function [cal, cals, fullFilename] = LoadCalFile(filespec, whichCal, dir, noWarning)
% [cal, cals, fullFilename] = LoadCalFile([filespec], [whichCal], [dir], [noWarning])
%
% Load calibration data from saved file in the CalData folder.
% Will search one level deep in the CalData folder if the
% file does not exist at the top level, but skips subdirs
% called 'xOld', 'Plots', and those that begin with '.'.
%
% If no argument is given, loads from file default.mat.  If
% an integer N is passed, loads from file screenN.mat.  If
% a string S is given, loads from S.mat.  You can pass the
% trailing .mat as well and it will still work.
%
% If whichCal is specified, the whichCal'th calibration
% in the file is returned.  If whichCal > nCals, an
% empty calibration is returned.  whichCal defaults
% to the most recent calibration, if not passed or passed
% as the empty matrix.  You can also pass Inf for whichCal
% to get the most recent calibration.
%
% If the specified file cannot be found, returns empty matrix.
%
% The returned variable cal is a structure containing calibration
% information.
%
% The returned cell array cals contains all of the calibrations
% stored in the file
%
% The returned string fullFilename is the full path to the calibration
% file.
%
% See also SaveCalFile, CalDataFolder.
%
% 5/28/96  dgp  Wrote it.
% 6/6/96   dgp  Use CalibrationsFolder.
% 6/6/96   dgp  Use whole path in filename so Matlab will only look there.
% 7/25/96  dgp  Use CalDataFolder.
% 8/4/96   dhb  More flexible filename interface.
% 8/21/97  dhb  Rewrite for calibrations stored as cell array.
%               Optional return of entire calibration history.
% 8/26/97  dhb  Handle case of isempty(cals).
%               Added whichCal argument.
% 5/18/99  dhb  Added dir argument.
% 8/15/00  dhb  Modify to handle local/demo cal directories.
% 4/2/13   dhb  Updated for subdir searching logic.
% 6/2/13   dhb  More robust about whether passed filespec contains the trailing '.mat'.
% 7/3/13   dhb  Fix buglet for check on trailing .mat when length of filename less than 4 chars.
% 12/11/14 dhb  Use fullfile rather than straight append to build up full path to cal file.
% 10/23/15 dhb  Suppress warning about enumeration being converted to
%               struct on load.  This can happen when the cal struct contains a field
%               that is an ennumeration, but is, I think, OK.

% Get whichCal
if nargin < 2 || isempty(whichCal)
    whichCal = Inf;
end

% Set filespec
if (nargin < 1 || isempty(filespec))
    filename = ['default.mat'];
elseif (ischar(filespec))
    if (length(filespec) < 4 || ~strcmp(filespec(end-3:end),'.mat'))
        filename = [filespec '.mat'];
    else
        filename = filespec;
    end
else
    filename = [sprintf('screen%d.mat', filespec)];
end

% Warning?
if (nargin < 4 || isempty(noWarning))
    noWarning = false;
end

% Set the directory if first character of passed filename is not
% the filesep character.  In the latter case, we assume that the full
% path to the desired calibration file was passed.
if nargin < 3 || isempty(dir)
    useDir = CalDataFolder(0,filename,[],noWarning);
else
    useDir = CalDataFolder(0,filename,dir,noWarning);
end
fullFilename = fullfile(useDir,filename);

% If the file doesn't exist in the usual location, take a look in the
% secondary location.
if (~exist(fullFilename, 'file') && (nargin < 3 || isempty(dir)))
    useDir = CalDataFolder(1,filename,[],noWarning);
    fullFilename = [useDir filename];
end

% Now read the sucker if it is there.
if exist(fullFilename, 'file')
    s = warning('off','MATLAB:class:EnumerationNameMissing');
    eval(['load ' QuoteString(fullFilename)]);
    warning(s.state,'MATLAB:class:EnumerationNameMissing');
    if isempty(cals) %#ok<NODEF>
        cal = [];
    else
        % Get the number of calibrations.
        nCals = length(cals);
        
        % User the most recent calibration (the last one in the cals cell
        % array) by default.  If the user specified a particular cal file
        % try to retrieve it or return an empty matrix if the cal index is
        % out of range.
        if whichCal == Inf
            cal = cals{nCals};
        elseif whichCal > nCals || whichCal < 1
            cal = [];
        else
            cal = cals{whichCal};
        end
    end
else
    cal = [];
    cals = {};
end