add blog RSS

src/main/kotlin/org/freenet/website/main.kt

@@ -18,6 +18,7 @@ import org.freenet.website.pages.developers.PivotalTracker
 import org.freenet.website.pages.developers.developersPage
 import org.freenet.website.pages.homePage
 import org.freenet.website.pages.faq.faqPage
+import org.freenet.website.util.BlogRssPlugin
 import org.freenet.website.util.HealthCheckPlugin
 import org.freenet.website.util.UrlToPathSegmentsRF
 import org.freenet.website.util.recordVisit
@@ -47,6 +48,7 @@ suspend fun main() {
         port = 8080,
         debug = isLocalTestingMode,
         plugins = listOf(
+            BlogRssPlugin(),
             HealthCheckPlugin,
             StaticFilesPlugin(ResourceFolder("static"), "/static",)
         ),
@@ -136,7 +138,14 @@ private fun HeadComponent.configureHead(title : KVal<String>) {
         meta["name"] = "viewport"
     }
 
-  //  element("script")["src"] = "https://js.stripe.com/v3/"
+    element("link") {
+        it["rel"] = "alternate"
+        it["type"] = "application/rss+xml"
+        it["title"] = "Freenet Blog RSS Feed"
+        it["href"] = "https://freenet.org/blog.rss"
+    }
+
+    //  element("script")["src"] = "https://js.stripe.com/v3/"
   //  element("script")["src"] = "/static/checkout.js"
 }
 

src/main/kotlin/org/freenet/website/pages/blog/blogPage.kt

@@ -26,7 +26,7 @@ fun Component.blogPage(number: Int? = null) {
                     h3 { it.text("Loading, please refresh page.") }
                 } else {
                     discussions.discussions.forEach { discussion ->
-                        a(href = "/blog/${discussion.number}/${formatForUrl(discussion.title)}.html") {
+                        a(href = discussion.freenetUrlPath) {
                             it["style"] = "color: #000000;"
                             div {
                                 it.classes("box")
@@ -69,7 +69,7 @@ fun Component.blogPage(number: Int? = null) {
     }
 }
 
-private fun formatForUrl(title: String): String {
+fun formatForUrl(title: String): String {
     return title.lowercase(Locale.getDefault())
         .replace(Regex("\\s"), "-")
         .replace(Regex("[^a-z0-9-]"), "")

src/main/kotlin/org/freenet/website/pages/blog/github.kt

@@ -27,15 +27,22 @@ object GitHubDiscussions {
 
     @Volatile var discussions: DiscussionStore? = null
 
-    data class DiscussionStore(val discussions : List<Discussion>) {
+    data class DiscussionStore(val discussions : List<Discussion>, val generated : Instant = Instant.now()) {
         val discussionsByNumber = discussions.associateBy { it.number }
     }
 
     init {
         scope.launch(Dispatchers.IO) {
             while(true) {
                 logger.info { "Retrieving discussions from GitHub" }
-                discussions = DiscussionStore(getDiscussions())
+                val newDiscussions = getDiscussions()
+                val curDiscussions = discussions
+                if (curDiscussions != null && newDiscussions == curDiscussions.discussions) {
+                    logger.debug { "Discussions unchanged" }
+                } else {
+                    logger.info { "Discussions updated" }
+                    discussions = DiscussionStore(newDiscussions)
+                }
                 logger.info { "Github discussions retrieved" }
                 delay(Duration.ofHours(1))
             }
@@ -130,7 +137,11 @@ object GitHubDiscussions {
         val url: String,
         val createdAt: Instant,
         val bodyHTML: String,
-    )
+    ) {
+        val freenetUrlPath : String by lazy {
+            "/blog/${number}/${formatForUrl(title)}.html"
+        }
+    }
 
     @Serializable
     data class GraphQLRequest(

src/main/kotlin/org/freenet/website/util/BlogRssPlugin.kt

@@ -0,0 +1,77 @@
+package org.freenet.website.util
+
+import io.ktor.http.*
+import io.ktor.http.HttpStatusCode.Companion.OK
+import io.ktor.server.application.*
+import io.ktor.server.response.*
+import io.ktor.server.routing.*
+import kweb.plugins.KwebPlugin
+import org.freenet.website.pages.blog.GitHubDiscussions
+import java.time.Instant
+
+class BlogRssPlugin : KwebPlugin() {
+    data class CachedRSS(val rss: String, val generated: Instant)
+
+    @Volatile var cachedRss: CachedRSS? = null
+
+    private fun getRss(): CachedRSS {
+        val discussionsGenerated = GitHubDiscussions.discussions?.generated ?: Instant.now()
+        val cached = cachedRss
+        if (cached == null || cached.generated.isBefore(discussionsGenerated)) {
+            val generatedRss = generateRss()
+            cachedRss = CachedRSS(generatedRss, discussionsGenerated)
+        }
+        return cachedRss!!
+    }
+
+    private fun generateRss() : String {
+        val rss = StringBuilder()
+        rss.append("""
+<?xml version="1.0" encoding="UTF-8"?>
+<rss version="2.0">
+    <channel>
+        <title>Freenet Blog</title>
+        <link>https://freenet.org/blog</link>
+        <description>News and updates from the Freenet Project</description>
+        <language>en-us</language>
+        <ttl>1440</ttl>
+        """.trimIndent())
+        val discussions = GitHubDiscussions.discussions
+        if (discussions != null) {
+            for (blog in discussions.discussions.take(20)) {
+                rss.append(
+                    """
+        <item>
+            <title>${blog.title}</title>
+            <link>https://freenet.org/blog/${blog.number}/${blog.title}</link>
+            <pubDate>${blog.createdAt}</pubDate>
+        </item> """.trimIndent()
+                )
+            }
+        }
+        rss.append("""
+   </channel>
+</rss>
+        """.trimIndent())
+
+        return rss.toString()
+    }
+
+    override fun appServerConfigurator(routeHandler: Routing) {
+        routeHandler.get("/blog.rss") {
+            val rssCache = getRss()
+            val etag = rssCache.generated.hashCode().toString()
+            val etagHeader = call.request.headers[HttpHeaders.IfNoneMatch]
+            if (etagHeader == etag) {
+                call.respond(HttpStatusCode.NotModified)
+            } else {
+                call.response.header(HttpHeaders.ETag, etag)
+                call.respondText(
+                    text = rssCache.rss,
+                    contentType = ContentType.Application.Xml,
+                    status = OK
+                )
+            }
+        }
+    }
+}