Add Plugin Update Checker

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

@@ -9,9 +9,12 @@ 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 javax.xml.parsers.DocumentBuilderFactory
+import dev.arbjerg.lavalink.protocol.v4.Version
 
 @SpringBootApplication
 class PluginManager(val config: PluginsConfig) {
@@ -83,6 +86,34 @@ 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 documentBuilder = DocumentBuilderFactory.newInstance().newDocumentBuilder()
+        val document = documentBuilder.parse(basePath)
+
+        var elements = document.getElementsByTagName("latest")
+        if(elements.length == 0) {
+            elements = document.getElementsByTagName("release")
+        }
+
+        if (elements.length > 0) {
+            val latest = elements.item(0).textContent
+            val latestVersion = Version.fromSemver(latest)
+            val currentVersion = Version.fromSemver(declaration.version)
+            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")
+            }
         }
     }
 

protocol/src/commonMain/kotlin/dev/arbjerg/lavalink/protocol/v4/info.kt

@@ -62,6 +62,70 @@ data class Version(
             return Version(semver, major.toInt(), minor.toInt(), patch.toInt(), preRelease)
         }
     }
+
+    override fun toString(): String {
+        var baseSemver = "${major}.${minor}.${patch}"
+
+        if(!preRelease.isNullOrEmpty())
+            baseSemver += "-${preRelease}"
+
+        return baseSemver
+    }
+
+    operator fun compareTo(other: Version): Int {
+        // Compare major, minor, and patch
+        val majorDiff = major - other.major
+        if (majorDiff != 0) return majorDiff
+
+        val minorDiff = minor - other.minor
+        if (minorDiff != 0) return minorDiff
+
+        val patchDiff = patch - other.patch
+        if (patchDiff != 0) return patchDiff
+
+        // Compare prerelease (null means no prerelease and is greater)
+        return when {
+            preRelease.isNullOrEmpty() && other.preRelease.isNullOrEmpty() -> 0
+            preRelease.isNullOrEmpty() && !other.preRelease.isNullOrEmpty() -> 1
+            !preRelease.isNullOrEmpty() && other.preRelease.isNullOrEmpty() -> -1
+            !preRelease.isNullOrEmpty() && !other.preRelease.isNullOrEmpty() -> comparePreRelease(preRelease, other.preRelease)
+            else -> 0
+        }
+    }
+
+    private fun comparePreRelease(part1: String, part2: String): Int {
+        val components1 = part1.split(".")
+        val components2 = part2.split(".")
+        val maxLength = maxOf(components1.size, components2.size)
+
+        for (i in 0 until maxLength) {
+            val comp1 = components1.getOrNull(i)
+            val comp2 = components2.getOrNull(i)
+
+            if (comp1 == null) return -1 // `part1` is shorter and considered smaller
+            if (comp2 == null) return 1  // `part2` is shorter and considered smaller
+
+            val isNumeric1 = comp1.all { it.isDigit() }
+            val isNumeric2 = comp2.all { it.isDigit() }
+
+            when {
+                isNumeric1 && isNumeric2 -> {
+                    // Compare numerically
+                    val diff = comp1.toInt() - comp2.toInt()
+                    if (diff != 0) return diff
+                }
+                isNumeric1 -> return -1 // Numeric parts come before string parts
+                isNumeric2 -> return 1  // String parts come after numeric parts
+                else -> {
+                    // Compare lexicographically
+                    val diff = comp1.compareTo(comp2)
+                    if (diff != 0) return diff
+                }
+            }
+        }
+
+        return 0 // Parts are equal
+    }
 }
 
 @Serializable