defmodule ClacksWeb.FrontendView do
  use ClacksWeb, :view
  alias Clacks.{Actor, Activity, Repo, Notification, Object}
  alias ClacksWeb.Router.Helpers, as: Routes
  alias ClacksWeb.Endpoint
  require Logger

  @spec display_username(actor :: Actor.t()) :: String.t()

  def display_username(%Actor{local: true, data: %{"preferredUsername" => username}}) do
    "@" <> username
  end

  def display_username(%Actor{
        local: false,
        ap_id: ap_id,
        data: %{"preferredUsername" => username}
      }) do
    %URI{host: host} = URI.parse(ap_id)
    "@" <> username <> "@" <> host
  end

  @spec display_name(actor :: Actor.t()) :: String.t()

  def display_name(%Actor{data: %{"name" => name, "preferredUsername" => username}}) do
    if is_binary(name) && String.length(name) > 0 do
      name
    else
      username
    end
  end

  def local_actor_link(%Actor{local: true, ap_id: ap_id}), do: ap_id

  def local_actor_link(%Actor{local: false, id: id}),
    do: Routes.frontend_path(Endpoint, :actor, id)

  @spec display_timestamp(
          datetime :: String.t() | DateTime.t() | NaiveDateTime.t() | Activity.t()
        ) :: String.t()

  def display_timestamp(str) when is_binary(str) do
    display_timestamp(Timex.parse!(str, "{ISO:Extended}"))
  end

  def display_timestamp(%Activity{data: data, inserted_at: inserted_at}) do
    display_timestamp(Map.get(data, "published", inserted_at))
  end

  def display_timestamp(%{__struct__: struct} = datetime)
      when struct == DateTime or struct == NaiveDateTime do
    diff = Timex.diff(Timex.now(), datetime, :seconds)

    cond do
      diff < 60 ->
        # less than a minute, seconds
        "#{diff}sec"

      diff < 60 * 60 ->
        # less than an hour, minutes
        "#{Integer.floor_div(diff, 60)}min"

      diff < 60 * 60 * 24 ->
        # less than a day, hours
        "#{Integer.floor_div(diff, 60 * 60)}hr"

      diff < 60 * 60 * 24 * 7 ->
        # less than a week, days
        "#{Integer.floor_div(diff, 60 * 60 * 24)}d"

      diff < 60 * 60 * 24 * 30 ->
        # less than a month(ish), weeks
        "#{Integer.floor_div(diff, 60 * 60 * 24 * 7)}wk"

      diff < 60 * 60 * 24 * 365 ->
        # less than a year, months(ish)
        # todo: figure out actually how many months
        "#{Integer.floor_div(diff, 60 * 60 * 24 * 30)}mo"

      true ->
        Timex.format!(datetime, "%F", :strftime)
    end
  end

  @spec iso_datetime(datetime :: String.t() | DateTime.t() | NaiveDateTime.t() | Activity.t()) ::
          String.t()

  def iso_datetime(str) when is_binary(str) do
    str
  end

  def iso_datetime(%Activity{data: data, inserted_at: inserted_at}) do
    iso_datetime(Map.get(data, "published", inserted_at))
  end

  def iso_datetime(%{__struct__: struct} = datetime)
      when struct == DateTime or struct == NaiveDateTime do
    Timex.format!(datetime, "{ISO:Extended:Z}")
  end

  @spec prev_page_path(conn :: Plug.Conn.t(), [
          Activity.t() | {Activity.t(), Actor.t()} | Notification.t()
        ]) ::
          String.t() | nil

  def prev_page_path(conn, activities) do
    if Map.has_key?(conn.query_params, "max_id") do
      Phoenix.Controller.current_path(conn, %{
        since_id: activities |> List.first() |> timeline_id()
      })
    else
      nil
    end
  end

  @spec next_page_path(conn :: Plug.Conn.t(), [
          Activity.t() | {Activity.t(), Actor.t()} | Notification.t()
        ]) ::
          String.t() | nil

  def next_page_path(conn, activities) do
    if length(activities) < 20 do
      nil
    else
      Phoenix.Controller.current_path(conn, %{
        max_id: activities |> List.last() |> timeline_id()
      })
    end
  end

  defp timeline_id(%Activity{id: id}), do: id
  defp timeline_id({%Activity{id: id}, _}), do: id
  defp timeline_id({%Activity{id: id}, _, _}), do: id
  defp timeline_id(%Notification{id: id}), do: id

  @spec mentions_for_replying_to(Activity.t()) :: String.t()
  defp mentions_for_replying_to(conn, %Activity{
         object: %Object{data: %{"actor" => actor, "tag" => tags}}
       }) do
    current_user = conn.assigns[:user] |> Repo.preload(:actor)

    tag_actors =
      tags
      |> Enum.filter(fn
        %{"type" => "Mention"} -> true
        _ -> false
      end)
      |> Enum.map(fn %{"href" => ap_id} -> ap_id end)

    actors =
      [actor | tag_actors]
      |> List.delete(current_user.actor.ap_id)
      |> Enum.uniq()

    mentions =
      actors
      |> Enum.map(fn ap_id ->
        actor = Actor.get_cached_by_ap_id(ap_id)
        "@#{actor.nickname}"
      end)

    case mentions do
      [] ->
        ""

      _ ->
        Enum.join(mentions, " ") <> ""
    end
  end

  defp mentions_for_replying_to(_), do: ""

  @spec render_status_content(activity :: Activity.t()) :: String.t()
  defp render_status_content(%Activity{
         object: %Object{data: %{"type" => "Note", "content" => content} = note}
       }) do
    with %{"tag" => tags} <- note,
         {:ok, tree} <- Floki.parse_fragment(content) do
      tree
      |> Floki.traverse_and_update(fn
        {"a", attrs, _children} = orig_tree ->
          {"href", href} = Enum.find(attrs, fn {name, _} -> name == "href" end)

          has_matching_tag =
            Enum.any?(tags, fn
              %{"type" => "Mention", "href" => ^href} -> true
              _ -> false
            end)

          with true <- has_matching_tag,
               %Actor{local: false} = actor <- Actor.get_cached_by_ap_id(href) do
            {
              "span",
              [],
              [
                orig_tree,
                {"a", [{"href", local_actor_link(actor)}, {"class", "local-actor-link"}], ["🔗"]}
              ]
            }
          else
            _ ->
              orig_tree
          end

        tree ->
          tree
      end)
      |> Floki.raw_html()
      # remove the <html> and </html> from the floki rendered output
      |> String.slice(6..-8)
      |> raw()
    else
      _ ->
        content
    end
  end
end