From 3da4aec99851683f0ad3db7b9c28a6d4e46560f3 Mon Sep 17 00:00:00 2001
From: Simon Ser <contact@emersion.fr>
Date: Sat, 24 Aug 2024 13:16:07 +0200
Subject: [PATCH] Add support for LIST-METADATA

---
 imapclient/list.go     | 20 +++++++++++++-----
 imapclient/metadata.go | 46 ++++++++++++++++++++++++++++++------------
 list.go                |  2 ++
 3 files changed, 50 insertions(+), 18 deletions(-)

diff --git a/imapclient/list.go b/imapclient/list.go
index eacda45d..d9d04ffe 100644
--- a/imapclient/list.go
+++ b/imapclient/list.go
@@ -49,6 +49,9 @@ func getReturnOpts(options *imap.ListOptions) []string {
 	if options.ReturnSpecialUse {
 		l = append(l, "SPECIAL-USE")
 	}
+	if options.ReturnMetadata {
+		l = append(l, "METADATA")
+	}
 	return l
 }
 
@@ -63,8 +66,9 @@ func getReturnOpts(options *imap.ListOptions) []string {
 // extension.
 func (c *Client) List(ref, pattern string, options *imap.ListOptions) *ListCommand {
 	cmd := &ListCommand{
-		mailboxes:    make(chan *imap.ListData, 64),
-		returnStatus: options != nil && options.ReturnStatus != nil,
+		mailboxes:      make(chan *imap.ListData, 64),
+		returnStatus:   options != nil && options.ReturnStatus != nil,
+		returnMetadata: options != nil && options.ReturnMetadata != nil,
 	}
 	enc := c.beginCommand("LIST", cmd)
 	if selectOpts := getSelectOpts(options); len(selectOpts) > 0 {
@@ -77,11 +81,16 @@ func (c *Client) List(ref, pattern string, options *imap.ListOptions) *ListComma
 		enc.SP().Atom("RETURN").SP().List(len(returnOpts), func(i int) {
 			opt := returnOpts[i]
 			enc.Atom(opt)
-			if opt == "STATUS" {
+			switch opt {
+			case "STATUS":
 				returnStatus := statusItems(options.ReturnStatus)
 				enc.SP().List(len(returnStatus), func(j int) {
 					enc.Atom(returnStatus[j])
 				})
+			case "METADATA":
+				enc.SP().List(len(options.ReturnMetadata), func(j int) {
+					enc.String(options.ReturnMetadata[j])
+				})
 			}
 		})
 	}
@@ -127,8 +136,9 @@ type ListCommand struct {
 	cmd
 	mailboxes chan *imap.ListData
 
-	returnStatus bool
-	pendingData  *imap.ListData
+	returnStatus   bool
+	returnMetadata bool
+	pendingData    *imap.ListData
 }
 
 // Next advances to the next mailbox.
diff --git a/imapclient/metadata.go b/imapclient/metadata.go
index 40633b6c..622684fe 100644
--- a/imapclient/metadata.go
+++ b/imapclient/metadata.go
@@ -108,28 +108,48 @@ func (c *Client) handleMetadata() error {
 		return fmt.Errorf("in metadata-resp: %v", err)
 	}
 
-	cmd := c.findPendingCmdFunc(func(anyCmd command) bool {
-		cmd, ok := anyCmd.(*GetMetadataCommand)
-		return ok && cmd.mailbox == data.Mailbox
-	})
-	if cmd != nil && len(data.EntryValues) > 0 {
-		cmd := cmd.(*GetMetadataCommand)
-		cmd.data.Mailbox = data.Mailbox
-		if cmd.data.Entries == nil {
-			cmd.data.Entries = make(map[string]*[]byte)
+	cmd := c.findPendingCmdFunc(func(cmd command) bool {
+		switch cmd := cmd.(type) {
+		case *GetMetadataCommand:
+			return cmd.mailbox == data.Mailbox
+		case *ListCommand:
+			return cmd.returnMetadata && cmd.pendingData != nil && cmd.pendingData.Mailbox == data.Mailbox
+		default:
+			return false
 		}
+	})
+	if len(data.EntryValues) == 0 {
+		cmd = nil // Response is unsolicited
+	}
+	switch cmd := cmd.(type) {
+	case *GetMetadataCommand:
 		// The server might send multiple METADATA responses for a single
 		// METADATA command
-		for k, v := range data.EntryValues {
-			cmd.data.Entries[k] = v
+		populateMetadata(cmd.data, data)
+	case *ListCommand:
+		// TODO: populateMetadata(cmd.pendingData.Metadata, data)
+		// TODO: send to chan
+	default:
+		if handler := c.options.unilateralDataHandler().Metadata; handler != nil && len(data.EntryList) > 0 {
+			handler(data.Mailbox, data.EntryList)
 		}
-	} else if handler := c.options.unilateralDataHandler().Metadata; handler != nil && len(data.EntryList) > 0 {
-		handler(data.Mailbox, data.EntryList)
 	}
 
 	return nil
 }
 
+func populateMetadata(dst, src *GetMetadataData) {
+	cmd.data.Mailbox = data.Mailbox
+	if cmd.data.Entries == nil {
+		cmd.data.Entries = make(map[string]*[]byte)
+	}
+	// The server might send multiple METADATA responses for a single
+	// METADATA command
+	for k, v := range data.EntryValues {
+		cmd.data.Entries[k] = v
+	}
+}
+
 // GetMetadataCommand is a GETMETADATA command.
 type GetMetadataCommand struct {
 	cmd
diff --git a/list.go b/list.go
index a3103a60..d2803b88 100644
--- a/list.go
+++ b/list.go
@@ -11,6 +11,7 @@ type ListOptions struct {
 	ReturnChildren   bool
 	ReturnStatus     *StatusOptions // requires IMAP4rev2 or LIST-STATUS
 	ReturnSpecialUse bool           // requires SPECIAL-USE
+	ReturnMetadata   []string       // requires LIST-METADATA
 }
 
 // ListData is the mailbox data returned by a LIST command.
@@ -23,6 +24,7 @@ type ListData struct {
 	ChildInfo *ListDataChildInfo
 	OldName   string
 	Status    *StatusData
+	Metadata  struct{} // TODO: *GetMetadataData
 }
 
 type ListDataChildInfo struct {