generator: isolate Atom feed in atom subpackage, document boundaries

Move Atom 1.0 XML generation to internal/generator/atom so it depends only
on config and post, not on themes or the HTML template pipeline.

Add generator/doc.go mapping files (orchestration, registry, themes, shared
nav templates) and dependency direction.

Made-with: Cursor

1 files changed, 106 insertions, 0 deletions

diff --git a/internal/generator/atom/atom.go b/internal/generator/atom/atom.go
new file mode 100644
index 0000000..f57ad0d
--- /dev/null
+++ b/internal/generator/atom/atom.go
@@ -0,0 +1,106 @@
+// Package atom serializes the site Atom 1.0 feed (atom.xml). It depends only on
+// internal/config and internal/post. It does not import HTML themes, shared nav
+// templates, or the html/template page pipeline — those live in the parent
+// generator package.
+package atom
+
+import (
+	"encoding/xml"
+	"fmt"
+	"os"
+	"path/filepath"
+	"time"
+
+	"codeberg.org/snonux/snonux/internal/config"
+	"codeberg.org/snonux/snonux/internal/post"
+)
+
+// feed is the root element of an Atom 1.0 feed document.
+type feed struct {
+	XMLName xml.Name `xml:"feed"`
+	XMLNS   string   `xml:"xmlns,attr"`
+	Title   string   `xml:"title"`
+	Link    link     `xml:"link"`
+	Updated string   `xml:"updated"`
+	ID      string   `xml:"id"`
+	Entries []entry  `xml:"entry"`
+}
+
+type link struct {
+	Href string `xml:"href,attr"`
+	Rel  string `xml:"rel,attr,omitempty"`
+}
+
+type entry struct {
+	Title   string  `xml:"title"`
+	Link    link    `xml:"link"`
+	ID      string  `xml:"id"`
+	Updated string  `xml:"updated"`
+	Content content `xml:"content"`
+}
+
+type content struct {
+	Type  string `xml:"type,attr"`
+	Value string `xml:",chardata"`
+}
+
+// Generate writes atom.xml to cfg.OutputDir containing the most recent
+// min(len(posts), config.PostsPerPage) entries. Posts must already be sorted
+// newest-first (as produced by generator.Run).
+func Generate(posts []*post.Post, cfg *config.Config) error {
+	limit := config.PostsPerPage
+	if len(posts) < limit {
+		limit = len(posts)
+	}
+
+	recent := posts[:limit]
+	entries := buildEntries(recent, cfg.BaseURL)
+
+	updated := time.Now().UTC().Format(time.RFC3339)
+	if len(recent) > 0 {
+		updated = recent[0].Timestamp.UTC().Format(time.RFC3339)
+	}
+
+	f := feed{
+		XMLNS:   "http://www.w3.org/2005/Atom",
+		Title:   "snonux.foo",
+		Link:    link{Href: cfg.BaseURL + "/"},
+		Updated: updated,
+		ID:      cfg.BaseURL + "/",
+		Entries: entries,
+	}
+
+	return writeFile(f, filepath.Join(cfg.OutputDir, "atom.xml"))
+}
+
+func buildEntries(posts []*post.Post, baseURL string) []entry {
+	entries := make([]entry, 0, len(posts))
+
+	for _, p := range posts {
+		entryURL := fmt.Sprintf("%s/posts/%s/", baseURL, p.ID)
+		entries = append(entries, entry{
+			Title:   fmt.Sprintf("Post %s", p.ID),
+			Link:    link{Href: entryURL, Rel: "alternate"},
+			ID:      entryURL,
+			Updated: p.Timestamp.UTC().Format(time.RFC3339),
+			Content: content{Type: "html", Value: p.Content},
+		})
+	}
+
+	return entries
+}
+
+func writeFile(f feed, path string) error {
+	data, err := xml.MarshalIndent(f, "", "  ")
+	if err != nil {
+		return fmt.Errorf("marshal atom feed: %w", err)
+	}
+
+	content := append([]byte(xml.Header), data...)
+
+	if err := os.WriteFile(path, content, 0o644); err != nil {
+		return fmt.Errorf("write atom.xml: %w", err)
+	}
+
+	return nil
+}