1 files changed, 58 insertions, 0 deletions
diff --git a/reader/opml/serializer.go b/reader/opml/serializer.go
new file mode 100644
index 0000000..20c7046
--- /dev/null
+++ b/reader/opml/serializer.go
@@ -0,0 +1,58 @@
+// Copyright 2017 Frédéric Guillot. All rights reserved.
+// Use of this source code is governed by the Apache 2.0
+// license that can be found in the LICENSE file.
+
+package opml
+
+import (
+	"bufio"
+	"bytes"
+	"encoding/xml"
+	"log"
+)
+
+func Serialize(subscriptions SubcriptionList) string {
+	var b bytes.Buffer
+	writer := bufio.NewWriter(&b)
+	writer.WriteString(xml.Header)
+
+	opml := new(Opml)
+	opml.Version = "2.0"
+	for categoryName, subs := range groupSubscriptionsByFeed(subscriptions) {
+		outline := Outline{Text: categoryName}
+
+		for _, subscription := range subs {
+			outline.Outlines = append(outline.Outlines, Outline{
+				Title:   subscription.Title,
+				Text:    subscription.Title,
+				FeedURL: subscription.FeedURL,
+				SiteURL: subscription.SiteURL,
+			})
+		}
+
+		opml.Outlines = append(opml.Outlines, outline)
+	}
+
+	encoder := xml.NewEncoder(writer)
+	encoder.Indent("  ", "    ")
+	if err := encoder.Encode(opml); err != nil {
+		log.Println(err)
+		return ""
+	}
+
+	return b.String()
+}
+
+func groupSubscriptionsByFeed(subscriptions SubcriptionList) map[string]SubcriptionList {
+	groups := make(map[string]SubcriptionList)
+
+	for _, subscription := range subscriptions {
+		// if subs, ok := groups[subscription.CategoryName]; !ok {
+		// groups[subscription.CategoryName] = SubcriptionList{}
+		// }
+
+		groups[subscription.CategoryName] = append(groups[subscription.CategoryName], subscription)
+	}
+
+	return groups
+}