def index(conn, params) do
  memberships = OrganizationMembership
  |> with_filters(params)
  |> preload([:organization, :member])
  |> Repo.all

  render(conn, "index.json-api", data: memberships)
end

defp with_filters(query, params) do
  query
  |> with_organization_filter(params)
  |> with_role_filter(params)
  |> with_member_filter(params)
end

defp with_organization_filter(query, %{"organization_id" => organization_id}) do
  query |> where([om], om.organization_id == ^organization_id)
end
defp with_organization_filter(query, _), do: query

defp with_role_filter(query, %{"roles" => roles}) do
  roles = roles |> coalesce_string
  query |> where([om], om.role in ^roles)
end
defp with_role_filter(query, _), do: query

defp with_member_filter(query, %{"filter" => id_list}) do
  ids = id_list |> coalesce_id_string
  query |> where([om], om.member_id in ^ids)
end
defp with_member_filter(query, _), do: query