Add Openbox pipe menu renderer

render/1 turns a list of #desktop_entry{} into the XML Openbox expects
on stdout from a pipe menu: hidden entries dropped, remaining ones
sorted case-insensitively by name, each as an <item> wrapping an
Execute action with its command and (if present) icon attribute.
XML-escapes label/command/icon values.

Icon values are passed through as-is (theme icon names, not resolved
paths) -- icon theme resolution is left for later, separate from
rendering. Service wiring (scan -> parse -> render, with caching and
invalidation) is also left for later.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

1 files changed, 58 insertions, 0 deletions

diff --git a/src/er_xdg_pipe_menu_renderer.erl b/src/er_xdg_pipe_menu_renderer.erl
new file mode 100644
index 0000000..fafed45
--- /dev/null
+++ b/src/er_xdg_pipe_menu_renderer.erl
@@ -0,0 +1,58 @@
+%%%-------------------------------------------------------------------
+%% @doc Renders parsed desktop entries as an Openbox pipe menu.
+%%
+%% Given a list of `#desktop_entry{}' records, produces the XML that
+%% Openbox expects on stdout from a pipe menu: one `<item>' per
+%% visible entry (entries with `hidden = true' are dropped), sorted
+%% case-insensitively by name, each wrapping an `Execute' action.
+%% @end
+%%%-------------------------------------------------------------------
+
+-module(er_xdg_pipe_menu_renderer).
+
+-include("er_xdg_pipe_menu.hrl").
+
+-export([render/1]).
+
+-spec render([#desktop_entry{}]) -> binary().
+render(Entries) ->
+    Visible = [E || E <- Entries, not E#desktop_entry.hidden],
+    Sorted = lists:sort(fun by_name/2, Visible),
+    iolist_to_binary([
+        <<"<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n">>,
+        <<"<openbox_pipe_menu>\n">>,
+        [render_item(E) || E <- Sorted],
+        <<"</openbox_pipe_menu>\n">>
+    ]).
+
+by_name(#desktop_entry{name = A}, #desktop_entry{name = B}) ->
+    string:lowercase(A) =< string:lowercase(B).
+
+render_item(#desktop_entry{name = Name, exec = Exec, icon = Icon}) ->
+    [
+        <<"  <item label=\"">>,
+        escape_attr(Name),
+        <<"\"">>,
+        icon_attr(Icon),
+        <<">\n">>,
+        <<"    <action name=\"Execute\">\n">>,
+        <<"      <command>">>,
+        escape_text(Exec),
+        <<"</command>\n">>,
+        <<"    </action>\n">>,
+        <<"  </item>\n">>
+    ].
+
+icon_attr(undefined) -> <<>>;
+icon_attr(Icon) -> [<<" icon=\"">>, escape_attr(Icon), <<"\"">>].
+
+%% Attribute values additionally need '"' escaped; text content doesn't.
+escape_attr(Bin) -> escape(Bin, [{<<"\"">>, <<"&quot;">>}]).
+escape_text(Bin) -> escape(Bin, []).
+
+escape(Bin, Extra) ->
+    lists:foldl(
+        fun({Pat, Repl}, Acc) -> binary:replace(Acc, Pat, Repl, [global]) end,
+        Bin,
+        [{<<"&">>, <<"&amp;">>}, {<<"<">>, <<"&lt;">>}, {<<">">>, <<"&gt;">>} | Extra]
+    ).