Revert "Make nnimap support IMAP namespaces"

This reverts commit 7b5b3ddb2dfa98d640aff7b5b160f777e22cc794.

Insufficiently tested before committing -- bugs out several places
when not using namespaces.

3 files changed, 27 insertions, 74 deletions

diff --git a/doc/misc/gnus.texi b/doc/misc/gnus.texi
index cd97cff2a05..6793ed2e9f1 100644
--- a/doc/misc/gnus.texi
+++ b/doc/misc/gnus.texi
@@ -14320,12 +14320,6 @@ fetch all textual parts, while leaving the rest on the server.
 If non-@code{nil}, record all @acronym{IMAP} commands in the
 @samp{"*imap log*"} buffer.
 
-@item nnimap-use-namespaces
-If non-@code{nil}, omit the IMAP namespace prefix in nnimap group
-names. If your IMAP mailboxes are called something like @samp{INBOX}
-and @samp{INBOX.Lists.emacs}, but you'd like the nnimap group names to
-be @samp{INBOX} and @samp{Lists.emacs}, you should enable this option.
-
 @end table
 
 
diff --git a/etc/NEWS b/etc/NEWS
index 57b51f61b60..fc2a5d4c039 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -46,11 +46,6 @@ option --enable-check-lisp-object-type is therefore no longer as
 useful and so is no longer enabled by default in developer builds,
 to reduce differences between developer and production builds.
 
-** Gnus
-
-+++
-*** The nnimap backend now has support for IMAP namespaces.
-
 
 * Startup Changes in Emacs 27.1
 
diff --git a/lisp/gnus/nnimap.el b/lisp/gnus/nnimap.el
index af7899f7897..3b397319272 100644
--- a/lisp/gnus/nnimap.el
+++ b/lisp/gnus/nnimap.el
@@ -55,13 +55,6 @@
 If nnimap-stream is `ssl', this will default to `imaps'.  If not,
 it will default to `imap'.")
 
-(defvoo nnimap-use-namespaces nil
-  "Whether to use IMAP namespaces.
-If in Gnus your folder names in all start with (e.g.) `INBOX',
-you probably want to set this to t. The effects of this are
-purely cosmetical, but changing this variable will affect the
-names of your nnimap groups. ")
-
 (defvoo nnimap-stream 'undecided
   "How nnimap talks to the IMAP server.
 The value should be either `undecided', `ssl' or `tls',
@@ -117,8 +110,6 @@ some servers.")
 
 (defvoo nnimap-current-infos nil)
 
-(defvoo nnimap-namespace nil)
-
 (defun nnimap-decode-gnus-group (group)
   (decode-coding-string group 'utf-8))
 
@@ -175,18 +166,6 @@ textual parts.")
 
 (defvar nnimap-inhibit-logging nil)
 
-(defun nnimap-group-to-imap (group)
-  "Convert Gnus group name to IMAP mailbox name."
-  (let* ((inbox (substring nnimap-namespace 0 -1)))
-    (utf7-encode
-     (cond ((or (not nnimap-namespace)
-                (string-equal group inbox))
-            group)
-           ((string-prefix-p "#" group)
-            (substring group 1))
-           (t
-            (concat nnimap-namespace group))) t)))
-
 (defun nnimap-buffer ()
   (nnimap-find-process-buffer nntp-server-buffer))
 
@@ -463,8 +442,7 @@ textual parts.")
              (props (cdr stream-list))
              (greeting (plist-get props :greeting))
              (capabilities (plist-get props :capabilities))
-             (stream-type (plist-get props :type))
-             (server (nnoo-current-server 'nnimap)))
+             (stream-type (plist-get props :type)))
         (when (and stream (not (memq (process-status stream) '(open run))))
           (setq stream nil))
 
