GoToSocial/internal/web/opengraph.go

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/*
GoToSocial
Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package web
import (
"html"
"strconv"
"strings"
apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
"github.com/superseriousbusiness/gotosocial/internal/text"
)
const maxOGDescriptionLength = 300
// ogMeta represents supported OpenGraph Meta tags
//
// see eg https://developer.yoast.com/features/opengraph/functional-specification/
type ogMeta struct {
// vanilla og tags
Locale string // og:locale
ResourceType string // og:type
Title string // og:title
URL string // og:url
SiteName string // og:site_name
Description string // og:description
Image string // og:image
ImageWidth string // og:image:width
ImageHeight string // og:image:height
// article tags
ArticlePublisher string // article:publisher
ArticleAuthor string // article:author
ArticleModifiedTime string // article:modified_time
ArticlePublishedTime string // article:published_time
}
// ogBase returns an *ogMeta suitable for serving at
// the base root of an instance. It also serves as a
// foundation for building account / status ogMeta on
// top of.
func ogBase(instance *apimodel.Instance) *ogMeta {
var locale string
if len(instance.Languages) > 0 {
locale = instance.Languages[0]
}
og := &ogMeta{
Locale: locale,
ResourceType: "website",
Title: text.SanitizePlaintext(instance.Title) + " - GoToSocial",
URL: instance.URI,
SiteName: instance.AccountDomain,
Description: parseDescription(instance.ShortDescription),
Image: instance.Thumbnail,
}
return og
}
// withAccount uses the given account to build an ogMeta
// struct specific to that account. It's suitable for serving
// at account profile pages.
func (og *ogMeta) withAccount(account *apimodel.Account) *ogMeta {
og.ResourceType = "profile"
og.Title = parseTitle(account, og.SiteName)
og.URL = account.URL
og.Description = parseDescription(account.Note)
og.Image = account.Avatar
return og
}
// withStatus uses the given status to build an ogMeta
// struct specific to that status. It's suitable for serving
// at status pages.
func (og *ogMeta) withStatus(status *apimodel.Status) *ogMeta {
if !status.Sensitive && len(status.MediaAttachments) > 0 {
a := status.MediaAttachments[0]
og.Image = a.PreviewURL
og.ImageWidth = strconv.Itoa(a.Meta.Small.Width)
og.ImageHeight = strconv.Itoa(a.Meta.Small.Height)
} else {
og.Image = status.Account.Avatar
}
if status.SpoilerText != "" {
og.Description = parseDescription("CW: " + status.SpoilerText)
} else {
og.Description = parseDescription(status.Text)
}
og.Locale = status.Language
og.ResourceType = "article"
og.Title = "Post by " + parseTitle(status.Account, og.SiteName)
og.URL = status.URL
og.ArticlePublisher = status.Account.URL
og.ArticleAuthor = status.Account.URL
og.ArticlePublishedTime = status.CreatedAt
og.ArticleModifiedTime = status.CreatedAt
return og
}
// parseTitle parses a page title from account and accountDomain
func parseTitle(account *apimodel.Account, accountDomain string) string {
user := "@" + account.Acct + "@" + accountDomain
if len(account.DisplayName) == 0 {
return user
}
return account.DisplayName + " (" + user + ")"
}
// parseDescription returns a string description which is
// safe to use as a template.HTMLAttr inside templates.
func parseDescription(in string) string {
i := html.UnescapeString(in)
i = text.SanitizePlaintext(i)
i = strings.ReplaceAll(i, "\"", "'")
i = strings.ReplaceAll(i, `\`, "")
i = strings.ReplaceAll(i, "\n", " ")
i = trim(i, maxOGDescriptionLength)
return `content="` + i + `"`
}
// trim strings trim s to specified length
func trim(s string, length int) string {
if len(s) < length {
return s
}
return s[:length]
}