From f2b1e44aaa8625242e1eb74257a599198ca33b57 Mon Sep 17 00:00:00 2001
From: Pedro Correa <pedro8correa@gmail.com>
Date: Fri, 16 May 2025 16:24:00 -0300
Subject: [PATCH] :sparkles: middleware to validate query param and create
 request id

---
 go.mod        |  2 ++
 go.sum        |  2 ++
 main.go       |  8 ++++++--
 middleware.go | 32 ++++++++++++++++++++++++++++++++
 4 files changed, 42 insertions(+), 2 deletions(-)
 create mode 100644 middleware.go

diff --git a/go.mod b/go.mod
index e5b9489..b755574 100644
--- a/go.mod
+++ b/go.mod
@@ -1,3 +1,5 @@
 module github.com/Tulkdan/go-sse
 
 go 1.24.2
+
+require github.com/google/uuid v1.6.0
diff --git a/go.sum b/go.sum
index e69de29..7790d7c 100644
--- a/go.sum
+++ b/go.sum
@@ -0,0 +1,2 @@
+github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
+github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
diff --git a/main.go b/main.go
index b49661e..bc9c432 100644
--- a/main.go
+++ b/main.go
@@ -1,6 +1,7 @@
 package main
 
 import (
+	"fmt"
 	"log"
 	"net/http"
 )
@@ -9,11 +10,14 @@ func main() {
 	pubsub := NewPubSub()
 
 	r := &http.ServeMux{}
-	r.HandleFunc("GET /subscribe", pubsub.HandleSubscribe)
-	r.HandleFunc("POST /publish", pubsub.HandlePublish)
+	r.HandleFunc("GET /subscribe", middlewareRequestId(middlewareTopicQueryParam(pubsub.HandleSubscribe)))
+	r.HandleFunc("POST /publish", middlewareRequestId(middlewareTopicQueryParam(pubsub.HandlePublish)))
 
 	server := http.Server{Addr: ":8000", Handler: r}
+	fmt.Println("Starting server on 0.0.0.0:8000")
 	if err := server.ListenAndServe(); err != nil {
 		log.Fatal(err)
+	} else {
+		fmt.Println("Killing server")
 	}
 }
diff --git a/middleware.go b/middleware.go
new file mode 100644
index 0000000..014e483
--- /dev/null
+++ b/middleware.go
@@ -0,0 +1,32 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"net/http"
+
+	"github.com/google/uuid"
+)
+
+func middlewareTopicQueryParam(next http.HandlerFunc) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		topicName := r.URL.Query().Get("topic")
+		if topicName == "" {
+			http.Error(w, errors.New("Missing 'topic' query param").Error(), http.StatusBadRequest)
+			return
+		}
+
+		next.ServeHTTP(w, r)
+	}
+}
+
+func middlewareRequestId(next http.HandlerFunc) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		id, _ := uuid.NewV7()
+
+		ctx := context.WithValue(r.Context(), "REQUEST_ID", id.String())
+		r = r.WithContext(ctx)
+
+		next.ServeHTTP(w, r)
+	}
+}
-- 
2.51.2