feat: 依存関係のimplementation、コマンド実行時の非同期化

- gradleをアップデート
- 依存関係をリモート化し、ファイルシステム上の依存を削除

.envrc

@@ -0,0 +1 @@
+use flake

.gitignore

@@ -1,23 +1,4 @@
-# ---> Gradle
+.direnv
+.kotlin
 .gradle
-**/build/
-!src/**/build/
-
-# Ignore Gradle GUI config
-gradle-app.setting
-
-# Avoid ignoring Gradle wrapper jar file (.jar files are usually ignored)
-!gradle-wrapper.jar
-
-# Avoid ignore Gradle wrappper properties
-!gradle-wrapper.properties
-
-# Cache of project
-.gradletasknamecache
-
-# Eclipse Gradle plugin generated files
-# Eclipse Core
-.project
-# JDT-specific (Eclipse Java Development Tools)
-.classpath
-
+build

.gitmodules

@@ -0,0 +1,4 @@
+[submodule "kommand-lib"]
+	path = kommand-lib
+	url = git@gitea.hareworks.net:Hare/kommand-lib.git
+	branch=master

build.gradle.kts

@@ -1,101 +1,61 @@
-import net.minecrell.pluginyml.bukkit.BukkitPluginDescription
+import net.minecrell.pluginyml.paper.PaperPluginDescription
 
 group = "net.hareworks"
-version = "1.0"
+version = "1.2"
 
-val exposedVersion = "0.54.0"
 
 plugins {
-    kotlin("jvm") version "2.0.20"
-    kotlin("plugin.serialization") version "2.0.20"
-    id("net.minecrell.plugin-yml.bukkit") version "0.6.0"
-    id("com.github.johnrengelman.shadow") version "8.1.1"
+    kotlin("jvm") version "2.2.21"
+    kotlin("plugin.serialization") version "2.2.21"
+    id("de.eldoria.plugin-yml.paper") version "0.8.0"
+    id("com.gradleup.shadow") version "9.2.2"
 }
 repositories {
     mavenCentral()
     maven("https://repo.papermc.io/repository/maven-public/")
     maven("https://repo.codemc.io/repository/maven-public/")
 }
+
+val exposedVersion = "0.54.0"
 dependencies {
-    compileOnly("io.papermc.paper:paper-api:1.21.3-R0.1-SNAPSHOT")
+    compileOnly("io.papermc.paper:paper-api:1.21.10-R0.1-SNAPSHOT")
+    implementation("org.jetbrains.kotlin:kotlin-stdlib")
+    implementation("net.hareworks:kommand-lib:1.1")
     implementation("net.kyori:adventure-api:4.17.0")
     implementation("net.kyori:adventure-text-minimessage:4.17.0")
-    // implementation("org.jetbrains.kotlinx:kotlinx-serialization-json:1.7.1")
+    implementation("org.jetbrains.kotlinx:kotlinx-serialization-json:1.7.1")
     implementation("org.postgresql:postgresql:42.7.1")
     implementation("org.jetbrains.exposed:exposed-core:$exposedVersion")
     implementation("org.jetbrains.exposed:exposed-dao:$exposedVersion")
     implementation("org.jetbrains.exposed:exposed-jdbc:$exposedVersion")
     implementation("org.jetbrains.kotlinx:kotlinx-datetime:0.6.1")
     implementation("org.jetbrains.exposed:exposed-kotlin-datetime:$exposedVersion")
-    compileOnly("de.tr7zw:item-nbt-api-plugin:2.14.0")
-    implementation("com.michael-bull.kotlin-result:kotlin-result:2.0.0")
+    implementation("de.tr7zw:item-nbt-api:2.15.3")
 }
 tasks {
-    shadowJar {
+    withType<Jar> {
         archiveBaseName.set("SimplyMCDB")
-        archiveClassifier.set("")
+    }
+    shadowJar {
+        minimize {
+            exclude(dependency("org.jetbrains.exposed:exposed-core"))
+            exclude(dependency("org.jetbrains.exposed:exposed-dao"))
+            exclude(dependency("org.jetbrains.exposed:exposed-jdbc"))
+            exclude(dependency("org.jetbrains.exposed:exposed-kotlin-datetime"))
+            exclude(dependency("org.postgresql:postgresql"))
+        }
+        archiveClassifier.set("min")
+        relocate("de.tr7zw.changeme.nbtapi", "net.hareworks.simplymcdb.libs.nbtapi")
     }
 }
 
