Plug: Forward requests to callback instead of passing assigns (#283)

This patch refactors the "AssignsPlug" to not only forward assigns, but
instead forward the conn to a function for processing the request.

Author: maltoe

CHANGELOG.md

@@ -2,12 +2,13 @@
 
 ### Added
 
+- Add `ChromicPDF.Plug` to forward Chrome requests on an internal endpoint to a template.
 - Add `Template.options/1` that returns the options for page dimensions, header, and footer, but does not require the content.
-- `ChromicPDF.Plug` mechanism to pass assigns to a template printed from `:url`.
 
 ### Changed
 
 - Strip styles generated in `Template.styles/1`.
+- Cookies set via `:set_cookie` are now `httpOnly: true` by default.
 
 ### Removed
 

lib/chromic_pdf/api/pdf_options.ex

@@ -4,47 +4,38 @@ defmodule ChromicPDF.PDFOptions do
   @moduledoc false
 
   require EEx
+  import ChromicPDF.Utils, only: [rendered_to_binary: 1]
 
   def prepare_input_options(source, opts) do
     opts
-    |> set_cookie_for_assigns_plug(source)
     |> put_source(source)
     |> replace_wait_for_with_evaluate()
     |> stringify_map_keys()
-    |> iolists_to_binary()
+    |> sanitize_binaries()
   end
 
-  defp set_cookie_for_assigns_plug(opts, source) do
-    cond do
-      !Keyword.has_key?(opts, :assigns) ->
-        opts
-
-      !match?({:url, _}, source) ->
-        raise(":assigns option invalid with :url source")
-
-      Keyword.has_key?(opts, :set_cookie) ->
-        raise(":assigns option conflicts with :set_cookie")
+  defp put_source(opts, {:file, source}), do: put_source(opts, {:url, source})
+  defp put_source(opts, {:path, source}), do: put_source(opts, {:url, source})
+  defp put_source(opts, {:html, source}), do: put_source(opts, :html, source)
 
-      true ->
-        do_set_cookie_for_assigns_plug(opts, source)
+  defp put_source(opts, {:plug, plug_opts}) do
+    if Keyword.has_key?(opts, :set_cookie) do
+      raise "plug source conflicts with set_cookie"
     end
-  end
 
-  defp do_set_cookie_for_assigns_plug(opts, {:url, url}) do
-    {assigns, rest} = Keyword.pop(opts, :assigns)
+    {url, plug_opts} = Keyword.pop!(plug_opts, :url)
 
     set_cookie_opts =
-      assigns
-      |> ChromicPDF.AssignsPlug.start_agent_and_get_cookie()
+      plug_opts
+      |> ChromicPDF.Plug.start_agent_and_get_cookie()
       |> Map.put(:url, url)
+      |> Map.put(:secure, String.starts_with?(url, "https"))
 
-    Keyword.put(rest, :set_cookie, set_cookie_opts)
+    opts
+    |> Keyword.put(:set_cookie, set_cookie_opts)
+    |> put_source(:url, url)
   end
 
-  defp put_source(opts, {:file, source}), do: put_source(opts, {:url, source})
-  defp put_source(opts, {:path, source}), do: put_source(opts, {:url, source})
-  defp put_source(opts, {:html, source}), do: put_source(opts, :html, source)
-
   defp put_source(opts, {:url, source}) do
     url =
       if File.exists?(source) do
@@ -110,19 +101,17 @@ defmodule ChromicPDF.PDFOptions do
     Enum.into(map, %{}, fn {k, v} -> {to_string(k), v} end)
   end
 
-  @iolist_options [
+  @binary_options [
     [:html],
     [:print_to_pdf, "headerTemplate"],
     [:print_to_pdf, "footerTemplate"]
   ]
 
-  defp iolists_to_binary(opts) do
-    Enum.reduce(@iolist_options, opts, fn path, acc ->
+  defp sanitize_binaries(opts) do
+    Enum.reduce(@binary_options, opts, fn path, acc ->
       update_in(acc, path, fn
         nil -> ""
-        {:safe, value} -> :erlang.iolist_to_binary(value)
-        value when is_list(value) -> :erlang.iolist_to_binary(value)
-        value -> value
+        other -> rendered_to_binary(other)
       end)
     end)
   end

lib/chromic_pdf/assigns_plug.ex

@@ -7,7 +7,8 @@ defmodule ChromicPDF.Navigate do
 
   steps do
     if_option :set_cookie do
-      call(:set_cookie, "Network.setCookie", &Map.fetch!(&1, :set_cookie), %{})
+      call(:set_cookie, "Network.setCookie", &Map.fetch!(&1, :set_cookie), %{httpOnly: true})
+
       await_response(:cookie_set, [])
     end