function varargout = jsave(filename, varargin)
%
% jsave
%   or
% jsave(fname)
% varlist=jsave(fname,'param1',value1,'param2',value2,...)
%
% Store variables in a workspace to a JSON or binary JSON file
%
% authors:Qianqian Fang (q.fang <at> neu.edu)
% created on 2020/05/31
%
% input:
%      fname: (optional) output file name; if not given, save to 'default.pmat'
%           if fname has a '.json' or '.jdt' suffix, a text-based
%           JSON/JData file will be created (slow); if the suffix is '.pmat' or
%           '.jdb', a Binary JData (https://github.com/NeuroJSON/bjdata/) file will be created.
%      opt: (optional) a struct to store parsing options, opt can be replaced by
%           a list of ('param',value) pairs - the param string is equivalent
%           to a field in opt. opt can have the following
%           fields (first in [.|.] is the default)
%
%           ws ['caller'|'base']: the name of the workspace in which the
%                         variables are to be saved
%           vars [{'var1','var2',...}]: cell array of variable names to be saved
%           matlab [0|1] if set to 1, use matlab's built-in jsonencode to
%                         store encoded data to a json file; output file
%                         must have a suffix of .jdt
%
%           all options for savebj/savejson (depends on file suffix)
%           can be used to adjust the output unless "'matlab',1" is used
%
% output:
%      varlist: a list of variables loaded
%
% examples:
%      jsave  % save all variables in the 'caller' workspace to jamdata.pmat
%      jsave('mydat.pmat','vars', {'v1','v2',...}) % save selected variables
%      jsave('mydat.pmat','compression','lzma')
%
% license:
%     BSD or GPL version 3, see LICENSE_{BSD,GPLv3}.txt files for details
%
% -- this function is part of JSONLab toolbox (http://openjdata.org/jsonlab)
%

if (nargin == 0)
    filename = [pwd filesep 'default.pmat'];
end

opt = varargin2struct(varargin{:});
if (~isfield(opt, 'nthread'))
    opt.nthread = 4;
end
if (~isfield(opt, 'compression'))
    if (exist('zipmat'))
        opt.compression = 'blosc2zstd';
    else
        opt.compression = 'zlib';
    end
end
if (~isfield(opt, 'shuffle'))
    opt.shuffle = 1;
end
if (~isfield(opt, 'typesize'))
    opt.typesize = 4;
end

ws = jsonopt('ws', 'caller', opt);

allvar = evalin(ws, 'whos');
varlist = jsonopt('vars', {allvar.name}, opt);

[isfound, dontsave] = ismember(varlist, {allvar.name});
if (any(isfound == 0))
    error('specified variable is not found');
end

header = struct;
body = struct;

metadata = struct('CreateDate', datestr(now, 29), ...
                  'CreateTime', datestr(now, 'hh:mm:ss'), ...
                  'OriginalName', filename, ...
                  'BJDataVersion', 'v1_draft-2');

vers = ver('MATLAB');
if (isempty(vers))
    vers = ver('Octave');
    [verstr, releasedate] = version;
    vers.Release = verstr;
    vers.Date = releasedate;
end

metadata.CreatorApp = vers.Name;
metadata.CreatorVersion = vers.Version;
metadata.CreatorRelease = vers.Release;
metadata.ReleaseDate = vers.Date;
metadata.FormatVersion = 1;
metadata.Parameters = opt;

header.(encodevarname('_DataInfo_')) = metadata;

for i = 1:length(varlist)
    header.(varlist{i}) = allvar(dontsave(i));
    body.(varlist{i}) = evalin(ws, varlist{i});
end

if (nargout == 1)
    varargout{1} = header;
end

defaultopt = {'compression', opt.compression, 'nthread', opt.nthread, ...
              'shuffle', opt.shuffle, 'typesize', opt.typesize, 'keeptype', 1, 'array2struct', 1};

if (jsonopt('matlab', 0, opt) && exist('jsonencode', 'builtin'))
    if (isempty(regexp(filename, '\.[jJ][sS][oO][nN]$', 'once')))
        filename = regexprep(filename, '\.[a-zA-Z]+$', '.jdt');
    end
    output.WorkspaceHeader = jdataencode(header, 'prefix', 'x', 'base64', 1, varargin{:});
    headerjson = jsonencode(output);
    clear output;

    output.WorkspaceData = jdataencode(body, 'AnnotateArray', 1, 'base64', 1, ...
                                       'UseArrayZipSize', 1, 'MapAsStruct', 1, 'prefix', 'x', defaultopt{:}, varargin{:});
    bodyjson = jsonencode(output);
    clear output;

    fid = fopen(filename, jsonopt('writemode', 'w', opt));
    fwrite(fid, headerjson);
    fwrite(fid, sprintf('\n\n\n'));
    fwrite(fid, bodyjson);
    fclose(fid);
elseif (jsonopt('usemmap', 0, opt) == 1)
    bodyjson = savejd('WorkspaceData', body, ...
                      defaultopt{:}, varargin{:});
    header.(encodevarname('_MMap_')) = loadjd(bodyjson, 'mmaponly', 1, varargin{:});
    savejd('WorkspaceHeader', header, 'filename', filename, varargin{:});
    fid = fopen(filename, 'ab+');
    fwrite(fid, bodyjson);
    fclose(fid);
else
    savejd('WorkspaceHeader', header, 'filename', filename, varargin{:});
    savejd('WorkspaceData', body, 'filename', filename, 'append', 1, ...
           defaultopt{:}, varargin{:});
end