From f45df5d4229d424435bffaff570b3bac37c1f656 Mon Sep 17 00:00:00 2001
From: Lars Strojny <lars@strojny.net>
Date: Thu, 24 Nov 2022 19:53:03 +0100
Subject: [PATCH] Clean up prefix handling

---
 src/prometheus.ts | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/prometheus.ts b/src/prometheus.ts
index 7ffdf7a..2ecb34e 100644
--- a/src/prometheus.ts
+++ b/src/prometheus.ts
@@ -3,7 +3,11 @@ import type { Logger } from 'homebridge'
 import type { HttpConfig, HttpResponse, HttpServer } from './adapters/http'
 
 export class MetricsRenderer {
-    constructor(private readonly prefix: string) {}
+    private readonly prefix: string
+
+    constructor(prefix: string) {
+        this.prefix = trimRight(prefix, '_')
+    }
 
     render(metric: Metric): string {
         const name = this.metricName(metric.name)
@@ -26,10 +30,14 @@ export class MetricsRenderer {
     private metricName(name: string): string {
         name = name.replace(/^(.*_)?(total)_(.*)$/, '$1$3_$2')
 
-        return sanitizePrometheusMetricName(stringReverse(stringReverse(this.prefix).replace(/^_+/, '')) + '_' + name)
+        return sanitizePrometheusMetricName(`${this.prefix}_${name}`)
     }
 }
 
+function trimRight(str: string, char: string): string {
+    return stringReverse(stringReverse(str).replace(new RegExp(`^[${char}]+`), ''))
+}
+
 function stringReverse(str: string): string {
     return str.split('').reverse().join('')
 }