tui: dynamic input textarea height and styling updates

Maintain a height of 4 up to half of the main content area

Add rounded border

pkg/tui/tui.go

@@ -126,9 +126,7 @@ var (
 			PaddingLeft(1).
 			PaddingRight(1).
 			Background(lipgloss.Color("0"))
-	footerStyle = lipgloss.NewStyle().
-			BorderTop(true).
-			BorderStyle(lipgloss.NormalBorder())
+	footerStyle = lipgloss.NewStyle()
 )
 
 func (m model) Init() tea.Cmd {
@@ -206,7 +204,7 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		m.width = msg.Width
 		m.height = msg.Height
 		m.content.Width = msg.Width
-		m.input.SetWidth(msg.Width)
+		m.input.SetWidth(msg.Width-m.input.FocusedStyle.Base.GetHorizontalBorderSize())
 		m.rebuildMessageCache()
 		m.updateContent()
 	case msgConversationLoaded:
@@ -295,6 +293,8 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		cmds = append(cmds, cmd)
 	}
 
+
+	prevInputLineCnt := m.input.LineCount()
 	inputCaptured := false
 	m.input, cmd = m.input.Update(msg)
 	if cmd != nil {
@@ -313,12 +313,42 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		m.cache.header = m.headerView()
 		m.cache.footer = m.footerView()
 		m.cache.error = m.errorView()
+
+		fixedHeight := height(m.cache.header) + height(m.cache.error) + height(m.cache.footer)
+
+		// calculate clamped input height to accomodate input text
+		newHeight := max(4, min((m.height-fixedHeight-1)/2, m.input.LineCount()))
+		m.input.SetHeight(newHeight)
 		m.cache.input = m.inputView()
-		fixedHeight := height(m.cache.header) + height(m.cache.error) + height(m.cache.input) + height(m.cache.footer)
-		m.content.Height = m.height - fixedHeight
+
+		m.content.Height = m.height - height(m.cache.input) - fixedHeight
 		m.cache.content = m.contentView()
 	}
 
+	// this is a pretty nasty hack to ensure the input area viewport doesn't
+	// scroll below its content, which can happen when the input viewport
+	// height has grown, or previously entered lines have been deleted
+	if prevInputLineCnt != m.input.LineCount() {
+		// dist is the distance we'd need to scroll up from the current cursor
+		// position to position the last input line at the bottom of the
+		// viewport. if negative, we're already scrolled above the bottom
+		dist := m.input.Line() - (m.input.LineCount() - m.input.Height())
+		if dist > 0 {
+			for i := 0; i < dist; i++ {
+				// move cursor up until content reaches the bottom of the viewport
+				m.input.CursorUp()
+			}
+			m.input, cmd = m.input.Update(nil)
+			cmds = append(cmds, cmd)
+			for i := 0; i < dist; i++ {
+				// move cursor back down to its previous position
+				m.input.CursorDown()
+			}
+			m.input, cmd = m.input.Update(nil)
+			cmds = append(cmds, cmd)
+		}
+	}
+
 	return m, tea.Batch(cmds...)
 }
 
@@ -468,16 +498,13 @@ func initialModel(ctx *lmcli.Context, convShortname string) model {
 	m.input.Placeholder = "Enter a message"
 
 	m.input.ShowLineNumbers = false
-	m.input.SetHeight(4)
 	m.input.Focus()
 	m.input.FocusedStyle.CursorLine = lipgloss.NewStyle()
 	m.input.FocusedStyle.Base = lipgloss.NewStyle().
-		BorderTop(true).
-		BorderStyle(lipgloss.NormalBorder())
+		Border(lipgloss.RoundedBorder(), true, true, true, false)
 	m.input.BlurredStyle.Base = lipgloss.NewStyle().
 		Faint(true).
-		BorderTop(true).
-		BorderStyle(lipgloss.NormalBorder())
+		Border(lipgloss.RoundedBorder(), true, true, true, false)
 
 	m.spinner = spinner.New(spinner.WithSpinner(
 		spinner.Spinner{