class Ability
  class << self
    # Given a list of users and a project this method returns the users that can
    # read the given project.
    def users_that_can_read_project(users, project)
      if project.public?
        users
      else
        users.select do |user|
          if user.admin?
            true
          elsif project.internal? && !user.external?
            true
          elsif project.owner == user
            true
          elsif project.team.members.include?(user)
            true
          else
            false
          end
        end
      end
    end

    # Given a list of users and a snippet this method returns the users that can
    # read the given snippet.
    def users_that_can_read_personal_snippet(users, snippet)
      case snippet.visibility_level
      when Snippet::INTERNAL, Snippet::PUBLIC
        users
      when Snippet::PRIVATE
        users.include?(snippet.author) ? [snippet.author] : []
      end
    end

    # Returns an Array of Issues that can be read by the given user.
    #
    # issues - The issues to reduce down to those readable by the user.
    # user - The User for which to check the issues
    def issues_readable_by_user(issues, user = nil)
      return issues if user && user.admin?

      issues.select { |issue| issue.visible_to_user?(user) }
    end

    # TODO: make this private and use the actual abilities stuff for this
    def can_edit_note?(user, note)
      return false if !note.editable? || !user.present?
      return true if note.author == user || user.admin?

      if note.project
        max_access_level = note.project.team.max_member_access(user.id)
        max_access_level >= Gitlab::Access::MASTER
      else
        false
      end
    end

    def allowed?(user, action, subject = :global)
      allowed(user, subject).include?(action)
    end

    def allowed(user, subject = :global)
      return BasePolicy::RuleSet.none if subject.nil?
      return uncached_allowed(user, subject) unless RequestStore.active?

      user_key = user ? user.id : 'anonymous'
      subject_key = subject == :global ? 'global' : "#{subject.class.name}/#{subject.id}"
      key = "/ability/#{user_key}/#{subject_key}"
      RequestStore[key] ||= uncached_allowed(user, subject).freeze
    end

    private

    def uncached_allowed(user, subject)
      BasePolicy.class_for(subject).abilities(user, subject)
    end
  end
end