notmuch: make maildir store path configurable

Add the "maildir-store" account configuration option to select the
maildir store to associate with the notmuch database.

This also allows the previous changes to be backward compatible since
not specifying this option will make the backend behave the same as if
there were no changes.

Fixes: https://todo.sr.ht/~rjarry/aerc/73
Signed-off-by: Julian Pidancet <julian.pidancet@oracle.com>
Acked-by: Robin Jarry <robin@jarry.cc>
Acked-by: Tim Culverhouse <tim@timculverhouse.com>

doc/aerc-notmuch.5.scd

@@ -66,12 +66,18 @@ This can for example be useful if you use an archive or spam tag.
 
 	Default: none
 
+*maildir-store*
+	Path to the maildir store containing the message files backing the
+	notmuch database. This is often the same as the notmuch database path.
+	This is optional. If specified, it will be used by aerc to list
+	available folders and enable commands such as :delete and :archive.
+
+	Default: none
+
 # USAGE
 
 Notmuch shows slightly different behavior than for example imap.++
-Some commands are simply unsupported because they have no proper counterpart
-in notmuch, like :delete and :archive.++
-Others are slightly different in semantics and mentioned below:
+Some commands are slightly different in semantics and mentioned below:
 
 *cf* <notmuch query>
 	The change folder command allows for arbitrary notmuch queries. Performing a

worker/notmuch/eventhandlers.go

@@ -20,6 +20,7 @@ func (w *worker) handleNotmuchEvent(et eventType) error {
 }
 
 func (w *worker) handleUpdateDirCounts(ev eventType) error {
+	if w.store != nil {
 		folders, err := w.store.FolderMap()
 		if err != nil {
 			logging.Errorf("failed listing directories: %v", err)
@@ -34,6 +35,7 @@ func (w *worker) handleUpdateDirCounts(ev eventType) error {
 			}
 			w.w.PostMessage(info, nil)
 		}
+	}
 
 	for name, query := range w.nameQueryMap {
 		info, err := w.buildDirInfo(name, query, true)

worker/notmuch/worker.go

@@ -179,11 +179,19 @@ func (w *worker) handleConfigure(msg *types.Configure) error {
 	}
 	excludedTags := w.loadExcludeTags(msg.Config)
 	w.db = notmuch.NewDB(pathToDB, excludedTags)
-	store, err := lib.NewMaildirStore(pathToDB, false)
+
+	val, ok := msg.Config.Params["maildir-store"]
+	if ok {
+		path, err := homedir.Expand(val)
+		if err != nil {
+			return err
+		}
+		store, err := lib.NewMaildirStore(path, false)
 		if err != nil {
 			return fmt.Errorf("Cannot initialize maildir store: %w", err)
 		}
 		w.store = store
+	}
 
 	return nil
 }
@@ -207,6 +215,7 @@ func (w *worker) handleConnect(msg *types.Connect) error {
 }
 
 func (w *worker) handleListDirectories(msg *types.ListDirectories) error {
+	if w.store != nil {
 		folders, err := w.store.FolderMap()
 		if err != nil {
 			logging.Errorf("failed listing directories: %v", err)
@@ -221,6 +230,7 @@ func (w *worker) handleListDirectories(msg *types.ListDirectories) error {
 				},
 			}, nil)
 		}
+	}
 
 	for _, name := range w.queryMapOrder {
 		w.w.PostMessage(&types.Directory{
@@ -287,10 +297,12 @@ func (w *worker) queryFromName(name string) (string, bool) {
 	// try the friendly name first, if that fails assume it's a query
 	q, ok := w.nameQueryMap[name]
 	if !ok {
+		if w.store != nil {
 			folders, _ := w.store.FolderMap()
 			if _, ok := folders[name]; ok {
 				return fmt.Sprintf("folder:%s", strconv.Quote(name)), true
 			}
+		}
 		return name, true
 	}
 	return q, false
@@ -713,6 +725,10 @@ func (w *worker) handleCheckMail(msg *types.CheckMail) {
 }
 
 func (w *worker) handleDeleteMessages(msg *types.DeleteMessages) error {
+	if w.store == nil {
+		return errUnsupported
+	}
+
 	var deleted []uint32
 
 	// With notmuch, two identical files can be referenced under
@@ -753,6 +769,10 @@ func (w *worker) handleDeleteMessages(msg *types.DeleteMessages) error {
 }
 
 func (w *worker) handleCopyMessages(msg *types.CopyMessages) error {
+	if w.store == nil {
+		return errUnsupported
+	}
+
 	// Only allow file to be copied to a maildir folder
 	folders, _ := w.store.FolderMap()
 	dest, ok := folders[msg.Destination]
@@ -781,6 +801,10 @@ func (w *worker) handleCopyMessages(msg *types.CopyMessages) error {
 }
 
 func (w *worker) handleMoveMessages(msg *types.MoveMessages) error {
+	if w.store == nil {
+		return errUnsupported
+	}
+
 	var moved []uint32
 
 	// With notmuch, two identical files can be referenced under
@@ -824,6 +848,10 @@ func (w *worker) handleMoveMessages(msg *types.MoveMessages) error {
 }
 
 func (w *worker) handleAppendMessage(msg *types.AppendMessage) error {
+	if w.store == nil {
+		return errUnsupported
+	}
+
 	// Only allow file to be created in a maildir folder
 	// since we are the "master" maildir process, we can modify the maildir directly
 	folders, _ := w.store.FolderMap()
@@ -859,6 +887,10 @@ func (w *worker) handleAppendMessage(msg *types.AppendMessage) error {
 }
 
 func (w *worker) handleCreateDirectory(msg *types.CreateDirectory) error {
+	if w.store == nil {
+		return errUnsupported
+	}
+
 	dir := w.store.Dir(msg.Directory)
 	if err := dir.Init(); err != nil {
 		logging.Errorf("could not create directory %s: %v",
@@ -870,6 +902,10 @@ func (w *worker) handleCreateDirectory(msg *types.CreateDirectory) error {
 }
 
 func (w *worker) handleRemoveDirectory(msg *types.RemoveDirectory) error {
+	if w.store == nil {
+		return errUnsupported
+	}
+
 	dir := w.store.Dir(msg.Directory)
 	if err := os.RemoveAll(string(dir)); err != nil {
 		logging.Errorf("could not remove directory %s: %v",