Add anti-idle feature (Closes #21).

build.gradle.kts

@@ -87,6 +87,7 @@ subprojects {
     implementation(platform("org.jetbrains.kotlin:kotlin-bom"))
     implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk8")
 
+    // Core libraries.
     implementation("io.insert-koin:koin-core:3.1.4")
     testImplementation("io.insert-koin:koin-test:3.1.4")
 

foundation-core/build.gradle.kts

@@ -3,4 +3,5 @@ dependencies {
 
   implementation("software.amazon.awssdk:s3:2.17.102")
   implementation("org.quartz-scheduler:quartz:2.3.2")
+  implementation("com.google.guava:guava:31.0.1-jre")
 }

foundation-core/src/main/kotlin/cloud/kubelet/foundation/core/features/player/PlayerConfig.kt

@@ -0,0 +1,17 @@
+package cloud.kubelet.foundation.core.features.player
+
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+
+@Serializable
+data class PlayerConfig(
+  @SerialName("anti-idle")
+  val antiIdle: AntiIdleConfig = AntiIdleConfig(),
+)
+
+@Serializable
+data class AntiIdleConfig(
+  val enabled: Boolean = false,
+  val idleDuration: Int = 3600,
+  val ignore: List<String> = listOf(),
+)

foundation-core/src/main/kotlin/cloud/kubelet/foundation/core/features/player/PlayerFeature.kt

@@ -1,14 +1,88 @@
 package cloud.kubelet.foundation.core.features.player
 
+import cloud.kubelet.foundation.core.FoundationCorePlugin
+import cloud.kubelet.foundation.core.Util
 import cloud.kubelet.foundation.core.abstraction.Feature
+import com.charleskorn.kaml.Yaml
+import com.google.common.cache.Cache
+import com.google.common.cache.CacheBuilder
+import com.google.common.cache.RemovalCause
+import net.kyori.adventure.text.Component
 import org.bukkit.GameMode
+import org.bukkit.event.EventHandler
+import org.bukkit.event.player.PlayerJoinEvent
+import org.bukkit.event.player.PlayerKickEvent
+import org.bukkit.event.player.PlayerMoveEvent
+import org.bukkit.event.player.PlayerQuitEvent
+import org.koin.core.component.inject
+import java.time.Duration
+import kotlin.io.path.inputStream
 
 class PlayerFeature : Feature() {
+  private val config by inject<PlayerConfig>()
+  private lateinit var playerActivity: Cache<String, String>
+
   override fun enable() {
+    playerActivity = CacheBuilder.newBuilder()
+      .expireAfterWrite(Duration.ofSeconds(config.antiIdle.idleDuration.toLong()))
+      .removalListener<String, String> z@{
+        if (!config.antiIdle.enabled) return@z
+        if (it.cause == RemovalCause.EXPIRED) {
+          if (!config.antiIdle.ignore.contains(it.key!!)) {
+            plugin.server.scheduler.runTask(plugin) { ->
+              plugin.server.getPlayer(it.key!!)
+                ?.kick(Component.text("Kicked for idling"), PlayerKickEvent.Cause.IDLING)
+            }
+          }
+        }
+      }.build()
+
+    // Expire player activity tokens occasionally.
+    plugin.server.scheduler.scheduleSyncRepeatingTask(plugin, {
+      playerActivity.cleanUp()
+    }, 20, 100)
+
     registerCommandExecutor(listOf("survival", "s"), GamemodeCommand(GameMode.SURVIVAL))
     registerCommandExecutor(listOf("creative", "c"), GamemodeCommand(GameMode.CREATIVE))
     registerCommandExecutor(listOf("adventure", "a"), GamemodeCommand(GameMode.ADVENTURE))
     registerCommandExecutor(listOf("spectator", "sp"), GamemodeCommand(GameMode.SPECTATOR))
     registerCommandExecutor(listOf("localweather", "lw"), LocalWeatherCommand())
   }
+
+  override fun module() = org.koin.dsl.module {
+    single {
+      val configPath = Util.copyDefaultConfig<FoundationCorePlugin>(
+        plugin.slF4JLogger,
+        plugin.pluginDataPath,
+        "player.yaml",
+      )
+      return@single Yaml.default.decodeFromStream(
+        PlayerConfig.serializer(),
+        configPath.inputStream()
+      )
+    }
+  }
+
+  @EventHandler
+  private fun onPlayerJoin(e: PlayerJoinEvent) {
+    if (!config.antiIdle.enabled) return
+
+    playerActivity.put(e.player.name, e.player.name)
+  }
+
+  @EventHandler
+  private fun onPlayerQuit(e: PlayerQuitEvent) {
+    if (!config.antiIdle.enabled) return
+
+    playerActivity.invalidate(e.player.name)
+  }
+
+  @EventHandler
+  private fun onPlayerMove(e: PlayerMoveEvent) {
+    if (!config.antiIdle.enabled) return
+
+    if (e.hasChangedPosition() || e.hasChangedOrientation()) {
+      playerActivity.put(e.player.name, e.player.name)
+    }
+  }
 }

foundation-core/src/main/resources/player.yaml

@@ -0,0 +1,10 @@
+# Kicks players idle for longer than a set amount of time.
+anti-idle:
+  # Whether anti-idle kicking is enabled.
+  enabled: false
+
+  # Number of seconds the player is idle before kick.
+  idleDuration: 3600
+
+  # List of usernames to ignore.
+  ignore: []