accessible.rb

module Accessible
  extend ActiveSupport::Concern

  included do
    has_many :accessibilities, as: :accessible, dependent: :destroy
    has_many :roles, -> { uniq }, through: :accessibilities
    scope :visible_to, ->(role_names) {
      role_names = [role_names] if [String, Symbol].include?(role_names.class)
      if role_names.include?(Role::ROOT_ROLE)
        all
      else
        joins(:roles).where(roles: {title: role_names})
      end
    }
    # validates :roles, presence: true
    after_save :update_visibility
  end

  VISIBILITIES = {
    public: %w(guest rookie patriot),
    team: %w(rookie patriot)#,
    # patriot: %w(patriot)
  }

  attr_accessor :visibility

  def visible_to
    roles.pluck(:title)
  end
  
  def visible_to?(role_titles)
    role_titles = [role_titles] if [String, Symbol].include?(role_titles.class)
    role_titles.map!{|role_name| role_name.to_s}
    if role_titles.include?(Role::ROOT_ROLE)
      true
    else
      (role_titles & roles.pluck(:title)).any?
    end
  end

  def allow_for(role_titles = [])
    role_titles = [role_titles] if [String, Symbol].include?(role_titles.class)
    if role_titles && role_titles.any?
      role_titles.map!{|role_name| role_name.to_s} 
    else
      Role.pluck(:title)
      return
    end
    role_titles.uniq.compact.each do |role_title|
      role = Role.where(title: role_title).first_or_create
      roles << role unless visible_to?(role.title)
    end
    roles
  end

  def update_roles(role_titles = [])
    role_titles = [role_titles] if [String, Symbol].include?(role_titles.class)
    if role_titles && role_titles.any?
      role_titles.map!{|role_name| role_name.to_s} 
    else
      Role.pluck(:title)
      return
    end
    roles.destroy_all
    role_titles.uniq.compact.each do |role_title|
      role = Role.where(title: role_title).first_or_create
      roles << role unless visible_to?(role.title)
    end
    roles
  end

  def disallow_for(role_titles = [])
    role_titles = [role_titles] if [String, Symbol].include?(role_titles.class)
    role_titles.map!{|role_name| role_name.to_s}
    return Role.pluck(:title) if role_titles.empty?
    role_titles.uniq.compact.each do |role_title|
    role_titles.map!{|role_name| role_name.to_s}
      role = Role.where(title: role_title).first_or_create
      roles.delete role if visible_to?(role.title)
    end
    roles
  end

  private

    def update_visibility
      puts "AAA"
      update_roles(VISIBILITIES[visibility.to_sym]) if visibility
    end
end

post_policy.rb

class PostPolicy < ApplicationPolicy
  class Scope < Struct.new(:user, :scope)
    def resolve
      if user
        scope.visible_to(user.roles.pluck(:title))
      else
        scope.visible_to(:guest).not_notices.order(:created_at)
      end
    end
  end

  def show?
    if user
      record.visible_to? user.role_names
    else
      record.visible_to?(:guest)
    end
  end

  def create?
    deppkind? || (user && user.has_role?(:patriot))
  end
  
  def update?
    deppkind? #|| (user && record.author == user)
  end

  def destroy?
    deppkind? || (user && record.user == user)
  end
end