Send Webmentions to linked URLs, excluding mentions

config/config.exs

@@ -38,10 +38,12 @@ config :http_signatures, adapter: Clacks.SignatureAdapter
 config :clacks, Oban,
   repo: Clacks.Repo,
   prune: {:maxlen, 10_000},
-  queues: [federate: 10]
+  queues: [federate: 5, send_webmention: 1]
 
 config :floki, :html_parser, Floki.HTMLParser.FastHtml
 
+config :clacks, :send_webmentions, true
+
 # Import environment specific config. This must remain at the bottom
 # of this file so it overrides the configuration defined above.
 import_config "#{Mix.env()}.exs"

lib/clacks/activitypub/helper.ex

@@ -13,18 +13,30 @@ defmodule Clacks.ActivityPub.Helper do
         :error
 
       {:ok, activity} ->
-        worker =
+        if Application.get_env(:clacks, :send_webmentions, true) do
-          %{id: activity.id, actor_id: actor.id}
+          Clacks.Worker.SendWebmention.enqueue_for_activity(activity)
-          |> Clacks.Worker.Federate.new()
+        end
 
-        case Oban.insert(worker) do
+        case enqueue_federate_job(activity, actor) do
-          {:ok, _} ->
+          :ok -> {:ok, activity}
-            {:ok, activity}
+          :error -> :error
-
-          {:error, changeset} ->
-            Logger.error("Couldn't save federate job: #{inspect(changeset)}")
-            :error
         end
     end
   end
+
+  @spec enqueue_federate_job(Activity.t(), Actor.t()) :: :ok | :error
+  defp enqueue_federate_job(activity, actor) do
+    worker =
+      %{id: activity.id, actor_id: actor.id}
+      |> Clacks.Worker.Federate.new()
+
+    case Oban.insert(worker) do
+      {:ok, _} ->
+        :ok
+
+      {:error, changeset} ->
+        Logger.error("Couldn't save federate job: #{inspect(changeset)}")
+        :error
+    end
+  end
 end

lib/clacks/http.ex

@@ -1,13 +1,13 @@
 defmodule Clacks.HTTP do
   require Logger
 
-  @spec get(url :: String.t(), headers :: [{String.t(), String.t()}]) ::
+  @spec get(url :: String.t(), headers :: HTTPoison.headers()) ::
           {:ok, HTTPoison.Response.t()} | {:error, String.t()}
   def get(url, headers \\ []) do
     fetch(:get, url, headers)
   end
 
-  @spec head(url :: String.t(), headers :: [{String.t(), String.t()}]) ::
+  @spec head(url :: String.t(), headers :: HTTPoison.headers()) ::
           {:ok, HTTPoison.Response.t()} | {:error, String.t()}
   def head(url, headers \\ []) do
     fetch(:head, url, headers)
@@ -27,7 +27,9 @@ defmodule Clacks.HTTP do
         |> Enum.find(fn {name, _value} -> String.downcase(name) == "location" end)
         |> case do
           {_, new_url} ->
-            new_url = URI.merge(URI.parse(url), URI.parse(new_url))
+            new_url =
+              URI.merge(URI.parse(url), URI.parse(new_url))
+              |> URI.to_string()
 
             Logger.debug("Got 301 redirect from #{url} to #{new_url}")
             fetch(method, new_url, headers)
@@ -49,4 +51,10 @@ defmodule Clacks.HTTP do
         {:error, inspect(reason)}
     end
   end
+
+  @spec post(String.t(), any(), HTTPoison.headers()) ::
+          {:ok, HTTPoison.Response.t()} | {:error, HTTPoison.Error.t()}
+  def post(url, body, headers \\ []) do
+    HTTPoison.post(url, body, headers)
+  end
 end

lib/clacks/webmention/endpoint.ex

@@ -56,7 +56,7 @@ defmodule Clacks.Webmention.Endpoint do
     uri_reference =
       value
       |> String.trim()
-      |> String.slice(1..-1)
+      |> String.slice(1..-2)
 
