function L=fwtlength(Ls,w,J,varargin)
%-*- texinfo -*-
%@deftypefn {Function} fwtlength
%@verbatim
%FWTLENGTH  FWT length from signal
%   Usage: L=fwtlength(Ls,w,J);
%
%   FWTLENGTH(Ls,w,J) returns the length of a Wavelet system that is long
%   enough to expand a signal of length Ls. Please see the help on
%   FWT for an explanation of the parameters w and J.
%
%   If the returned length is longer than the signal length, the signal
%   will be zero-padded by FWT to length L.
%
%   In addition, the function accepts flags defining boundary extension
%   technique as in FWT. The returned length can be longer than the
%   signal length only in case of 'per' (periodic extension).
%
%@end verbatim
%@strong{Url}: @url{http://ltfat.github.io/doc/wavelets/fwtlength.html}
%@seealso{fwt}
%@end deftypefn

% Copyright (C) 2005-2023 Peter L. Soendergaard <peter@sonderport.dk> and others.
% This file is part of LTFAT version 2.6.0
%
% This program 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.
%
% This program 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 program.  If not, see <http://www.gnu.org/licenses/>.

% AUTHOR: Zdenek Prusa

complainif_notposint(Ls,'Ls','FWTLENGTH');
complainif_notposint(J,'J','FWTLENGTH');

% Initialize the wavelet filters structure
w = fwtinit(w);

definput.import = {'fwtext'};
[flags,kv]=ltfatarghelper({},definput,varargin);

if flags.do_per
   blocksize=w.a(1)^J;
   L=ceil(Ls/blocksize)*blocksize;
% elseif flags.do_valid
%    m = numel(w.g{1}.h);
%    a = w.a(1);
%    rred = (a^J-1)/(a-1)*(m-a);
%    blocksize=w.a(1)^J;
%    L=rred+floor((Ls-rred)/blocksize)*blocksize;
else
   L = Ls;
end