-bukkit {
+paper {
     main = "net.hareworks.simplymcdb.App"
     name = "Simply-Minecraft-DB"
     description = "It provides a simple way to manage player data through a database."
     version = getVersion().toString()
-		apiVersion = "1.21.3"
-    authors =
-            listOf("Hare-K02")
-    depend = listOf("NBTAPI")
-    permissions {
-        register("simplydb.*") {
-            children = listOf("simplydb.command", "simplydb.admin")
-        }
-        register("simplydb.command") {
-            description = "Allows access to the /simplydb command"
-            default = BukkitPluginDescription.Permission.Default.TRUE
-        }
-        register("simplydb.command.*") {
-            children = listOf(
-                "simplydb.command.config",
-                "simplydb.command.config.*",
-                "simplydb.command.on",
-                "simplydb.command.off",
-            )
-        }
-        register("simplydb.command.config") {
-            description = "Allows access to the /simplydb config command"
-            default = BukkitPluginDescription.Permission.Default.OP
-        }
-        register("simplydb.command.config.*") {
-            children = listOf(
-                "simplydb.command.config.reload",
-                "simplydb.command.config.fetch",
-                "simplydb.command.config.upload",
-            )
-        }
-        register("simplydb.command.config.reload") {
-            description = "Allows access to the /simplydb config reload command"
-            default = BukkitPluginDescription.Permission.Default.OP
-        }
-        register("simplydb.command.config.fetch") {
-            description = "Allows access to the /simplydb config fetch command"
-            default = BukkitPluginDescription.Permission.Default.OP
-        }
-        register("simplydb.command.config.upload") {
-            description = "Allows access to the /simplydb config upload command"
-            default = BukkitPluginDescription.Permission.Default.OP
-        }
-        register("simplydb.command.on") {
-            description = "Allows access to the /simplydb on command"
-            default = BukkitPluginDescription.Permission.Default.OP
-        }
-        register("simplydb.command.off") {
-            description = "Allows access to the /simplydb off command"
-            default = BukkitPluginDescription.Permission.Default.OP
-        }
-        register("simplydb.admin") {
-            description = "Allows configration/manage simplydb"
-            default = BukkitPluginDescription.Permission.Default.OP
-        }
-		}
+	apiVersion = "1.21.10"
+    authors = listOf(
+        "Hare-K02"
+    )
 }

flake.lock

@@ -0,0 +1,61 @@
+{
+  "nodes": {
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1731533236,
+        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1764173365,
+        "narHash": "sha256-JaNFPy3nywPNxSDpEgFFqvngQww5Igb6twG4NhMo8oc=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "2fecba9952096ba043c16b9ef40b92851ff3e5d9",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-25.11",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,43 @@
+{
+  description = "Minecraft dev environment with JDK 21 and Gradle";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-25.11";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs =
+    {
+      self,
+      nixpkgs,
+      flake-utils,
+      ...
+    }:
+    flake-utils.lib.eachDefaultSystem (
+      system:
+      let
+        pkgs = import nixpkgs {
+          inherit system;
+        };
+      in
+      {
+        devShells.default = pkgs.mkShell {
+          packages = with pkgs; [
+            jdk21
+            gradle
+            kotlin
+            git
+            unzip
+          ];
+
+          # 必要に応じて環境変数を設定
+          shellHook = ''
+            export JAVA_HOME=${pkgs.jdk21}/lib/openjdk
+            export PATH="$JAVA_HOME/bin:$PATH"
+
+            export GRADLE_USER_HOME="$PWD/.gradle"
+          '';
+        };
+      }
+    );
+}

gradle.properties

@@ -0,0 +1,5 @@
+org.gradle.configuration-cache=true
+org.gradle.parallel=true
+org.gradle.caching=true
+
+kotlin.stdlib.default.dependency=false

gradle/libs.versions.toml

@@ -0,0 +1,2 @@
+# This file was generated by the Gradle 'init' task.
+# https://docs.gradle.org/current/userguide/platforms.html#sub::toml-dependencies-format

