Initial commit

matrix/replyutil.go

@@ -0,0 +1,107 @@
+// maubot - A plugin-based Matrix bot system written in Go.
+// Copyright (C) 2018 Tulir Asokan
+//
+// 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 <https://www.gnu.org/licenses/>.
+
+package matrix
+
+import (
+	"regexp"
+	"strings"
+	"fmt"
+	"maunium.net/go/gomatrix"
+	"golang.org/x/net/html"
+)
+
+var HTMLReplyFallbackRegex = regexp.MustCompile(`^<mx-reply>[\s\S]+?</mx-reply>`)
+
+func TrimReplyFallbackHTML(html string) string {
+	return HTMLReplyFallbackRegex.ReplaceAllString(html, "")
+}
+
+func TrimReplyFallbackText(text string) string {
+	if !strings.HasPrefix(text, "> ") || !strings.Contains(text, "\n") {
+		return text
+	}
+
+	lines := strings.Split(text, "\n")
+	for len(lines) > 0 && strings.HasPrefix(lines[0], "> ") {
+		lines = lines[1:]
+	}
+	return strings.Join(lines, "\n")
+}
+
+func RemoveReplyFallback(evt *gomatrix.Event) {
+	if format, ok := evt.Content["format"].(string); ok && format == "org.matrix.custom.html" {
+		htmlBody, _ := evt.Content["formatted_body"].(string)
+		evt.Content["formatted_body"] = TrimReplyFallbackHTML(htmlBody)
+	}
+	plainBody, _ := evt.Content["body"].(string)
+	evt.Content["body"] = TrimReplyFallbackText(plainBody)
+}
+
+const ReplyFormat = `<mx-reply><blockquote>
+<a href="https://matrix.to/#/%s/%s">In reply to</a>
+<a href="https://matrix.to/#/%s">%s</a>
+%s
+</blockquote></mx-reply>
+`
+
+func ReplyFallbackHTML(evt *gomatrix.Event) string {
+	body, ok := evt.Content["formatted_body"].(string)
+	if !ok {
+		body, _ = evt.Content["body"].(string)
+		body = html.EscapeString(body)
+	}
+
+	senderDisplayName := evt.Sender
+
+	return fmt.Sprintf(ReplyFormat, evt.RoomID, evt.ID, evt.Sender, senderDisplayName, body)
+}
+
+func ReplyFallbackText(evt *gomatrix.Event) string {
+	body, _ := evt.Content["body"].(string)
+	lines := strings.Split(strings.TrimSpace(body), "\n")
+	firstLine, lines := lines[0], lines[1:]
+
+	senderDisplayName := evt.Sender
+
+	var fallbackText strings.Builder
+	fmt.Fprintf(&fallbackText, "> <%s> %s", senderDisplayName, firstLine)
+	for _, line := range lines {
+		fmt.Fprintf(&fallbackText, "\n> %s", line)
+	}
+	fallbackText.WriteString("\n\n")
+	return fallbackText.String()
+}
+
+func SetReply(content map[string]interface{}, inReplyTo *gomatrix.Event) map[string]interface{} {
+	content["m.relates_to"] = map[string]interface{}{
+		"m.in_reply_to": map[string]interface{}{
+			"event_id": inReplyTo.ID,
+			"room_id":  inReplyTo.RoomID,
+		},
+	}
+
+	body, _ := content["body"].(string)
+	content["body"] = ReplyFallbackText(inReplyTo) + body
+
+	htmlBody, ok := content["formatted_body"].(string)
+	if !ok {
+		htmlBody = html.EscapeString(body)
+		content["format"] = "org.matrix.custom.html"
+	}
+	content["formatted_body"] = ReplyFallbackHTML(inReplyTo) + htmlBody
+	return content
+}