Add basic update checking.

build.gradle.kts

@@ -83,6 +83,7 @@ subprojects {
 
     // Serialization
     implementation("com.charleskorn.kaml:kaml:0.38.0")
+    implementation("org.jetbrains.kotlinx:kotlinx-serialization-json:1.3.1")
 
     // Paper API
     compileOnly("io.papermc.paper:paper-api:1.18.1-R0.1-SNAPSHOT")

foundation-core/build.gradle.kts

@@ -1,2 +1,3 @@
 dependencies {
+  // TODO: might be able to ship all dependencies in core? are we duplicating classes in JARs?
 }

foundation-core/src/main/kotlin/cloud/kubelet/foundation/core/FoundationCorePlugin.kt

@@ -3,6 +3,7 @@ package cloud.kubelet.foundation.core
 import cloud.kubelet.foundation.core.command.BackupCommand
 import cloud.kubelet.foundation.core.command.GamemodeCommand
 import cloud.kubelet.foundation.core.command.LeaderboardCommand
+import cloud.kubelet.foundation.core.command.UpdateCommand
 import net.kyori.adventure.text.Component
 import org.bukkit.GameMode
 import org.bukkit.command.CommandExecutor
@@ -41,6 +42,7 @@ class FoundationCorePlugin : JavaPlugin(), Listener {
 
     // Register commands.
     registerCommandExecutor("fbackup", BackupCommand(this, backupPath))
+    registerCommandExecutor("fupdate", UpdateCommand())
     registerCommandExecutor(listOf("survival", "s"), GamemodeCommand(GameMode.SURVIVAL))
     registerCommandExecutor(listOf("creative", "c"), GamemodeCommand(GameMode.CREATIVE))
     registerCommandExecutor(listOf("adventure", "a"), GamemodeCommand(GameMode.ADVENTURE))

foundation-core/src/main/kotlin/cloud/kubelet/foundation/core/command/UpdateCommand.kt

@@ -0,0 +1,37 @@
+package cloud.kubelet.foundation.core.command
+
+import cloud.kubelet.foundation.core.update.UpdateUtil
+import org.bukkit.command.Command
+import org.bukkit.command.CommandExecutor
+import org.bukkit.command.CommandSender
+
+class UpdateCommand : CommandExecutor {
+  override fun onCommand(
+    sender: CommandSender,
+    command: Command,
+    label: String,
+    args: Array<out String>
+  ): Boolean {
+    // TODO: Move to separate thread?
+    val modules = UpdateUtil.fetchManifest()
+    val plugins = sender.server.pluginManager.plugins.associateBy { it.name.lowercase() }
+
+    sender.sendMessage("Updates:")
+    modules.forEach { (name, manifest) ->
+      // Dumb naming problem. Don't want to fix it right now.
+      val plugin = if (name == "foundation-core") {
+        plugins["foundation"]
+      } else {
+        plugins[name.lowercase()]
+      }
+
+      if (plugin == null) {
+        sender.sendMessage("Plugin in manifest, but not installed: $name (${manifest.version})")
+      } else {
+        sender.sendMessage("${plugin.name}: ${manifest.version} (have ${plugin.description.version})")
+      }
+    }
+
+    return true
+  }
+}

foundation-core/src/main/kotlin/cloud/kubelet/foundation/core/update/ModuleManifest.kt

@@ -0,0 +1,9 @@
+package cloud.kubelet.foundation.core.update
+
+import kotlinx.serialization.Serializable
+
+@Serializable
+data class ModuleManifest(
+  val version: String,
+  val artifacts: List<String>,
+)

foundation-core/src/main/kotlin/cloud/kubelet/foundation/core/update/UpdateUtil.kt

@@ -0,0 +1,40 @@
+package cloud.kubelet.foundation.core.update
+
+import kotlinx.serialization.DeserializationStrategy
+import kotlinx.serialization.builtins.MapSerializer
+import kotlinx.serialization.builtins.serializer
+import kotlinx.serialization.json.Json
+import java.net.URI
+import java.net.http.HttpClient
+import java.net.http.HttpRequest
+import java.net.http.HttpResponse
+
+object UpdateUtil {
+  private val client = HttpClient.newBuilder().followRedirects(HttpClient.Redirect.NORMAL).build()
+
+  // TODO: Add environment variable override. Document it.
+  private const val manifestUrl =
+    "https://git.gorence.io/lgorence/foundation/-/jobs/artifacts/main/raw/build/manifests/update.json?job=build"
+
+  fun fetchManifest() = fetchFile(
+    manifestUrl, MapSerializer(String.serializer(), ModuleManifest.serializer()),
+  )
+
+  private inline fun <reified T> fetchFile(url: String, strategy: DeserializationStrategy<T>): T {
+    val request = HttpRequest
+      .newBuilder()
+      .GET()
+      .uri(URI.create(url))
+      .build()
+
+    val response = client.send(
+      request,
+      HttpResponse.BodyHandlers.ofString()
+    )
+
+    return Json.decodeFromString(
+      strategy,
+      response.body()
+    )
+  }
+}

foundation-core/src/main/resources/plugin.yml

@@ -8,9 +8,13 @@ authors:
   - kubelet
 commands:
   fbackup:
-    description: Foundation Backup
+    description: Back the server up now
     usage: /fbackup
-    permission: foundation.backup
+    permission: foundation.command.backup
+  fupdate:
+    description: List updates to the Foundation plugin
+    usage: /fupdate
+    permission: foundation.command.update
   survival:
     description: Switch to survival gamemode
     usage: /survival