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,7 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.10.1-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.14.3-bin.zip
 networkTimeout=10000
+validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists

gradlew

@@ -15,6 +15,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
+# SPDX-License-Identifier: Apache-2.0
+#
 
 ##############################################################################
 #
@@ -55,7 +57,7 @@
 #       Darwin, MinGW, and NonStop.
 #
 #   (3) This script is generated from the Groovy template
-#       https://github.com/gradle/gradle/blob/HEAD/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       https://github.com/gradle/gradle/blob/HEAD/platforms/jvm/plugins-application/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
 #       within the Gradle project.
 #
 #       You can find Gradle at https://github.com/gradle/gradle/.
@@ -83,10 +85,8 @@ done
 # This is normally unused
 # shellcheck disable=SC2034
 APP_BASE_NAME=${0##*/}
-APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
-
-# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+# Discard cd standard output in case $CDPATH is set (https://github.com/gradle/gradle/issues/25036)
+APP_HOME=$( cd -P "${APP_HOME:-./}" > /dev/null && printf '%s\n' "$PWD" ) || exit
 
 # Use the maximum available, or set MAX_FD != -1 to use that value.
 MAX_FD=maximum
@@ -114,7 +114,7 @@ case "$( uname )" in                #(
   NONSTOP* )        nonstop=true ;;
 esac
 
-CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+CLASSPATH="\\\"\\\""
 
 
 # Determine the Java command to use to start the JVM.
@@ -133,10 +133,13 @@ location of your Java installation."
     fi
 else
     JAVACMD=java
-    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+    if ! command -v java >/dev/null 2>&1
+    then
+        die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
 
 Please set the JAVA_HOME variable in your environment to match the
 location of your Java installation."
+    fi
 fi
 
 # Increase the maximum file descriptors if we can.
@@ -144,7 +147,7 @@ if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
     case $MAX_FD in #(
       max*)
         # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
-        # shellcheck disable=SC3045
+        # shellcheck disable=SC2039,SC3045
         MAX_FD=$( ulimit -H -n ) ||
             warn "Could not query maximum file descriptor limit"
     esac
@@ -152,7 +155,7 @@ if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
       '' | soft) :;; #(
       *)
         # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
-        # shellcheck disable=SC3045
+        # shellcheck disable=SC2039,SC3045
         ulimit -n "$MAX_FD" ||
             warn "Could not set maximum file descriptor limit to $MAX_FD"
     esac
@@ -197,16 +200,20 @@ if "$cygwin" || "$msys" ; then
     done
 fi
 
-# Collect all arguments for the java command;
-#   * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
-#     shell script including quotes and variable substitutions, so put them in
-#     double quotes to make sure that they get re-expanded; and
-#   * put everything else in single quotes, so that it's not re-expanded.
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Collect all arguments for the java command:
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments,
+#     and any embedded shellness will be escaped.
+#   * For example: A user cannot expect ${Hostname} to be expanded, as it is an environment variable and will be
+#     treated as '${Hostname}' itself on the command line.
 
 set -- \
         "-Dorg.gradle.appname=$APP_BASE_NAME" \
         -classpath "$CLASSPATH" \
-        org.gradle.wrapper.GradleWrapperMain \
+        -jar "$APP_HOME/gradle/wrapper/gradle-wrapper.jar" \
         "$@"
 
 # Stop when "xargs" is not available.

gradlew.bat

@@ -13,6 +13,8 @@
 @rem See the License for the specific language governing permissions and
 @rem limitations under the License.
 @rem
+@rem SPDX-License-Identifier: Apache-2.0
+@rem
 
