feat: TUI detail pane + status bar (#15)

Add detail pane with cursor navigation and enhanced status bar for the TUI interface. Closes #13.

Author: clarabennettdev

internal/tui/model.go

@@ -27,16 +27,31 @@ var (
 			Background(lipgloss.Color("#333333")).
 			Bold(true).
 			Padding(0, 1)
+
+	cursorStyle = lipgloss.NewStyle().
+			Background(lipgloss.Color("#3C3C5C"))
+
+	detailBorderStyle = lipgloss.NewStyle().
+			Foreground(lipgloss.Color("#7D56F4"))
+
+	detailKeyStyle = lipgloss.NewStyle().
+			Foreground(lipgloss.Color("#117")).
+			Bold(true)
+
+	detailValStyle = lipgloss.NewStyle().
+			Foreground(lipgloss.Color("#252"))
 )
 
 // LogMsg carries a new parsed and rendered log line into the TUI.
 type LogMsg struct {
 	Rendered string
+	Entry    parser.LogEntry
 }
 
 // LogBatchMsg carries multiple rendered log lines at once.
 type LogBatchMsg struct {
-	Lines []string
+	Lines   []string
+	Entries []parser.LogEntry
 }
 
 // ErrMsg carries a source error into the TUI.
@@ -51,14 +66,22 @@ type Model struct {
 	ready  bool
 
 	// Log buffer — stores rendered strings for display.
-	lines []string
+	lines   []string
+	entries []parser.LogEntry // parallel to lines; stores parsed entries
 
 	// Virtual scrolling state.
 	offset     int  // index of the first visible line
 	autoScroll bool // stick to bottom when new lines arrive
 
+	// Cursor and detail pane.
+	cursor    int  // index of the highlighted line
+	showDetail bool // whether the detail pane is visible
+
 	// Source info for status bar.
 	sourceName string
+
+	// Filter status for status bar.
+	filterText string
 }
 
 // NewModel creates a new LogPilot TUI model with no sources.
@@ -87,6 +110,31 @@ func (m Model) viewHeight() int {
 	return h
 }
 
+// detailPaneHeight returns the height of the detail pane when visible.
+func (m Model) detailPaneHeight() int {
+	h := m.viewHeight() / 3
+	if h < 5 {
+		h = 5
+	}
+	if h > 15 {
+		h = 15
+	}
+	return h
+}
+
+// logPaneHeight returns the log viewport height when detail pane is visible.
+func (m Model) logPaneHeight() int {
+	if !m.showDetail {
+		return m.viewHeight()
+	}
+	// detail pane takes detailPaneHeight + 1 (border line)
+	h := m.viewHeight() - m.detailPaneHeight() - 1
+	if h < 3 {
+		return 3
+	}
+	return h
+}
+
 // maxOffset returns the maximum valid scroll offset.
 func (m Model) maxOffset() int {
 	max := len(m.lines) - m.viewHeight()
@@ -96,6 +144,35 @@ func (m Model) maxOffset() int {
 	return max
 }
 
