function[obj] = label(obj, params)
%% extract labels from all MSG events


%% Step 1: read pattern from label_pattern (the varying part)
for p = 1:length(obj.label_patterns)
    [token remainder] = strtok(obj.label_patterns{p},'%');
    match{p} = strtrim(token);
    
    if isempty(match{p})        
        match{p} = strtrim(strtok(remainder));
    end    
end

%% allocate only MSG events
msg_ind = regexp(obj.events_, 'MSG');
ind = find(~cellfun(@isempty,msg_ind));

l_ind = 1;

if (exist('match', 'var'))

for m = 1:length(match)    
    %% match all messages at once
    s = regexp(obj.events_(ind), match{m});
    m_ind = find(~cellfun(@isempty,s));
    
    % m_ind now contains all events, that contain the match
    for pe = 1:length(m_ind);
        event_ind = ind(m_ind(pe));
        
        label_timestamp= sscanf(obj.events_{event_ind},'%*s %d %*s');
        pos = s{m_ind(pe)} + length(match{m});
        
        obj.labels(l_ind).time = label_timestamp;
        obj.labels(l_ind).label = strtrim(obj.events_{event_ind}(pos:end));
        obj.labels(l_ind).match = match{m};
        obj.labels(l_ind).type = 'normal';
        obj.labels(l_ind).color = [0.4 0.4 0.4];
        l_ind = l_ind + 1;
    end                     
end
end
%% hook all matches up to stimuli


for t = 1:length(obj.trials)
    
    trial = obj.trials(t);

    %% in case no labels are defined, continue..
    if (isempty(obj.labels))        
        continue;
    end
    
    for l = 1:length(obj.labels)
        label_timestamps(l) = obj.labels(l).time(1);
    end
               
    % labels are set before or during
    earlier_labels = find(label_timestamps < trial.trial_end);
    later_labels = find(label_timestamps > trial.trial_start);
    
    % variable is set during trial:
    common = intersect(earlier_labels, later_labels);
    
    if isempty(params.ForcePrecursorLabels)
        params.ForcePrecursorLabels{2} = 0;
    end
    
    if	(~params.ForcePrecursorLabels{2} && ~isempty(common))
                trial.labels = obj.labels(common);        
        else
        
        % no variables set during, perhaps a precursor variable?
        if ~isempty(earlier_labels)
            if t > 1
                %% check later than previous trials
                previous_trial = obj.trials(t-1);
                later_than_previous = find(label_timestamps >= previous_trial.trial_end);
                precursors = intersect(earlier_labels, later_than_previous);
     
                trial.labels = obj.labels(precursors);
            else
                trial.labels = obj.labels(earlier_labels);
            end
        end
    end
    
    %% assign variables to trial in field 'type'
    for l = 1:length(trial.labels)
        varname = regexprep(trial.labels(l).match,'\s' ,'_');
        trial.type.(varname) = trial.labels(l).label;
    end
        
    obj.trials(t) = trial;
end