();
	  mln_qiter(W) q(win, p);
	  for_all(q) if (input.has(q))
	    med.take(input(q));
	}

	void down()
	{
	  for_all(q_dm) if (input.has(q_dm))
	    med.untake(input(q_dm));
	  for_all(q_dp) if (input.has(q_dp))
	    med.take(input(q_dp));
	  output(p) = med;
	}

	void fwd()
	{
	  for_all(q_fm) if (input.has(q_fm))
	    med.untake(input(q_fm));
	  for_all(q_fp) if (input.has(q_fp))
	    med.take(input(q_fp));
	  output(p) = med;
	}

	void bkd()
	{
	  for_all(q_bm) if (input.has(q_bm))
	    med.untake(input(q_bm));
	  for_all(q_bp) if (input.has(q_bp))
	    med.take(input(q_bp));
	  output(p) = med;
	}

      }; // end of median_functor


      template <typename I, typename W, typename O>
      void median(I& input, const W& win, O& output)
      {
	// FIXME: resize border!
	impl::median_functor<I,W,O> f(input, win, output);
	canvas::sbrowsing(f);
      }


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    } // end of namespace mln::level::impl


    // facade

    template <typename I, typename W, typename O>
    void median(const Image<I>& input, const Window<W>& win,
		Image<O>& output)
    {
      impl::median(exact(input), exact(win), exact(output)); 
    }

# endif // ! MLN_INCLUDE_ONLY

  } // end of namespace mln::level

} // end of namespace mln


#endif // ! MLN_LEVEL_MEDIAN_HH