# Pleroma: A lightweight social networking server
# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
# SPDX-License-Identifier: AGPL-3.0-only

defmodule Pleroma.Instances do
  @moduledoc "Instances context."

  @adapter Pleroma.Instances.Instance

  defdelegate filter_reachable(urls_or_hosts), to: @adapter
  defdelegate reachable?(url_or_host), to: @adapter
  defdelegate set_reachable(url_or_host), to: @adapter
  defdelegate set_unreachable(url_or_host, unreachable_since \\ nil), to: @adapter

  def set_consistently_unreachable(url_or_host),
    do: set_unreachable(url_or_host, reachability_datetime_threshold())

  def reachability_datetime_threshold do
    federation_reachability_timeout_days =
      Pleroma.Config.get([:instance, :federation_reachability_timeout_days], 0)

    if federation_reachability_timeout_days > 0 do
      NaiveDateTime.add(
        NaiveDateTime.utc_now(),
        -federation_reachability_timeout_days * 24 * 3600,
        :second
      )
    else
      ~N[0000-01-01 00:00:00]
    end
  end

  def host(url_or_host) when is_binary(url_or_host) do
    if url_or_host =~ ~r/^http/i do
      URI.parse(url_or_host).host
    else
      url_or_host
    end
  end

  def get_cached_favicon(instance_url) when is_binary(instance_url) do
    Cachex.fetch!(:instances_cache, instance_url, fn _ -> get_favicon(instance_url) end)
  end

  def get_cached_favicon(_instance_url) do
    nil
  end

  def get_favicon(instance_url) when is_binary(instance_url) do
    try do
      with {:ok, %Tesla.Env{body: html}} <-
             Pleroma.HTTP.get(instance_url, [{:Accept, "text/html"}]),
           favicon_rel <-
             html
             |> Floki.parse_document!()
             |> Floki.attribute("link[rel=icon]", "href")
             |> List.first(),
           favicon_url <- URI.merge(URI.parse(instance_url), favicon_rel) |> to_string(),
           true <- is_binary(favicon_url) do
        favicon_url
      else
        _ -> nil
      end
    rescue
      _ -> nil
    end
  end
end