msgview: enable next/prev with unfetched headers

Fix message view behavior for unfetched headers. When scrolling "over"
the message list boundary, current behavior is to close the message
viewer tab. Now, the headers will be fetched so that we can scroll
through the messages uninterrupted.

Fixes: https://todo.sr.ht/~rjarry/aerc/90
Signed-off-by: Koni Marti <koni.marti@gmail.com>
Acked-by: Robin Jarry <robin@jarry.cc>

1 files changed, 26 insertions, 14 deletions

diff --git a/commands/msgview/next.go b/commands/msgview/next.go
index 6341f931..5df7847d 100644
--- a/commands/msgview/next.go
+++ b/commands/msgview/next.go
@@ -5,7 +5,9 @@ import (
 
 	"git.sr.ht/~rjarry/aerc/commands/account"
 	"git.sr.ht/~rjarry/aerc/lib"
+	"git.sr.ht/~rjarry/aerc/models"
 	"git.sr.ht/~rjarry/aerc/widgets"
+	"git.sr.ht/~rjarry/aerc/worker/types"
 )
 
 type NextPrevMsg struct{}
@@ -37,20 +39,30 @@ func (NextPrevMsg) Execute(aerc *widgets.Aerc, args []string) error {
 	if err != nil {
 		return err
 	}
-	nextMsg := store.Selected()
-	if nextMsg == nil {
-		aerc.RemoveTab(mv)
-		return nil
+	executeNextPrev := func(nextMsg *models.MessageInfo) {
+		lib.NewMessageStoreView(nextMsg, mv.MessageView().SeenFlagSet(),
+			store, aerc.Crypto, aerc.DecryptKeys,
+			func(view lib.MessageView, err error) {
+				if err != nil {
+					aerc.PushError(err.Error())
+					return
+				}
+				nextMv := widgets.NewMessageViewer(acct,
+					aerc.Config(), view)
+				aerc.ReplaceTab(mv, nextMv,
+					nextMsg.Envelope.Subject)
+			})
 	}
-	lib.NewMessageStoreView(nextMsg, mv.MessageView().SeenFlagSet(),
-		store, aerc.Crypto, aerc.DecryptKeys,
-		func(view lib.MessageView, err error) {
-			if err != nil {
-				aerc.PushError(err.Error())
-				return
-			}
-			nextMv := widgets.NewMessageViewer(acct, aerc.Config(), view)
-			aerc.ReplaceTab(mv, nextMv, nextMsg.Envelope.Subject)
-		})
+	if nextMsg := store.Selected(); nextMsg != nil {
+		executeNextPrev(nextMsg)
+	} else {
+		store.FetchHeaders([]uint32{store.SelectedUid()},
+			func(msg types.WorkerMessage) {
+				if m, ok := msg.(*types.MessageInfo); ok {
+					executeNextPrev(m.Info)
+				}
+			})
+	}
+
 	return nil
 }