#4257 Added functionality to create previews for post links using open graph data from those links. (#4890)

1 files changed, 329 insertions, 0 deletions

diff --git a/vendor/github.com/dyatlov/go-opengraph/opengraph/opengraph.go b/vendor/github.com/dyatlov/go-opengraph/opengraph/opengraph.go
new file mode 100644
index 000000000..5468d86bb
--- /dev/null
+++ b/vendor/github.com/dyatlov/go-opengraph/opengraph/opengraph.go
@@ -0,0 +1,329 @@
+package opengraph
+
+import (
+	"encoding/json"
+	"io"
+	"strconv"
+	"time"
+
+	"golang.org/x/net/html"
+	"golang.org/x/net/html/atom"
+)
+
+// Image defines Open Graph Image type
+type Image struct {
+	URL       string `json:"url"`
+	SecureURL string `json:"secure_url"`
+	Type      string `json:"type"`
+	Width     uint64 `json:"width"`
+	Height    uint64 `json:"height"`
+}
+
+// Video defines Open Graph Video type
+type Video struct {
+	URL       string `json:"url"`
+	SecureURL string `json:"secure_url"`
+	Type      string `json:"type"`
+	Width     uint64 `json:"width"`
+	Height    uint64 `json:"height"`
+}
+
+// Audio defines Open Graph Audio Type
+type Audio struct {
+	URL       string `json:"url"`
+	SecureURL string `json:"secure_url"`
+	Type      string `json:"type"`
+}
+
+// Article contain Open Graph Article structure
+type Article struct {
+	PublishedTime  *time.Time `json:"published_time"`
+	ModifiedTime   *time.Time `json:"modified_time"`
+	ExpirationTime *time.Time `json:"expiration_time"`
+	Section        string     `json:"section"`
+	Tags           []string   `json:"tags"`
+	Authors        []*Profile `json:"authors"`
+}
+
+// Profile contains Open Graph Profile structure
+type Profile struct {
+	FirstName string `json:"first_name"`
+	LastName  string `json:"last_name"`
+	Username  string `json:"username"`
+	Gender    string `json:"gender"`
+}
+
+// Book contains Open Graph Book structure
+type Book struct {
+	ISBN        string     `json:"isbn"`
+	ReleaseDate *time.Time `json:"release_date"`
+	Tags        []string   `json:"tags"`
+	Authors     []*Profile `json:"authors"`
+}
+
+// OpenGraph contains facebook og data
+type OpenGraph struct {
+	isArticle        bool
+	isBook           bool
+	isProfile        bool
+	Type             string   `json:"type"`
+	URL              string   `json:"url"`
+	Title            string   `json:"title"`
+	Description      string   `json:"description"`
+	Determiner       string   `json:"determiner"`
+	SiteName         string   `json:"site_name"`
+	Locale           string   `json:"locale"`
+	LocalesAlternate []string `json:"locales_alternate"`
+	Images           []*Image `json:"images"`
+	Audios           []*Audio `json:"audios"`
+	Videos           []*Video `json:"videos"`
+	Article          *Article `json:"article,omitempty"`
+	Book             *Book    `json:"book,omitempty"`
+	Profile          *Profile `json:"profile,omitempty"`
+}
+
+// NewOpenGraph returns new instance of Open Graph structure
+func NewOpenGraph() *OpenGraph {
+	return &OpenGraph{}
+}
+
+// ToJSON a simple wrapper around json.Marshal
+func (og *OpenGraph) ToJSON() ([]byte, error) {
+	return json.Marshal(og)
+}
+
+// String return json representation of structure, or error string
+func (og *OpenGraph) String() string {
+	data, err := og.ToJSON()
+
+	if err != nil {
+		return err.Error()
+	}
+
+	return string(data[:])
+}
+
+// ProcessHTML parses given html from Reader interface and fills up OpenGraph structure
