stuff

main.go

@@ -157,7 +157,7 @@ func (s *server) handleIndex(w http.ResponseWriter, r *http.Request) {
 		updatedLabel = updatedAt.Format("02.01.2006 15:04:05")
 	}
 	if err := page.Execute(w, map[string]any{
-		"Watts":        watts,
+		"Watts":        formatGermanNumber(watts),
 		"UpdatedAt":    updatedLabel,
 		"HistoryChart": buildHistoryChart(history, s.chartMax),
 	}); err != nil {
@@ -165,6 +165,34 @@ func (s *server) handleIndex(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
+func formatGermanNumber(n int) string {
+	s := strconv.Itoa(n)
+	if len(s) <= 3 {
+		return s
+	}
+
+	neg := false
+	if s[0] == '-' {
+		neg = true
+		s = s[1:]
+	}
+
+	var b strings.Builder
+	if neg {
+		b.WriteByte('-')
+	}
+	rem := len(s) % 3
+	if rem == 0 {
+		rem = 3
+	}
+	b.WriteString(s[:rem])
+	for i := rem; i < len(s); i += 3 {
+		b.WriteByte('.')
+		b.WriteString(s[i : i+3])
+	}
+	return b.String()
+}
+
 func buildHistoryChart(history []sample, maxWatts int) template.HTML {
 	const (
 		width  = 640
@@ -242,8 +270,8 @@ func buildHistoryChart(history []sample, maxWatts int) template.HTML {
 	fmt.Fprintf(&b, `<path d="M %.1f %.1f V %.1f"/>`, x1, yTop, yBottom)
 	b.WriteString(`</g>`)
 	b.WriteString(`<g fill="#64748b" font-size="12" font-family="system-ui, sans-serif">`)
-	fmt.Fprintf(&b, `<text x="%.1f" y="%d" text-anchor="end">%d W</text>`, x0-10, int(yTop)+14, maxV)
-	fmt.Fprintf(&b, `<text x="%.1f" y="%d" text-anchor="end">%d W</text>`, x0-10, int(yMid)+14, midV)
+	fmt.Fprintf(&b, `<text x="%.1f" y="%d" text-anchor="end">%s W</text>`, x0-10, int(yTop)+14, formatGermanNumber(maxV))
+	fmt.Fprintf(&b, `<text x="%.1f" y="%d" text-anchor="end">%s W</text>`, x0-10, int(yMid)+14, formatGermanNumber(midV))
 	fmt.Fprintf(&b, `<text x="%.1f" y="%d" text-anchor="end">0 W</text>`, x0-10, int(yBottom)+14)
 	fmt.Fprintf(&b, `<text x="%.1f" y="%d" text-anchor="middle">%s</text>`, x0, int(height)-10, start.Format("15:04"))
 	fmt.Fprintf(&b, `<text x="%.1f" y="%d" text-anchor="middle">%s</text>`, x0+(plotW/2), int(height)-10, midT.Format("15:04"))