Refactor server: use render func for templates

server/template.go

@@ -3,6 +3,7 @@ package server
 import (
 	"embed"
 	"html/template"
+	"net/http"
 )
 
 //go:embed templates/*
@@ -13,3 +14,18 @@ func (h *Server) loadTemplates() error {
 	h.tmpl, err = template.ParseFS(templates, "templates/*")
 	return err
 }
+
+func (s *Server) render(fetch fetcher, templateName string) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("content-type", "text/html")
+		data, err := fetch(r)
+		if err != nil {
+			errorPage(err, http.StatusInternalServerError).ServeHTTP(w, r)
+			return
+		}
+		err = s.tmpl.ExecuteTemplate(w, templateName, data)
+		if err != nil {
+			errorPage(err, http.StatusInternalServerError).ServeHTTP(w, r)
+		}
+	}
+}