start of adding html renderer

renderer/renderer.go

@@ -0,0 +1,46 @@
+package renderer
+
+import (
+	"fmt"
+	"html/template"
+	"io"
+	"io/fs"
+)
+
+type Renderer interface {
+	// Render will write the template to given the given writer.
+	// Will return an error if we can't write to the writer or we can
+	// can't find the template.
+	Render(w io.Writer, templateName string, data interface{}) error
+}
+
+type ErrTemplateNotFound struct {
+	Err  error
+	Name string
+}
+
+func (e *ErrTemplateNotFound) Error() string {
+	return fmt.Sprintf("unable to find the template '%s', err: %v", e.Name, e.Err)
+}
+
+type ErrFailedToWrite struct {
+	Err error
+}
+
+func (e *ErrFailedToWrite) Error() string {
+	return fmt.Sprintf("failed to write template, err: %v", e.Err)
+}
+
+type HTMLRender struct {
+	templates *template.Template
+}
+
+func New(fs fs.FS, pattern string) (*HTMLRender, error) {
+	return &HTMLRender{
+		templates: template.Must(template.ParseFS(fs, pattern)),
+	}, nil
+}
+
+func (h *HTMLRender) Render(w io.Writer, templateName string, data interface{}) error {
+	return h.templates.ExecuteTemplate(w, templateName, data)
+}