     {_, rel} =
       params

lib/clacks/worker/send_webmention.ex

@@ -0,0 +1,110 @@
+defmodule Clacks.Worker.SendWebmention do
+  use Oban.Worker, queue: :send_webmention
+  alias Clacks.Activity
+  alias ClacksWeb.Router.Helpers, as: Routes
+  alias ClacksWeb.Endpoint
+  require Logger
+
+  @spec enqueue_for_activity(Activity.t()) :: :ok
+  def enqueue_for_activity(
+        %Activity{data: %{"type" => "Create", "object" => %{"content" => content} = note}} =
+          activity
+      ) do
+    tags = Map.get(note, "tag", [])
+    tag_hrefs = Enum.map(tags, fn %{"href" => href} -> href end)
+
+    case Floki.parse_fragment(content) do
+      {:ok, html_tree} ->
+        # todo: should this also skip anchors with the .mention class?
+        Floki.find(html_tree, "a")
+        |> Enum.each(fn {"a", attrs, _} ->
+          case Enum.find(attrs, fn {name, _} -> name == "href" end) do
+            {"href", link} ->
+              IO.inspect("Found link: #{link}")
+              maybe_enqueue_for_candidate(activity, tag_hrefs, link)
+
+            nil ->
+              :ok
+          end
+        end)
+
+      {:error, reason} ->
+        Logger.warn("Unable to parse HTML for sending Webmentions: #{reason}")
+    end
+  end
+
+  @spec maybe_enqueue_for_candidate(Activity.t(), [String.t()], String.t()) :: boolean()
+  defp maybe_enqueue_for_candidate(
+         %Activity{data: %{"object" => %{"in_reply_to" => in_reply_to}}} = activity,
+         activity_tag_hrefs,
+         link
+       ) do
+    # todo: checking in_reply_to != link won't be adequate after we support replying via Webmention to non-AP posts
+    with false <- in_reply_to == link,
+         false <- Enum.member?(activity_tag_hrefs, link),
+         %URI{scheme: scheme} when scheme in ["http", "https"] <- URI.parse(link) do
+      enqueue(activity, link) == :ok
+    else
+      _ ->
+        false
+    end
+  end
+
+  defp maybe_enqueue_for_candidate(activity, activity_tag_hrefs, link) do
+    with false <- Enum.member?(activity_tag_hrefs, link),
+         %URI{scheme: scheme} when scheme in ["http", "https"] <- URI.parse(link) do
+      enqueue(activity, link) == :ok
+    else
+      _ ->
+        false
+    end
+  end
+
+  @spec enqueue(Activity.t(), String.t()) :: :ok | :error
+  defp enqueue(activity, link) do
+    worker = __MODULE__.new(%{activity: activity.id, link: link})
+
+    case Oban.insert(worker) do
+      {:ok, _} ->
+        :ok
+
+      {:error, reason} ->
+        Logger.error("Couldn't save send Webmention job: #{inspect(reason)}")
+        :error
+    end
+  end
+
+  @impl Oban.Worker
+  def perform(%{"activity" => activity_id, "link" => link}, _job) do
+    case Clacks.Webmention.Endpoint.find_endpoint(link) do
+      nil ->
+        :ok
+
+      endpoint ->
+        endpoint = URI.to_string(endpoint)
+
+        source = Routes.activities_url(Endpoint, :get, activity_id)
+        target = URI.encode_www_form(link)
+        body = "source=#{source}&target=#{target}"
+
+        case Clacks.HTTP.post(endpoint, body, [
+               {"Content-Type", "application/x-www-form-urlencoded"}
+             ]) do
+          {:ok, %HTTPoison.Response{status_code: status_code}} when status_code in 200..299 ->
+            Logger.debug("Successfully sent Webmention to '#{link}'")
+            :ok
+
+          {:ok, %HTTPoison.Response{status_code: status_code}} ->
+            Logger.error(
+              "Unhandled status code #{status_code} for sending Webmention to '#{link}'"
+            )
+
+            {:error, "Unhandled status code for Webmention '#{link}': #{status_code}"}
+
+          {:error, error} ->
+            Logger.error("Failed sending Webmention to '#{link}': #{inspect(error)}")
+            {:error, error}
+        end
+    end
+  end
+end

lib/clacks_web/controllers/activities_controller.ex

@@ -4,11 +4,9 @@ defmodule ClacksWeb.ActivitiesController do
   alias ClacksWeb.Router.Helpers, as: Routes
   alias ClacksWeb.Endpoint
 
-  def get(conn, _params) do
+  def get(conn, %{"id" => id}) do
-    ap_id = current_url(conn, %{})
+    case Activity.get(id) do
-
+      %Activity{local: true, data: data} ->
-    case Activity.get_by_ap_id(ap_id) do
-      %Activity{local: true, id: id, data: data} ->
         case conn.assigns[:format] do
           "activity+json" ->
             json(conn, data)
@@ -29,16 +27,4 @@ defmodule ClacksWeb.ActivitiesController do
         end
     end
   end
-
-  def get_status(conn, %{"id" => status_id}) do
-    case Activity.get(status_id) do
-      %Activity{local: true, data: data} ->
-        json(conn, data)
-
-      _ ->
-        conn
-        |> put_status(404)
-        |> json(%{error: "Not Found"})
-    end
-  end
 end

lib/clacks_web/templates/frontend/_status.html.eex

@@ -1,15 +1,17 @@
 <div class="<%= assigns[:class] || "status h-entry" %>">
   <div class="status-meta">
-    <h2 class="status-author-nickname">
+    <div class="p-author h-card">
-      <a href="<%= local_actor_link(@author) %>" class="p-author">
+      <h2 class="status-author-nickname">
-        <%= @author.data["preferredUsername"] %>
+        <a href="<%= local_actor_link(@author) %>">
-      </a>
+          <%= @author.data["preferredUsername"] %>
-    </h2>
+        </a>
-    <h3 class="status-author-username">
+      </h2>
-      <a href="<%= @author.ap_id %>">
+      <h3 class="status-author-username">
-        <%= display_username(@author) %>
+        <a href="<%= @author.ap_id %>" class="p-name u-url">
-      </a>
+          <%= display_username(@author) %>
-    </h3>
+        </a>
+      </h3>
+    </div>
     <p class="status-meta-right">
       <time datetime="<%= @note["published"] %>" class="dt-published"><%= display_timestamp(@note["published"]) %></time>
       <a href="<%= @note["url"] || @note["id"] %>" class="status-permalink u-url">Permalink</a>