From b1b6a16fc6e92f71588ce7a9d5faf9ac8a50d398 Mon Sep 17 00:00:00 2001
From: Sam Willcocks <sam@wlcx.cc>
Date: Thu, 4 Aug 2022 14:43:06 +0300
Subject: [PATCH] Add support for multiple screen_names

---
 main.go | 35 +++++++++++++++++++----------------
 1 file changed, 19 insertions(+), 16 deletions(-)

diff --git a/main.go b/main.go
index 3173abc..a92425e 100644
--- a/main.go
+++ b/main.go
@@ -14,15 +14,7 @@ import (
 	log "github.com/sirupsen/logrus"
 )
 
-func probeTwitter(ctx context.Context, target string, registry *prometheus.Registry) (success bool) {
-	followersGauge := prometheus.NewGaugeVec(prometheus.GaugeOpts{
-		Name: "twitter_followers",
-		Help: "The number of followers of the twitter account.",
-	},
-		[]string{"screen_name"})
-
-	registry.MustRegister(followersGauge)
-
+func probeTwitterFollowers(ctx context.Context, target string, gauge *prometheus.GaugeVec) (success bool) {
 	res, err := http.Get(fmt.Sprintf("https://cdn.syndication.twimg.com/widgets/followbutton/info.json?screen_names=%s", url.QueryEscape(target)))
 	if err != nil {
 		log.Errorf("fetching url: %s", err)
@@ -44,24 +36,35 @@ func probeTwitter(ctx context.Context, target string, registry *prometheus.Regis
 		log.Errorf("Unexpected (>1) results returned. WTF twitter??")
 		return false
 	}
-	followersGauge.With(prometheus.Labels{"screen_name": target}).Set(float64(data[0].FollowersCount))
+	gauge.With(prometheus.Labels{"screen_name": target}).Set(float64(data[0].FollowersCount))
 	return true
 }
 
 func twitterHandler(w http.ResponseWriter, r *http.Request) {
-	screenName := r.URL.Query().Get("screen_name")
-	if screenName == "" {
+	reg := prometheus.NewRegistry()
+	followersGauge := prometheus.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Name: "twitter_followers",
+			Help: "The number of followers of the twitter account.",
+		},
+		[]string{"screen_name"},
+	)
+
+	reg.MustRegister(followersGauge)
+
+	screenNames, ok := r.URL.Query()["screen_name"]
+	if !ok {
 		http.Error(w, "screen_name parameter is missing", http.StatusBadRequest)
 		return
 	}
 
-	reg := prometheus.NewRegistry()
-
 	ctx, cancel := context.WithTimeout(r.Context(), time.Duration(5*time.Second))
 	defer cancel()
 
-	if success := probeTwitter(ctx, screenName, reg); !success {
-		log.Error("Probe failed!")
+	for _, screenName := range screenNames {
+		if success := probeTwitterFollowers(ctx, screenName, followersGauge); !success {
+			log.Error("Probe for screenname %s failed!", screenName)
+		}
 	}
 
 	h := promhttp.HandlerFor(reg, promhttp.HandlerOpts{})