package transform import ( htmltran "code.google.com/p/go-html-transform/html/transform" "io" "net/url" ) type Transformer struct { BaseURL string } func (t *Transformer) Apply(r io.Reader, w io.Writer) (err error) { var tr *htmltran.Transformer if tr, err = htmltran.NewFromReader(r); err != nil { return } if err = t.absUrlify(tr, elattr{"a", "href"}, elattr{"script", "src"}); err != nil { return } return tr.Render(w) } type elattr struct { tag, attr string } func (t *Transformer) absUrlify(tr *htmltran.Transformer, selectors ...elattr) (err error) { var baseURL, inURL *url.URL if baseURL, err = url.Parse(t.BaseURL); err != nil { return } replace := func(in string) string { if inURL, err = url.Parse(in); err != nil { return in + "?" } if fragmentOnly(inURL) { return in } return baseURL.ResolveReference(inURL).String() } for _, el := range selectors { if err = tr.Apply(htmltran.TransformAttrib(el.attr, replace), el.tag); err != nil { return } } return } func fragmentOnly(u *url.URL) bool { return u.Fragment != "" && u.Scheme == "" && u.Opaque == "" && u.User == nil && u.Host == "" && u.Path == "" && u.Path == "" && u.RawQuery == "" }