module Tournaments
  class FillKnockoutSources
    def self.call(tournament)
      new(tournament).call
    end

    def initialize(tournament)
      @tournament = tournament
    end

    def call
      @tournament.matches.find_each do |match|
        next if match.home_source_kind.blank? && match.away_source_kind.blank?
        home = resolve(match, :home)
        away = resolve(match, :away)
        attrs = {}
        attrs[:home_participant] = home if home && match.home_participant_id.blank?
        attrs[:away_participant] = away if away && match.away_participant_id.blank?
        match.update!(attrs) if attrs.any?
      end
    end

    private

    def resolve(match, side)
      kind = match.public_send("#{side}_source_kind")
      case kind
      when "winner_match"
        source = Match.find_by(id: match.public_send("#{side}_source_match_id"))
        source&.winner_participant
      when "group_rank"
        group = TournamentGroup.find_by(id: match.public_send("#{side}_source_group_id"))
        rank = match.public_send("#{side}_source_rank").to_i
        return nil unless group && rank.positive?

        Tournaments::Standings.call(group)[rank - 1]&.participant
      end
    end
  end
end