Fix humiture environmental sensor

There can be multiple topics with the same last segment, which causes
incorrect calculations for humiture as we're mix-matching data sources.

Since the topic is a string, use the whole thing as a key which is
unique.

collectors/environmental.go

@@ -146,7 +146,7 @@ func (c *EnvironmentalCollector) Collect(ch chan<- prometheus.Metric) {
 				log.Print(err.Error())
 				continue
 			}
-			humidity[last(s.Info().Topic, "/")] = v
+			humidity[s.Info().Topic] = v
 			ch <- prometheus.MustNewConstMetric(c.relativeHumidity,
 				prometheus.GaugeValue, v, s.Info().Topic)
 		}
@@ -156,7 +156,7 @@ func (c *EnvironmentalCollector) Collect(ch chan<- prometheus.Metric) {
 				log.Print(err.Error())
 				continue
 			}
-			temperature[last(s.Info().Topic, "/")] = v
+			temperature[s.Info().Topic] = v
 			ch <- prometheus.MustNewConstMetric(c.temperature,
 				prometheus.GaugeValue, v, s.Info().Topic)
 		}

collectors/helpers.go

@@ -2,7 +2,6 @@ package collectors // import "hemtjan.st/sensorer/collectors"
 
 import (
 	"strconv"
-	"strings"
 )
 
 // namespace is the Prometheus namespaces for all collectors in this package
@@ -16,9 +15,3 @@ func toFloat(s string) (float64, error) {
 	}
 	return f, nil
 }
-
-// last returns the last element of s split on sep
-func last(s, sep string) string {
-	sp := strings.Split(s, sep)
-	return sp[len(sp)-1]
-}