feat(tui): ntcharts sparkline with Y-axis labels and stats

Replaced streamline chart with ntcharts sparkline (block elements,
auto-scaling). Height=2, Y-axis labels (max/min ms) on the left,
Min/Avg/Max stats below. Denser and more readable than the line chart.

internal/tui/chart.go

@@ -1,36 +1,98 @@
 package tui
 
 import (
+	"fmt"
+	"strings"
 	"time"
 
-	"github.com/NimbleMarkets/ntcharts/canvas/runes"
-	"github.com/NimbleMarkets/ntcharts/linechart/streamlinechart"
+	"github.com/NimbleMarkets/ntcharts/sparkline"
 	"github.com/charmbracelet/lipgloss"
 )
 
 func (m Model) latencyChart(latencies []time.Duration, statuses []bool, width, height int) string {
-	if len(latencies) == 0 || width < 10 || height < 3 {
+	if len(latencies) == 0 || width < 20 || height < 2 {
 		return ""
 	}
 
-	chartW := len(latencies)
-	if chartW > width {
-		chartW = width
+	var minMs, maxMs, sumMs int64
+	minMs = latencies[0].Milliseconds()
+	maxMs = minMs
+	for i, l := range latencies {
+		ms := l.Milliseconds()
+		if i < len(statuses) && !statuses[i] {
+			continue
+		}
+		if ms < minMs {
+			minMs = ms
+		}
+		if ms > maxMs {
+			maxMs = ms
+		}
+		sumMs += ms
+	}
+	upCount := 0
+	for _, s := range statuses {
+		if s {
+			upCount++
+		}
+	}
+	var avgMs int64
+	if upCount > 0 {
+		avgMs = sumMs / int64(upCount)
 	}
 
-	lineStyle := lipgloss.NewStyle().Foreground(m.theme.Accent)
-	slc := streamlinechart.New(chartW, height,
-		streamlinechart.WithStyles(runes.ThinLineStyle, lineStyle),
-	)
+	maxLabel := fmt.Sprintf("%dms", maxMs)
+	minLabel := fmt.Sprintf("%dms", minMs)
+	labelW := len(maxLabel)
+	if len(minLabel) > labelW {
+		labelW = len(minLabel)
+	}
+	labelW += 1
 
+	chartW := width - labelW
+	if chartW > len(latencies) {
+		chartW = len(latencies)
+	}
+	if chartW < 10 {
+		chartW = 10
+	}
+
+	style := lipgloss.NewStyle().Foreground(m.theme.Accent)
+	sl := sparkline.New(chartW, height, sparkline.WithStyle(style))
+
+	vals := make([]float64, len(latencies))
 	for i, l := range latencies {
 		ms := float64(l.Milliseconds())
 		if i < len(statuses) && !statuses[i] {
 			ms = 0
 		}
-		slc.Push(ms)
+		vals[i] = ms
 	}
-	slc.Draw()
+	sl.PushAll(vals)
+	sl.Draw()
 
-	return slc.View()
+	chartLines := strings.Split(sl.View(), "\n")
+
+	var result []string
+	labelStyle := m.st.subtleStyle
+	for i, line := range chartLines {
+		var label string
+		if i == 0 {
+			label = fmt.Sprintf("%*s", labelW, maxLabel)
+		} else if i == len(chartLines)-1 {
+			label = fmt.Sprintf("%*s", labelW, minLabel)
+		} else {
+			label = strings.Repeat(" ", labelW)
+		}
+		result = append(result, labelStyle.Render(label)+line)
+	}
+
+	stats := fmt.Sprintf("%*s Min %s  Avg %s  Max %s",
+		labelW, "",
+		m.fmtLatency(time.Duration(minMs)*time.Millisecond),
+		m.fmtLatency(time.Duration(avgMs)*time.Millisecond),
+		m.fmtLatency(time.Duration(maxMs)*time.Millisecond))
+	result = append(result, stats)
+
+	return strings.Join(result, "\n")
 }