GoToSocial/internal/text/link.go

87 lines
2.8 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"
"net/url"
"strings"
"github.com/superseriousbusiness/gotosocial/internal/regexes"
)
// FindLinks parses the given string looking for recognizable URLs (including scheme).
// It returns a list of those URLs, without changing the string, or an error if something goes wrong.
// If no URLs are found within the given string, an empty slice and nil will be returned.
func FindLinks(in string) []*url.URL {
var urls []*url.URL
// bail already if we don't find anything
found := regexes.LinkScheme.FindAllString(in, -1)
if len(found) == 0 {
return nil
}
urlmap := map[string]struct{}{}
// for each string we find, we want to parse it into a URL if we can
// if we fail to parse it, just ignore this match and continue
for _, f := range found {
u, err := url.Parse(f)
if err != nil {
continue
}
// Calculate string
ustr := u.String()
if _, ok := urlmap[ustr]; !ok {
// Has not been encountered yet
urls = append(urls, u)
urlmap[ustr] = struct{}{}
}
}
return urls
}
// ReplaceLinks replaces all detected links in a piece of text with their HTML (href) equivalents.
// Note: because Go doesn't allow negative lookbehinds in regex, it's possible that an already-formatted
// href will end up double-formatted, if the text you pass here contains one or more hrefs already.
// To avoid this, you should sanitize any HTML out of text before you pass it into this function.
func (f *formatter) ReplaceLinks(ctx context.Context, in string) string {
return regexes.ReplaceAllStringFunc(regexes.LinkScheme, in, func(urlString string, buf *bytes.Buffer) string {
thisURL, err := url.Parse(urlString)
if err != nil {
return urlString // we can't parse it as a URL so don't replace it
}
// <a href="thisURL.String()" rel="noopener">urlString</a>
urlString = thisURL.String()
buf.WriteString(`<a href="`)
buf.WriteString(thisURL.String())
buf.WriteString(`" rel="noopener">`)
urlString = strings.TrimPrefix(urlString, thisURL.Scheme)
urlString = strings.TrimPrefix(urlString, "://")
buf.WriteString(urlString)
buf.WriteString(`</a>`)
return buf.String()
})
}