public List<ScadaHistogram> prepareHistogram(HistogramDTO histogramDTO) {
		if (histogramDTO == null) {
			return Collections.emptyList();
		}

		Double min = histogramDTO.getMin();
		Double max = histogramDTO.getMax();

		if (min == null || max == null) {
			return Collections.emptyList();
		}

		List<ScadaHistogram> result = new ArrayList<>();
		List<E5ScadaIntervalData> points = new ArrayList<>();
		List<E5ScadaIntervalData> allPoints = new ArrayList<>();

		//pierwszy histogram jest histogramem globalnym
		result.add(generateHistogram(histogramDTO, points, true, null));
		result.get(0).setId((long) -1);
		result.get(0).setType("global");

		//dla serii
		if(histogramDTO.getSeries() != null){
			for(HistogramSerieConfigurationDTO idWithTimeRange : histogramDTO.getSeries()){
				if(idWithTimeRange != null){
					ChartSerieDTO chartSerieDTOArg = new ChartSerieDTO();
					chartSerieDTOArg.setTimeRange(idWithTimeRange.getTimeRange());
					chartSerieDTOArg.setId(idWithTimeRange.getId());
					chartSerieDTOArg.setName(idWithTimeRange.getName());

					//pobierz punkty
					ChartSerieData data = chartSerieDataProvider.getData(chartSerieDTOArg);
					points = data.getData();


					result.add(generateHistogram(histogramDTO, points, true, idWithTimeRange.getColor()));
					result.get(result.size() - 1).setId(idWithTimeRange.getId());
					result.get(result.size() - 1).setType("serie");
					result.get(result.size() - 1).setName(idWithTimeRange.getName());
					allPoints.addAll(points);
				}
			}
		}
		if(histogramDTO.getEquations() != null){
			for(HistogramSerieConfigurationDTO idWithTimeRange : histogramDTO.getEquations()){
				if(idWithTimeRange.getId() != null){
					points = getEquationPoints(idWithTimeRange.getId());
					if (points == null)
						return null;

					result.add(generateHistogram(histogramDTO, points, true, idWithTimeRange.getColor()));
					result.get(result.size() - 1).setId(idWithTimeRange.getId());
					result.get(result.size() - 1).setType("calculation");
					result.get(result.size() - 1).setName(idWithTimeRange.getName());
					allPoints.addAll(points);
				}
			}
		}

		result.get(0).setStatistics(chartDataStatisticsService.calcStatistics(allPoints));
		fillHistogram(result.get(0), allPoints);
		return result;
	}


	private ScadaHistogram generateHistogram(HistogramDTO histogramDTO, List<E5ScadaIntervalData> points, boolean useGlobalMinMax, String color) {
		//min/max do wyznaczenia granic histogramu
		double min, max;

		StatisticsDTO statistics;
		if(points.size() > 0){
			statistics = chartDataStatisticsService.calcStatistics(points);
		}
		else {
			statistics = new StatisticsDTO();
		}

		if(useGlobalMinMax){
			min = histogramDTO.getMin();
			max = histogramDTO.getMax();
		}
		else {
			min = statistics.getMin().getValue();
			max = statistics.getMax().getValue();
		}

		ScadaHistogram histogram = new ScadaHistogram();
		histogram.setColor(color);
		List<ScadaContinuousHistogramData> cols = new ArrayList<>();

		if(histogramDTO.getSplitPoints() != null && !histogramDTO.getSplitPoints().isEmpty()){
			cols = prepareEmptyHistogramColumnsByListOfSplitpoints(histogramDTO.getSplitPoints());
		}
		else if (histogramDTO.getNumOfSplitPoints() > 0){
			cols = prepareEmptyHistogramColumnsByRange(min, max, histogramDTO.getNumOfSplitPoints());
		}

		for(ScadaContinuousHistogramData d : cols) {
			histogram.addColumn(d);
		}

		if(histogram.getColumns().size() > 0){
			fillHistogram(histogram, points);
			((ScadaContinuousHistogramData)histogram.getColumns().get(0)).setMinRange(min);
			((ScadaContinuousHistogramData)histogram.getColumns().get(histogram.getColumns().size() - 1)).setMaxRange(max);

			histogram.setStatistics(statistics);
		}
		return histogram;
	}