From 169bd00e1ae09f7933b1d91dfe501e82f7a56147 Mon Sep 17 00:00:00 2001
From: Leander Beernaert <leander.beernaert@proton.ch>
Date: Thu, 16 Feb 2023 11:01:44 +0100
Subject: [PATCH] fix(GODT-2201): Flag list can be empty

---
 imap/command/flags.go      | 36 +++++++++++++++++++-----------------
 imap/command/flags_test.go |  2 +-
 2 files changed, 20 insertions(+), 18 deletions(-)

diff --git a/imap/command/flags.go b/imap/command/flags.go
index 28706cad..60ac2cb6 100644
--- a/imap/command/flags.go
+++ b/imap/command/flags.go
@@ -24,27 +24,29 @@ func ParseFlagList(p *rfcparser.Parser) ([]string, error) {
 		return nil, err
 	}
 
-	{
-		firstFlag, err := ParseFlag(p)
-		if err != nil {
-			return nil, err
+	if !p.Check(rfcparser.TokenTypeRParen) {
+		{
+			firstFlag, err := ParseFlag(p)
+			if err != nil {
+				return nil, err
+			}
+			flags = append(flags, firstFlag)
 		}
-		flags = append(flags, firstFlag)
-	}
 
-	for {
-		if ok, err := p.Matches(rfcparser.TokenTypeSP); err != nil {
-			return nil, err
-		} else if !ok {
-			break
-		}
+		for {
+			if ok, err := p.Matches(rfcparser.TokenTypeSP); err != nil {
+				return nil, err
+			} else if !ok {
+				break
+			}
 
-		flag, err := ParseFlag(p)
-		if err != nil {
-			return nil, err
-		}
+			flag, err := ParseFlag(p)
+			if err != nil {
+				return nil, err
+			}
 
-		flags = append(flags, flag)
+			flags = append(flags, flag)
+		}
 	}
 
 	if err := p.Consume(rfcparser.TokenTypeRParen, "Expected ')' at end of flag list"); err != nil {
diff --git a/imap/command/flags_test.go b/imap/command/flags_test.go
index 63a2b337..bbc2184b 100644
--- a/imap/command/flags_test.go
+++ b/imap/command/flags_test.go
@@ -11,6 +11,7 @@ func TestParser_ParseFlagList(t *testing.T) {
 	values := map[string][]string{
 		`(\Answered)`:                {`\Answered`},
 		`(\Answered Foo \Something)`: {`\Answered`, `Foo`, `\Something`},
+		`()`:                         nil,
 	}
 
 	for input, expected := range values {
@@ -24,7 +25,6 @@ func TestParser_ParseFlagList(t *testing.T) {
 
 func TestParser_ParseFlagListInvalid(t *testing.T) {
 	inputs := [][]byte{
-		[]byte(`()`),
 		[]byte(`(\Foo\Bar)`),
 		[]byte(`"(\Recent)`),
 		[]byte(`(\Foo )`),