defmodule Ami.Role do
  use Bitwise

  def roles do
    [
      :admin,
      :instructor,
      :community_moderator,
      :course_admin,
      :learning_facilitator,
      :buddy,
      :accountibility_partner,
      :respondent,
      :system_admin
    ]
  end

  def roles_from_mask(mask) do
    Enum.reject(roles(), fn role ->
      (mask &&& :math.pow(2, Enum.find_index(roles(), fn r -> r == role end)) |> round) == 0
    end)
  end

  def has_role?(user_struct, role) do
    if user_struct.roles_mask != nil do
      roles_from_mask(user_struct.roles_mask)
      |> Enum.any?(fn r -> r == role end)
    else
      false
    end
  end

  def has_any_role?(user_struct, roles) do
    grants = MapSet.new(roles)

    if user_struct.roles_mask != nil do
      user_roles =
        __MODULE__.roles_from_mask(user_struct.roles_mask)
        |> Enum.into(MapSet.new())

      MapSet.intersection(grants, user_roles) |> MapSet.size() > 0
    else
      false
    end
  end

  def has_all_roles?(user_struct, roles) do
    grants = MapSet.new(roles)

    if user_struct.roles_mask != nil do
      user_roles =
        __MODULE__.roles_from_mask(user_struct.roles_mask)
        |> Enum.into(MapSet.new())

      MapSet.intersection(grants, user_roles)
      |> MapSet.size() == MapSet.size(grants)
    else
      false
    end
  end
end