defmodule NullaWeb.ActivityPub.FollowJSON do
  def following(actor, total) do
    Jason.OrderedObject.new(
      "@context": "https://www.w3.org/ns/activitystreams",
      id: "#{actor.ap_id}/following",
      type: "OrderedCollection",
      totalItems: total,
      first: "#{actor.ap_id}/following?page=1"
    )
  end

  def following(actor, total, following_list, page, limit) when is_integer(page) and page > 0 do
    data = [
      "@context": "https://www.w3.org/ns/activitystreams",
      id: "#{actor.ap_id}/following?page=#{page}",
      type: "OrderedCollectionPage",
      totalItems: total,
      next: "#{actor.ap_id}/following?page=#{page + 1}",
      prev: "#{actor.ap_id}/following?page=#{page - 1}",
      partOf: "#{actor.ap_id}/following",
      orderedItems: following_list
    ]

    data =
      if page <= 1 do
        Keyword.delete(data, :prev)
      else
        data
      end

    data =
      if page * limit > total do
        data
        |> Keyword.delete(:next)
        |> Keyword.delete(:prev)
      else
        data
      end

    Jason.OrderedObject.new(data)
  end

  def followers(actor, total) do
    Jason.OrderedObject.new(
      "@context": "https://www.w3.org/ns/activitystreams",
      id: "#{actor.ap_id}/followers",
      type: "OrderedCollection",
      totalItems: total,
      first: "#{actor.ap_id}/followers?page=1"
    )
  end

  def followers(actor, total, followers_list, page, limit)
      when is_integer(page) and page > 0 do
    data = [
      "@context": "https://www.w3.org/ns/activitystreams",
      id: "#{actor.ap_id}/followers?page=#{page}",
      type: "OrderedCollectionPage",
      totalItems: total,
      next: "#{actor.ap_id}/followers?page=#{page + 1}",
      prev: "#{actor.ap_id}/followers?page=#{page - 1}",
      partOf: "#{actor.ap_id}/followers",
      orderedItems: followers_list
    ]

    data =
      if page <= 1 do
        Keyword.delete(data, :prev)
      else
        data
      end

    data =
      if page * limit > total do
        data
        |> Keyword.delete(:next)
        |> Keyword.delete(:prev)
      else
        data
      end

    Jason.OrderedObject.new(data)
  end
end