Add SPC provider parsing helpers

internal/providers/spc/rss.go

@@ -0,0 +1,81 @@
+package spc
+
+import (
+	"encoding/xml"
+	"fmt"
+	"strings"
+	"time"
+)
+
+// RSSFeed is a minimal view of the optional SPC RSS feed.
+type RSSFeed struct {
+	Title         string
+	Link          string
+	Description   string
+	LastBuildDate *time.Time
+	Items         []RSSItem
+}
+
+// RSSItem is a minimal view of one optional SPC RSS item.
+type RSSItem struct {
+	Title       string
+	Link        string
+	Description string
+	PubDate     string
+	GUID        string
+}
+
+// ParseRSSFeed decodes supplemental SPC RSS metadata.
+func ParseRSSFeed(raw string) (RSSFeed, error) {
+	var doc struct {
+		Channel struct {
+			Title         string `xml:"title"`
+			Link          string `xml:"link"`
+			Description   string `xml:"description"`
+			LastBuildDate string `xml:"lastBuildDate"`
+			Items         []struct {
+				Title       string `xml:"title"`
+				Link        string `xml:"link"`
+				Description string `xml:"description"`
+				PubDate     string `xml:"pubDate"`
+				GUID        string `xml:"guid"`
+			} `xml:"item"`
+		} `xml:"channel"`
+	}
+	if err := xml.Unmarshal([]byte(raw), &doc); err != nil {
+		return RSSFeed{}, fmt.Errorf("decode rss: %w", err)
+	}
+
+	feed := RSSFeed{
+		Title:         strings.TrimSpace(doc.Channel.Title),
+		Link:          strings.TrimSpace(doc.Channel.Link),
+		Description:   strings.TrimSpace(doc.Channel.Description),
+		LastBuildDate: parseRSSDate(doc.Channel.LastBuildDate),
+		Items:         make([]RSSItem, 0, len(doc.Channel.Items)),
+	}
+	for _, item := range doc.Channel.Items {
+		feed.Items = append(feed.Items, RSSItem{
+			Title:       strings.TrimSpace(item.Title),
+			Link:        strings.TrimSpace(item.Link),
+			Description: strings.TrimSpace(item.Description),
+			PubDate:     strings.TrimSpace(item.PubDate),
+			GUID:        strings.TrimSpace(item.GUID),
+		})
+	}
+	return feed, nil
+}
+
+func parseRSSDate(value string) *time.Time {
+	value = strings.TrimSpace(value)
+	if value == "" {
+		return nil
+	}
+	for _, layout := range []string{time.RFC1123Z, time.RFC1123} {
+		t, err := time.Parse(layout, value)
+		if err == nil {
+			tt := t.UTC()
+			return &tt
+		}
+	}
+	return nil
+}