Show currently pressed keys in statusline

This patch adds the currently pressed keys to the statusline. This is
useful when keybindings are multiple keys long and you might forget
which keys are already pressed.

widgets/aerc.go

@@ -58,6 +58,8 @@ func NewAerc(conf *config.AercConfig, logger *log.Logger,
 		tabs:       tabs,
 	}
 
+	statusline.SetAerc(aerc)
+
 	for i, acct := range conf.Accounts {
 		view := NewAccountView(conf, &conf.Accounts[i], logger, aerc)
 		aerc.accounts[acct.Name] = view
@@ -150,6 +152,7 @@ func (aerc *Aerc) Event(event tcell.Event) bool {
 			Key:  event.Key(),
 			Rune: event.Rune(),
 		})
+		aerc.statusline.Invalidate()
 		bindings := aerc.getBindings()
 		incomplete := false
 		result, strokes := bindings.GetBinding(aerc.pendingKeys)

widgets/status.go

@@ -4,6 +4,7 @@ import (
 	"time"
 
 	"github.com/gdamore/tcell"
+	"github.com/mattn/go-runewidth"
 
 	"git.sr.ht/~sircmpwn/aerc/lib/ui"
 )
@@ -12,6 +13,7 @@ type StatusLine struct {
 	ui.Invalidatable
 	stack    []*StatusMessage
 	fallback StatusMessage
+	aerc     *Aerc
 }
 
 type StatusMessage struct {
@@ -42,7 +44,14 @@ func (status *StatusLine) Draw(ctx *ui.Context) {
 	style := tcell.StyleDefault.
 		Background(line.bg).Foreground(line.fg).Reverse(true)
 	ctx.Fill(0, 0, ctx.Width(), ctx.Height(), ' ', style)
-	ctx.Printf(0, 0, style, "%s", line.message)
+	pendingKeys := ""
+	if status.aerc != nil {
+		for _, pendingKey := range status.aerc.pendingKeys {
+			pendingKeys += string(pendingKey.Rune)
+		}
+	}
+	message := runewidth.FillRight(line.message, ctx.Width()-len(pendingKeys)-5)
+	ctx.Printf(0, 0, style, "%s%s", message, pendingKeys)
 }
 
 func (status *StatusLine) Set(text string) *StatusMessage {
@@ -79,6 +88,10 @@ func (status *StatusLine) Expire() {
 	status.stack = nil
 }
 
+func (status *StatusLine) SetAerc(aerc *Aerc) {
+	status.aerc = aerc
+}
+
 func (msg *StatusMessage) Color(bg tcell.Color, fg tcell.Color) {
 	msg.bg = bg
 	msg.fg = fg