1 files changed, 82 insertions, 0 deletions
diff --git a/modules/sitemap/sitemap.go b/modules/sitemap/sitemap.go
new file mode 100644
index 0000000..280ca1d
--- /dev/null
+++ b/modules/sitemap/sitemap.go
@@ -0,0 +1,82 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package sitemap
+
+import (
+	"bytes"
+	"encoding/xml"
+	"fmt"
+	"io"
+	"time"
+)
+
+const (
+	sitemapFileLimit = 50 * 1024 * 1024 // the maximum size of a sitemap file
+	urlsLimit        = 50000
+
+	schemaURL        = "http://www.sitemaps.org/schemas/sitemap/0.9"
+	urlsetName       = "urlset"
+	sitemapindexName = "sitemapindex"
+)
+
+// URL represents a single sitemap entry
+type URL struct {
+	URL     string     `xml:"loc"`
+	LastMod *time.Time `xml:"lastmod,omitempty"`
+}
+
+// Sitemap represents a sitemap
+type Sitemap struct {
+	XMLName   xml.Name
+	Namespace string `xml:"xmlns,attr"`
+
+	URLs     []URL `xml:"url"`
+	Sitemaps []URL `xml:"sitemap"`
+}
+
+// NewSitemap creates a sitemap
+func NewSitemap() *Sitemap {
+	return &Sitemap{
+		XMLName:   xml.Name{Local: urlsetName},
+		Namespace: schemaURL,
+	}
+}
+
+// NewSitemapIndex creates a sitemap index.
+func NewSitemapIndex() *Sitemap {
+	return &Sitemap{
+		XMLName:   xml.Name{Local: sitemapindexName},
+		Namespace: schemaURL,
+	}
+}
+
+// Add adds a URL to the sitemap
+func (s *Sitemap) Add(u URL) {
+	if s.XMLName.Local == sitemapindexName {
+		s.Sitemaps = append(s.Sitemaps, u)
+	} else {
+		s.URLs = append(s.URLs, u)
+	}
+}
+
+// WriteTo writes the sitemap to a response
+func (s *Sitemap) WriteTo(w io.Writer) (int64, error) {
+	if l := len(s.URLs); l > urlsLimit {
+		return 0, fmt.Errorf("The sitemap contains %d URLs, but only %d are allowed", l, urlsLimit)
+	}
+	if l := len(s.Sitemaps); l > urlsLimit {
+		return 0, fmt.Errorf("The sitemap contains %d sub-sitemaps, but only %d are allowed", l, urlsLimit)
+	}
+	buf := bytes.NewBufferString(xml.Header)
+	if err := xml.NewEncoder(buf).Encode(s); err != nil {
+		return 0, err
+	}
+	if err := buf.WriteByte('\n'); err != nil {
+		return 0, err
+	}
+	if buf.Len() > sitemapFileLimit {
+		return 0, fmt.Errorf("The sitemap has %d bytes, but only %d are allowed", buf.Len(), sitemapFileLimit)
+	}
+	return buf.WriteTo(w)
+}