Replace hand-rolled IMAP with go-imap

backend/05-imap-target.go

@@ -1,41 +1,44 @@
 package backend
 
-import "strings"
+import (
+	"fmt"
+	"strings"
+
+	"github.com/emersion/go-imap/v2"
+)
 
 // TargetMailbox = das Ziel-Postfach (neuer Host). Der Umzug schreibt hier per
 // IMAP APPEND hinein -- NICHT per SMTP. APPEND erhaelt Ordner, Flags und
 // Original-Datum; SMTP wuerde alles als "neu/ungelesen" mit falschem Datum
 // zustellen und die Ordnerstruktur zerstoeren.
 type TargetMailbox interface {
-	Folders() ([]TargetFolder, error)         // vorhandene Ziel-Ordner (fuer Rollen-Zuordnung)
-	Delim() string                            // Hierarchie-Trenner des Ziels
-	EnsureFolder(name string) error           // anlegen + subscriben, falls fehlt
-	Append(folder string, m RawMessage) error // mit m.Flags und m.InternalDate
+	Folders() ([]TargetFolder, error)          // vorhandene Ziel-Ordner (fuer Rollen-Zuordnung)
+	Delim() string                             // Hierarchie-Trenner des Ziels
+	EnsureFolder(name string) error            // anlegen + subscriben, falls fehlt
+	Append(folder string, m RawMessage) error  // mit m.Flags und m.InternalDate
 	Fetch(folder string) ([]RawMessage, error) // Ziel-Audit: geschriebene Mail wiederfinden
 	Close() error
 }
 
-// OpenIMAPTarget verbindet das Ziel per go-imap/v2 (Security wie Quelle, siehe
-// a.DstSecurity/a.DstInsecure; meist "tls").
 func OpenIMAPTarget(a Account) (TargetMailbox, error) {
-	c, err := dialIMAP(a.DstHost, a.DstPort, a.DstSecurity, a.DstInsecure)
+	c, err := dialIMAPClient(a.DstHost, a.DstPort, a.DstSecurity, a.DstInsecure)
 	if err != nil {
 		return nil, err
 	}
-	if err := c.login(a.DstUser, a.DstPass); err != nil {
+	if err := c.Login(a.DstUser, a.DstPass).Wait(); err != nil {
 		_ = c.Close()
 		return nil, err
 	}
-	return &imapTarget{c: c}, nil
+	return &imapTarget{mailbox: &imapClientMailbox{c: c}}, nil
 }
 
 type imapTarget struct {
-	c     *simpleIMAP
-	delim string
+	mailbox *imapClientMailbox
+	delim   string
 }
 
 func (t *imapTarget) Folders() ([]TargetFolder, error) {
-	boxes, err := t.c.listMailboxes()
+	boxes, err := t.mailbox.listMailboxes()
 	if err != nil {
 		return nil, err
 	}
@@ -63,29 +66,64 @@ func (t *imapTarget) Delim() string {
 }
 
 func (t *imapTarget) EnsureFolder(name string) error {
-	if name == "INBOX" {
+	name = strings.TrimSpace(name)
+	if name == "" || strings.EqualFold(name, "INBOX") {
 		return nil
 	}
-	if err := t.c.simple("CREATE " + imapQuote(name)); err != nil {
-		if !strings.Contains(strings.ToLower(err.Error()), "exist") && !strings.Contains(strings.ToLower(err.Error()), "already") {
-			return err
-		}
+	if err := t.ensureParentFolders(name); err != nil {
+		return err
 	}
-	_ = t.c.simple("SUBSCRIBE " + imapQuote(name))
+	if err := t.createFolder(name); err != nil {
+		return err
+	}
+	_ = t.mailbox.c.Subscribe(name).Wait()
 	return nil
 }
 
+func (t *imapTarget) ensureParentFolders(name string) error {
+	delim := t.Delim()
+	if delim == "" || !strings.Contains(name, delim) {
+		return nil
+	}
+	parts := strings.Split(name, delim)
+	for i := 1; i < len(parts); i++ {
+		parent := strings.Join(parts[:i], delim)
+		if strings.TrimSpace(parent) == "" || strings.EqualFold(parent, "INBOX") {
+			continue
+		}
+		if err := t.createFolder(parent); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (t *imapTarget) createFolder(name string) error {
+	err := t.mailbox.c.Create(name, nil).Wait()
+	if err == nil || isAlreadyExistsError(err) {
+		return nil
+	}
+	return fmt.Errorf("imap create %q failed: %w", name, err)
+}
+
 func (t *imapTarget) Append(folder string, m RawMessage) error {
-	return t.c.appendMessage(folder, m)
+	opts := &imap.AppendOptions{Flags: stringsToFlags(m.Flags), Time: m.InternalDate}
+	cmd := t.mailbox.c.Append(folder, int64(len(m.Body)), opts)
+	if _, err := cmd.Write(m.Body); err != nil {
+		_ = cmd.Close()
+		return err
+	}
+	if err := cmd.Close(); err != nil {
+		return err
+	}
+	_, err := cmd.Wait()
+	return err
 }
 
 func (t *imapTarget) Fetch(folder string) ([]RawMessage, error) {
-	if err := t.c.selectMailbox(folder); err != nil {
-		return nil, err
-	}
-	return t.c.fetchAll()
+	return t.mailbox.fetchAll(folder)
 }
 
 func (t *imapTarget) Close() error {
-	return t.c.Close()
+	return t.mailbox.Close()
 }