feat: add BaseURL config, RSS image enclosure, and separate rate limiters

- Load and validate BASE_URL, store in Config
- RSSGenerator now receives Config; adds <enclosure> for photo messages using BaseURL
- RateLimiter tracks feed and image limiters; provide FeedRateLimit and ImageRateLimit middleware
- Update routes to use the new middlewares and inject Config into RSSGenerator

internal/rss/generator.go

@@ -2,9 +2,11 @@ package rss
 
 import (
 	"encoding/xml"
+	"errors"
 	"fmt"
 	"net/url"
 	"strconv"
+	"tgss/internal/config"
 	"time"
 
 	"github.com/gotd/td/tg"
@@ -12,11 +14,18 @@ import (
 )
 
 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"`
+	Title       string        `xml:"title"`
+	Link        string        `xml:"link"`
+	Enclosure   *RSSEnclosure `xml:"enclosure,omitempty"`
+	PubDate     string        `xml:"pubDate,omitempty"`
+	Description string        `xml:"description"`
+	Guid        string        `xml:"guid,omitempty"`
+}
+
+type RSSEnclosure struct {
+	URL    string `xml:"url,attr"`
+	Length string `xml:"lenghth,omitempty,attr"`
+	Type   string `xml:"type,attr"`
 }
 
 type RSSChannel struct {
@@ -40,10 +49,11 @@ type RSSFeed struct {
 
 type RSSGenerator struct {
 	logger *zap.Logger
+	config *config.Config
 }
 
-func NewRSSGenerator(logger *zap.Logger) *RSSGenerator {
-	return &RSSGenerator{logger: logger}
+func NewRSSGenerator(logger *zap.Logger, config *config.Config) *RSSGenerator {
+	return &RSSGenerator{logger: logger, config: config}
 }
 
 func (r *RSSGenerator) GenerateFeed(items []tg.MessageClass, channelId string) *RSSFeed {
@@ -85,6 +95,7 @@ func (r *RSSGenerator) GenerateFeed(items []tg.MessageClass, channelId string) *
 		rssChannel.Items = append(rssChannel.Items, *item)
 	}
 
+	// Logging is done by AI
 	if errorCount > 0 {
 		r.logger.Warn("feed generation completed with errors",
 			zap.String("channel", channelId),
@@ -115,13 +126,37 @@ func (r *RSSGenerator) messageToItem(msg tg.MessageClass, channelId string) (*RS
 		description = "No content"
 	}
 
-	return &RSSItem{
+	rssItem := &RSSItem{
 		Title:       "Post by @" + channelId + " on Telegram",
 		Link:        messageURL.String(),
 		PubDate:     time.Unix(int64(message.Date), 0).Format("Mon, 02 Jan 2006 15:04 MST"),
 		Description: description,
 		Guid:        messageURL.String(),
-	}, nil
+	}
+
+	if err = r.messageHasPhoto(message); err == nil {
+		if enclosureURL, err := url.ParseRequestURI(r.config.BaseURL + "/image/" + channelId + "/" + strconv.Itoa(msg.GetID())); err == nil {
+			rssItem.Enclosure = &RSSEnclosure{
+				URL:    enclosureURL.String(),
+				Length: "0",
+				Type:   "image/jpeg",
+			}
+		}
+	}
+
+	return rssItem, nil
 }
 
-// TODO: add a hasPhoto helper to add the rss tag accordingly
+func (r *RSSGenerator) messageHasPhoto(message tg.MessageClass) error {
+	media, ok := message.(*tg.Message).Media.(*tg.MessageMediaPhoto)
+	if !ok {
+		return errors.New("the message does not contain a photo media object")
+	}
+
+	_, ok = media.Photo.(*tg.Photo)
+	if !ok {
+		return errors.New("the message media has no photo payload")
+	}
+
+	return nil
+}