Implement template writer helper

frontend/renderer/output.go

@@ -0,0 +1,38 @@
+package renderer
+
+import (
+	"io"
+
+	"code.tokarch.uk/mainnika/nikita-tokarch-uk/frontend/templates"
+	routing "github.com/jackwhelpton/fasthttp-routing/v2"
+	"github.com/valyala/fasthttp"
+)
+
+var _ routing.DataWriter = (*TemplateWriter)(nil)
+
+// staticWriter is thread-safe static instance of template writer
+var staticWriter = &TemplateWriter{}
+
+// TemplateWriter is the fasthttp data writer that loads and executes template using the content
+type TemplateWriter struct{}
+
+// SetHeader sets the content type to HTML since all templates are HTML
+func (tw *TemplateWriter) SetHeader(rh *fasthttp.ResponseHeader) {
+	rh.SetContentType(routing.MIME_HTML)
+}
+
+// Write executes the template and writes result to the response writer
+func (tw *TemplateWriter) Write(w io.Writer, content interface{}) error {
+
+	template := templates.GetTemplateOf(content)
+
+	return template.Execute(w, content)
+}
+
+// useTemplateWriter is the routing middleware to set the default data writer
+func (r *Renderer) useTemplateWriter(c *routing.Context) (err error) {
+
+	c.SetDataWriter(staticWriter)
+
+	return
+}