Various refactoring and typespec improvements

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

lib/federation/web_finger/web_finger.ex

@@ -27,7 +27,7 @@ defmodule Mobilizon.Federation.WebFinger do
     base_url = Endpoint.url()
     %URI{host: host} = URI.parse(base_url)
 
-    {
+    XmlBuilder.to_doc({
       :XRD,
       %{
         xmlns: "http://docs.oasis-open.org/ns/xri/xrd-1.0",
@@ -47,8 +47,7 @@ defmodule Mobilizon.Federation.WebFinger do
           }
         }
       ]
-    }
-    |> XmlBuilder.to_doc()
+    })
   end
 
   @doc """
@@ -150,7 +149,7 @@ defmodule Mobilizon.Federation.WebFinger do
 
           {:error, err} ->
             Logger.debug("Couldn't process webfinger data for #{actor}")
-            err
+            {:error, err}
         end
 
       {:error, err} ->
@@ -187,7 +186,8 @@ defmodule Mobilizon.Federation.WebFinger do
     end
   end
 
-  # Fetches the Extensible Resource Descriptor endpoint `/.well-known/host-meta` to find the Webfinger endpoint (usually `/.well-known/webfinger?resource=`)
+  # Fetches the Extensible Resource Descriptor endpoint `/.well-known/host-meta`
+  # to find the Webfinger endpoint (usually `/.well-known/webfinger?resource=`)
   @spec find_webfinger_endpoint(String.t()) ::
           {:ok, String.t()} | {:error, :link_not_found} | {:error, any()}
   defp find_webfinger_endpoint(domain) when is_binary(domain) do

lib/federation/web_finger/xml_builder.ex

@@ -5,42 +5,54 @@
 
 defmodule Mobilizon.Federation.WebFinger.XmlBuilder do
   @moduledoc """
-  Builds XRD for WebFinger host_meta.
+  Extremely basic XML encoder. Builds XRD for WebFinger host_meta.
   """
 
-  def to_xml({tag, attributes, content}) do
+  @typep content :: list({tag :: atom(), attributes :: map()}) | String.t()
+  @typep document :: {tag :: atom(), attributes :: map(), content :: content}
+
+  @doc """
+  Return the XML representation for a document.
+  """
+  @spec to_doc(document :: document) :: String.t()
+  def to_doc(document), do: ~s(<?xml version="1.0" encoding="UTF-8"?>) <> to_xml(document)
+
+  @spec to_xml(document) :: String.t()
+  @spec to_xml({tag :: atom(), attributes :: map()}) :: String.t()
+  @spec to_xml({tag :: atom(), content :: content}) :: String.t()
+  @spec to_xml(content :: content) :: String.t()
+  defp to_xml({tag, attributes, content}) do
     open_tag = make_open_tag(tag, attributes)
     content_xml = to_xml(content)
 
     "<#{open_tag}>#{content_xml}</#{tag}>"
   end
 
-  def to_xml({tag, %{} = attributes}) do
+  defp to_xml({tag, %{} = attributes}) do
     open_tag = make_open_tag(tag, attributes)
 
     "<#{open_tag} />"
   end
 
-  def to_xml({tag, content}), do: to_xml({tag, %{}, content})
+  defp to_xml({tag, content}), do: to_xml({tag, %{}, content})
 
-  def to_xml(content) when is_binary(content), do: to_string(content)
+  defp to_xml(content) when is_binary(content), do: to_string(content)
 
-  def to_xml(content) when is_list(content) do
+  defp to_xml(content) when is_list(content) do
     content
     |> Enum.map(&to_xml/1)
     |> Enum.join()
   end
 
-  def to_xml(%NaiveDateTime{} = time), do: NaiveDateTime.to_iso8601(time)
-
-  def to_doc(content), do: ~s(<?xml version="1.0" encoding="UTF-8"?>) <> to_xml(content)
+  defp to_xml(%NaiveDateTime{} = time), do: NaiveDateTime.to_iso8601(time)
 
+  @spec make_open_tag(tag :: atom, attributes :: map()) :: String.t()
   defp make_open_tag(tag, attributes) do
     attributes_string =
       attributes
       |> Enum.map(fn {attribute, value} -> "#{attribute}=\"#{value}\"" end)
       |> Enum.join(" ")
 
-    [tag, attributes_string] |> Enum.join(" ") |> String.trim()
+    [to_string(tag), attributes_string] |> Enum.join(" ") |> String.trim()
   end
 end