% ========================================================================
% 
% nrrdwriter_dan
% 
% filename  - 'myimage.ext' - 'veins.nrrd'
% matrix    - data - Matlab matrix
% pixelspacing - boxel size
% origin    - point from the image is generated
% encoding  - raw, ascii, gzip
% 
% ========================================================================

function ok = nrrdWriter(filename, matrix, pixelspacing, origin, encoding)

% This line gets the path, name and extension of our file:
% pathf = /home/mario/.../myfile.myext
% fname = myfile
% ext = .myext
[pathf, fname, ext] = fileparts(filename);

format=ext(2:end); % We remove the . from .ext
% so we extract the output format from the argument filename, instead of
% put two different arguments

matrix = permute(matrix, [2 1 3]); % so we undo permute of index in nrrdreader

dims=(size(matrix));    % matrix dimensions (size NxMxP)
ndims=length(dims);     % number of dimensions (dim n)



% =====================================================================
% Conditions to make sure our file is goint to be created succesfully.
% 
% First the code puts the argument 'encoding' in lowercase
encoding = lower(encoding);

encodingCond = isequal(encoding, 'ascii') || isequal(encoding, 'raw') || isequal(encoding, 'gzip');
assert(encodingCond, 'Unsupported encoding')

% The same with output format
format = lower(format);
formatCond = isequal(format,'nhdr') || isequal(format,'nrrd');
assert(formatCond, 'Unexpected format');

% ======================================================================

% Now, if our conditions are satisfied:
if (encodingCond && formatCond)
    
    % Header
    
    % Open, filename (which specifies output format) and write binary
    fid = fopen(filename, 'wb');
    fprintf(fid,'NRRD0004\n');      % NRRD type 4
    
    % Type of variable we're storing in our file
    mtype=class(matrix);
    outtype=setDatatype(mtype);
    fprintf(fid,['type: ', outtype, '\n']);
    
    % 
    fprintf(fid,['dimension: ', num2str(ndims), '\n']);
    
    if isequal(ndims, 2)
        fprintf(fid,'space: left-posterior\n');
    elseif isequal (ndims, 3)
        fprintf(fid,'space: left-posterior-superior\n');
    end

    fprintf(fid,['sizes: ', num2str(dims), '\n']);
    
    if isequal(ndims, 2)
        fprintf(fid,['space directions: (', num2str(pixelspacing(1)), ...
            ',0) (0,', num2str(pixelspacing(2)), ')\n']);
        fprintf(fid,'kinds: domain domain\n');
    elseif isequal (ndims, 3)
        fprintf(fid,['space directions: (', num2str(pixelspacing(1)), ...
            ',0,0) (0,', num2str(pixelspacing(2)), ',0) (0,0,', ...
            num2str(pixelspacing(3)), ')\n']);
        fprintf(fid,'kinds: domain domain domain\n');
    end
    
    fprintf(fid,['encoding: ', encoding, '\n']);
    
    [~,~,endian] = computer();
    
    if (isequal(endian, 'B'))
        fprintf(fid,'endian: big\n');
    else
        fprintf(fid,'endian: little\n');
    end
    
    if isequal(ndims, 2)
        fprintf(fid,['space origin: (', num2str(origin(1)),',', num2str(origin(2)),')\n']);
    elseif isequal (ndims, 3)
        fprintf(fid,['space origin: (', num2str(origin(1)), ...
            ',',num2str(origin(2)),',', num2str(origin(3)),')\n']);
    end    
    
    if (isequal(format, 'nhdr')) % Si hay que separar
        % Escribir el nombre del fichero con los datos
        fprintf(fid, ['data file: ', [fname, '.', encoding], '\n']);
        
        fclose(fid);
        if isequal(length(pathf),0)
            fid = fopen([fname, '.', encoding], 'wb');
        else
            fid = fopen([pathf, filesep, fname, '.', encoding], 'wb');
        end
    else
        fprintf(fid,'\n');
    end
    
    ok = writeData(fid, matrix, outtype, encoding);
    fclose(fid);
end


% ========================================================================
% Determine the datatype --> From mtype (matlab) to outtype (NRRD) -->    
% ========================================================================
function datatype = setDatatype(metaType)

% Determine the datatype
switch (metaType)
 case {'int8', 'uint8', 'int16', 'uint16', 'int32', 'uint32', 'int64',...
       'uint64', 'double'}
   datatype = metaType;
  
 case {'single'}
  datatype = 'float';
  
 otherwise
  assert(false, 'Unknown datatype')
end
   
% HACER!!!!!!!!!!!!!!!!!!!!!!!!!
% ========================================================================
% writeData -->
% fidIn is the open file we're overwriting
% matrix - data that have to be written
% datatype - type of data: int8, string, double...
% encoding - raw, gzip, ascii
% ========================================================================
function ok = writeData(fidIn, matrix, datatype, encoding)

switch (encoding)
 case {'raw'}
  
  ok = fwrite(fidIn, matrix(:), datatype);
  
 case {'gzip'}
     
     % Store in a raw file before compressing
     tmpBase = tempname(pwd);
     tmpFile = [tmpBase '.gz'];
     fidTmpRaw = fopen(tmpBase, 'wb');
     assert(fidTmpRaw > 3, 'Could not open temporary file for GZIP compression');
     
     fwrite(fidTmpRaw, matrix(:), datatype);
     fclose(fidTmpRaw);
     
     % Now we gzip our raw file
     gzip(tmpBase);
     
     % Finally, we put this info into our nrrd file (fidIn)
     fidTmpRaw = fopen(tmpFile, 'rb');
     tmp = fread(fidTmpRaw, inf, [datatype '=>' datatype]);
     cleaner = onCleanup(@() fclose(fidTmpRaw));
     ok = fwrite (fidIn, tmp, datatype);
     
     delete (tmpBase);
     delete (tmpFile);


 case {'ascii'}
  
  ok = fprintf(fidIn,'%u ',matrix(:));
  %ok = fprintf(fidIn,matrix(:), class(matrix));
  
 otherwise
  assert(false, 'Unsupported encoding')
end