Sync all IMAP folders

backend/11-folders.go

@@ -107,6 +107,28 @@ type TargetFolder struct {
 // Antwort). override kommt aus folder_map.
 func MapSourceToTarget(srcName string, srcAttrs []string, srcDelim, dstDelim string,
 	targets []TargetFolder, override string) string {
-	// TODO Codex.
-	return ""
+	if strings.TrimSpace(override) != "" {
+		return override
+	}
+	srcRole := Role(srcAttrs, srcName, srcDelim)
+	if srcRole == RoleInbox {
+		return "INBOX"
+	}
+	if srcRole != RoleNone {
+		for _, target := range targets {
+			if Role(target.Attrs, target.Name, dstDelim) == srcRole {
+				return target.Name
+			}
+		}
+	}
+	if srcDelim == "" {
+		srcDelim = "/"
+	}
+	if dstDelim == "" {
+		dstDelim = "/"
+	}
+	if srcDelim != dstDelim {
+		return strings.ReplaceAll(srcName, srcDelim, dstDelim)
+	}
+	return srcName
 }