otiai10/opengraph

package opengraph

import "golang.org/x/net/html"

// Link represents any "<link ...>" HTML tag.
// <link> will NOT be used when Intent.String == true.
type Link struct {
    Rel  string
    Href string
}

// LinkTag constructs Link
func LinkTag(n *html.Node) *Link {
    link := new(Link)
    for _, attr := range n.Attr {
        switch attr.Key {
        case "rel":
            link.Rel = attr.Val
        case "href":
            link.Href = attr.Val
        }
    }
    return link
}

// Contribute contributes OpenGraph
func (link *Link) Contribute(og *OpenGraph) error {
    switch {
    case link.IsFavicon():
        og.Favicon = Favicon{URL: link.Href}
    }
    return nil
}

// IsFavicon returns if it can be "favicon" of *opengraph.OpenGraph
func (link *Link) IsFavicon() bool {
    return link.Rel == "shortcut icon" || link.Rel == "icon"
}

// Title represents any "<title ...>" HTML tag.
// <title> will NOT be used when Intent.Strict == true.
type Title struct {
    Text string
}

// TitleTag constructs Title.
func TitleTag(n *html.Node) *Title {
    t := new(Title)
    if n.FirstChild != nil {
        t.Text = n.FirstChild.Data
    }
    return t
}

// Contribute contributes to OpenGraph
func (t *Title) Contribute(og *OpenGraph) error {
    if og.Title == "" && t.Text != "" {
        og.Title = t.Text
    }
    return nil
}