discourse/app/services/spam_rule/auto_silence.rb

class SpamRule::AutoSilence

  attr_reader :group_message

  def initialize(user, post = nil)
    @user = user
    @post = post
  end

  def perform
    I18n.with_locale(SiteSetting.default_locale) do
      silence_user if should_autosilence?
    end
  end

  def self.prevent_posting?(user)
    user.blank? || user.silenced? || new(user).should_autosilence?
  end

  def should_autosilence?
    return false if @user.blank?
    return false if @user.staged?
    return false if @user.has_trust_level?(TrustLevel[1])

    if SiteSetting.num_spam_flags_to_silence_new_user > 0 &&
        SiteSetting.num_users_to_silence_new_user > 0 &&
        num_spam_flags_against_user >= SiteSetting.num_spam_flags_to_silence_new_user &&
        num_users_who_flagged_spam_against_user >= SiteSetting.num_users_to_silence_new_user
      return true
    end

    if SiteSetting.num_tl3_flags_to_silence_new_user > 0 &&
        SiteSetting.num_tl3_users_to_silence_new_user > 0 &&
        num_tl3_flags_against_user >= SiteSetting.num_tl3_flags_to_silence_new_user &&
        num_tl3_users_who_flagged >= SiteSetting.num_tl3_users_to_silence_new_user
      return true
    end

    false
  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).pluck(:user_id).uniq.size
  end

  def num_tl3_flags_against_user
    if flagged_post_ids.empty?
      0
    else
      PostAction.where(post_id: flagged_post_ids).joins(:user).where('users.trust_level >= ?', 3).count
    end
  end

  def num_tl3_users_who_flagged
    if flagged_post_ids.empty?
      0
    else
      PostAction.where(post_id: flagged_post_ids).joins(:user).where('users.trust_level >= ?', 3).pluck(:user_id).uniq.size
    end
  end

  def flagged_post_ids
    Post.where(user_id: @user.id)
      .where('spam_count > 0 OR off_topic_count > 0 OR inappropriate_count > 0')
      .pluck(:id)
  end

  def silence_user
    Post.transaction do

      silencer = UserSilencer.new(
        @user,
        Discourse.system_user,
        message: :too_many_spam_flags,
        post_id: @post&.id
      )

      if silencer.silence && SiteSetting.notify_mods_when_user_silenced
        @group_message = GroupMessage.create(Group[:moderators].name, :user_automatically_silenced, user: @user, limit_once_per: false)
      end
    end
  end
end