split: refactor split update logic

Refactor split update logic to more simply update the split. Through the
evolution of the split logic, additional variables were stored within
the account which allows for cleaner updating of the split.

Compare selected UID instead of pointer to message when deciding not to
update split.

Allow splits to be created and closed when no message is selected. The
split will be filled with a ui.Fill (blank). The user will only see a
border at the split location when no message is selected.

Rename clearSplit to closeSplit, as it is only used in the case when the
user doesn't want a split anymore.

Ensure that the selected UID is reset to the magic UID when there are no
messages left in the message store.

Signed-off-by: Tim Culverhouse <tim@timculverhouse.com>
Tested-by: Bence Ferdinandy <bence@ferdinandy.com>

2 files changed, 41 insertions, 29 deletions

diff --git a/widgets/account.go b/widgets/account.go
index 6bcb5b83..6f1b7cc3 100644
--- a/widgets/account.go
+++ b/widgets/account.go
@@ -39,7 +39,7 @@ type AccountView struct {
 	split         *MessageViewer
 	splitSize     int
 	splitDebounce *time.Timer
-	splitMsg      *models.MessageInfo
+	splitUid      uint32
 	splitDir      string
 
 	// Check-mail ticker
@@ -479,7 +479,7 @@ func (acct *AccountView) CheckMailTimer(d time.Duration) {
 	}()
 }
 
-func (acct *AccountView) clearSplit() {
+func (acct *AccountView) closeSplit() {
 	if acct.split != nil {
 		acct.split.Close()
 	}
@@ -506,31 +506,25 @@ func (acct *AccountView) UpdateSplitView() {
 	if acct.Store() == nil {
 		return
 	}
-	if acct.splitMsg == acct.msglist.Selected() {
+	if acct.Store().SelectedUid() == acct.splitUid {
 		return
 	}
 	if acct.splitDebounce != nil {
 		acct.splitDebounce.Stop()
 	}
 	fn := func() {
-		msg, err := acct.SelectedMessage()
-		if err != nil {
+		var err error
+		switch acct.SplitDirection() {
+		case "split":
+			err = acct.Split(acct.SplitSize())
+		case "vsplit":
+			err = acct.Vsplit(acct.SplitSize())
+		default:
 			return
 		}
-		lib.NewMessageStoreView(msg, false, acct.Store(), acct.aerc.Crypto, acct.aerc.DecryptKeys,
-			func(view lib.MessageView, err error) {
-				if err != nil {
-					acct.aerc.PushError(err.Error())
-					return
-				}
-				orig := acct.split
-				acct.split = NewMessageViewer(acct, view)
-				acct.grid.ReplaceChild(orig, acct.split)
-				if orig != nil {
-					orig.Close()
-				}
-			})
-		acct.splitMsg = msg
+		if err != nil {
+			log.Errorf("could not update split: %v", err)
+		}
 		ui.Invalidate()
 	}
 	acct.splitDebounce = time.AfterFunc(100*time.Millisecond, func() {
@@ -550,13 +544,9 @@ func (acct *AccountView) SplitDirection() string {
 // rows high. If n is 0, any existing split is removed
 func (acct *AccountView) Split(n int) error {
 	if n == 0 {
-		acct.clearSplit()
+		acct.closeSplit()
 		return nil
 	}
-	msg, err := acct.SelectedMessage()
-	if err != nil {
-		return fmt.Errorf("could not create split: %w", err)
-	}
 	acct.splitSize = n
 	acct.splitDir = "split"
 	if acct.split != nil {
@@ -577,6 +567,18 @@ func (acct *AccountView) Split(n int) error {
 		acct.grid.AddChild(ui.NewBordered(acct.dirlist, ui.BORDER_RIGHT, acct.uiConf)).Span(2, 1)
 	}
 	acct.grid.AddChild(ui.NewBordered(acct.msglist, ui.BORDER_BOTTOM, acct.uiConf)).At(0, 1)
+
+	if acct.msglist.Empty() {
+		acct.grid.AddChild(ui.NewFill(' ', tcell.StyleDefault)).At(1, 1)
+		ui.Invalidate()
+		return nil
+	}
+
+	msg, err := acct.SelectedMessage()
+	if err != nil {
+		return fmt.Errorf("could not create split: %w", err)
+	}
+	acct.splitUid = msg.Uid
 	lib.NewMessageStoreView(msg, false, acct.Store(), acct.aerc.Crypto, acct.aerc.DecryptKeys,
 		func(view lib.MessageView, err error) {
 			if err != nil {
@@ -594,13 +596,9 @@ func (acct *AccountView) Split(n int) error {
 // rows wide. If n is 0, any existing split is removed
 func (acct *AccountView) Vsplit(n int) error {
 	if n == 0 {
-		acct.clearSplit()
+		acct.closeSplit()
 		return nil
 	}
-	msg, err := acct.SelectedMessage()
-	if err != nil {
-		return fmt.Errorf("could not create split: %w", err)
-	}
 	acct.splitSize = n
 	acct.splitDir = "vsplit"
 	if acct.split != nil {
@@ -620,6 +618,19 @@ func (acct *AccountView) Vsplit(n int) error {
 		acct.grid.AddChild(ui.NewBordered(acct.dirlist, ui.BORDER_RIGHT, acct.uiConf)).At(0, 0)
 	}
 	acct.grid.AddChild(ui.NewBordered(acct.msglist, ui.BORDER_RIGHT, acct.uiConf)).At(0, 1)
+
+	if acct.msglist.Empty() {
+		acct.grid.AddChild(ui.NewFill(' ', tcell.StyleDefault)).At(0, 2)
+		ui.Invalidate()
+		return nil
+	}
+
+	msg, err := acct.SelectedMessage()
+	if err != nil {
+		return fmt.Errorf("could not create split: %w", err)
+	}
+	acct.splitUid = msg.Uid
+
 	lib.NewMessageStoreView(msg, false, acct.Store(), acct.aerc.Crypto, acct.aerc.DecryptKeys,
 		func(view lib.MessageView, err error) {
 			if err != nil {
diff --git a/widgets/msglist.go b/widgets/msglist.go
index a12a4687..fc5b46b5 100644
--- a/widgets/msglist.go
+++ b/widgets/msglist.go
@@ -391,6 +391,7 @@ func (ml *MessageList) Select(index int) {
 	store := ml.Store()
 	uids := store.Uids()
 	if len(uids) == 0 {
+		store.Select(lib.MagicUid)
 		return
 	}