Fetch Stacker News RSS feed and post to TG

.vscode/launch.json

@@ -0,0 +1,15 @@
+{
+  // Use IntelliSense to learn about possible attributes.
+  // Hover to view descriptions of existing attributes.
+  // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+  "version": "0.2.0",
+  "configurations": [
+    {
+      "name": "sn-rss-to-tg",
+      "type": "go",
+      "request": "launch",
+      "mode": "debug",
+      "program": "."
+    }
+  ]
+}

go.mod

@@ -3,6 +3,7 @@ module gitlab.com/ekzyis/stackernews_rss-to-tg
 go 1.20
 
 require (
+	github.com/dustin/go-humanize v1.0.1 // indirect
 	github.com/joho/godotenv v1.5.1 // indirect
 	github.com/namsral/flag v1.7.4-pre // indirect
 )

go.sum

@@ -1,3 +1,5 @@
+github.com/dustin/go-humanize v1.0.1 h1:GzkhY7T5VNhEkwH0PVJgjz+fX1rhBrR7pRT3mDkpeCY=
+github.com/dustin/go-humanize v1.0.1/go.mod h1:Mu1zIs6XwVuF/gI1OepvI0qD18qycQx+mFykh5fBlto=
 github.com/joho/godotenv v1.5.1 h1:7eLL/+HRGLY0ldzfGMeQkb7vMd0as4CfYvUVzLqw0N0=
 github.com/joho/godotenv v1.5.1/go.mod h1:f4LDr5Voq0i2e/R5DDNOoa2zzDfwtkZa6DnEwAbqwq4=
 github.com/namsral/flag v1.7.4-pre h1:b2ScHhoCUkbsq0d2C15Mv+VU8bl8hAXV8arnWiOHNZs=

main.go

@@ -1,4 +1,53 @@
 package main
 
-func main() {
+import (
+	"log"
+	"time"
+)
+
+func WaitUntilNextUpdate() {
+	now := time.Now()
+	dur := now.Truncate(time.Hour).Add(time.Hour).Sub(now)
+	log.Println("sleeping for", dur.Round(time.Second))
+	time.Sleep(dur)
+}
+
+func contains(rss *Rss, a Item) bool {
+	if rss == nil {
+		return false
+	}
+	for _, x := range rss.Channel.Items {
+		if x.Title == a.Title {
+			return true
+		}
+	}
+	return false
+}
+
+func main() {
+	var oldRss *Rss
+	for {
+		rss, err := FetchStackerNewsRssFeed()
+		if err != nil {
+			log.Println(err)
+			WaitUntilNextUpdate()
+			continue
+		}
+
+		for _, item := range rss.Channel.Items {
+			// TODO: We ignore errors during sending items to telegram.
+			//   This means these items will be missed since they will be skipped in the next run
+			if contains(oldRss, item) {
+				continue
+			}
+			err := SendItemToTelegram(&item)
+			if err != nil {
+				log.Println(err)
+				continue
+			}
+		}
+
+		oldRss = rss
+		WaitUntilNextUpdate()
+	}
 }

rss.go

@@ -0,0 +1,69 @@
+package main
+
+import (
+	"encoding/xml"
+	"fmt"
+	"log"
+	"net/http"
+	"time"
+)
+
+type Item struct {
+	Guid        string  `xml:"guid"`
+	Title       string  `xml:"title"`
+	Link        string  `xml:"link"`
+	Description string  `xml:"description"`
+	PubDate     RssDate `xml:"pubDate"`
+}
+
+type Channel struct {
+	Title         string  `xml:"title"`
+	Description   string  `xml:"description"`
+	Link          string  `xml:"link"`
+	Items         []Item  `xml:"item"`
+	LastBuildDate RssDate `xml:"lastBuildDate"`
+}
+
+type Rss struct {
+	Channel Channel `xml:"channel"`
+}
+
+type RssDate struct {
+	time.Time
+}
+
+func (c *RssDate) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
+	var v string
+	dateFormat := "Mon, 02 Jan 2006 15:04:05 GMT"
+	d.DecodeElement(&v, &start)
+	parse, err := time.Parse(dateFormat, v)
+	if err != nil {
+		return err
+	}
+	*c = RssDate{parse}
+	return nil
+}
+
+var (
+	StackerNewsRssFeedUrl = "https://stacker.news/rss"
+)
+
+func FetchStackerNewsRssFeed() (*Rss, error) {
+	resp, err := http.Get(StackerNewsRssFeedUrl)
+	if err != nil {
+		err = fmt.Errorf("error fetching RSS feed: %w\n", err)
+		log.Println(err)
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	var rss Rss
+	err = xml.NewDecoder(resp.Body).Decode(&rss)
+	if err != nil {
+		err = fmt.Errorf("error decoding RSS feed XML: %w\n", err)
+		return nil, err
+	}
+
+	return &rss, nil
+
+}

tg.go

@@ -4,7 +4,9 @@ import (
 	"fmt"
 	"log"
 	"net/http"
+	"net/url"
 
+	"github.com/dustin/go-humanize"
 	"github.com/joho/godotenv"
 	"github.com/namsral/flag"
 )
@@ -30,14 +32,24 @@ func init() {
 	}
 }
 
-func SendTextToTelegram(text string) {
-	url := fmt.Sprintf("https://api.telegram.org/bot%s/sendMessage?chat_id=%d&text=%s", BotToken, ChatId, text)
+func SendItemToTelegram(item *Item) error {
+	text := fmt.Sprintf("%s (%s)\n", item.Title, humanize.Time(item.PubDate.Time))
+	linkItem := item.Link != item.Guid
+	if linkItem {
+		text += fmt.Sprintf("[Link](%s) ", item.Link)
+	}
+	text += fmt.Sprintf("[Comments](%s)", item.Guid)
+	return SendTextToTelegram(text)
+}
+
+func SendTextToTelegram(text string) error {
+	url := fmt.Sprintf("https://api.telegram.org/bot%s/sendMessage?parse_mode=markdown&disable_web_page_preview=true&chat_id=%d&text=%s", BotToken, ChatId, url.QueryEscape(text))
 	resp, err := http.Get(url)
 	if err != nil {
 		err = fmt.Errorf("error during GET %s: %w", url, err)
-		log.Println(err)
-		return
+		return err
 	}
 	defer resp.Body.Close()
 	log.Printf("GET %s: %d\n", url, resp.StatusCode)
+	return nil
 }