## Copyright (C) 1993-2012 John W. Eaton
##
## This file is part of Octave.
##
## Octave is free software; you can redistribute it and/or modify it
## under the terms of the GNU General Public License as published by
## the Free Software Foundation; either version 3 of the License, or (at
## your option) any later version.
##
## Octave 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 Octave; see the file COPYING.  If not, see
## <http://www.gnu.org/licenses/>.

## -*- texinfo -*-
## @deftypefn  {Function File} {} stairs (@var{y})
## @deftypefnx {Function File} {} stairs (@var{x}, @var{y})
## @deftypefnx {Function File} {} stairs (@dots{}, @var{style})
## @deftypefnx {Function File} {} stairs (@dots{}, @var{prop}, @var{val}, @dots{})
## @deftypefnx {Function File} {} stairs (@var{hax}, @dots{})
## @deftypefnx {Function File} {@var{h} =} stairs (@dots{})
## @deftypefnx {Function File} {[@var{xstep}, @var{ystep}] =} stairs (@dots{})
## Produce a stairstep plot.
##
## The arguments @var{x} and @var{y} may be vectors or matrices.
## If only one argument is given, it is taken as a vector of Y values
## and the X coordinates are taken to be the indices of the elements.
## 
## The style to use for the plot can be defined with a line style @var{style}
## of the same format as the @code{plot} command.
##
## Multiple property/value pairs may be specified, but they must appear in
## pairs.
##
## If the first argument @var{hax} is an axis handle, then plot into this axis,
## rather than the current axis handle returned by @code{gca}.
##
## If one output argument is requested, return a graphics handle to the
## created plot.  If two output arguments are specified, the data are generated
## but not plotted.  For example,
##
## @example
## stairs (x, y);
## @end example
##
## @noindent
## and
##
## @example
## @group
## [xs, ys] = stairs (x, y);
## plot (xs, ys);
## @end group
## @end example
##
## @noindent
## are equivalent.
## @seealso{bar, hist, plot, stem}
## @end deftypefn

## Author: jwe

function [xs, ys] = stairs (varargin)

  [hax, varargin, nargin] = __plt_get_axis_arg__ ("stairs", varargin{:});

  if (nargin < 1)
    print_usage ();
  endif

  if (nargout < 2)
    oldfig = [];
    if (! isempty (hax))
      oldfig = get (0, "currentfigure");
    endif
    unwind_protect
      hax = newplot (hax);
      [htmp, xxs, yys] = __stairs__ (true, varargin{:});
    unwind_protect_cleanup
      if (! isempty (oldfig))
        set (0, "currentfigure", oldfig);
      endif
    end_unwind_protect
    if (nargout == 1)
      xs = htmp;
    endif
  else
    [~, xs, ys] = __stairs__ (false, varargin{:});
  endif

endfunction

function [h, xs, ys] = __stairs__ (doplot, varargin)

  if (nargin == 2 || ischar (varargin{2}))
    y = varargin{1};
    varargin(1) = [];
    if (! ismatrix (y) || ndims (y) > 2)
      error ("stairs: Y must be a numeric 2-D vector or matrix");
    endif
    if (isvector (y))
      y = y(:);
    endif
    x = 1:rows (y);
  else
    x = varargin{1};
    y = varargin{2};
    varargin(1:2) = [];
    if (! ismatrix (x) || ! ismatrix (y) || ndims (x) > 2 || ndims (y) > 2)
      error ("stairs: X and Y must be numeric 2-D vectors or matrices");
    endif
  endif

  vec_x = isvector (x);
  if (vec_x)
    x = x(:);
  endif

  if (isvector (y))
    y = y(:);
  elseif (ismatrix (y) && vec_x)
    x = repmat (x, [1, columns(y)]);
  endif

  if (! size_equal (x, y))
    error ("stairs: X and Y sizes must match");
  endif

  len = 2*nr - 1;

  xs = ys = zeros (len, nc);

  xs(1,:) = x(1,:);
  ys(1,:) = y(1,:);

  xtmp = x(2:nr,:);
  ridx = 2:2:len-1;
  xs(ridx,:) = xtmp;
  ys(ridx,:) = y(1:nr-1,:);

  ridx = 3:2:len;
  xs(ridx,:) = xtmp;
  ys(ridx,:) = y(2:nr,:);

  have_line_spec = false;
  for i = 1:2:numel (varargin)
    arg = varargin{i};
    if (ischar (arg) || iscell (arg))
      [linespec, valid] = __pltopt__ ("stairs", arg, false);
      if (valid)
        have_line_spec = true;
        varargin(i) = [];
        break;
      endif
    endif
  endfor

  if (doplot)
    h = [];
    hold_state = get (gca (), "nextplot");
    unwind_protect
      for i = 1 : columns (y)

        if (have_line_spec)
          lc = linespec.color;
          if (isempty (lc))
            lc = __next_line_color__ ();
          endif
          ls = linespec.linestyle;
          if (isempty (ls))
            ls = "-";
          endif
          mk = linespec.marker;
          if (isempty (mk))
            mk = "none";
          endif
        else
          lc = __next_line_color__ ();
          ls = "-";
          mk = "none";
        endif

