From 2ce4f96f6ef535ede6dd4fa6a91fff45690f053d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Charlotte=20=F0=9F=A6=9D=20Delenk?= <lotte@chir.rs>
Date: Sat, 7 Jan 2023 21:58:56 +0100
Subject: [PATCH 1/2] Use actual ISO8601 timestamps for masto API

Elixir uses an incompatible superset of ISO8601 that breaks some clients
---
 lib/pleroma/web/common_api/utils.ex        | 13 ++++++++++---
 test/pleroma/web/common_api/utils_test.exs |  8 ++++++++
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/lib/pleroma/web/common_api/utils.ex b/lib/pleroma/web/common_api/utils.ex
index aee19a840..d0452c428 100644
--- a/lib/pleroma/web/common_api/utils.ex
+++ b/lib/pleroma/web/common_api/utils.ex
@@ -328,9 +328,16 @@ defmodule Pleroma.Web.CommonAPI.Utils do
   end
 
   def to_masto_date(%NaiveDateTime{} = date) do
-    date
-    |> NaiveDateTime.to_iso8601()
-    |> String.replace(~r/(\.\d+)?$/, ".000Z", global: false)
+    # NOTE: Elixir’s ISO 8601 format is a superset of the real standard
+    # It supports negative years for example.
+    # ISO8601 only supports years before 1583 with mutual agreement
+    if date.year < 1583 do
+      ""
+    else
+      date
+      |> NaiveDateTime.to_iso8601()
+      |> String.replace(~r/(\.\d+)?$/, ".000Z", global: false)
+    end
   end
 
   def to_masto_date(date) when is_binary(date) do
diff --git a/test/pleroma/web/common_api/utils_test.exs b/test/pleroma/web/common_api/utils_test.exs
index a88d7681a..40137a10e 100644
--- a/test/pleroma/web/common_api/utils_test.exs
+++ b/test/pleroma/web/common_api/utils_test.exs
@@ -498,6 +498,14 @@ defmodule Pleroma.Web.CommonAPI.UtilsTest do
     test "returns empty string when date invalid" do
       assert Utils.to_masto_date("2015-01?23T23:50:07.123Z") == ""
     end
+
+    test "returns empty string when date is before the introduction of the Gregorian Calendar" do
+      assert Utils.to_masto_date("0621-01-01T00:00:00Z") == ""
+    end
+
+    test "returns empty string when date is BCE" do
+      assert Utils.to_masto_date("-420-01-01T00:00:00Z") == ""
+    end
   end
 
   describe "maybe_notify_mentioned_recipients/2" do
-- 
2.34.1


From 8d55b8c6d94794c4566d1867a1c3600d522c68d9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Charlotte=20=F0=9F=A6=9D=20Delenk?= <lotte@chir.rs>
Date: Sun, 8 Jan 2023 09:15:23 +0100
Subject: [PATCH 2/2] Replace invalid/unsupported dates with with epoch
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Masto API requires “ISO 8601 Datetime”, not “ISO 8601 Datetime or empty”
---
 lib/pleroma/web/common_api/utils.ex        |  6 +++---
 test/pleroma/web/common_api/utils_test.exs | 12 ++++++------
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/lib/pleroma/web/common_api/utils.ex b/lib/pleroma/web/common_api/utils.ex
index d0452c428..345c5d10d 100644
--- a/lib/pleroma/web/common_api/utils.ex
+++ b/lib/pleroma/web/common_api/utils.ex
@@ -332,7 +332,7 @@ defmodule Pleroma.Web.CommonAPI.Utils do
     # It supports negative years for example.
     # ISO8601 only supports years before 1583 with mutual agreement
     if date.year < 1583 do
-      ""
+      "1970-01-01T00:00:00Z"
     else
       date
       |> NaiveDateTime.to_iso8601()
@@ -344,11 +344,11 @@ defmodule Pleroma.Web.CommonAPI.Utils do
     with {:ok, date} <- NaiveDateTime.from_iso8601(date) do
       to_masto_date(date)
     else
-      _ -> ""
+      _ -> "1970-01-01T00:00:00Z"
     end
   end
 
-  def to_masto_date(_), do: ""
+  def to_masto_date(_), do: "1970-01-01T00:00:00Z"
 
   defp shortname(name) do
     with max_length when max_length > 0 <-
diff --git a/test/pleroma/web/common_api/utils_test.exs b/test/pleroma/web/common_api/utils_test.exs
index 40137a10e..f56d21c70 100644
--- a/test/pleroma/web/common_api/utils_test.exs
+++ b/test/pleroma/web/common_api/utils_test.exs
@@ -495,16 +495,16 @@ defmodule Pleroma.Web.CommonAPI.UtilsTest do
       assert Utils.to_masto_date("2015-01-23T23:50:07.123Z") == "2015-01-23T23:50:07.000Z"
     end
 
-    test "returns empty string when date invalid" do
-      assert Utils.to_masto_date("2015-01?23T23:50:07.123Z") == ""
+    test "returns unix epoch when date invalid" do
+      assert Utils.to_masto_date("2015-01?23T23:50:07.123Z") == "1970-01-01T00:00:00Z"
     end
 
-    test "returns empty string when date is before the introduction of the Gregorian Calendar" do
-      assert Utils.to_masto_date("0621-01-01T00:00:00Z") == ""
+    test "returns unix epoch when date is before the introduction of the Gregorian Calendar" do
+      assert Utils.to_masto_date("0621-01-01T00:00:00Z") == "1970-01-01T00:00:00Z"
     end
 
-    test "returns empty string when date is BCE" do
-      assert Utils.to_masto_date("-420-01-01T00:00:00Z") == ""
+    test "returns unix epoch when date is BCE" do
+      assert Utils.to_masto_date("-0420-01-01T00:00:00Z") == "1970-01-01T00:00:00Z"
     end
   end
 
-- 
2.34.1