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gotosocial/internal/text/markdown.go

118 lines
3.9 KiB
Go

/*
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 text
import (
"bytes"
"context"
"io"
"strings"
"github.com/russross/blackfriday/v2"
"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
"github.com/superseriousbusiness/gotosocial/internal/log"
"github.com/tdewolff/minify/v2"
"github.com/tdewolff/minify/v2/html"
)
var (
bfExtensions = blackfriday.NoIntraEmphasis | blackfriday.FencedCode | blackfriday.Autolink | blackfriday.Strikethrough | blackfriday.SpaceHeadings | blackfriday.HardLineBreak
m *minify.M
)
type renderer struct {
f *formatter
ctx context.Context
mentions []*gtsmodel.Mention
tags []*gtsmodel.Tag
blackfriday.HTMLRenderer
}
func (r *renderer) RenderNode(w io.Writer, node *blackfriday.Node, entering bool) blackfriday.WalkStatus {
if node.Type == blackfriday.Text {
// call RenderNode to do the html escaping
var buff bytes.Buffer
status := r.HTMLRenderer.RenderNode(&buff, node, entering)
html := buff.String()
html = r.f.ReplaceTags(r.ctx, html, r.tags)
html = r.f.ReplaceMentions(r.ctx, html, r.mentions)
// we don't have much recourse if this fails
if _, err := io.WriteString(w, html); err != nil {
log.Errorf("error outputting markdown text: %s", err)
}
return status
}
return r.HTMLRenderer.RenderNode(w, node, entering)
}
func (f *formatter) FromMarkdown(ctx context.Context, markdownText string, mentions []*gtsmodel.Mention, tags []*gtsmodel.Tag, emojis []*gtsmodel.Emoji) string {
renderer := &renderer{
f: f,
ctx: ctx,
mentions: mentions,
tags: tags,
HTMLRenderer: *blackfriday.NewHTMLRenderer(blackfriday.HTMLRendererParameters{
// same as blackfriday.CommonHTMLFlags, but with Smartypants disabled
// ref: https://github.com/superseriousbusiness/gotosocial/issues/1028
Flags: blackfriday.UseXHTML,
}),
}
// 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
htmlContentBytes := blackfriday.Run([]byte(markdownText), blackfriday.WithExtensions(bfExtensions), blackfriday.WithRenderer(renderer))
htmlContent := string(htmlContentBytes)
// 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", &html.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
}