+// clampCursor ensures cursor is within valid bounds.
+func (m *Model) clampCursor() {
+	if m.cursor < 0 {
+		m.cursor = 0
+	}
+	if max := len(m.lines) - 1; m.cursor > max {
+		if max < 0 {
+			m.cursor = 0
+		} else {
+			m.cursor = max
+		}
+	}
+}
+
+// scrollToCursor adjusts offset so the cursor is visible.
+func (m *Model) scrollToCursor() {
+	vh := m.viewHeight()
+	if m.showDetail {
+		vh = m.logPaneHeight()
+	}
+	if m.cursor < m.offset {
+		m.offset = m.cursor
+	}
+	if m.cursor >= m.offset+vh {
+		m.offset = m.cursor - vh + 1
+	}
+	m.clampOffset()
+}
+
 // clampOffset ensures offset is within valid bounds.
 func (m *Model) clampOffset() {
 	if m.offset < 0 {
@@ -123,43 +200,66 @@ func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		switch msg.String() {
 		case "q", "ctrl+c":
 			return m, tea.Quit
+		case "enter":
+			if len(m.lines) > 0 {
+				m.showDetail = !m.showDetail
+			}
+		case "esc":
+			if m.showDetail {
+				m.showDetail = false
+			}
 		case "j", "down":
 			m.autoScroll = false
-			m.offset++
-			m.clampOffset()
+			m.cursor++
+			m.clampCursor()
+			m.scrollToCursor()
 			if m.isAtBottom() {
 				m.autoScroll = true
 			}
 		case "k", "up":
 			m.autoScroll = false
-			m.offset--
-			m.clampOffset()
+			m.cursor--
+			m.clampCursor()
+			m.scrollToCursor()
 		case "g", "home":
 			m.autoScroll = false
+			m.cursor = 0
 			m.offset = 0
 		case "G", "end":
+			m.cursor = len(m.lines) - 1
+			if m.cursor < 0 {
+				m.cursor = 0
+			}
 			m.offset = m.maxOffset()
 			m.autoScroll = true
 		case "pgdown", "f", "ctrl+f":
 			m.autoScroll = false
+			m.cursor += m.viewHeight()
+			m.clampCursor()
 			m.offset += m.viewHeight()
 			m.clampOffset()
 			if m.isAtBottom() {
 				m.autoScroll = true
 			}
 		case "pgup", "b", "ctrl+b":
 			m.autoScroll = false
+			m.cursor -= m.viewHeight()
+			m.clampCursor()
 			m.offset -= m.viewHeight()
 			m.clampOffset()
 		case "d", "ctrl+d":
 			m.autoScroll = false
+			m.cursor += m.viewHeight() / 2
+			m.clampCursor()
 			m.offset += m.viewHeight() / 2
 			m.clampOffset()
 			if m.isAtBottom() {
 				m.autoScroll = true
 			}
 		case "u", "ctrl+u":
 			m.autoScroll = false
+			m.cursor -= m.viewHeight() / 2
+			m.clampCursor()
 			m.offset -= m.viewHeight() / 2
 			m.clampOffset()
 		}
@@ -175,14 +275,24 @@ func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 
 	case LogMsg:
 		m.lines = append(m.lines, msg.Rendered)
+		m.entries = append(m.entries, msg.Entry)
 		if m.autoScroll {
 			m.offset = m.maxOffset()
+			m.cursor = len(m.lines) - 1
+			if m.cursor < 0 {
+				m.cursor = 0
+			}
 		}
 
 	case LogBatchMsg:
 		m.lines = append(m.lines, msg.Lines...)
+		m.entries = append(m.entries, msg.Entries...)
 		if m.autoScroll {
 			m.offset = m.maxOffset()
+			m.cursor = len(m.lines) - 1
+			if m.cursor < 0 {
+				m.cursor = 0
+			}
 		}
 
 	case ErrMsg:
@@ -209,7 +319,7 @@ func (m Model) View() string {
 	b.WriteByte('\n')
 
 	// Log viewport — virtual scrolling: only render visible slice.
-	vh := m.viewHeight()
+	vh := m.logPaneHeight()
 	if len(m.lines) == 0 {
 		// Empty state.
 		for i := 0; i < vh; i++ {
@@ -229,10 +339,14 @@ func (m Model) View() string {
 		if start < 0 {
 			start = 0
 		}
-		// Render visible lines.
+		// Render visible lines with cursor highlight.
 		rendered := 0
 		for i := start; i < end; i++ {
-			b.WriteString(m.lines[i])
+			line := m.lines[i]
+			if i == m.cursor {
+				line = cursorStyle.Render(line)
+			}
+			b.WriteString(line)
 			b.WriteByte('\n')
 			rendered++
 		}
@@ -242,6 +356,11 @@ func (m Model) View() string {
 		}
 	}
 
+	// Detail pane.
+	if m.showDetail && len(m.entries) > 0 && m.cursor < len(m.entries) {
+		b.WriteString(m.renderDetailPane())
+	}
+
 	// Status bar.
 	total := len(m.lines)
 	scrollInfo := "bottom"
@@ -262,18 +381,107 @@ func (m Model) View() string {
 	right := statusKeyStyle.Render("Pos:") + statusBarStyle.Render(fmt.Sprintf(" %s ", scrollInfo))
 	srcInfo := statusKeyStyle.Render("Src:") + statusBarStyle.Render(fmt.Sprintf(" %s ", src))
 
