1 files changed, 71 insertions, 0 deletions
diff --git a/app/src/main/java/org/terst/feedreader/opml/Opml.kt b/app/src/main/java/org/terst/feedreader/opml/Opml.kt
new file mode 100644
index 0000000..65510fb
--- /dev/null
+++ b/app/src/main/java/org/terst/feedreader/opml/Opml.kt
@@ -0,0 +1,71 @@
+package org.terst.feedreader.opml
+
+import android.util.Xml
+import org.terst.feedreader.data.FeedEntity
+import org.xmlpull.v1.XmlPullParser
+import java.io.InputStream
+import java.io.OutputStream
+
+data class OpmlFeed(val title: String, val xmlUrl: String, val htmlUrl: String?)
+
+/**
+ * OPML import/export. Any folder nesting (<outline> containing other
+ * <outline> elements instead of an xmlUrl) is flattened -- this app has no
+ * folder concept, per the "simple design" scope, so a folder's contents
+ * are just imported as a flat list of feeds.
+ */
+object Opml {
+
+    fun parse(input: InputStream): List<OpmlFeed> {
+        val parser = Xml.newPullParser()
+        parser.setFeature(XmlPullParser.FEATURE_PROCESS_NAMESPACES, false)
+        parser.setInput(input, null)
+
+        val feeds = mutableListOf<OpmlFeed>()
+        var eventType = parser.eventType
+        while (eventType != XmlPullParser.END_DOCUMENT) {
+            if (eventType == XmlPullParser.START_TAG && parser.name.equals("outline", ignoreCase = true)) {
+                val xmlUrl = parser.getAttributeValue(null, "xmlUrl")
+                if (xmlUrl != null) {
+                    val title = parser.getAttributeValue(null, "title")
+                        ?: parser.getAttributeValue(null, "text")
+                        ?: xmlUrl
+                    val htmlUrl = parser.getAttributeValue(null, "htmlUrl")
+                    feeds += OpmlFeed(title, xmlUrl, htmlUrl)
+                }
+            }
+            eventType = parser.next()
+        }
+        return feeds
+    }
+
+    fun write(feeds: List<FeedEntity>, output: OutputStream) {
+        val serializer = Xml.newSerializer()
+        serializer.setOutput(output, "UTF-8")
+        serializer.startDocument("UTF-8", true)
+        serializer.startTag(null, "opml")
+        serializer.attribute(null, "version", "2.0")
+
+        serializer.startTag(null, "head")
+        serializer.startTag(null, "title")
+        serializer.text("Feeds subscriptions")
+        serializer.endTag(null, "title")
+        serializer.endTag(null, "head")
+
+        serializer.startTag(null, "body")
+        for (feed in feeds) {
+            serializer.startTag(null, "outline")
+            serializer.attribute(null, "text", feed.title)
+            serializer.attribute(null, "title", feed.title)
+            serializer.attribute(null, "type", "rss")
+            serializer.attribute(null, "xmlUrl", feed.id)
+            feed.siteUrl?.let { serializer.attribute(null, "htmlUrl", it) }
+            serializer.endTag(null, "outline")
+        }
+        serializer.endTag(null, "body")
+
+        serializer.endTag(null, "opml")
+        serializer.endDocument()
+        serializer.flush()
+    }
+}