defmodule ExAdmin.BreadCrumb do
  @moduledoc false
  require Logger

  def get_breadcrumbs(conn, resource) do
    defn = conn.assigns.defn
    get_breadcrumbs conn, resource, defn, Map.get(defn, :page_name), conn.private[:phoenix_action]
  end

  defp get_breadcrumbs(conn, _resource, _, nil, :index) do
    case conn.path_info do
      [admin | _] -> [{admin_link(admin), admin}]
      _ -> []
    end
  end
  defp get_breadcrumbs(conn, _resource, defn, nil, action) when action in [:new, :show, :create] do
    case conn.path_info do
      [admin, name | _] ->
        admin_link = admin_link(admin)
        [{admin_link, admin}, {resource_link(admin_link, name), get_label(defn, name)}]
      _ -> []
    end
  end
  defp get_breadcrumbs(conn, resource, defn, nil, action) when action in [:edit, :update] do
    id = case resource.__struct__.__schema__(:primary_key) do
      [key | _] -> Map.get resource, key
      _ -> nil
    end
    display_name = ExAdmin.Helpers.display_name(resource)
    get_breadcrumbs(conn, resource, defn, nil, :new) ++
    case conn.path_info do
      [admin, name | _] ->
        resource_link = admin_link(admin)
        |> resource_link(name)
        [{resource_link <> "/#{id}", get_name(id, display_name)}]
      _ -> []
    end
  end
  defp get_breadcrumbs(_conn, _resource, _, _, _), do: []

  defp get_name(_id, name) when not is_nil(name), do: to_string(name)
  defp get_name(id, _), do: to_string(id)

  defp get_label(defn, name) do
    case Map.get defn, :menu do
      %{label: label} -> label
      _ -> name
    end
  end

  defp admin_link(admin), do: "/" <> admin
  defp resource_link(admin_link, name), do: admin_link <> "/" <> name

end