From 3954a76a285fe435e965603e05b3e57d24442ff9 Mon Sep 17 00:00:00 2001
From: Saddam H <thedevsaddam@gmail.com>
Date: Thu, 19 Oct 2023 06:03:46 +0600
Subject: [PATCH] feat(middleware): add sunset/deprecation header middleware
 (#844)

---
 middleware/sunset.go      |  25 +++++++++
 middleware/sunset_test.go | 104 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 129 insertions(+)
 create mode 100644 middleware/sunset.go
 create mode 100644 middleware/sunset_test.go

diff --git a/middleware/sunset.go b/middleware/sunset.go
new file mode 100644
index 00000000..18815d58
--- /dev/null
+++ b/middleware/sunset.go
@@ -0,0 +1,25 @@
+package middleware
+
+import (
+	"net/http"
+	"time"
+)
+
+// Sunset set Deprecation/Sunset header to response
+// This can be used to enable Sunset in a route or a route group
+// For more: https://www.rfc-editor.org/rfc/rfc8594.html
+func Sunset(sunsetAt time.Time, links ...string) func(http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			if !sunsetAt.IsZero() {
+				w.Header().Set("Sunset", sunsetAt.Format(http.TimeFormat))
+				w.Header().Set("Deprecation", sunsetAt.Format(http.TimeFormat))
+
+				for _, link := range links {
+					w.Header().Add("Link", link)
+				}
+			}
+			next.ServeHTTP(w, r)
+		})
+	}
+}
diff --git a/middleware/sunset_test.go b/middleware/sunset_test.go
new file mode 100644
index 00000000..a36c793d
--- /dev/null
+++ b/middleware/sunset_test.go
@@ -0,0 +1,104 @@
+package middleware
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+
+	"github.com/go-chi/chi/v5"
+)
+
+func TestSunset(t *testing.T) {
+
+	t.Run("Sunset without link", func(t *testing.T) {
+		req, _ := http.NewRequest("GET", "/", nil)
+		w := httptest.NewRecorder()
+
+		r := chi.NewRouter()
+
+		sunsetAt := time.Date(2025, 12, 24, 10, 20, 0, 0, time.UTC)
+		r.Use(Sunset(sunsetAt))
+
+		var sunset, deprecation string
+		r.Get("/", func(w http.ResponseWriter, r *http.Request) {
+			clonedHeader := w.Header().Clone()
+			sunset = clonedHeader.Get("Sunset")
+			deprecation = clonedHeader.Get("Deprecation")
+			w.Write([]byte("I'll be unavailable soon"))
+		})
+		r.ServeHTTP(w, req)
+
+		if w.Code != 200 {
+			t.Fatal("Response Code should be 200")
+		}
+
+		if sunset != "Wed, 24 Dec 2025 10:20:00 GMT" {
+			t.Fatal("Test get sunset error.", sunset)
+		}
+
+		if deprecation != "Wed, 24 Dec 2025 10:20:00 GMT" {
+			t.Fatal("Test get deprecation error.")
+		}
+	})
+
+	t.Run("Sunset with link", func(t *testing.T) {
+		req, _ := http.NewRequest("GET", "/", nil)
+		w := httptest.NewRecorder()
+
+		r := chi.NewRouter()
+
+		sunsetAt := time.Date(2025, 12, 24, 10, 20, 0, 0, time.UTC)
+		deprecationLink := "https://example.com/v1/deprecation-details"
+		r.Use(Sunset(sunsetAt, deprecationLink))
+
+		var sunset, deprecation, link string
+		r.Get("/", func(w http.ResponseWriter, r *http.Request) {
+			clonedHeader := w.Header().Clone()
+			sunset = clonedHeader.Get("Sunset")
+			deprecation = clonedHeader.Get("Deprecation")
+			link = clonedHeader.Get("Link")
+
+			w.Write([]byte("I'll be unavailable soon"))
+		})
+
+		r.ServeHTTP(w, req)
+
+		if w.Code != 200 {
+			t.Fatal("Response Code should be 200")
+		}
+
+		if sunset != "Wed, 24 Dec 2025 10:20:00 GMT" {
+			t.Fatal("Test get sunset error.", sunset)
+		}
+
+		if deprecation != "Wed, 24 Dec 2025 10:20:00 GMT" {
+			t.Fatal("Test get deprecation error.")
+		}
+
+		if link != deprecationLink {
+			t.Fatal("Test get deprecation link error.")
+		}
+	})
+
+}
+
+/**
+EXAMPLE USAGES
+func main() {
+	r := chi.NewRouter()
+
+	sunsetAt := time.Date(2025, 12, 24, 10, 20, 0, 0, time.UTC)
+	r.Use(middleware.Sunset(sunsetAt))
+
+	// can provide additional link for updated resource
+	// r.Use(middleware.Sunset(sunsetAt, "https://example.com/v1/deprecation-details"))
+
+	r.Get("/", func(w http.ResponseWriter, r *http.Request) {
+		w.Write([]byte("This endpoint will be removed soon"))
+	})
+
+	log.Println("Listening on port: 3000")
+	http.ListenAndServe(":3000", r)
+}
+**/