@@ -497,7 +475,9 @@ textual parts.")
                                ;; the virtual server name and the address
                                (nnimap-credentials
                                 (gnus-delete-duplicates
-                                 (list server nnimap-address))
+                                 (list
+                                  (nnoo-current-server 'nnimap)
+                                  nnimap-address))
                                 ports
                                 nnimap-user))))
                   (setq nnimap-object nil)
@@ -516,17 +496,8 @@ textual parts.")
                       (dolist (response (cddr (nnimap-command "CAPABILITY")))
                         (when (string= "CAPABILITY" (upcase (car response)))
                           (setf (nnimap-capabilities nnimap-object)
-                                (mapcar #'upcase (cdr response)))))
-                      (when (and nnimap-use-namespaces
-                                 (nnimap-capability "NAMESPACE"))
-                        (erase-buffer)
-                        (nnimap-wait-for-response (nnimap-send-command "NAMESPACE"))
-                        (let ((response (nnimap-last-response-string)))
-                          (when (string-match
-                                 "^\\*\\W+NAMESPACE\\W+((\"\\([^\"\n]+\\)\"\\W+\"\\(.\\)\"))\\W+"
-                                 response)
-                            (setq nnimap-namespace (match-string 1 response))))))
-                  ;; If the login failed, then forget the credentials
+                                (mapcar #'upcase (cdr response))))))
+                  ;; If the login failed, then forget the credentials
                   ;; that are now possibly cached.
                   (dolist (host (list (nnoo-current-server 'nnimap)
                                       nnimap-address))
@@ -866,7 +837,7 @@ textual parts.")
       (with-current-buffer (nnimap-buffer)
         (erase-buffer)
         (let ((group-sequence
-               (nnimap-send-command "SELECT %S" (nnimap-group-to-imap group)))
+               (nnimap-send-command "SELECT %S" (utf7-encode group t)))
               (flag-sequence
                (nnimap-send-command "UID FETCH 1:* FLAGS")))
           (setf (nnimap-group nnimap-object) group)
@@ -899,13 +870,13 @@ textual parts.")
   (setq group (nnimap-decode-gnus-group group))
   (when (nnimap-change-group nil server)
     (with-current-buffer (nnimap-buffer)
-      (car (nnimap-command "CREATE %S" (nnimap-group-to-imap group))))))
+      (car (nnimap-command "CREATE %S" (utf7-encode group t))))))
 
 (deffoo nnimap-request-delete-group (group &optional _force server)
   (setq group (nnimap-decode-gnus-group group))
   (when (nnimap-change-group nil server)
     (with-current-buffer (nnimap-buffer)
-      (car (nnimap-command "DELETE %S" (nnimap-group-to-imap group))))))
+      (car (nnimap-command "DELETE %S" (utf7-encode group t))))))
 
 (deffoo nnimap-request-rename-group (group new-name &optional server)
   (setq group (nnimap-decode-gnus-group group))
@@ -913,7 +884,7 @@ textual parts.")
     (with-current-buffer (nnimap-buffer)
       (nnimap-unselect-group)
       (car (nnimap-command "RENAME %S %S"
-                           (nnimap-group-to-imap group) (nnimap-group-to-imap new-name))))))
+                           (utf7-encode group t) (utf7-encode new-name t))))))
 
 (defun nnimap-unselect-group ()
   ;; Make sure we don't have this group open read/write by asking
@@ -973,7 +944,7 @@ textual parts.")
                                 "UID COPY %d %S"))
                      (result (nnimap-command
                               command article
-                              (nnimap-group-to-imap internal-move-group))))
+                              (utf7-encode internal-move-group t))))
                 (when (and (car result) (not can-move))
                   (nnimap-delete-article article))
                 (cons internal-move-group
@@ -1040,7 +1011,7 @@ textual parts.")
                     "UID MOVE %s %S"
                   "UID COPY %s %S")
                 (nnimap-article-ranges (gnus-compress-sequence articles))
-                (nnimap-group-to-imap (gnus-group-real-name nnmail-expiry-target)))
+                (utf7-encode (gnus-group-real-name nnmail-expiry-target) t))
                (set (if can-move 'deleted-articles 'articles-to-delete) articles))))
       t)
      (t
@@ -1165,7 +1136,7 @@ If LIMIT, first try to limit the search to the N last articles."
                       (unsubscribe "UNSUBSCRIBE")))))
       (when command
         (with-current-buffer (nnimap-buffer)
-          (nnimap-command "%s %S" (cadr command) (nnimap-group-to-imap group)))))))
+          (nnimap-command "%s %S" (cadr command) (utf7-encode group t)))))))
 
 (deffoo nnimap-request-set-mark (group actions &optional server)
   (setq group (nnimap-decode-gnus-group group))
@@ -1220,7 +1191,7 @@ If LIMIT, first try to limit the search to the N last articles."
             (nnimap-unselect-group))
           (erase-buffer)
           (setq sequence (nnimap-send-command
-                          "APPEND %S {%d}" (nnimap-group-to-imap group)
+                          "APPEND %S {%d}" (utf7-encode group t)
                           (length message)))
           (unless nnimap-streaming
             (nnimap-wait-for-connection "^[+]"))
@@ -1300,11 +1271,8 @@ If LIMIT, first try to limit the search to the N last articles."
 
