Unify HTTP metadata handling

lib/parrhesia/http.ex

@@ -0,0 +1,48 @@
+defmodule Parrhesia.HTTP do
+  @moduledoc false
+
+  alias Parrhesia.Metadata
+
+  @default_headers [{"user-agent", Metadata.user_agent()}]
+
+  @spec default_headers() :: [{String.t(), String.t()}]
+  def default_headers, do: @default_headers
+
+  @spec get(Keyword.t()) :: {:ok, Req.Response.t()} | {:error, Exception.t()}
+  def get(options) when is_list(options) do
+    Req.get(put_default_headers(options))
+  end
+
+  @spec post(Keyword.t()) :: {:ok, Req.Response.t()} | {:error, Exception.t()}
+  def post(options) when is_list(options) do
+    Req.post(put_default_headers(options))
+  end
+
+  @spec put_default_headers(Keyword.t()) :: Keyword.t()
+  def put_default_headers(options) when is_list(options) do
+    Keyword.update(options, :headers, @default_headers, &merge_headers(&1, @default_headers))
+  end
+
+  defp merge_headers(headers, defaults) do
+    existing_names =
+      headers
+      |> List.wrap()
+      |> Enum.reduce(MapSet.new(), fn
+        {name, _value}, acc -> MapSet.put(acc, normalize_header_name(name))
+        _other, acc -> acc
+      end)
+
+    headers ++
+      Enum.reject(defaults, fn {name, _value} ->
+        MapSet.member?(existing_names, normalize_header_name(name))
+      end)
+  end
+
+  defp normalize_header_name(name) when is_atom(name) do
+    name
+    |> Atom.to_string()
+    |> String.downcase()
+  end
+
+  defp normalize_header_name(name) when is_binary(name), do: String.downcase(name)
+end

lib/parrhesia/metadata.ex

@@ -0,0 +1,29 @@
+defmodule Parrhesia.Metadata do
+  @moduledoc false
+
+  @metadata Application.compile_env(:parrhesia, :metadata, [])
+  @name Keyword.get(@metadata, :name, "Parrhesia")
+  @version Keyword.get(@metadata, :version, "0.0.0")
+  @hide_version? Keyword.get(@metadata, :hide_version?, true)
+
+  @spec name() :: String.t()
+  def name, do: @name
+
+  @spec version() :: String.t()
+  def version, do: @version
+
+  @spec hide_version?() :: boolean()
+  def hide_version?, do: @hide_version?
+
+  @spec name_and_version() :: String.t()
+  def name_and_version, do: "#{@name}/#{@version}"
+
+  @spec user_agent() :: String.t()
+  def user_agent do
+    if hide_version?() do
+      name()
+    else
+      name_and_version()
+    end
+  end
+end

lib/parrhesia/nip66/probe.ex

@@ -1,6 +1,7 @@
 defmodule Parrhesia.NIP66.Probe do
   @moduledoc false
 
+  alias Parrhesia.HTTP
   alias Parrhesia.Sync.Transport.WebSockexClient
 
   @type result :: %{
@@ -145,7 +146,7 @@ defmodule Parrhesia.NIP66.Probe do
   defp fetch_nip11(relay_url, timeout_ms) do
     started_at = System.monotonic_time()
 
-    case Req.get(
+    case HTTP.get(
            url: relay_info_url(relay_url),
            headers: [{"accept", "application/nostr+json"}],
            decode_body: false,

lib/parrhesia/sync/relay_info_client.ex

@@ -1,6 +1,7 @@
 defmodule Parrhesia.Sync.RelayInfoClient do
   @moduledoc false
 
+  alias Parrhesia.HTTP
   alias Parrhesia.Sync.TLS
 
   @spec verify_remote_identity(map(), keyword()) :: :ok | {:error, term()}
@@ -18,7 +19,7 @@ defmodule Parrhesia.Sync.RelayInfoClient do
   end
 
   defp default_request(url, opts) do
-    case Req.get(
+    case HTTP.get(
            url: url,
            headers: [{"accept", "application/nostr+json"}],
            decode_body: false,

lib/parrhesia/web/relay_info.ex

@@ -4,21 +4,27 @@ defmodule Parrhesia.Web.RelayInfo do
   """
 
   alias Parrhesia.API.Identity
+  alias Parrhesia.Metadata
   alias Parrhesia.NIP43
   alias Parrhesia.Web.Listener
 
   @spec document(Listener.t()) :: map()
   def document(listener) do
-    %{
-      "name" => "Parrhesia",
+    document = %{
+      "name" => Metadata.name(),
       "description" => "Nostr/Marmot relay",
       "pubkey" => relay_pubkey(),
       "self" => relay_pubkey(),
       "supported_nips" => supported_nips(),
       "software" => "https://git.teralink.net/self/parrhesia",
-      "version" => Application.spec(:parrhesia, :vsn) |> to_string(),
       "limitation" => limitations(listener)
     }
+
+    if Metadata.hide_version?() do
+      document
+    else
+      Map.put(document, "version", Metadata.version())
+    end
   end
 
   defp supported_nips do