function selectButterflies ( varargin ) 
% function selectButterflies ( s_img, s_dest ) 
% 
% BRIEF
%   Select bounding boxes for images, save those guys to a specified
%   folder, and keep track of everything with a small cache.
% 
% INPUT
%      either a struct with required fields 's_img' and optional fields 
%      's_dest', 's_cacheDest'
%                     OR
%       combinations of 'string', value for the beforementioned fields
% 
% OUTPUT
%    none
% 

   % fetch specified inputs and set default values if possible
    %% parse inputs
    myInput   = parseMyInputs ( varargin{:} );
   
   % shorten writening
   s_img       = myInput.s_img;
   s_dest      = myInput.s_dest;
   s_cacheDest = myInput.s_cacheDest;   
  
   % check whether a cache is available
   if ( exist ( s_cacheDest ) )
       load ( s_cacheDest, 'cacheButterflies', 'i_counter' );
   end
   

   % current image
   im = imread ( s_img );  
   
   % allocated figures
   figImg   = figure;
   figCrop  = figure;   
   
   b_continueSelection = true;
   
   % ask for 1 bounding box at a time
   i_numBoxesPerClick  = 1;
   
   % image to be shown to the user to visualize currently selected boxes
   imWithBoxes = im;
   
   %
   i_linewidth = 4;
   partcolor = [255,0,0];
   
   % if cache exists, plot the boxes belonging to the current image
   if ( ~exist ( 'cacheButterflies' ) )
       cacheButterflies = struct( 'name', 'rectangle' ) ;
   else
       idxSameImg = strcmp ( {cacheButterflies.name}, s_img);
       bBox = {cacheButterflies.rectangle};
       bBoxSameImg = cell2mat(bBox(idxSameImg));
       imWithBoxes = drawBoxesToImg(imWithBoxes, bBoxSameImg, partcolor, i_linewidth);         
   end
   
   if ( ~exist ( 'i_counter') )
       i_counter = 1 ;
   end   
   
 
   
   
   
   % prompt user help
   s_prompt = sprintf('Press enter for save+continue, r for retry, and X for abort\n');
   
   % ask for selection as long as user is interested...
   while b_continueSelection
      
       % bring bbox-vis figure to front
       figure ( figImg );
       imshow ( imWithBoxes );
       
       % ask for a new bounding box
       [xmin, ymin, xmax, ymax] = clickBoundingBoxes2D ( i_numBoxesPerClick );       
       xmin = int32(round(xmin));
       ymin = int32(round(ymin));
       xmax = int32(round(xmax));
       ymax = int32(round(ymax));
      
       % crop selection and present it to user
       imTmp = imcrop(im, [xmin, ymin, xmax-xmin, ymax-ymin]);
       
       figure ( figCrop );
       imshow ( imTmp );       
       
       % ask user for judgement (okay, retry, abort)
       result = input(s_prompt, 's');
       while ( ~isempty(result) && (strcmp(result,'r')==0) && (strcmp(result,'X')==0) )
           disp(sprintf('Retry input!\n'))
           result = input(s_prompt, 's');
       end
       
       
       % did user wanted to quit?
       if ( strcmp(result,'X') )
           return;
       end
       
       if ( isempty(result) )
           
           % write current proposal
           s_destFig = sprintf('%s_%03d.png',s_dest, i_counter);
           imwrite ( imTmp, s_destFig );

           % save results to cache           
           cacheButterflies( i_counter ).name      = s_img;
           cacheButterflies( i_counter ).rectangle = [xmin,ymin,xmax,ymax];
           i_counter = i_counter +1;           
           save ( s_cacheDest, 'cacheButterflies', 'i_counter' );


           
           
            % plot current result 
            newproposal = [xmin,ymin,xmax,ymax];
            imWithBoxes = drawBoxesToImg(imWithBoxes, newproposal, partcolor, i_linewidth);            
       end
            
   end
   
   
end


function myInput = parseMyInputs(varargin)

    if ( (nargin == 1) && isstruct( varargin{1} ) )
        %% was only a struct given? If so, use it :)
        myInput = varargin{1};
    else
        %% check for explicitely specified settings
        for i=1:2:nargin
            if ( strcmp ( varargin{i},    's_img' ) )
                myInput.s_img          = varargin{i+1};                
            %    
            elseif ( strcmp ( varargin{i}, 's_dest' ) )
                myInput.s_dest         = varargin{i+1};            
            %
            elseif ( strcmp ( varargin{i}, 's_cacheDest' ) )
                myInput.s_cacheDest    = varargin{i+1};            
            % 
            end                    
        end 
    end
    
    
    %% now check default stuff
    checkCrucialField ( myInput, 's_img'  );
    
    myInput = setFieldDefault ( myInput, 's_dest', './butterflies-' );
    myInput = setFieldDefault ( myInput, 's_cacheDest', './cacheButterflies.mat' );
    
   
end


function myInput = setFieldDefault ( myInput, s_fieldname, value )
    if ( ~(isfield(myInput, s_fieldname) ) || isempty(myInput.(s_fieldname)) )
        myInput = setfield( myInput, s_fieldname, value );
    end  
end

function checkCrucialField ( myInput, s_fieldname )
    assert (  (isfield(myInput, s_fieldname) ) && ~isempty(myInput.(s_fieldname)), ...
              sprintf('No %s specified, aborting...', s_fieldname) ...
           );
end