GoToSocial/internal/text/markdown.go

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/*
GoToSocial
Copyright (C) 2021-2023 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 text
import (
"bytes"
"context"
"strings"
"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
"github.com/superseriousbusiness/gotosocial/internal/log"
"github.com/tdewolff/minify/v2"
minifyHtml "github.com/tdewolff/minify/v2/html"
"github.com/yuin/goldmark"
"github.com/yuin/goldmark/extension"
"github.com/yuin/goldmark/renderer/html"
)
var (
m *minify.M
)
func (f *formatter) FromMarkdown(ctx context.Context, markdownText string, mentions []*gtsmodel.Mention, tags []*gtsmodel.Tag, emojis []*gtsmodel.Emoji) string {
// Temporarily replace all found emoji shortcodes in the markdown text with
// their ID so that they're not parsed as anything by the markdown parser -
// this fixes cases where emojis with some underscores in them are parsed as
// words with emphasis, eg `:_some_emoji:` becomes `:<em>some</em>emoji:`
//
// Since the IDs of the emojis are just uppercase letters + numbers they should
// be safe to pass through the markdown parser without unexpected effects.
for _, e := range emojis {
markdownText = strings.ReplaceAll(markdownText, ":"+e.Shortcode+":", ":"+e.ID+":")
}
// parse markdown text into html, using custom renderer to add hashtag/mention links
md := goldmark.New(
goldmark.WithRendererOptions(
html.WithXHTML(),
html.WithHardWraps(),
html.WithUnsafe(), // allows raw HTML
),
goldmark.WithExtensions(
&customRenderer{f, ctx, mentions, tags},
extension.Linkify, // turns URLs into links
extension.Strikethrough,
),
)
var htmlContentBytes bytes.Buffer
err := md.Convert([]byte(markdownText), &htmlContentBytes)
if err != nil {
log.Errorf("error rendering markdown to HTML: %s", err)
}
htmlContent := htmlContentBytes.String()
// Replace emoji IDs in the parsed html content with their shortcodes again
for _, e := range emojis {
htmlContent = strings.ReplaceAll(htmlContent, ":"+e.ID+":", ":"+e.Shortcode+":")
}
// clean anything dangerous out of the html
htmlContent = SanitizeHTML(htmlContent)
if m == nil {
m = minify.New()
m.Add("text/html", &minifyHtml.Minifier{
KeepEndTags: true,
KeepQuotes: true,
})
}
minified, err := m.String("text/html", htmlContent)
if err != nil {
log.Errorf("error minifying markdown text: %s", err)
}
return minified
}