# An array of IndexMatch instances returned by the ModelIndex
#
# Index matches can be sorted, filtered and truncated.
#
# Thanks to the fluent interface, the index matches can be manipulated in chain
# from a model index query:
#
# ~~~nitish
# var res = index.find("Foo").
#   uniq.
#	sort(new ScoreComparator, new MEntityComparator).
#	limit(10).
#	sort(new VisibilityComparator)
# ~~~
class IndexMatches
	super Array[IndexMatch]

	# Create a new ModelMatches from an array of matches
	#
	# Elements are copied.
	init from_matches(matches: Array[IndexMatch]) do self.add_all matches

	# Sort the matches with `comparator` (or a list of comparators)
	#
	# Return a new IndexMatches instance with the sorted results.
	#
	# When more than one comparator is given, the comparators are applied in a
	# pipeline where the `n`th comparator is applied only if the `n-1`th comparator
	# returned 0.
	fun sort(comparator: ScoreComparator...): IndexMatches do
		var res = to_a
		if comparator.length == 1 then
			comparator.first.sort res
		else
			var comparators = new MatchComparators(comparator)
			comparators.sort res
		end
		return new IndexMatches.from_matches(res)
	end

	# Limit the matches with `limit`
	#
	# Return a new IndexMatches instance with only the `limit` first matches.
	fun limit(limit: Int): IndexMatches do
		var res = new Array[IndexMatch]
		for match in self do
			if res.length >= limit then break
			res.add match
		end
		return new IndexMatches.from_matches(res)
	end

	# Remove doublons from the matches
	#
	# Preverse the lowest score of all the matches for a MEntity.
	fun uniq: IndexMatches do
		var scores = new HashMap[MEntity, IndexMatch]
		var res = new Array[IndexMatch]
		for match in self do
			var mentity = match.mentity
			if scores.has_key(mentity) then
				var older = scores[mentity]
				if match.score < older.score then older.score = match.score
			else
				scores[mentity] = match
				res.add match
			end
		end
		return new IndexMatches.from_matches(res)
	end

	# Reset score of each matches to follow `self` order
	#
	# Usefull when you need to apply one sorter over another.
	fun rerank: IndexMatches do
		var res = new IndexMatches
		for match in self do
			res.add match
			match.score = res.length
		end
		return res
	end

	# Aggregate the mentities for all the matches
	#
	# Preserve the match order.
	fun mentities: Array[MEntity] do
		var res = new Array[MEntity]
		for match in self do res.add match.mentity
		return res
	end
end