From 1c81e23eb9472e1103eeeaf850bf423ce297d6df Mon Sep 17 00:00:00 2001
From: Viacheslav Poturaev <vearutop@gmail.com>
Date: Thu, 27 Apr 2023 17:22:47 +0200
Subject: [PATCH] Fix json5 downgrade with dangling comma (#21)

---
 json5/json5.go      | 12 +++++++++++-
 json5/json5_test.go | 12 ++++++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/json5/json5.go b/json5/json5.go
index a01a42c..cc32ccf 100644
--- a/json5/json5.go
+++ b/json5/json5.go
@@ -32,7 +32,17 @@ func Downgrade(data []byte) ([]byte, error) {
 		return nil, err
 	}
 
-	return json.Marshal(v)
+	if d, err := json.Marshal(v); err == nil {
+		return d, nil
+	}
+
+	// Fallback decoding for cases like a dangling comma.
+	var i interface{}
+	if err := Unmarshal(data, &i); err != nil {
+		return nil, err
+	}
+
+	return json.Marshal(i)
 }
 
 // Unmarshal parses the JSON5-encoded data and stores the result
diff --git a/json5/json5_test.go b/json5/json5_test.go
index 6badfbd..d0071a7 100644
--- a/json5/json5_test.go
+++ b/json5/json5_test.go
@@ -56,6 +56,18 @@ func TestDowngrade(t *testing.T) {
 	assert.Equal(t, `{"xyz":123,"abc":987}`, string(j))
 }
 
+func TestDowngrade2(t *testing.T) {
+	dd, err := json5.Downgrade([]byte(`{
+  "values": {
+    "app_token::$appToken::web_tracking_enabled": "1",
+    "app_token::$appToken::web_redirect_base_url": "http://redirect.com",
+  }
+}`))
+
+	require.NoError(t, err)
+	assert.Equal(t, `{"values":{"app_token::$appToken::web_redirect_base_url":"http://redirect.com","app_token::$appToken::web_tracking_enabled":"1"}}`, string(dd))
+}
+
 func TestDowngrade_array(t *testing.T) {
 	j5 := `		[{
 		// XYZ.