attesto_mcp

if Code.ensure_loaded?(Phoenix.Controller) do
  defmodule AttestoMCP.MetadataController do
    @moduledoc """
    Phoenix controller that serves RFC 9728 protected-resource metadata.

    Routes mounted by `AttestoMCP.Router.attesto_mcp_protected_resource_metadata/2`
    dispatch here. The controller reads the resource path and metadata options
    placed in `conn.private` by the route, builds the document with
    `AttestoMCP.Metadata.protected_resource/3`, and renders it as JSON. The
    `resource` identifier and default `authorization_servers` origin come from
    `AttestoMCP.Metadata.resolve_origin/2`: a `:base_url`/`:origin`/`:issuer`
    passed to the router macro pins it; otherwise it is the live request origin.

    Because the `resource` identifier is resolved the same way
    `AttestoMCP.Plug.ProtectResource` resolves its `WWW-Authenticate`
    `resource_metadata` challenge, the discovered metadata URL and the served
    `resource` value match - provided both call sites receive the same origin
    (with no pin they both derive from the request; behind a proxy pass the same
    `:base_url`/`:origin` to the router macro and the plug).

    The controller compiles only when Phoenix is available; Plug-only consumers
    do not pull it in.
    """

    use Phoenix.Controller, formats: [:json]

    alias AttestoMCP.Metadata

    @doc """
    Render protected-resource metadata for the resource bound to this route.
    """
    @spec show(Plug.Conn.t(), map()) :: Plug.Conn.t()
    def show(conn, _params) do
      resource_path = Map.fetch!(conn.private, :attesto_mcp_resource_path)
      opts = Map.get(conn.private, :attesto_mcp_metadata_opts, [])

      metadata = Metadata.protected_resource(conn, resource_path, metadata_opts(opts))

      json(conn, metadata)
    end

    # `:scopes` is the ergonomic name on the router macro; the RFC 9728 field is
    # `scopes_supported`. Translate it unless the host passed the field directly.
    defp metadata_opts(opts) do
      case Keyword.fetch(opts, :scopes) do
        {:ok, scopes} ->
          opts
          |> Keyword.delete(:scopes)
          |> Keyword.put_new(:scopes_supported, scopes)

        :error ->
          opts
      end
    end
  end
end