ensure we send the right files for preferred fe

lib/pleroma/web/fallback/redirect_controller.ex

@@ -20,7 +20,7 @@ def api_not_implemented(conn, _params) do
   def redirector(conn, _params, code \\ 200) do
     conn
     |> put_resp_content_type("text/html")
-    |> send_file(code, index_file_path())
+    |> send_file(code, index_file_path(conn))
   end
 
   def redirector_with_meta(conn, %{"maybe_nickname_or_id" => maybe_nickname_or_id} = params) do
@@ -33,7 +33,7 @@ def redirector_with_meta(conn, %{"maybe_nickname_or_id" => maybe_nickname_or_id}
   end
 
   def redirector_with_meta(conn, params) do
-    {:ok, index_content} = File.read(index_file_path())
+    {:ok, index_content} = File.read(index_file_path(conn))
 
     tags = build_tags(conn, params)
     preloads = preload_data(conn, params)
@@ -53,7 +53,7 @@ def redirector_with_preload(conn, %{"path" => ["pleroma", "admin"]}) do
   end
 
   def redirector_with_preload(conn, params) do
-    {:ok, index_content} = File.read(index_file_path())
+    {:ok, index_content} = File.read(index_file_path(conn))
     preloads = preload_data(conn, params)
     tags = Metadata.build_static_tags(params)
     title = "<title>#{Pleroma.Config.get([:instance, :name])}</title>"
@@ -77,8 +77,9 @@ def empty(conn, _params) do
     |> text("")
   end
 
-  defp index_file_path do
-    Pleroma.Web.Plugs.InstanceStatic.file_path("index.html")
+  defp index_file_path(conn) do
+    frontend_type = Pleroma.Web.Plugs.FrontendStatic.preferred_or_fallback(conn, :primary)
+    Pleroma.Web.Plugs.InstanceStatic.file_path("index.html", frontend_type)
   end
 
   defp build_tags(conn, params) do

lib/pleroma/web/plugs/frontend_static.ex

@@ -5,17 +5,23 @@
 defmodule Pleroma.Web.Plugs.FrontendStatic do
   require Pleroma.Constants
 
+  @frontend_cookie_name "preferred_frontend"
+
   @moduledoc """
   This is a shim to call `Plug.Static` but with runtime `from` configuration`. It dispatches to the different frontends.
   """
   @behaviour Plug
 
-  def file_path(path, frontend_type \\ :primary) do
-    if configuration = Pleroma.Config.get([:frontends, frontend_type]) do
-      instance_static_path = Pleroma.Config.get([:instance, :static_dir], "instance/static")
+  defp instance_static_path do
+    Pleroma.Config.get([:instance, :static_dir], "instance/static")
+  end
 
+  def file_path(path, frontend_type \\ :primary)
+
+  def file_path(path, frontend_type) when is_atom(frontend_type) do
+    if configuration = Pleroma.Config.get([:frontends, frontend_type]) do
       Path.join([
-        instance_static_path,
+        instance_static_path(),
         "frontends",
         configuration["name"],
         configuration["ref"],
@@ -26,6 +32,15 @@ def file_path(path, frontend_type \\ :primary) do
     end
   end
 
+  def file_path(path, frontend_type) when is_binary(frontend_type) do
+    Path.join([
+      instance_static_path(),
+      "frontends",
+      frontend_type,
+      path
+    ])
+  end
+
   def init(opts) do
     opts
     |> Keyword.put(:from, "__unconfigured_frontend_static_plug")
@@ -38,7 +53,8 @@ def call(conn, opts) do
     with false <- api_route?(conn.path_info),
          false <- invalid_path?(conn.path_info),
          true <- enabled?(opts[:if]),
-         frontend_type <- Map.get(opts, :frontend_type, :primary),
+         fallback_frontend_type <- Map.get(opts, :frontend_type, :primary),
+         frontend_type <- preferred_or_fallback(conn, fallback_frontend_type),
          path when not is_nil(path) <- file_path("", frontend_type) do
       call_static(conn, opts, path)
     else
@@ -47,6 +63,24 @@ def call(conn, opts) do
     end
   end
 
+  def preferred_frontend(conn) do
+    %{req_cookies: cookies} =
+      conn
+      |> Plug.Conn.fetch_cookies()
+
+    Map.get(cookies, @frontend_cookie_name)
+  end
+
+  def preferred_or_fallback(conn, fallback) do
+    case preferred_frontend(conn) do
+      nil ->
+        fallback
+
+      frontend ->
+        frontend
+    end
+  end
+
   defp enabled?(if_opt) when is_function(if_opt), do: if_opt.()
   defp enabled?(true), do: true
   defp enabled?(_), do: false
@@ -68,6 +102,7 @@ defp api_route?([h | t]) do
 
   defp call_static(conn, opts, from) do
     opts = Map.put(opts, :from, from)
+    IO.inspect(opts, label: "opts")
     Plug.Static.call(conn, opts)
   end
 end

lib/pleroma/web/plugs/instance_static.ex

@@ -12,11 +12,11 @@ defmodule Pleroma.Web.Plugs.InstanceStatic do
   """
   @behaviour Plug
 
-  def file_path(path) do
+  def file_path(path, frontend_type \\ :primary) do
     instance_path =
       Path.join(Pleroma.Config.get([:instance, :static_dir], "instance/static/"), path)
 
-    frontend_path = Pleroma.Web.Plugs.FrontendStatic.file_path(path, :primary)
+    frontend_path = Pleroma.Web.Plugs.FrontendStatic.file_path(path, frontend_type)
 
     (File.exists?(instance_path) && instance_path) ||
       (frontend_path && File.exists?(frontend_path) && frontend_path) ||