 @if "%DEBUG%"=="" @echo off
 @rem ##########################################################################
@@ -43,11 +45,11 @@ set JAVA_EXE=java.exe
 %JAVA_EXE% -version >NUL 2>&1
 if %ERRORLEVEL% equ 0 goto execute
 
-echo.
-echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
-echo.
-echo Please set the JAVA_HOME variable in your environment to match the
-echo location of your Java installation.
+echo. 1>&2
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH. 1>&2
+echo. 1>&2
+echo Please set the JAVA_HOME variable in your environment to match the 1>&2
+echo location of your Java installation. 1>&2
 
 goto fail
 
@@ -57,22 +59,22 @@ set JAVA_EXE=%JAVA_HOME%/bin/java.exe
 
 if exist "%JAVA_EXE%" goto execute
 
-echo.
-echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
-echo.
-echo Please set the JAVA_HOME variable in your environment to match the
-echo location of your Java installation.
+echo. 1>&2
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME% 1>&2
+echo. 1>&2
+echo Please set the JAVA_HOME variable in your environment to match the 1>&2
+echo location of your Java installation. 1>&2
 
 goto fail
 
 :execute
 @rem Setup the command line
 
-set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+set CLASSPATH=
 
 
 @rem Execute Gradle
-"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" -jar "%APP_HOME%\gradle\wrapper\gradle-wrapper.jar" %*
 
 :end
 @rem End local scope for the variables with windows NT shell

settings.gradle.kts

@@ -0,0 +1,3 @@
+rootProject.name = "simply-mcdb"
+
+includeBuild("kommand-lib")

