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

cmd/server/main.go

@@ -4,6 +4,7 @@ import (
 	"tgss/internal/config"
 	"tgss/internal/handlers"
 	"tgss/internal/infra"
+	"tgss/internal/rss"
 	"tgss/internal/server"
 	"tgss/internal/telegram"
 
@@ -19,6 +20,8 @@ func main() {
 
 			handlers.NewChannelHandler,
 			handlers.NewAuthHandler,
+
+			rss.NewRSSGenerator,
 		),
 		telegram.Module,
 		fx.Invoke(server.RegisterRoutes),

internal/handlers/channel_handler.go

@@ -3,6 +3,7 @@ package handlers
 import (
 	"context"
 	"strconv"
+	"tgss/internal/rss"
 	"tgss/internal/telegram"
 	"time"
 
@@ -13,6 +14,7 @@ import (
 type ChannelHandler struct {
 	logger    *zap.Logger
 	tgService *telegram.Service
+	rss       *rss.RSSGenerator
 }
 
 func NewChannelHandler(
@@ -25,7 +27,7 @@ func NewChannelHandler(
 	}
 }
 
-func (ch *ChannelHandler) GetLatestMessages(c *gin.Context) {
+func (ch *ChannelHandler) GetMessagesJson(c *gin.Context) {
 	channelId := c.Param("id")
 	limit := 5
 
@@ -51,3 +53,32 @@ func (ch *ChannelHandler) GetLatestMessages(c *gin.Context) {
 
 	c.JSON(200, messages)
 }
+
+func (ch *ChannelHandler) GetMessagesRSS(c *gin.Context) {
+	channelId := c.Param("id")
+	limit := 5
+
+	if limitStr := c.Query("limit"); limitStr != "" {
+		var err error
+		limit, err = strconv.Atoi(limitStr)
+		if err != nil || limit > 50 {
+			ch.logger.Warn("Invalid limit value provided", zap.String("limit", limitStr))
+			c.JSON(400, gin.H{"error": "Limit value provided is invalid or bigger than 50"})
+			return
+		}
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+
+	messages, err := ch.tgService.LastMessages(ctx, channelId, limit)
+	if err != nil {
+		ch.logger.Error("Error getting channel messages:", zap.Error(err))
+		c.JSON(500, gin.H{"error": "Unable to get channel messages"})
+		return
+	}
+
+	rssFeed := ch.rss.GenerateFeed(messages, channelId)
+
+	c.XML(200, rssFeed)
+}

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()),
+	}
+}

internal/server/http.go

@@ -41,7 +41,8 @@ func RegisterRoutes(params RouterParams) {
 				})
 			})
 
-			params.GinEngine.GET("/channel/:id", params.ChannelHandler.GetLatestMessages)
+			// params.GinEngine.GET("/channel/:id/json", params.ChannelHandler.GetMessagesJson)
+			params.GinEngine.GET("/channel/:id", params.ChannelHandler.GetMessagesRSS)
 
 			params.GinEngine.POST("/auth/send-code", params.AuthHandler.SendCode)
 			params.GinEngine.POST("/auth/verify", params.AuthHandler.Verify)