classdef ucfmulti < handle
  % High-level class to treat a directory with UCF files similarly to UCFtar files
  properties (Access = public)
    Directory           % directory name
    Seq                 % sequence number
    IOMode              % file opened in read-only or read-write mode?
    NumberOfSubfiles    % number of subfiles
  end
  properties (Access = private)
    % File info
    fileID
    ioflag
    subFile
    subFileAlias
    subFileSize
    scanBuffSize = 2^17;    % buffer size of scanner (max. number of files in tar) 
  end
  %% ------------------------------------------------------------------------%%
  %%                      CONSTRUCORS/DESTRUCTORS                            %%
  %% ------------------------------------------------------------------------%%
  methods(Access=public)
    function obj = ucfmulti()
      % obj = ucf()
      % Default contructor
      obj.resetPublicProperties();
      obj.resetPrivateProperties();
    end
    function delete(obj)
      % obj.delete()
      % Default destructor
      obj.close();
    end
  end
  %% ------------------------------------------------------------------------%%
  %%                     INITIALIZATION METHODS                              %%
  %% ------------------------------------------------------------------------%%
  methods(Access=public)
    function open(obj,directory,iseq)
      % obj.open(file)
      % Opens a file in read-only mode
      tmp = what(directory);  % get absoulte path
      obj.Directory = tmp.path;
      obj.Seq = iseq;
      obj.IOMode = 'read';
      obj.ioflag = 'r';     
      if ~exist(directory,'dir')
        error('Unable to open directory: %s',obj.Directory);
      end
      obj.scanDirectory();
    end
  end
  %% ------------------------------------------------------------------------%%
  %%                         PUBLIC METHODS                                  %%
  %% ------------------------------------------------------------------------%%
  methods(Access=public)
    function close(obj)
      % obj.close()
      % Closes a file
      if obj.fileID<0
        return;
      end
      status = fclose(obj.fileID);
      if status<0
        warning('Unable to close file (exit code: %d)',status);
        return;
      end
      obj.resetPublicProperties();
      obj.resetPrivateProperties();
      obj.fileID = -1;
    end
    function [ptr] = pointer(obj,fname)
      % [ptr] = obj.pointer(fname)
      % Returns a 'pointer' to the requested file within the tar-ball
      % which can be used to read the data without extracting.
      % Input
      %   fname           file name of subfile within tar-ball
      % Output
      %   ptr             pointer: [fid,first byte,number of bytes]
      if obj.fileID>=0
        fclose(obj.fileID);
      end
      idx = obj.findSubfile(fname);
      filepath = sprintf('%s/%s',obj.Directory,obj.subFile{idx});
      obj.fileID = fopen(filepath,obj.ioflag);
      ptr = [obj.fileID,0,obj.subFileSize(idx)];
    end
    function [fname,fsize] = list(obj)
      % [fname,fsize] = obj.list()
      % Returns a list of name/size of all subfiles within the tar-ball
      % Output
      %   fname           cell array with filenames
      %   fsize           array with file sizes in bytes
      fname = obj.subFileAlias;
      fsize = obj.subFileSize;
    end
    function [flag] = isSubfile(obj,fname)
      % [flag] = obj.isSubfile(fname)
      % Checks if a subfile exists within tar-ball.
      % Input
      %   fname           name of subfile
      flag = any(ismember(obj.subFileAlias,fname));
    end
  end
  %% ------------------------------------------------------------------------%%
  %%                          PRIVATE METHODS                                %%
  %% ------------------------------------------------------------------------%%
  methods(Access=private)
    function scanDirectory(obj)
      % obj.scanArchive()
      % Scans the directory for subfiles and stores meta-data in class variables.
      obj.subFile     = cell(obj.scanBuffSize,1);
      obj.subFileSize = zeros(obj.scanBuffSize,1);
      
      tmp = dir(obj.Directory);
      strseq = sprintf('_%04d.',obj.Seq);
      ii = 0;
      for itmp=1:numel(tmp)
        if tmp(itmp).isdir || isempty(strfind(tmp(itmp).name,strseq))
          continue;
        end
        ii = ii+1;
        obj.subFile{ii} = tmp(itmp).name;
        obj.subFileSize(ii) = tmp(itmp).bytes;
        obj.subFileAlias{ii} = strrep(tmp(itmp).name,strseq,'.');
      end
      % Truncate preallocated arrays
      obj.NumberOfSubfiles = ii;
      obj.subFile     = obj.subFile(1:ii);
      obj.subFileAlias= obj.subFileAlias(1:ii);
      obj.subFileSize = obj.subFileSize(1:ii);
      if obj.NumberOfSubfiles>obj.scanBuffSize
        warning('Number of subfiles exceeds scanBuffSize.');
      end
    end
    function [idx] = findSubfile(obj,fname)
      % [idx] = obj.findSubfile(fname)
      % Get index of requested subfile
      % Input
      %   fname             name of subfile
      % Output
      %   idx               index of subfile
      isReqFile = ismember(obj.subFileAlias,fname);
      switch sum(isReqFile)
      case 0;    error('File not found: %s',fname);
      case 1;
      otherwise; warning('More than one matching file found.');
      end
      idx = find(isReqFile);
    end
    function resetPublicProperties(obj)
      obj.Directory        = [];
      obj.Seq              = [];
      obj.IOMode           = [];
      obj.NumberOfSubfiles = [];
    end
    function resetPrivateProperties(obj)
      obj.ioflag      = [];
      obj.subFile     = [];
      obj.subFileAlias= [];
      obj.subFileSize = [];
    end
  end
end