# A MetricSet is a metric holder
#
# It purpose is to be extended with a metric collect service
class MetricSet

	# Type of element measured by this `MetricSet`.
	type ELM: Object

	# Metrics to compute
	var metrics: Set[Metric] = new HashSet[Metric]

	# Add a metric to the set
	fun register(metrics: Metric...) do for metric in metrics do self.metrics.add(metric)

	# Clear all results for all metrics
	fun clear do for metric in metrics do metric.clear

	# Collect all metrics for this set of class
	fun collect(elements: Set[ELM]) do
		for metric in metrics do metric.collect(elements)
	end

	# Pretty print the resuls in console
	fun to_console(indent: Int, colors: Bool) do
		for metric in metrics do metric.to_console(indent, colors)
	end

	# Export the metric set in CSV format
	fun to_csv: CsvDocument do
		var csv = new CsvDocument
		csv.separator = ';'

		# set csv headers
		csv.header.add("entry")
		for metric in metrics do csv.header.add(metric.name)

		# collect all entries to merge metric results
		var entries = new HashSet[ELM]
		for metric in metrics do
			for entry in metric.values.keys do entries.add(entry)
		end

		# collect results
		for entry in entries do
			var line = [entry.to_s]
			for metric in metrics do
				if metric.has_element(entry) then
					line.add(metric[entry].to_s)
				else
					line.add("n/a")
				end
			end
			csv.records.add(line)
		end
		return csv
	end
end