+func (og *OpenGraph) ProcessHTML(buffer io.Reader) error {
+	z := html.NewTokenizer(buffer)
+	for {
+		tt := z.Next()
+		switch tt {
+		case html.ErrorToken:
+			if z.Err() == io.EOF {
+				return nil
+			}
+			return z.Err()
+		case html.StartTagToken, html.SelfClosingTagToken, html.EndTagToken:
+			name, hasAttr := z.TagName()
+			if atom.Lookup(name) == atom.Body {
+				return nil // OpenGraph is only in head, so we don't need body
+			}
+			if atom.Lookup(name) != atom.Meta || !hasAttr {
+				continue
+			}
+			m := make(map[string]string)
+			var key, val []byte
+			for hasAttr {
+				key, val, hasAttr = z.TagAttr()
+				m[atom.String(key)] = string(val)
+			}
+			og.ProcessMeta(m)
+		}
+	}
+	return nil
+}
+
+// ProcessMeta processes meta attributes and adds them to Open Graph structure if they are suitable for that
+func (og *OpenGraph) ProcessMeta(metaAttrs map[string]string) {
+	switch metaAttrs["property"] {
+	case "og:description":
+		og.Description = metaAttrs["content"]
+	case "og:type":
+		og.Type = metaAttrs["content"]
+		switch og.Type {
+		case "article":
+			og.isArticle = true
+		case "book":
+			og.isBook = true
+		case "profile":
+			og.isProfile = true
+		}
+	case "og:title":
+		og.Title = metaAttrs["content"]
+	case "og:url":
+		og.URL = metaAttrs["content"]
+	case "og:determiner":
+		og.Determiner = metaAttrs["content"]
+	case "og:site_name":
+		og.SiteName = metaAttrs["content"]
+	case "og:locale":
+		og.Locale = metaAttrs["content"]
+	case "og:locale:alternate":
+		og.LocalesAlternate = append(og.LocalesAlternate, metaAttrs["content"])
+	case "og:image":
+		og.Images = append(og.Images, &Image{URL: metaAttrs["content"]})
+	case "og:image:url":
+		if len(og.Images) > 0 {
+			og.Images[len(og.Images)-1].URL = metaAttrs["content"]
+		}
+	case "og:image:secure_url":
+		if len(og.Images) > 0 {
+			og.Images[len(og.Images)-1].SecureURL = metaAttrs["content"]
+		}
+	case "og:image:type":
+		if len(og.Images) > 0 {
+			og.Images[len(og.Images)-1].Type = metaAttrs["content"]
+		}
+	case "og:image:width":
+		if len(og.Images) > 0 {
+			w, err := strconv.ParseUint(metaAttrs["content"], 10, 64)
+			if err == nil {
+				og.Images[len(og.Images)-1].Width = w
+			}
+		}
+	case "og:image:height":
+		if len(og.Images) > 0 {
+			h, err := strconv.ParseUint(metaAttrs["content"], 10, 64)
+			if err == nil {
+				og.Images[len(og.Images)-1].Height = h
+			}
+		}
+	case "og:video":
+		og.Videos = append(og.Videos, &Video{URL: metaAttrs["content"]})
+	case "og:video:url":
+		if len(og.Videos) > 0 {
+			og.Videos[len(og.Videos)-1].URL = metaAttrs["content"]
+		}
+	case "og:video:secure_url":
+		if len(og.Videos) > 0 {
+			og.Videos[len(og.Videos)-1].SecureURL = metaAttrs["content"]
+		}
+	case "og:video:type":
+		if len(og.Videos) > 0 {
+			og.Videos[len(og.Videos)-1].Type = metaAttrs["content"]
+		}
+	case "og:video:width":
+		if len(og.Videos) > 0 {
+			w, err := strconv.ParseUint(metaAttrs["content"], 10, 64)
+			if err == nil {
+				og.Videos[len(og.Videos)-1].Width = w
+			}
+		}
+	case "og:video:height":
+		if len(og.Videos) > 0 {
+			h, err := strconv.ParseUint(metaAttrs["content"], 10, 64)
+			if err == nil {
+				og.Videos[len(og.Videos)-1].Height = h
+			}
+		}
+	default:
+		if og.isArticle {
+			og.processArticleMeta(metaAttrs)
+		} else if og.isBook {
+			og.processBookMeta(metaAttrs)
+		} else if og.isProfile {