src/main/kotlin/net/hareworks/kommandlib/main.kt

@@ -1,147 +0,0 @@
-package net.hareworks.kommandlib
-
-import com.github.michaelbull.result.*
-import kotlin.collections.listOf
-import org.bukkit.Bukkit
-import org.bukkit.command.CommandMap
-import org.bukkit.command.CommandSender
-import org.bukkit.command.PluginCommand
-import org.bukkit.command.TabCompleter
-import org.bukkit.plugin.java.JavaPlugin
-import net.hareworks.simplymcdb.App
-
-class KommandLib(plugin: JavaPlugin, vararg routes: Argument) {
-  val entries = routes.toList()
-  init {
-    val f = Bukkit.getServer().javaClass.getDeclaredField("commandMap")
-    f.isAccessible = true
-    val commandMap = f.get(Bukkit.getServer()) as CommandMap
-    for (route in routes) {
-      commandMap.register(
-              plugin.getName(),
-              (PluginCommand::class
-                              .java
-                              .declaredConstructors
-                              .first()
-                              .apply { isAccessible = true }
-                              .newInstance(route.name, plugin) as
-                              PluginCommand)
-                      .apply {
-                        this.name = name
-                        this.setExecutor { sender, _, alias, args ->
-                          val routeargs = routeTreeSearch(arrayOf(alias, *args))
-                          if (routeargs.size == args.size + 1)
-                                  routeargs.last().onCommand(sender, args)
-                          true
-                        }
-                        this.tabCompleter = TabCompleter { sender, _, alias, args ->
-                          val routeargs = routeTreeSearch(arrayOf(alias, *args))
-                          if (routeargs.size == args.size)
-                                  routeargs.last().getCompletList(sender, args)
-                          else listOf()
-                        }
-                      }
-      )
-    }
-  }
-
-  fun routeTreeSearch(args: Array<String>): List<Argument> {
-    val list =
-            mutableListOf<Argument>(
-                    entries.find { it.name == args[0] } ?: throw Exception("Invalid command")
-            )
-    var i = 1
-    while (i + 1 <= args.size) {
-      if (list.last().routes.isEmpty()) break
-      val route = list.last().routes.sortedBy { it.priority }.find { it.name == args[i] } ?: break
-      list.add(route)
-      i += route.unit
-    }
-    return list
-  }
-
-  fun unregister() {
-    val f = Bukkit.getServer().javaClass.getDeclaredField("commandMap")
-    f.isAccessible = true
-    val commandMap = f.get(Bukkit.getServer()) as CommandMap
-    for (route in entries) {
-      commandMap.getCommand(route.name)?.unregister(commandMap)
-    }
-  }
-}
-
-abstract class Argument(
-        val argname: String,
-        vararg routes: Argument,
-        val execute: (CommandSender, Array<String>) -> Unit
-) {
-  val name = argname
-  var routes = routes.toList()
-  var permission: String = ""
-    set(value) {
-      field = value
-      if (value.isEmpty()) return
-      for (route in routes) {
-        route.permission = value + "." + route.name
-      }
-    }
-  var condition: (CommandSender) -> Boolean = { true }
-
-  public fun addArgs(vararg routes: Argument): Argument {
-    this.routes += routes
-    return this
-  }
-
-  abstract var priority: Int
-  open var unit: Int = 1
-  open fun onCommand(sender: CommandSender, args: Array<String>) {
-    execute(sender, args)
-  }
-
-  abstract fun suggest(sender: CommandSender, args: Array<String>): List<String>
-
-  fun getCompletList(sender: CommandSender, args: Array<String>): List<String> {
-    return routes
-            .filter { sender.hasPermission(it.permission) && it.condition(sender) }
-            .map { it.suggest(sender, args) }
-            .flatten()
-  }
-}
-
-class Route(
-        name: String,
-        vararg routes: Argument,
-        execute: (CommandSender, Array<String>) -> Unit
-) : Argument(name, *routes, execute = execute) {
-  override var priority: Int = 2
-
-  override fun suggest(sender: CommandSender, args: Array<String>): List<String> {
-    return if (sender.hasPermission(this.permission) &&
-                    this.condition(sender) &&
-                    this.name.startsWith(args.last())
-    )
-            listOf(this.name)
-    else listOf()
-  }
-}
-
-class Text(name: String, vararg routes: Argument, execute: (CommandSender, Array<String>) -> Unit) :
-        Argument(name, *routes, execute = execute) {
-  override var priority: Int = 0
-
-  override fun suggest(sender: CommandSender, args: Array<String>): List<String> {
-    return listOf(args.last())
-  }
-}
-
-class Integer(
-        name: String,
-        vararg routes: Argument,
-        execute: (CommandSender, Array<String>) -> Unit
-) : Argument(name, *routes, execute = execute) {
-  override var priority: Int = 1
-
-  override fun suggest(sender: CommandSender, args: Array<String>): List<String> {
-    return listOf()
-  }
-}

src/main/kotlin/net/hareworks/simplymcdb/App.kt

@@ -1,7 +1,7 @@
 package net.hareworks.simplymcdb
 
-import net.hareworks.kommandlib.KommandLib
-import net.hareworks.simplymcdb.command.smcdb
+import net.hareworks.kommand_lib.KommandLib
+import net.hareworks.simplymcdb.command.registerCommands
 import net.hareworks.simplymcdb.database.Database
 import org.bukkit.plugin.java.JavaPlugin
 
@@ -18,22 +18,25 @@ public class App : JavaPlugin() {
       field = value
       Config.config.set("enabled", !value.equals(State.DISABLED))
     }
+
   companion object {
     lateinit var instance: App
       private set
   }
+
   lateinit var command: KommandLib
     private set
 
   override fun onEnable() {
     instance = this
     Config.init()
-    command = KommandLib(this, smcdb)
+    command = registerCommands(this)
 
     server.pluginManager.registerEvents(EventListener, this)
 
     if (Config.check()) enable()
   }
+
   override fun onDisable() {
     enabled = State.DISABLED
     Database.disconnect()
@@ -56,4 +59,4 @@ public class App : JavaPlugin() {
     logger.info("simplymcdb disabled.")
     enabled = State.DISABLED
   }
-}
+}

