5 files changed, 40 insertions, 10 deletions

diff --git a/commands/account/compose.go b/commands/account/compose.go
index 10be9ae..8097d10 100644
--- a/commands/account/compose.go
+++ b/commands/account/compose.go
@@ -3,8 +3,6 @@ package account
 import (
 	"errors"
 
-	"github.com/mattn/go-runewidth"
-
 	"git.sr.ht/~sircmpwn/aerc2/widgets"
 )
 
@@ -19,9 +17,15 @@ func Compose(aerc *widgets.Aerc, args []string) error {
 	}
 	acct := aerc.SelectedAccount()
 	composer := widgets.NewComposer(aerc.Config(), acct.AccountConfig())
-	// TODO: Change tab name when message subject changes
-	aerc.NewTab(composer, runewidth.Truncate(
-		"New email", 32, "…"))
+	tab := aerc.NewTab(composer, "New email")
+	composer.OnSubjectChange(func(subject string) {
+		if subject == "" {
+			tab.Name = "New email"
+		} else {
+			tab.Name = subject
+		}
+		tab.Content.Invalidate()
+	})
 	return nil
 }
 
diff --git a/commands/account/view-message.go b/commands/account/view-message.go
index ea6addc..3697aa7 100644
--- a/commands/account/view-message.go
+++ b/commands/account/view-message.go
@@ -3,8 +3,6 @@ package account
 import (
 	"errors"
 
-	"github.com/mattn/go-runewidth"
-
 	"git.sr.ht/~sircmpwn/aerc2/widgets"
 )
 
@@ -26,8 +24,7 @@ func ViewMessage(aerc *widgets.Aerc, args []string) error {
 		return nil
 	}
 	viewer := widgets.NewMessageViewer(aerc.Config(), store, msg)
-	aerc.NewTab(viewer, runewidth.Truncate(
-		msg.Envelope.Subject, 32, "…"))
+	aerc.NewTab(viewer, msg.Envelope.Subject)
 	return nil
 }
 
diff --git a/lib/ui/tab.go b/lib/ui/tab.go
index 49bdffa..c39e327 100644
--- a/lib/ui/tab.go
+++ b/lib/ui/tab.go
@@ -2,6 +2,7 @@ package ui
 
 import (
 	"github.com/gdamore/tcell"
+	"github.com/mattn/go-runewidth"
 )
 
 type Tabs struct {
@@ -87,7 +88,8 @@ func (strip *TabStrip) Draw(ctx *Context) {
 		if strip.Selected == i {
 			style = tcell.StyleDefault
 		}
-		x += ctx.Printf(x, 0, style, " %s ", tab.Name)
+		trunc := runewidth.Truncate(tab.Name, 32, "…")
+		x += ctx.Printf(x, 0, style, " %s ", trunc)
 	}
 	style := tcell.StyleDefault.Reverse(true)
 	ctx.Fill(x, 0, ctx.Width()-x, 1, ' ', style)
diff --git a/lib/ui/textinput.go b/lib/ui/textinput.go
index 688d91d..9d2cdc7 100644
--- a/lib/ui/textinput.go
+++ b/lib/ui/textinput.go
@@ -17,6 +17,7 @@ type TextInput struct {
 	prompt string
 	scroll int
 	text   []rune
+	change []func(ti *TextInput)
 }
 
 // Creates a new TextInput. TextInputs will render a "textbox" in the entire
@@ -69,6 +70,7 @@ func (ti *TextInput) insert(ch rune) {
 	ti.text = append(left, append([]rune{ch}, right...)...)
 	ti.index++
 	ti.Invalidate()
+	ti.onChange()
 }
 
 func (ti *TextInput) deleteWord() {
@@ -88,12 +90,14 @@ func (ti *TextInput) deleteWord() {
 	ti.text = append(ti.text[:i+1], ti.text[ti.index:]...)
 	ti.index = i + 1
 	ti.Invalidate()
+	ti.onChange()
 }
 
 func (ti *TextInput) deleteChar() {
 	if len(ti.text) > 0 && ti.index != len(ti.text) {
 		ti.text = append(ti.text[:ti.index], ti.text[ti.index+1:]...)
 		ti.Invalidate()
+		ti.onChange()
 	}
 }
 
@@ -102,9 +106,20 @@ func (ti *TextInput) backspace() {
 		ti.text = append(ti.text[:ti.index-1], ti.text[ti.index:]...)
 		ti.index--
 		ti.Invalidate()
+		ti.onChange()
 	}
 }
 
+func (ti *TextInput) onChange() {
+	for _, change := range ti.change {
+		change(ti)
+	}
+}
+
+func (ti *TextInput) OnChange(onChange func(ti *TextInput)) {
+	ti.change = append(ti.change, onChange)
+}
+
 func (ti *TextInput) Event(event tcell.Event) bool {
 	switch event := event.(type) {
 	case *tcell.EventKey:
diff --git a/widgets/compose.go b/widgets/compose.go
index 9460397..71b55e7 100644
--- a/widgets/compose.go
+++ b/widgets/compose.go
@@ -100,6 +100,12 @@ func NewComposer(conf *config.AercConfig,
 	return c
 }
 
+func (c *Composer) OnSubjectChange(fn func(subject string)) {
+	c.headers.subject.OnChange(func() {
+		fn(c.headers.subject.input.String())
+	})
+}
+
 func (c *Composer) Draw(ctx *ui.Context) {
 	c.grid.Draw(ctx)
 }
@@ -287,6 +293,12 @@ func (he *headerEditor) Event(event tcell.Event) bool {
 	return he.input.Event(event)
 }
 
+func (he *headerEditor) OnChange(fn func()) {
+	he.input.OnChange(func(_ *ui.TextInput) {
+		fn()
+	})
+}
+
 type reviewMessage struct {
 	composer *Composer
 	grid     *ui.Grid