+			og.processProfileMeta(metaAttrs)
+		}
+	}
+}
+
+func (og *OpenGraph) processArticleMeta(metaAttrs map[string]string) {
+	if og.Article == nil {
+		og.Article = &Article{}
+	}
+	switch metaAttrs["property"] {
+	case "article:published_time":
+		t, err := time.Parse(time.RFC3339, metaAttrs["content"])
+		if err == nil {
+			og.Article.PublishedTime = &t
+		}
+	case "article:modified_time":
+		t, err := time.Parse(time.RFC3339, metaAttrs["content"])
+		if err == nil {
+			og.Article.ModifiedTime = &t
+		}
+	case "article:expiration_time":
+		t, err := time.Parse(time.RFC3339, metaAttrs["content"])
+		if err == nil {
+			og.Article.ExpirationTime = &t
+		}
+	case "article:secttion":
+		og.Article.Section = metaAttrs["content"]
+	case "article:tag":
+		og.Article.Tags = append(og.Article.Tags, metaAttrs["content"])
+	case "article:author:first_name":
+		if len(og.Article.Authors) == 0 {
+			og.Article.Authors = append(og.Article.Authors, &Profile{})
+		}
+		og.Article.Authors[len(og.Article.Authors)-1].FirstName = metaAttrs["content"]
+	case "article:author:last_name":
+		if len(og.Article.Authors) == 0 {
+			og.Article.Authors = append(og.Article.Authors, &Profile{})
+		}
+		og.Article.Authors[len(og.Article.Authors)-1].LastName = metaAttrs["content"]
+	case "article:author:username":
+		if len(og.Article.Authors) == 0 {
+			og.Article.Authors = append(og.Article.Authors, &Profile{})
+		}
+		og.Article.Authors[len(og.Article.Authors)-1].Username = metaAttrs["content"]
+	case "article:author:gender":
+		if len(og.Article.Authors) == 0 {
+			og.Article.Authors = append(og.Article.Authors, &Profile{})
+		}
+		og.Article.Authors[len(og.Article.Authors)-1].Gender = metaAttrs["content"]
+	}
+}
+
+func (og *OpenGraph) processBookMeta(metaAttrs map[string]string) {
+	if og.Book == nil {
+		og.Book = &Book{}
+	}
+	switch metaAttrs["property"] {
+	case "book:release_date":
+		t, err := time.Parse(time.RFC3339, metaAttrs["content"])
+		if err == nil {
+			og.Book.ReleaseDate = &t
+		}
+	case "book:isbn":
+		og.Book.ISBN = metaAttrs["content"]
+	case "book:tag":
+		og.Book.Tags = append(og.Book.Tags, metaAttrs["content"])
+	case "book:author:first_name":
+		if len(og.Book.Authors) == 0 {
+			og.Book.Authors = append(og.Book.Authors, &Profile{})
+		}
+		og.Book.Authors[len(og.Book.Authors)-1].FirstName = metaAttrs["content"]
+	case "book:author:last_name":
+		if len(og.Book.Authors) == 0 {
+			og.Book.Authors = append(og.Book.Authors, &Profile{})
+		}
+		og.Book.Authors[len(og.Book.Authors)-1].LastName = metaAttrs["content"]
+	case "book:author:username":
+		if len(og.Book.Authors) == 0 {
+			og.Book.Authors = append(og.Book.Authors, &Profile{})
+		}
+		og.Book.Authors[len(og.Book.Authors)-1].Username = metaAttrs["content"]
+	case "book:author:gender":
+		if len(og.Book.Authors) == 0 {
+			og.Book.Authors = append(og.Book.Authors, &Profile{})
+		}
+		og.Book.Authors[len(og.Book.Authors)-1].Gender = metaAttrs["content"]
+	}
+}
+
+func (og *OpenGraph) processProfileMeta(metaAttrs map[string]string) {
+	if og.Profile == nil {
+		og.Profile = &Profile{}
+	}
+	switch metaAttrs["property"] {
+	case "profile:first_name":
+		og.Profile.FirstName = metaAttrs["content"]
+	case "profile:last_name":
+		og.Profile.LastName = metaAttrs["content"]
+	case "profile:username":
+		og.Profile.Username = metaAttrs["content"]
+	case "profile:gender":
+		og.Profile.Gender = metaAttrs["content"]
+	}
+}