tui: add a "scroll bar" and error view

pkg/tui/tui.go

@@ -29,6 +29,9 @@ const (
 )
 
 type model struct {
+	width  int
+	height int
+
 	ctx           *lmcli.Context
 	convShortname string
 
@@ -135,9 +138,11 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 			}
 		}
 	case tea.WindowSizeMsg:
+		m.width = msg.Width
+		m.height = msg.Height
 		m.content.Width = msg.Width
-		m.content.Height = msg.Height - m.input.Height() - lipgloss.Height(m.footerView()) - lipgloss.Height(m.headerView())
-		m.input.SetWidth(msg.Width - 1)
+		m.content.Height = msg.Height - m.getFixedComponentHeight()
+		m.input.SetWidth(msg.Width-1)
 		m.updateContent()
 	case msgConversationLoaded:
 		m.conversation = (*models.Conversation)(msg)
@@ -202,6 +207,8 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 				cmds = append(cmds, wrapError(err))
 			}
 		}
+	case msgError:
+		m.err = error(msg)
 	}
 
 	if len(cmds) > 0 {
@@ -229,15 +236,45 @@ func (m model) View() string {
 		// without this, the below view functions may do weird things
 		return ""
 	}
+
+	m.content.Height = m.height - m.getFixedComponentHeight()
+
+	sections := make([]string, 0, 6)
+	error := m.errorView()
+	scrollbar := m.scrollbarView()
+	sections = append(sections, m.headerView())
+	if scrollbar != "" {
+		sections = append(sections, scrollbar)
+	}
+	sections = append(sections, m.contentView())
+	if error != "" {
+		sections = append(sections, error)
+	}
+	sections = append(sections, m.inputView())
+	sections = append(sections, m.footerView())
+
 	return lipgloss.JoinVertical(
 		lipgloss.Left,
-		m.headerView(),
-		m.contentView(),
-		m.inputView(),
-		m.footerView(),
+		sections...,
 	)
 }
 
+func (m *model) getFixedComponentHeight() int {
+	h := 0
+	h += m.input.Height()
+	h += lipgloss.Height(m.headerView())
+	h += lipgloss.Height(m.footerView())
+	scrollbar := m.scrollbarView()
+	if scrollbar != "" {
+		h += lipgloss.Height(scrollbar)
+	}
+	errorView := m.errorView()
+	if errorView != "" {
+		h += lipgloss.Height(errorView)
+	}
+	return h
+}
+
 func (m *model) headerView() string {
 	titleStyle := lipgloss.NewStyle().
 		PaddingLeft(1).
@@ -258,6 +295,32 @@ func (m *model) contentView() string {
 	return m.content.View()
 }
 
+func (m *model) errorView() string {
+	if m.err == nil {
+		return ""
+	}
+	return lipgloss.NewStyle().
+		Bold(true).
+		Foreground(lipgloss.Color("1")).
+		Width(m.content.Width).
+		AlignHorizontal(lipgloss.Center).
+		Render(fmt.Sprintf("%s", m.err))
+}
+
+func (m *model) scrollbarView() string {
+	if m.content.AtTop() {
+		return ""
+	}
+
+	count := int(m.content.ScrollPercent() * float64(m.content.Width-2))
+	fill := strings.Repeat("-", count)
+	return lipgloss.NewStyle().
+		PaddingLeft(1).
+		PaddingRight(1).
+		Width(m.content.Width).
+		Render(fill)
+}
+
 func (m *model) inputView() string {
 	return m.input.View()
 }
@@ -284,8 +347,8 @@ func (m *model) footerView() string {
 	left := strings.Join(leftSegments, segmentSeparator)
 	right := strings.Join(rightSegments, segmentSeparator)
 
-	totalWidth := lipgloss.Width(left + right)
-	remaining := m.content.Width - totalWidth
+	totalWidth := lipgloss.Width(left) + lipgloss.Width(right)
+	remaining := m.width - totalWidth
 
 	var padding string
 	if remaining > 0 {
@@ -295,7 +358,7 @@ func (m *model) footerView() string {
 	footer := left + padding + right
 	if remaining < 0 {
 		ellipses := "... "
-		footer = footer[:m.content.Width-len(ellipses)] + ellipses
+		footer = footer[:m.width-len(ellipses)] + ellipses
 	}
 	return footerStyle.Render(footer)
 }