        ## Must occur after __next_line_color__ in order to work correctly.
        hg = hggroup ();
        h = [h; hg];
        args = __add_datasource__ ("stairs", hg, {"x", "y"}, varargin{:});

        addproperty ("xdata", hg, "data", x(:,i).');
        addproperty ("ydata", hg, "data", y(:,i).');

        addlistener (hg, "xdata", @update_data);
        addlistener (hg, "ydata", @update_data);

        htmp = line (xs(:,i).', ys(:,i).', "color", lc, "linestyle", ls,
                                           "marker", mk, "parent", hg);

        addproperty ("color", hg, "linecolor", get (htmp, "color"));
        addproperty ("linestyle", hg, "linelinestyle", get (htmp, "linestyle"));
        addproperty ("linewidth", hg, "linelinewidth", get (htmp, "linewidth"));

        addproperty ("marker", hg, "linemarker", get (htmp, "marker"));
        addproperty ("markeredgecolor", hg, "linemarkeredgecolor",
                     get (htmp, "markeredgecolor"));
        addproperty ("markerfacecolor", hg, "linemarkerfacecolor",
                     get (htmp, "markerfacecolor"));
        addproperty ("markersize", hg, "linemarkersize",
                     get (htmp, "markersize"));

        addlistener (hg, "color", @update_props);
        addlistener (hg, "linestyle", @update_props);
        addlistener (hg, "linewidth", @update_props);
        addlistener (hg, "marker", @update_props);
        addlistener (hg, "markeredgecolor", @update_props);
        addlistener (hg, "markerfacecolor", @update_props);
        addlistener (hg, "markersize", @update_props);

        if (! isempty (args))
          set (hg, args{:});
        endif
      endfor
    unwind_protect_cleanup
      set (gca (), "nextplot", hold_state);
    end_unwind_protect
  else
    h = 0;
  endif

endfunction

function update_props (h, ~)
  set (get (h, "children"),
       "color", get (h, "color"),
       "linestyle", get (h, "linestyle"),
       "linewidth", get (h, "linewidth"),
       "marker", get (h, "marker"),
       "markeredgecolor", get (h, "markeredgecolor"),
       "markerfacecolor", get (h, "markerfacecolor"),
       "markersize", get (h, "markersize"));
endfunction

function update_data (h, ~)
  x = get (h, "xdata");
  y = get (h, "ydata");

  sz = min ([size(x); size(y)]);
  x = x(1:sz(1), 1:sz(2));
  y = y(1:sz(1), 1:sz(2));

  nr = length (x);
  len = 2 * nr - 1;
  xs = ys = zeros (1, len);

  xs(1) = x(1);
  ys(1) = y(1);

  xtmp = x(2:nr);
  ridx = 2:2:len-1;
  xs(ridx) = xtmp;
  ys(ridx) = y(1:nr-1);

  ridx = 3:2:len;
  xs(ridx) = xtmp;
  ys(ridx) = y(2:nr);

  set (get (h, "children"), "xdata", xs, "ydata", ys);
endfunction


%!demo
%! clf;
%! rand_1x10_data1 = [0.073, 0.455, 0.837, 0.124, 0.426, 0.781, 0.004, 0.024, 0.519, 0.698];
%! y = rand_1x10_data1;
%! stairs (y);
%! title ('stairs() plot of y-data');

%!demo
%! clf;
%! x = 1:10;
%! rand_1x10_data2 = [0.014, 0.460, 0.622, 0.394, 0.531, 0.378, 0.466, 0.788, 0.342, 0.893];
%! y = rand_1x10_data2;
%! [xs, ys] = stairs (x, y);
%! plot (xs, ys);
%! title ('plot() of stairs() generated data');

%!demo
%! clf;
%! stairs (1:9, '-o');
%! title ('stairs() plot with linespec to modify marker');

%!demo
%! clf;
%! stairs (9:-1:1, 'marker', 's', 'markersize', 10, 'markerfacecolor', 'm');
%! title ('stairs() plot with prop/val pairs to modify appearance');

%!demo
%! clf;
%! N = 11;
%! x = 0:(N-1);
%! y = rand (1, N);
%! hs = stairs (x(1), y(1));
%! axis ([1, N-1 0, 1]);
%! title ('stairs plot data modified through handle');
%! for k = 2:N
%!   set (hs, 'xdata', x(1:k), 'ydata', y(1:k));
%!   drawnow ();
%!   pause (0.2);
%! end

## Invisible figure used for tests
%!shared hf, hax
%! hf = figure ("visible", "off");
%! hax = axes;

%!error stairs ()
%!error <Y must be a numeric 2-D vector> stairs (hax, {1})
%!error <Y must be a numeric 2-D vector> stairs (ones (2,2,2))
%!error <X and Y must be numeric 2-D vector> stairs ({1}, 1)
%!error <X and Y must be numeric 2-D vector> stairs (1, {1})
%!error <X and Y must be numeric 2-D vector> stairs (ones (2,2,2), 1)
%!error <X and Y must be numeric 2-D vector> stairs (1, ones (2,2,2))
%!error <X and Y sizes must match> stairs (1:2, 1:3)

## Close figure used for testing
%!test
%! close (hf);