extends RefCounted

# Mirrors api/QuestionsApi/Services/Flashcards/FlashcardClozeParser.cs so the study screen can
# render a cloze note's front/back without a round trip to the server.

static func _regex() -> RegEx:
	var regex := RegEx.new()
	regex.compile("(?s)\\{\\{c(\\d+)::((?:(?!\\}\\}).)*)\\}\\}")
	return regex


static func render_front(text: String, cloze_number: int) -> String:
	var regex := _regex()
	var result := ""
	var last_end := 0
	for match in regex.search_all(text):
		result += text.substr(last_end, match.get_start() - last_end)
		var number := int(match.get_string(1))
		var inner := match.get_string(2)
		var parts := inner.split("::", true, 1)
		if number == cloze_number:
			var hint := parts[1].strip_edges() if parts.size() > 1 else ""
			result += ("[%s]" % hint) if not hint.is_empty() else "[...]"
		else:
			result += parts[0].strip_edges()
		last_end = match.get_end()
	result += text.substr(last_end)
	return result


static func render_back(text: String) -> String:
	var regex := _regex()
	var result := ""
	var last_end := 0
	for match in regex.search_all(text):
		result += text.substr(last_end, match.get_start() - last_end)
		var inner := match.get_string(2)
		result += inner.split("::", true, 1)[0].strip_edges()
		last_end = match.get_end()
	result += text.substr(last_end)
	return result