From 9d3c4384e43ea1388c15df97b0e31d471cc972b3 Mon Sep 17 00:00:00 2001
From: John Whitington <john@coherentgraphics.co.uk>
Date: Wed, 12 Jun 2024 16:15:33 +0100
Subject: [PATCH] Report natural language

---
 Changes          | 1 +
 cpdfmetadata.ml  | 8 ++++++++
 cpdfmetadata.mli | 2 ++
 cpdfua.ml        | 3 ++-
 4 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/Changes b/Changes
index 2b0e072..773c83b 100644
--- a/Changes
+++ b/Changes
@@ -8,6 +8,7 @@ o Verify compliance to PDF/UA via the Matterhorn protocol
 o Extract, edit and reapply document structure tree
 o Split structure tree when splitting PDF to save size
 o Combine structure trees when stamping PDFs
+o Report natural language on -info
 
 2.7 (February 2024)
 
diff --git a/cpdfmetadata.ml b/cpdfmetadata.ml
index 0b6cb72..6e43839 100644
--- a/cpdfmetadata.ml
+++ b/cpdfmetadata.ml
@@ -442,6 +442,11 @@ let determine_subformats pdf =
           end;
           !formats
 
+let language pdf =
+  match Pdf.lookup_chain pdf pdf.Pdf.trailerdict ["/Root"; "/Lang"] with
+  | Some (Pdf.String x) -> Some x
+  | _ -> None
+
 let output_xmp_info ?(json=ref [("none", `Null)]) encoding pdf =
   let notjson = !json = [("none", `Null)] in
   let print_out tree title namespace name =
@@ -459,6 +464,9 @@ let output_xmp_info ?(json=ref [("none", `Null)]) encoding pdf =
     if notjson
       then Printf.printf "Subformats: %s\n" (combine_with_commas (determine_subformats pdf))
       else json =| ("Subformats", `List (map (fun x -> `String x) (determine_subformats pdf)));
+    if notjson
+      then Printf.printf "Language: %s\n" (match language pdf with None -> "" | Some x -> "\"" ^ x ^ "\"")
+      else json =| ("Language", match language pdf with None -> `Null | Some x -> `String x);
     match get_metadata pdf with
       None -> ()
     | Some metadata ->
diff --git a/cpdfmetadata.mli b/cpdfmetadata.mli
index ebbda15..189be8c 100644
--- a/cpdfmetadata.mli
+++ b/cpdfmetadata.mli
@@ -87,6 +87,8 @@ val get_viewer_pref_item : string -> Pdf.t -> string
 
 val determine_subformats : Pdf.t -> string list
 
+val language : Pdf.t -> string option
+
 val adobe : string
 val xmp : string
 val dc : string
diff --git a/cpdfua.ml b/cpdfua.ml
index d76b2fd..8d3f77d 100644
--- a/cpdfua.ml
+++ b/cpdfua.ml
@@ -164,7 +164,8 @@ let matterhorn_10_001 pdf =
   unimpl ()
 
 (* Natural language for text in page content cannot be determined. *)
-let matterhorn_11_001 pdf = todo ()
+let matterhorn_11_001 pdf =
+  unimpl ()
 
 (* Natural language for text in Alt, ActualText and E attributes cannot be
    determined. *)