summaryrefslogtreecommitdiff
path: root/internal/web/opengraph.go
blob: 12989160cda78b58809328046b216ec6b4136c98 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
// GoToSocial
// Copyright (C) GoToSocial Authors admin@gotosocial.org
// SPDX-License-Identifier: AGPL-3.0-or-later
//
// 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://ogp.me/
type ogMeta struct {
	// vanilla og tags
	Title       string // og:title
	Type        string // og:type
	Locale      string // og:locale
	URL         string // og:url
	SiteName    string // og:site_name
	Description string // og:description

	// image tags
	Image       string // og:image
	ImageWidth  string // og:image:width
	ImageHeight string // og:image:height
	ImageAlt    string // og:image:alt

	// article tags
	ArticlePublisher     string // article:publisher
	ArticleAuthor        string // article:author
	ArticleModifiedTime  string // article:modified_time
	ArticlePublishedTime string // article:published_time

	// profile tags
	ProfileUsername string // profile:username
}

// 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.InstanceV1) *ogMeta {
	var locale string
	if len(instance.Languages) > 0 {
		locale = instance.Languages[0]
	}

	og := &ogMeta{
		Title:       text.SanitizePlaintext(instance.Title) + " - GoToSocial",
		Type:        "website",
		Locale:      locale,
		URL:         instance.URI,
		SiteName:    instance.AccountDomain,
		Description: parseDescription(instance.ShortDescription),

		Image:    instance.Thumbnail,
		ImageAlt: instance.ThumbnailDescription,
	}

	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.Title = parseTitle(account, og.SiteName)
	og.Type = "profile"
	og.URL = account.URL
	if account.Note != "" {
		og.Description = parseDescription(account.Note)
	} else {
		og.Description = `content="This GoToSocial user hasn't written a bio yet!"`
	}

	og.Image = account.Avatar
	og.ImageAlt = "Avatar for " + account.Username

	og.ProfileUsername = account.Username

	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 {
	og.Title = "Post by " + parseTitle(status.Account, og.SiteName)
	og.Type = "article"
	if status.Language != nil {
		og.Locale = *status.Language
	}
	og.URL = status.URL
	switch {
	case status.SpoilerText != "":
		og.Description = parseDescription("CW: " + status.SpoilerText)
	case status.Text != "":
		og.Description = parseDescription(status.Text)
	default:
		og.Description = og.Title
	}

	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)
		if a.Description != nil {
			og.ImageAlt = *a.Description
		}
	} else {
		og.Image = status.Account.Avatar
		og.ImageAlt = "Avatar for " + status.Account.Username
	}

	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 := text.SanitizePlaintext(in)
	i = strings.ReplaceAll(i, "\n", " ")
	i = strings.Join(strings.Fields(i), " ")
	i = html.EscapeString(i)
	i = strings.ReplaceAll(i, `\`, "&bsol;")
	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]
}