-	gap := m.width - lipgloss.Width(left) - lipgloss.Width(right) - lipgloss.Width(srcInfo)
+	// Filter status.
+	filterInfo := ""
+	if m.filterText != "" {
+		filterInfo = statusKeyStyle.Render("Filter:") + statusBarStyle.Render(fmt.Sprintf(" %s ", m.filterText))
+	}
+
+	gap := m.width - lipgloss.Width(left) - lipgloss.Width(right) - lipgloss.Width(srcInfo) - lipgloss.Width(filterInfo)
 	if gap < 0 {
 		gap = 0
 	}
-	statusLine := left + srcInfo + strings.Repeat(" ", gap) + right
+	statusLine := left + srcInfo + filterInfo + strings.Repeat(" ", gap) + right
 	// Fill background.
 	statusLine = statusBarStyle.Render(statusLine)
 	b.WriteString(statusLine)
 
 	return b.String()
 }
 
+// renderDetailPane renders the detail pane for the selected log entry.
+func (m Model) renderDetailPane() string {
+	var b strings.Builder
+
+	// Separator line.
+	sep := detailBorderStyle.Render(strings.Repeat("─", m.width))
+	b.WriteString(sep)
+	b.WriteByte('\n')
+
+	entry := m.entries[m.cursor]
+	dh := m.detailPaneHeight()
+	rendered := 0
+
+	// Header.
+	header := detailBorderStyle.Render("▼ Detail")
+	b.WriteString(header)
+	b.WriteByte('\n')
+	rendered++
+
+	// Timestamp.
+	if !entry.Timestamp.IsZero() && rendered < dh {
+		b.WriteString(detailKeyStyle.Render("  timestamp") + " " + detailValStyle.Render(entry.Timestamp.Format("2006-01-02 15:04:05.000")))
+		b.WriteByte('\n')
+		rendered++
+	}
+
+	// Level.
+	if entry.Level != "" && rendered < dh {
+		b.WriteString(detailKeyStyle.Render("  level    ") + " " + detailValStyle.Render(entry.Level))
+		b.WriteByte('\n')
+		rendered++
+	}
+
+	// Message.
+	if entry.Message != "" && rendered < dh {
+		b.WriteString(detailKeyStyle.Render("  message  ") + " " + detailValStyle.Render(entry.Message))
+		b.WriteByte('\n')
+		rendered++
+	}
+
+	// Format.
+	if rendered < dh {
+		b.WriteString(detailKeyStyle.Render("  format   ") + " " + detailValStyle.Render(entry.Format.String()))
+		b.WriteByte('\n')
+		rendered++
+	}
+
+	// Fields.
+	if len(entry.Fields) > 0 {
+		keys := make([]string, 0, len(entry.Fields))
+		for k := range entry.Fields {
+			keys = append(keys, k)
+		}
+		sortDetailKeys(keys)
+		for _, k := range keys {
+			if rendered >= dh {
+				break
+			}
+			label := fmt.Sprintf("  %-10s", k)
+			b.WriteString(detailKeyStyle.Render(label) + " " + detailValStyle.Render(entry.Fields[k]))
+			b.WriteByte('\n')
+			rendered++
+		}
+	}
+
+	// Pad remaining.
+	for rendered < dh {
+		b.WriteByte('\n')
+		rendered++
+	}
+
+	return b.String()
+}
+
+// sortDetailKeys sorts keys alphabetically (simple insertion sort).
+func sortDetailKeys(s []string) {
+	for i := 1; i < len(s); i++ {
+		for j := i; j > 0 && s[j] < s[j-1]; j-- {
+			s[j], s[j-1] = s[j-1], s[j]
+		}
+	}
+}
+
 // WaitForLines returns a tea.Cmd that reads from a source and sends LogMsg
 // messages to the TUI. Call this to wire a source into the model.
 func WaitForLines(src source.Source, p *parser.AutoParser, r *Renderer) tea.Cmd {
@@ -284,7 +492,7 @@ func WaitForLines(src source.Source, p *parser.AutoParser, r *Renderer) tea.Cmd
 		}
 		entry := p.Parse(line.Line)
 		rendered := r.RenderEntry(entry)
-		return LogMsg{Rendered: rendered}
+		return LogMsg{Rendered: rendered, Entry: entry}
 	}
 }
 
@@ -295,7 +503,7 @@ func ListenForLines(src source.Source, p *parser.AutoParser, r *Renderer, prog *
 		for line := range src.Lines() {
 			entry := p.Parse(line.Line)
 			rendered := r.RenderEntry(entry)
-			prog.Send(LogMsg{Rendered: rendered})
+			prog.Send(LogMsg{Rendered: rendered, Entry: entry})
 		}
 	}()
 	go func() {