Add Plugin Update Checker

LavalinkServer/build.gradle.kts

@@ -65,6 +65,7 @@ dependencies {
     implementation(libs.kotlin.reflect)
     implementation(libs.logback)
     implementation(libs.sentry.logback)
+    implementation(libs.semver)
     implementation(libs.oshi) {
         // This version of SLF4J does not recognise Logback 1.2.3
         exclude(group = "org.slf4j", module = "slf4j-api")

LavalinkServer/src/main/java/lavalink/server/bootstrap/PluginManager.kt

@@ -9,9 +9,11 @@ import java.io.FileOutputStream
 import java.io.InputStream
 import java.net.URL
 import java.net.URLClassLoader
+import java.net.HttpURLConnection
 import java.nio.channels.Channels
 import java.util.*
 import java.util.jar.JarFile
+import io.github.z4kn4fein.semver.toVersion
 
 @SpringBootApplication
 class PluginManager(val config: PluginsConfig) {
@@ -83,6 +85,37 @@ class PluginManager(val config: PluginsConfig) {
                 val file = File(directory, declaration.canonicalJarName)
                 downloadJar(file, url)
             }
+
+            checkPluginForUpdates(declaration)
+        }
+    }
+
+    private fun checkPluginForUpdates(declaration: Declaration) {
+        val splitPath = declaration.url.split('/')
+
+        val baseSplitPath = splitPath.dropLast(2)
+        val basePath = baseSplitPath.joinToString("/") + "/maven-metadata.xml"
+
+        val connection = URL(basePath).openConnection() as HttpURLConnection
+        connection.inputStream.bufferedReader().use {
+            val lines = it.readLines()
+            for (line in lines) {
+                val regex = "<latest>(.*?)</latest>".toRegex()
+                val match = regex.find(line)
+                val latest = match?.groups?.get(1)?.value
+                if (latest != null) {
+                    val latestVersion = latest.toVersion()
+                    val currentVersion = declaration.version.toVersion()
+
+                    if(latestVersion > currentVersion) {
+                        log.warn("A newer version of ${declaration.name} was found: $latestVersion. " +
+                                "The current version is $currentVersion.")
+                    } else {
+                        log.info("Plugin ${declaration.name} is up to date")
+                    }
+                    break
+                }
+            }
         }
     }
 

settings.gradle.kts

@@ -76,6 +76,7 @@ fun VersionCatalogBuilder.common() {
     library("logback",        "ch.qos.logback",       "logback-classic").version("1.5.6")
     library("sentry-logback", "io.sentry",            "sentry-logback").version("7.10.0")
     library("oshi",           "com.github.oshi",      "oshi-core").version("6.4.11")
+    library("semver",         "io.github.z4kn4fein",  "semver").version("2.0.0")
 }
 
 fun VersionCatalogBuilder.other() {