From 1b87305b7503c1c7deb88793b428d5278b42f14c Mon Sep 17 00:00:00 2001
From: Fredrick Brennan <copypaste@kittens.ph>
Date: Thu, 25 Nov 2021 23:43:26 -0500
Subject: [PATCH] fix(packages): Add \pdf:metadata support for dates

---
 packages/pdf.lua   | 20 ++++++++++++++++++--
 tests/bug-1280.sil |  7 +++++--
 2 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/packages/pdf.lua b/packages/pdf.lua
index 4d20a1cde..7f37aa118 100644
--- a/packages/pdf.lua
+++ b/packages/pdf.lua
@@ -106,6 +106,10 @@ SILE.registerCommand("pdf:link", function (options, content)
   })
 end)
 
+local function validate_date(date)
+  return string.match(date, [[^D:%d+%s*-%s*%d%d%s*'%s*%d%d%s*'?$]]) ~= nil
+end
+
 SILE.registerCommand("pdf:metadata", function (options, _)
   local key = SU.required(options, "key", "pdf:metadata")
   local value
@@ -116,8 +120,20 @@ SILE.registerCommand("pdf:metadata", function (options, _)
     value = SU.required(options, "value", "pdf:metadata")
   end
 
-  -- see comment in pdf:bookmark
-  value = SU.utf8_to_utf16be(value)
+  if key == "Trapped" then
+    SU.warn("Skipping special metadata key \\Trapped")
+    return
+  end
+
+  if key == "ModDate" or key == "CreationDate" then
+    if not validate_date(value) then
+      SU.warn("Invalid date: " .. value)
+      return
+    end
+  else
+    -- see comment in pdf:bookmark
+    value = SU.utf8_to_utf16be(value)
+  end
   SILE.typesetter:pushHbox({
     value = nil,
     height = SILE.measurement(0),
diff --git a/tests/bug-1280.sil b/tests/bug-1280.sil
index a4f8dc60e..fa535ae25 100644
--- a/tests/bug-1280.sil
+++ b/tests/bug-1280.sil
@@ -49,6 +49,9 @@
     SILE.registerCommand("pdf:metadata", function (_, _) end)
   end
 }
-\pdf:metadata[key=Author, val=Erwin Schrödinger]
-\pdf:metadata[key=Title, val=Erwin Schrödinger’s 猫🐈]
+\pdf:metadata[key=Author, value=Erwin Schrödinger]
+\pdf:metadata[key=Title, value=Erwin Schrödinger’s 猫🐈]
+\pdf:metadata[key=CreationDate, value=D:19990209153925 - 08 ' 00 ']
+\pdf:metadata[key=ModDate, value=should fail]
+\pdf:metadata[key=Trapped, value=should be skipped]
 \end{document}