feat: Add RSS feed generation for channel messages and update route handling

internal/rss/generator.go

@@ -1 +1,75 @@
-package rss
+package rss
+
+import (
+	"encoding/xml"
+	"strconv"
+	"time"
+
+	"github.com/gotd/td/tg"
+	"go.uber.org/zap"
+)
+
+type RSSItem struct {
+	Title       string `xml:"title"`
+	Link        string `xml:"link"`
+	PubDate     string `xml:"pubDate,omitempty"`
+	Description string `xml:"description"`
+	Guid        string `xml:"guid,omitempty"`
+}
+
+type RSSChannel struct {
+	Title         string `xml:"title"`
+	Link          string `xml:"link"`
+	Description   string `xml:"description"`
+	PubDate       string `xml:"pubDate,omitempty"`
+	LastBuildDate string `xml:"lastBuildDate,omitempty"`
+	Generator     string `xml:"generator,omitempty"`
+
+	Items []RSSItem `xml:"item"`
+}
+
+type RSSFeed struct {
+	XMLName   xml.Name `xml:"rss"`
+	Version   string   `xml:"version,attr"`
+	XmlnsAtom string   `xml:"xmlns:atom,attr"`
+
+	Channel RSSChannel `xml:"channel"`
+}
+
+type RSSGenerator struct {
+	logger *zap.Logger
+}
+
+func NewRSSGenerator(logger zap.Logger) *RSSGenerator {
+	return &RSSGenerator{logger: &logger}
+}
+
+func (r *RSSGenerator) GenerateFeed(items []tg.MessageClass, channelId string) *RSSFeed {
+	rssChannel := &RSSChannel{
+		Title: "Recent posts from @" + channelId,
+		Link:  "https://t.me/" + channelId,
+		Description: "This feed contains the most recent posts from the Telegram channel @" + channelId + ". " +
+			"Stay updated with the latest news and updates from the channel.",
+		PubDate:       time.Now().Format("Mon, 02 Jan 2006 15:04 MST"),
+		LastBuildDate: time.Now().Format("Mon, 02 Jan 2006 15:04 MST"),
+		Generator:     "Telegram RSS Generator",
+	}
+	for _, m := range items {
+		rssChannel.Items = append(rssChannel.Items, *r.messageToItem(m, channelId))
+	}
+	return &RSSFeed{
+		Version:   "2.0",
+		XmlnsAtom: "http://www.w3.org/2005/Atom",
+		Channel:   *rssChannel,
+	}
+}
+
+func (r *RSSGenerator) messageToItem(msg tg.MessageClass, channelId string) *RSSItem {
+	return &RSSItem{
+		Title:       "Post by @" + channelId + " on Telegram",
+		Link:        "https://t.me/" + channelId + "/" + strconv.Itoa(msg.GetID()), // TODO: URL parse it
+		PubDate:     time.Unix(int64(msg.(*tg.Message).Date), 0).Format("Mon, 02 Jan 2006 15:04 MST"),
+		Description: msg.(*tg.Message).Message,
+		Guid:        "https://t.me/" + channelId + "/" + strconv.Itoa(msg.GetID()),
+	}
+}