feat: add permissions on user create, CORS middleware, cors server playground.

projects/greenlight/cmd/api/middleware.go

@@ -244,3 +244,30 @@ func (app *application) requirePermission(code string, next http.HandlerFunc) ht
 	// Wrap this with the requireActivatedUser() middleware before returning it.
 	return app.requireActivatedUser(fn)
 }
+
+func (app *application) enableCORS(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		// Add the "Vary: Origin" header.
+		w.Header().Add("Vary", "Origin")
+
+		// Get the value of the request's Origin header.
+		origin := r.Header.Get("Origin")
+
+		// Only run this if there's an Origin request header present AND at least one
+		// trusted origin is configured.
+		if origin != "" && len(app.config.cors.trustedOrigins) != 0 {
+			// Loop through the list of trusted origins, checking to see if the request
+			// origin exactly matches one of them.
+			for i := range app.config.cors.trustedOrigins {
+				if origin == app.config.cors.trustedOrigins[i] {
+					// If there is a match, then set a "Access-Control-Allow-Origin
+					// response header with the request origin as the value.
+					w.Header().Set("Access-Control-Allow-Origin", origin)
+				}
+			}
+		}
+
+		// Call the next handler in the chain.
+		next.ServeHTTP(w, r)
+	})
+}