133 lines
2.7 KiB
Go
133 lines
2.7 KiB
Go
package links
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import (
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"errors"
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"io"
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"net/http"
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"strings"
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"time"
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"golang.org/x/net/html"
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"golang.org/x/net/html/atom"
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)
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var (
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Client = &http.Client{
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Timeout: 15 * time.Second,
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}
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ErrContentType = errors.New("Unsupported Content-Type")
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)
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type Meta struct {
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URL string `json:"URL"`
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SiteName string `json:"siteName,omitempty"`
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Color string `json:"color,omitempty"`
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Title string `json:"title"`
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Description string `json:"description"`
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ImageURL string `json:"imageURL,omitempty"`
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VideoURL string `json:"videoURL,omitempty"`
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}
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func Fetch(url string) (*Meta, error) {
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resp, err := http.Get(url)
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if err != nil {
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return nil, err
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}
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defer resp.Body.Close()
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// TODO: Image links
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if !strings.HasPrefix(resp.Header.Get("Content-Type"), "text/html") {
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return nil, ErrContentType
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}
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return ExtractMeta(resp.Body, url)
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}
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func ExtractMeta(body io.Reader, url string) (*Meta, error) {
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meta := Meta{URL: url}
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var currentNode atom.Atom
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z := html.NewTokenizer(body)
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for {
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tt := z.Next()
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switch tt {
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case html.ErrorToken:
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if z.Err() == io.EOF {
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return &meta, nil
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}
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return nil, z.Err()
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case html.TextToken:
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if currentNode == atom.Title && meta.Title == "" {
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meta.Title = string(z.Text())
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}
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case html.StartTagToken, html.SelfClosingTagToken, html.EndTagToken:
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name, hasAttr := z.TagName()
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node := atom.Lookup(name)
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if node == atom.Meta && hasAttr {
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var key, val []byte
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var name, content string
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for hasAttr {
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key, val, hasAttr = z.TagAttr()
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switch atom.String(key) {
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case "name":
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name = string(val)
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case "property":
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name = string(val)
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case "content":
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content = string(val)
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}
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}
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if content != "" {
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switch name {
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case "og:site_name":
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meta.SiteName = content
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case "theme-color", "msapplication-TileColor":
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meta.Color = content
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case "og:title", "twitter:title", "title":
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meta.Title = content
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case "og:description", "twitter:description":
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meta.Description = content
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case "description":
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if meta.Description == "" {
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meta.Description = content
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}
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case "og:image", "og:image:secure_url", "twitter:image":
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if !strings.HasPrefix(meta.ImageURL, "https:") {
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meta.ImageURL = content
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}
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case "og:video:url", "og:video:secure_url", "twitter:player":
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if !strings.HasPrefix(meta.VideoURL, "https:") {
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meta.VideoURL = content
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}
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}
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}
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continue
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}
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if tt == html.StartTagToken {
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currentNode = node
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} else {
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currentNode = 0
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}
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if (node == atom.Head && tt == html.EndTagToken) || node == atom.Body {
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return &meta, nil
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}
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}
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}
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}
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