discourse/app/services/spam_rules_enforcer.rb

# The SpamRulesEnforcer class takes action against users based on flags that their posts
# receive, their trust level, etc.
class SpamRulesEnforcer

  include Rails.application.routes.url_helpers

  # The exclamation point means that this method may make big changes to posts and the user.
  def self.enforce!(user)
    SpamRulesEnforcer.new(user).enforce!
  end

  def self.block?(user)
    SpamRulesEnforcer.new(user).block?
  end

  def self.punish!(user)
    SpamRulesEnforcer.new(user).punish_user
  end


  def initialize(user)
    @user = user
  end

  def enforce!
    punish_user if block?
    true
  end

  def block?
    @user.blocked? or
      (!@user.has_trust_level?(:basic) and
        SiteSetting.num_flags_to_block_new_user > 0 and
        SiteSetting.num_users_to_block_new_user > 0 and
        num_spam_flags_against_user >= SiteSetting.num_flags_to_block_new_user and
        num_users_who_flagged_spam_against_user >= SiteSetting.num_users_to_block_new_user)
  end

  def num_spam_flags_against_user
    Post.where(user_id: @user.id).sum(:spam_count)
  end

  def num_users_who_flagged_spam_against_user
    post_ids = Post.where('user_id = ? and spam_count > 0', @user.id).pluck(:id)
    return 0 if post_ids.empty?
    PostAction.spam_flags.where(post_id: post_ids).uniq.pluck(:user_id).size
  end

  def punish_user
    Post.transaction do
      UserBlocker.block(@user, nil, {message: :too_many_spam_flags})
      GroupMessage.create(Group[:moderators].name, :user_automatically_blocked, {user: @user, limit_once_per: false})
    end
  end


end