[feature] Add opt-in RSS feed for account's latest Public posts (#897)

* start adding rss functionality

* add gorilla/feeds dependency

* first bash at building rss feed
still needs work, this is an interim commit

* tidy up a bit

* add publicOnly option to GetAccountLastPosted

* implement rss endpoint

* fix test

* add initial user docs for rss

* update rss logo

* docs update

* add rssFeed to frontend

* feed -> feed.rss

* enableRSS

* increase rss logo size a lil bit

* add rss toggle

* move emojify to text package

* fiddle with rss feed formatting

* add Text field to test statuses

* move status to rss item to typeconverter

* update bun schema for enablerss

* simplify 304 checking

* assume account not rss

* update tests

* update swagger docs

* allow more characters in title, trim nicer

* update last posted to be more consistent

internal/text/emojify.go

@@ -0,0 +1,67 @@
+/*
+   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"
+	"html"
+
+	"github.com/superseriousbusiness/gotosocial/internal/api/model"
+	"github.com/superseriousbusiness/gotosocial/internal/regexes"
+)
+
+// Emojify replaces shortcodes in `inputText` with the emoji in `emojis`.
+//
+// Callers should ensure that inputText and resulting text are escaped
+// appropriately depending on what they're used for.
+func Emojify(emojis []model.Emoji, inputText string) string {
+	emojisMap := make(map[string]model.Emoji, len(emojis))
+
+	for _, emoji := range emojis {
+		shortcode := ":" + emoji.Shortcode + ":"
+		emojisMap[shortcode] = emoji
+	}
+
+	return regexes.ReplaceAllStringFunc(
+		regexes.EmojiFinder,
+		inputText,
+		func(shortcode string, buf *bytes.Buffer) string {
+			// Look for emoji according to this shortcode
+			emoji, ok := emojisMap[shortcode]
+			if !ok {
+				return shortcode
+			}
+
+			// Escape raw emoji content
+			safeURL := html.EscapeString(emoji.URL)
+			safeCode := html.EscapeString(emoji.Shortcode)
+
+			// Write HTML emoji repr to buffer
+			buf.WriteString(`<img src="`)
+			buf.WriteString(safeURL)
+			buf.WriteString(`" title=":`)
+			buf.WriteString(safeCode)
+			buf.WriteString(`:" alt=":`)
+			buf.WriteString(safeCode)
+			buf.WriteString(`:" class="emoji"/>`)
+
+			return buf.String()
+		},
+	)
+}