WIP

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

lib/service/web_finger/web_finger.ex

@@ -0,0 +1,94 @@
+defmodule Eventos.Service.WebFinger do
+
+  alias Eventos.Accounts
+  alias Eventos.Service.XmlBuilder
+  alias Eventos.Repo
+  require Jason
+  require Logger
+
+  def host_meta do
+    base_url = EventosWeb.Endpoint.url()
+
+    {
+      :XRD,
+      %{xmlns: "http://docs.oasis-open.org/ns/xri/xrd-1.0"},
+      {
+        :Link,
+        %{
+          rel: "lrdd",
+          type: "application/xrd+xml",
+          template: "#{base_url}/.well-known/webfinger?resource={uri}"
+        }
+      }
+    }
+    |> XmlBuilder.to_doc()
+  end
+
+  def webfinger(resource, "JSON") do
+    host = EventosWeb.Endpoint.host()
+    regex = ~r/(acct:)?(?<username>\w+)@#{host}/
+
+    with %{"username" => username} <- Regex.named_captures(regex, resource) do
+      user = Accounts.get_account_by_username(username)
+      {:ok, represent_user(user, "JSON")}
+    else
+      _e ->
+        with user when not is_nil(user) <- Accounts.get_account_by_url(resource) do
+          {:ok, represent_user(user, "JSON")}
+        else
+          _e ->
+            {:error, "Couldn't find user"}
+        end
+    end
+  end
+
+  def represent_user(user, "JSON") do
+    %{
+      "subject" => "acct:#{user.username}@#{EventosWeb.Endpoint.host() <> ":4001"}",
+      "aliases" => [user.url],
+      "links" => [
+        %{"rel" => "self", "type" => "application/activity+json", "href" => user.url},
+      ]
+    }
+  end
+
+  defp webfinger_from_json(doc) do
+    data =
+      Enum.reduce(doc["links"], %{"subject" => doc["subject"]}, fn link, data ->
+        case {link["type"], link["rel"]} do
+          {"application/activity+json", "self"} ->
+            Map.put(data, "url", link["href"])
+          _ ->
+            Logger.debug("Unhandled type: #{inspect(link["type"])}")
+            data
+        end
+      end)
+
+    {:ok, data}
+  end
+
+  def finger(account) do
+    account = String.trim_leading(account, "@")
+
+    domain =
+      with [_name, domain] <- String.split(account, "@") do
+        domain
+      else
+        _e ->
+          URI.parse(account).host
+      end
+
+      address = "http://#{domain}/.well-known/webfinger?resource=acct:#{account}"
+
+    with response <- HTTPoison.get(address, [Accept: "application/json"],follow_redirect: true),
+         {:ok, %{status_code: status_code, body: body}} when status_code in 200..299 <- response do
+          {:ok, doc} = Jason.decode(body)
+          webfinger_from_json(doc)
+    else
+      e ->
+        Logger.debug(fn -> "Couldn't finger #{account}" end)
+        Logger.debug(fn -> inspect(e) end)
+        {:error, e}
+    end
+  end
+end