7 files changed, 39 insertions, 23 deletions

diff --git a/commands/account/next-result.go b/commands/account/next-result.go
index 78d437d..fe835ea 100644
--- a/commands/account/next-result.go
+++ b/commands/account/next-result.go
@@ -34,13 +34,13 @@ func (NextPrevResult) Execute(aerc *widgets.Aerc, args []string) error {
 		if store != nil {
 			store.PrevResult()
 		}
-		acct.Messages().Scroll()
+		acct.Messages().Invalidate()
 	} else {
 		store := acct.Store()
 		if store != nil {
 			store.NextResult()
 		}
-		acct.Messages().Scroll()
+		acct.Messages().Invalidate()
 	}
 	return nil
 }
diff --git a/commands/account/next.go b/commands/account/next.go
index 5e4838e..427f563 100644
--- a/commands/account/next.go
+++ b/commands/account/next.go
@@ -65,13 +65,13 @@ func ExecuteNextPrevMessage(args []string, acct *widgets.AccountView, pct bool,
 		store := acct.Store()
 		if store != nil {
 			store.NextPrev(-n)
-			acct.Messages().Scroll()
+			acct.Messages().Invalidate()
 		}
 	} else {
 		store := acct.Store()
 		if store != nil {
 			store.NextPrev(n)
-			acct.Messages().Scroll()
+			acct.Messages().Invalidate()
 		}
 	}
 	return nil
diff --git a/commands/account/search.go b/commands/account/search.go
index 1d2e7a2..607dc24 100644
--- a/commands/account/search.go
+++ b/commands/account/search.go
@@ -45,7 +45,7 @@ func (SearchFilter) Execute(aerc *widgets.Aerc, args []string) error {
 			acct.Logger().Printf("Search results: %v", uids)
 			store.ApplySearch(uids)
 			// TODO: Remove when stores have multiple OnUpdate handlers
-			acct.Messages().Scroll()
+			acct.Messages().Invalidate()
 		}
 	}
 	store.Search(args, cb)
diff --git a/commands/msg/archive.go b/commands/msg/archive.go
index 5561674..07de13f 100644
--- a/commands/msg/archive.go
+++ b/commands/msg/archive.go
@@ -53,7 +53,7 @@ func (Archive) Execute(aerc *widgets.Aerc, args []string) error {
 	}
 	archiveDir := acct.AccountConfig().Archive
 	store.Next()
-	acct.Messages().Scroll()
+	acct.Messages().Invalidate()
 
 	var uidMap map[string][]uint32
 	switch args[1] {
diff --git a/commands/msg/delete.go b/commands/msg/delete.go
index 4bda8b9..e74bf10 100644
--- a/commands/msg/delete.go
+++ b/commands/msg/delete.go
@@ -62,7 +62,7 @@ func (Delete) Execute(aerc *widgets.Aerc, args []string) error {
 			// no more messages in the list
 			if next == nil {
 				aerc.RemoveTab(h.msgProvider)
-				acct.Messages().Scroll()
+				acct.Messages().Invalidate()
 				return nil
 			}
 			lib.NewMessageStoreView(next, store, aerc.DecryptKeys,
@@ -76,7 +76,7 @@ func (Delete) Execute(aerc *widgets.Aerc, args []string) error {
 				})
 		}
 	}
-	acct.Messages().Scroll()
+	acct.Messages().Invalidate()
 	return nil
 }
 
diff --git a/commands/msg/move.go b/commands/msg/move.go
index 830e752..41f61da 100644
--- a/commands/msg/move.go
+++ b/commands/msg/move.go
@@ -62,7 +62,7 @@ func (Move) Execute(aerc *widgets.Aerc, args []string) error {
 		aerc.RemoveTab(h.msgProvider)
 	}
 	store.Next()
-	acct.Messages().Scroll()
+	acct.Messages().Invalidate()
 	joinedArgs := strings.Join(args[optind:], " ")
 	store.Move(uids, joinedArgs, createParents, func(
 		msg types.WorkerMessage) {
diff --git a/widgets/msglist.go b/widgets/msglist.go
index 5aedb44..38b6369 100644
--- a/widgets/msglist.go
+++ b/widgets/msglist.go
@@ -63,6 +63,8 @@ func (ml *MessageList) Draw(ctx *ui.Context) {
 		}
 	}
 
+	ml.ensureScroll()
+
 	var (
 		needsHeaders []uint32
 		row          int = 0
@@ -179,12 +181,12 @@ func (ml *MessageList) MouseEvent(localX int, localY int, event tcell.Event) {
 			if ml.store != nil {
 				ml.store.Next()
 			}
-			ml.Scroll()
+			ml.Invalidate()
 		case tcell.WheelUp:
 			if ml.store != nil {
 				ml.store.Prev()
 			}
-			ml.Scroll()
+			ml.Invalidate()
 		}
 	}
 }
@@ -225,7 +227,6 @@ func (ml *MessageList) storeUpdate(store *lib.MessageStore) {
 		ml.nmsgs = len(uids)
 	}
 
-	ml.Scroll()
 	ml.Invalidate()
 }
 
@@ -266,25 +267,40 @@ func (ml *MessageList) Selected() *models.MessageInfo {
 func (ml *MessageList) Select(index int) {
 	store := ml.Store()
 	store.Select(index)
-	ml.Scroll()
+	ml.Invalidate()
 }
 
-func (ml *MessageList) Scroll() {
+func (ml *MessageList) ensureScroll() {
 	store := ml.Store()
-
 	if store == nil || len(store.Uids()) == 0 {
 		return
 	}
-	if ml.Height() != 0 {
-		// I'm too lazy to do the math right now
-		for store.SelectedIndex()-ml.scroll >= ml.Height() {
-			ml.scroll += 1
-		}
-		for store.SelectedIndex()-ml.scroll < 0 {
-			ml.scroll -= 1
+
+	h := ml.Height()
+
+	maxScroll := len(store.Uids()) - h
+	if maxScroll < 0 {
+		maxScroll = 0
+	}
+
+	selectedIndex := store.SelectedIndex()
+
+	if selectedIndex >= ml.scroll && selectedIndex < ml.scroll+h {
+		if ml.scroll > maxScroll {
+			ml.scroll = maxScroll
 		}
+		return
+	}
+
+	if selectedIndex >= ml.scroll+h {
+		ml.scroll = selectedIndex - h + 1
+	} else if selectedIndex < ml.scroll {
+		ml.scroll = selectedIndex
+	}
+
+	if ml.scroll > maxScroll {
+		ml.scroll = maxScroll
 	}
-	ml.Invalidate()
 }
 
 func (ml *MessageList) drawEmptyMessage(ctx *ui.Context) {