 (defun nnimap-get-groups ()
   (erase-buffer)
-  (let* ((sequence (nnimap-send-command "LIST \"\" \"*\""))
-         (prefix nnimap-namespace)
-         (prefix-len (length prefix))
-         (inbox (substring prefix 0 -1))
-         groups)
+  (let ((sequence (nnimap-send-command "LIST \"\" \"*\""))
+        groups)
     (nnimap-wait-for-response sequence)
     (subst-char-in-region (point-min) (point-max)
                           ?\\ ?% t)
@@ -1321,15 +1289,11 @@ If LIMIT, first try to limit the search to the N last articles."
                            (skip-chars-backward " \r\"")
                            (point)))))
         (unless (member '%NoSelect flags)
-          (let* ((group (utf7-decode (if (stringp group) group
-                                       (format "%s" group)) t))
-                 (group (cond ((equal inbox group)
-                               group)
-                              ((string-prefix-p prefix group)
-                               (substring group prefix-len))
-                              (t
-                               (concat "#" group)))))
-            (push group groups)))))
+          (push (utf7-decode (if (stringp group)
+                                 group
+                               (format "%s" group))
+                             t)
+                groups))))
     (nreverse groups)))
 
 (defun nnimap-get-responses (sequences)
@@ -1355,7 +1319,7 @@ If LIMIT, first try to limit the search to the N last articles."
             (dolist (group groups)
               (setf (nnimap-examined nnimap-object) group)
               (push (list (nnimap-send-command "EXAMINE %S"
-                                               (nnimap-group-to-imap group))
+                                               (utf7-encode group t))
                           group)
                     sequences))
             (nnimap-wait-for-response (caar sequences))
@@ -1427,7 +1391,7 @@ If LIMIT, first try to limit the search to the N last articles."
                    unexist)
               (push
                (list (nnimap-send-command "EXAMINE %S (%s (%s %s))"
-                                          (nnimap-group-to-imap group)
+                                          (utf7-encode group t)
                                           (nnimap-quirk "QRESYNC")
                                           uidvalidity modseq)
                      'qresync
@@ -1449,7 +1413,7 @@ If LIMIT, first try to limit the search to the N last articles."
                 (cl-incf (nnimap-initial-resync nnimap-object))
                 (setq start 1))
               (push (list (nnimap-send-command "%s %S" command
-                                               (nnimap-group-to-imap group))
+                                               (utf7-encode group t))
                           (nnimap-send-command "UID FETCH %d:* FLAGS" start)
                           start group command)
                     sequences))))
@@ -1883,7 +1847,7 @@ Return the server's response to the SELECT or EXAMINE command."
                                       (if read-only
                                           "EXAMINE"
                                         "SELECT")
-                                      (nnimap-group-to-imap group))))
+                                      (utf7-encode group t))))
           (when (car result)
             (setf (nnimap-group nnimap-object) group
                   (nnimap-select-result nnimap-object) result)
@@ -2141,7 +2105,7 @@ Return the server's response to the SELECT or EXAMINE command."
             (dolist (spec specs)
               (when (and (not (member (car spec) groups))
                          (not (eq (car spec) 'junk)))
-                (nnimap-command "CREATE %S" (nnimap-group-to-imap (car spec)))))
+                (nnimap-command "CREATE %S" (utf7-encode (car spec) t))))
             ;; Then copy over all the messages.
             (erase-buffer)
             (dolist (spec specs)
@@ -2157,7 +2121,7 @@ Return the server's response to the SELECT or EXAMINE command."
                                      "UID MOVE %s %S"
                                    "UID COPY %s %S")
                                  (nnimap-article-ranges ranges)
-                                (nnimap-group-to-imap group))
+                                 (utf7-encode group t))
                                 ranges)
                           sequences)))))
             ;; Wait for the last COPY response...