% EEG_MERGELOCS - merge channel structure while preserving channel
%                   order
%
%      >> mergedlocs = eeg_mergelocs(loc1, loc2, loc3, ...);
%
% Inputs: 
%     loc1     - EEGLAB channel location structure
%     loc2     - second EEGLAB channel location structure
%
% Output: 
%     mergedlocs - merged channel location structure
%     warning    - [0|1] dissimilar structures found (0=false, 1=true)
%
% Author: Arnaud Delorme, August 2006

% Copyright (C) Arnaud Delorme, CERCO, 2006, arno@salk.edu
%
% This file is part of EEGLAB, see http://www.eeglab.org
% for the documentation and details.
%
% Redistribution and use in source and binary forms, with or without
% modification, are permitted provided that the following conditions are met:
%
% 1. Redistributions of source code must retain the above copyright notice,
% this list of conditions and the following disclaimer.
%
% 2. Redistributions in binary form must reproduce the above copyright notice,
% this list of conditions and the following disclaimer in the documentation
% and/or other materials provided with the distribution.
%
% THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
% AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
% IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
% ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
% LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
% CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
% SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
% INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
% CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
% ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
% THE POSSIBILITY OF SUCH DAMAGE.

function [alllocs warn] = eeg_mergelocs(varargin)

persistent warning_shown;
warn = 0;

try
    % sort by length
    % --------------
    len = cellfun(@length, varargin);
    [tmp so] = sort(len, 2, 'descend');
    varargin = varargin(so);

    alllocs = varargin{1};
    for index = 2:length(varargin)

        % fuse while preserving order (assumes the same channel order)
        % ------------------------------------------------------------
        tmplocs = varargin{index};
        newlocs = myunion(alllocs, tmplocs);

        if length(newlocs) > length(union({ alllocs.labels }, { tmplocs.labels }))

            warn = 1;
            if isempty(warning_shown)
                disp('Warning: different channel montage or electrode order for the different datasets');
                warning_shown = 1;
            end

            % trying to preserve order of the longest array
            %----------------------------------------------
            if length(alllocs) < length(tmplocs)
                tmp     = alllocs;
                alllocs = tmplocs;
                tmplocs = tmp;
            end
            allchans = { alllocs.labels tmplocs.labels };
            [uniquechan, ord1, ord2 ]  = unique_bc( lower(allchans) );

            [~, rminds] = intersect_bc( uniquechan, lower({ alllocs.labels }));
            ord1(rminds) = [];
            tmplocsind = ord1-length(alllocs);

            newlocs = [ alllocs tmplocs(tmplocsind) ];

        end
        alllocs = newlocs;
    end
catch
    % temporary fix for dissimilar structures
    % should check channel structure consistency instead
    % using checkchan function
    disp('Channel merging warning: dissimilar fields in the two structures');
    [alllocs, warn ] = eeg_mergelocs_diffstruct(varargin{:});
end

% Checking consistency of chanlocs
alllocs = eeg_checkchanlocs(alllocs);

% union of two channel location structure
% without losing the order information
% ---------------------------------------
function alllocs = myunion(locs1, locs2)

   labs1 = { locs1.labels };
   labs2 = { locs2.labels };
   
   count1 = 1;
   count2 = 1;
   count3 = 1;
   alllocs = locs1; alllocs(:) = [];
   while count1 <= length(locs1) || count2 <= length(locs2)
       
       if count1 > length(locs1)
           alllocs(count3) = locs2(count2);
           count2 = count2 + 1;
           count3 = count3 + 1;
       elseif count2 > length(locs2)
           alllocs(count3) = locs1(count1);
           count1 = count1 + 1;
           count3 = count3 + 1;
       elseif strcmpi(labs1{count1}, labs2{count2})
           alllocs(count3) = locs1(count1);
           count1 = count1 + 1;
           count2 = count2 + 1;
           count3 = count3 + 1;
       elseif isempty(strmatch(lower(labs1{count1}), lower(labs2), 'exact'))
           alllocs(count3) = locs1(count1);
           count1 = count1 + 1;
           count3 = count3 + 1;
       else 
           alllocs(count3) = locs2(count2);
           count2 = count2 + 1;
           count3 = count3 + 1;
       end
       
   end