add rss feed #9

src/internal/app/app.go

@@ -9,12 +9,14 @@ import (
 type App struct {
 	articles   *database.ArticleRepository
 	articleVMs *database.ArticleViewModelRepository
+	rssItems   *database.RSSItemRepository
 }
 
 func NewApp(db *sql.DB) *App {
 	return &App{
 		articles:   &database.ArticleRepository{DB: db},
 		articleVMs: &database.ArticleViewModelRepository{DB: db},
+		rssItems:   &database.RSSItemRepository{DB: db},
 	}
 }
 
@@ -22,6 +24,8 @@ func (app *App) Routes() http.Handler {
 	mux := http.NewServeMux()
 
 	// dynamic routes
+	mux.Handle("GET /rss.xml", http.HandlerFunc(app.RSS))
+
 	mux.Handle("GET /", http.HandlerFunc(app.Index))
 	mux.Handle("GET /page/{id}", http.HandlerFunc(app.Index))
 	mux.Handle("POST /up/search", http.HandlerFunc(app.UpSearch))

src/internal/app/rss.go

@@ -0,0 +1,28 @@
+package app
+
+import (
+	"crowsnest/internal/model"
+	"encoding/xml"
+	"net/http"
+)
+
+// List the latest articles using the base template.
+func (app *App) RSS(w http.ResponseWriter, req *http.Request) {
+	// set response headers
+	w.Header().Set("Content-Type", "application/rss+xml")
+	w.WriteHeader(http.StatusOK)
+
+	// get articles
+	feed, err := app.rssItems.All(30)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	// write RSS feed to response
+	encoder := xml.NewEncoder(w)
+	encoder.Indent("", "  ")
+	if err := encoder.Encode(model.RSSFeedFromItems(feed)); err != nil {
+		http.Error(w, "Error generating RSS feed", http.StatusInternalServerError)
+	}
+}

src/internal/model/database/rssitemrepository.go

@@ -0,0 +1,60 @@
+package database
+
+import (
+	"crowsnest/internal/model"
+	"database/sql"
+	"strconv"
+	"time"
+)
+
+type RSSItemRepository struct {
+	DB *sql.DB
+}
+
+// Gets all the article as view models objects from the database. This may throw
+// an error if the connection to the database fails.
+func (m *RSSItemRepository) All(limit int) ([]model.RSSItem, error) {
+	stmt := `
+        SELECT a.id, a.title, a.sourceUrl, a.publishDate, d.summary
+        FROM articles a JOIN documents d ON a.document_id = d.id
+        ORDER BY a.publishDate DESC
+		LIMIT $1
+    `
+	rows, err := m.DB.Query(stmt, limit)
+	if err != nil {
+		return nil, err
+	}
+
+	items := make([]model.RSSItem, 0, limit)
+	for rows.Next() {
+		i := model.RSSItem{}
+
+		var id int
+		var sourceUrl string
+		var date time.Time
+
+		err := rows.Scan(&id, &i.Title, &sourceUrl, &date, &i.Description)
+		if err != nil {
+			return nil, err
+		}
+
+		// description
+		if i.Description == "" {
+			i.Description = "N/A"
+		}
+		// format date
+		i.PubDate = date.Format(time.RFC1123Z)
+		// link
+		i.Link = "https://crowsnest.kohout-dev.de/article/" + strconv.Itoa(id)
+		// identifier
+		i.Guid = model.RSSGuid{IsPermaLink: "false", Value: strconv.Itoa(id)}
+
+		items = append(items, i)
+	}
+
+	if err = rows.Err(); err != nil {
+		return nil, err
+	}
+
+	return items, nil
+}

src/internal/model/rss.go

@@ -0,0 +1,51 @@
+package model
+
+import (
+	"encoding/xml"
+	"time"
+)
+
+// RSS represents the RSS feed structure.
+type RSSFeed struct {
+	XMLName xml.Name   `xml:"rss"`
+	Version string     `xml:"version,attr"`
+	Channel RSSChannel `xml:"channel"`
+}
+
+// Channel represents the channel element in the RSS feed.
+type RSSChannel struct {
+	Title       string    `xml:"title"`
+	Link        string    `xml:"link"`
+	Description string    `xml:"description"`
+	PubDate     string    `xml:"pubDate"`
+	Items       []RSSItem `xml:"item"`
+}
+
+// Item represents an individual item in the RSS feed.
+type RSSItem struct {
+	Title       string  `xml:"title"`
+	Link        string  `xml:"link"`
+	Description string  `xml:"description"`
+	Guid        RSSGuid `xml:"guid"`
+	PubDate     string  `xml:"pubDate"`
+}
+
+type RSSGuid struct {
+	IsPermaLink string `xml:"isPermaLink,attr,omitempty"`
+	Value       string `xml:",chardata"`
+}
+
+func RSSFeedFromItems(items []RSSItem) *RSSFeed {
+	rssChannel := RSSChannel{
+		Title:       "crowsnest",
+		Link:        "https://crowsnest.kohout-dev.de",
+		Description: "N/A",
+		PubDate:     time.Now().Format(time.RFC1123Z),
+		Items:       items,
+	}
+
+	return &RSSFeed{
+		Version: "2.0",
+		Channel: rssChannel,
+	}
+}