Add RSS/Atom feed support for user actions (#16002)

Return rss/atom feed for user based on rss url suffix or Content-Type header.

vendor/github.com/gorilla/feeds/json.go

@@ -0,0 +1,183 @@
+package feeds
+
+import (
+	"encoding/json"
+	"strings"
+	"time"
+)
+
+const jsonFeedVersion = "https://jsonfeed.org/version/1"
+
+// JSONAuthor represents the author of the feed or of an individual item
+// in the feed
+type JSONAuthor struct {
+	Name   string `json:"name,omitempty"`
+	Url    string `json:"url,omitempty"`
+	Avatar string `json:"avatar,omitempty"`
+}
+
+// JSONAttachment represents a related resource. Podcasts, for instance, would
+// include an attachment that’s an audio or video file.
+type JSONAttachment struct {
+	Url      string        `json:"url,omitempty"`
+	MIMEType string        `json:"mime_type,omitempty"`
+	Title    string        `json:"title,omitempty"`
+	Size     int32         `json:"size,omitempty"`
+	Duration time.Duration `json:"duration_in_seconds,omitempty"`
+}
+
+// MarshalJSON implements the json.Marshaler interface.
+// The Duration field is marshaled in seconds, all other fields are marshaled
+// based upon the definitions in struct tags.
+func (a *JSONAttachment) MarshalJSON() ([]byte, error) {
+	type EmbeddedJSONAttachment JSONAttachment
+	return json.Marshal(&struct {
+		Duration float64 `json:"duration_in_seconds,omitempty"`
+		*EmbeddedJSONAttachment
+	}{
+		EmbeddedJSONAttachment: (*EmbeddedJSONAttachment)(a),
+		Duration:               a.Duration.Seconds(),
+	})
+}
+
+// UnmarshalJSON implements the json.Unmarshaler interface.
+// The Duration field is expected to be in seconds, all other field types
+// match the struct definition.
+func (a *JSONAttachment) UnmarshalJSON(data []byte) error {
+	type EmbeddedJSONAttachment JSONAttachment
+	var raw struct {
+		Duration float64 `json:"duration_in_seconds,omitempty"`
+		*EmbeddedJSONAttachment
+	}
+	raw.EmbeddedJSONAttachment = (*EmbeddedJSONAttachment)(a)
+
+	err := json.Unmarshal(data, &raw)
+	if err != nil {
+		return err
+	}
+
+	if raw.Duration > 0 {
+		nsec := int64(raw.Duration * float64(time.Second))
+		raw.EmbeddedJSONAttachment.Duration = time.Duration(nsec)
+	}
+
+	return nil
+}
+
+// JSONItem represents a single entry/post for the feed.
+type JSONItem struct {
+	Id            string           `json:"id"`
+	Url           string           `json:"url,omitempty"`
+	ExternalUrl   string           `json:"external_url,omitempty"`
+	Title         string           `json:"title,omitempty"`
+	ContentHTML   string           `json:"content_html,omitempty"`
+	ContentText   string           `json:"content_text,omitempty"`
+	Summary       string           `json:"summary,omitempty"`
+	Image         string           `json:"image,omitempty"`
+	BannerImage   string           `json:"banner_,omitempty"`
+	PublishedDate *time.Time       `json:"date_published,omitempty"`
+	ModifiedDate  *time.Time       `json:"date_modified,omitempty"`
+	Author        *JSONAuthor      `json:"author,omitempty"`
+	Tags          []string         `json:"tags,omitempty"`
+	Attachments   []JSONAttachment `json:"attachments,omitempty"`
+}
+
+// JSONHub describes an endpoint that can be used to subscribe to real-time
+// notifications from the publisher of this feed.
+type JSONHub struct {
+	Type string `json:"type"`
+	Url  string `json:"url"`
+}
+
+// JSONFeed represents a syndication feed in the JSON Feed Version 1 format.
+// Matching the specification found here: https://jsonfeed.org/version/1.
+type JSONFeed struct {
+	Version     string      `json:"version"`
+	Title       string      `json:"title"`
+	HomePageUrl string      `json:"home_page_url,omitempty"`
+	FeedUrl     string      `json:"feed_url,omitempty"`
+	Description string      `json:"description,omitempty"`
+	UserComment string      `json:"user_comment,omitempty"`
+	NextUrl     string      `json:"next_url,omitempty"`
+	Icon        string      `json:"icon,omitempty"`
+	Favicon     string      `json:"favicon,omitempty"`
+	Author      *JSONAuthor `json:"author,omitempty"`
+	Expired     *bool       `json:"expired,omitempty"`
+	Hubs        []*JSONItem `json:"hubs,omitempty"`
+	Items       []*JSONItem `json:"items,omitempty"`
+}
+
+// JSON is used to convert a generic Feed to a JSONFeed.
+type JSON struct {
+	*Feed
+}
+
+// ToJSON encodes f into a JSON string. Returns an error if marshalling fails.
+func (f *JSON) ToJSON() (string, error) {
+	return f.JSONFeed().ToJSON()
+}
+
+// ToJSON encodes f into a JSON string. Returns an error if marshalling fails.
+func (f *JSONFeed) ToJSON() (string, error) {
+	data, err := json.MarshalIndent(f, "", "  ")
+	if err != nil {
+		return "", err
+	}
+
+	return string(data), nil
+}
+
+// JSONFeed creates a new JSONFeed with a generic Feed struct's data.
+func (f *JSON) JSONFeed() *JSONFeed {
+	feed := &JSONFeed{
+		Version:     jsonFeedVersion,
+		Title:       f.Title,
+		Description: f.Description,
+	}
+
+	if f.Link != nil {
+		feed.HomePageUrl = f.Link.Href
+	}
+	if f.Author != nil {
+		feed.Author = &JSONAuthor{
+			Name: f.Author.Name,
+		}
+	}
+	for _, e := range f.Items {
+		feed.Items = append(feed.Items, newJSONItem(e))
+	}
+	return feed
+}
+
+func newJSONItem(i *Item) *JSONItem {
+	item := &JSONItem{
+		Id:      i.Id,
+		Title:   i.Title,
+		Summary: i.Description,
+
+		ContentHTML: i.Content,
+	}
+
+	if i.Link != nil {
+		item.Url = i.Link.Href
+	}
+	if i.Source != nil {
+		item.ExternalUrl = i.Source.Href
+	}
+	if i.Author != nil {
+		item.Author = &JSONAuthor{
+			Name: i.Author.Name,
+		}
+	}
+	if !i.Created.IsZero() {
+		item.PublishedDate = &i.Created
+	}
+	if !i.Updated.IsZero() {
+		item.ModifiedDate = &i.Updated
+	}
+	if i.Enclosure != nil && strings.HasPrefix(i.Enclosure.Type, "image/") {
+		item.Image = i.Enclosure.Url
+	}
+
+	return item
+}