src/main/kotlin/net/hareworks/simplymcdb/Command.kt

@@ -1,202 +1,281 @@
 package net.hareworks.simplymcdb.command
 
-import com.github.michaelbull.result.*
-import net.hareworks.kommandlib.*
-import net.hareworks.simplymcdb.*
+import java.util.UUID
+import net.hareworks.kommand_lib.KommandLib
+import net.hareworks.kommand_lib.kommand
+import net.hareworks.simplymcdb.App
+import net.hareworks.simplymcdb.Config
+import net.hareworks.simplymcdb.State
 import net.hareworks.simplymcdb.database.Database
+import net.hareworks.simplymcdb.fetch
+import net.hareworks.simplymcdb.findPlayersNeedingMigration
+import net.hareworks.simplymcdb.isRegistered
+import net.hareworks.simplymcdb.overwritePlayerData
+import net.hareworks.simplymcdb.register
+import net.hareworks.simplymcdb.update
+import net.hareworks.simplymcdb.PlayerSerializer
 import net.kyori.adventure.audience.Audience
 import net.kyori.adventure.text.minimessage.MiniMessage
 import org.bukkit.entity.Player
+import org.bukkit.plugin.java.JavaPlugin
+
+private val miniMessage = MiniMessage.miniMessage()
+private val commandBuffer = mutableMapOf<UUID, String>()
 
 public fun Audience.sendMM(message: String) {
-  this.sendMessage(MiniMessage.miniMessage().deserialize(message))
+  this.sendMessage(miniMessage.deserialize(message))
 }
 
-val command_buffer = mutableMapOf<java.util.UUID, String>()
-public val smcdb =
-        Route("smcdb") { sender, _ -> sender.sendMessage("simptlymcdb command") }
-                .addArgs(
-                        Route("config") { sender, _ ->
-                                  (sender as Player).performCommand("smcdb config help")
-                                }
-                                .addArgs(
-                                        Route("reload") { sender, _ ->
-                                          sender.sendMessage("reloading config...")
-                                          Config.reload()
-                                          sender.sendMessage("reloaded.")
-                                        },
-                                        Route("fetch") { sender, _ ->
-                                          sender.sendMessage("fetching config...")
-                                        },
-                                        Route("upload") { sender, _ ->
-                                          sender.sendMessage("uploading config...")
-                                        },
-                                        Route("help") { sender, _ ->
-                                          var help =
-                                                  MiniMessage.miniMessage()
-                                                          .deserialize(
-                                                                  "<red>simplymcdb config help<newline><gray>reload: <green>reload the config from config.yml<newline><gray>fetch: <green>fetch the config from the database<newline><gray>upload: <green>upload the current config to the database"
-                                                          )
-                                          sender.sendMessage(help)
-                                        }
-                                ),
-                        Route("help") { sender, _ ->
-                          sender.sendMM(
-                                  "<red>simplymcdb help<newline><gray>config: <green>configre the plugin<newline><gray>activate: <green>when the plugin is disabled, activate it<newline><gray>deactivate: <green>when the plugin is enabled, deactivate it"
-                          )
-                        },
-                        Route("activate") { sender, _ ->
-                          if (App.instance.enabled == State.ACTIVE) {
-                            sender.sendMessage("simplymcdb is already enabled.")
-                            return@Route
-                          }
-                          App.instance.enable()
-                          sender.sendMessage("simplymcdb enabled.")
-                        },
-                        Route("deactivate") { sender, _ ->
-                          if (App.instance.enabled == State.DISABLED) {
-                            sender.sendMessage("simplymcdb is already disabled.")
-                            return@Route
-                          }
-                          App.instance.disable()
-                          sender.sendMessage("simplymcdb disabled.")
-                        },
-                        Route("database") { _, _ -> }
-                                .addArgs(
-                                        Route("init") { sender, _ ->
-                                          Database.initialize()
-                                          sender.sendMessage("database initialized.")
-                                        },
-                                        Route("reset") { sender, _ ->
-                                          Database.reset()
-                                          sender.sendMessage("database reset.")
-                                        },
-                                ),
-                        Route("check") { sender, _ ->
-                          sender.sendMM(
-                                  "${when (App.instance.enabled) {
-                                              State.ACTIVE -> "<green>●"
-                                              State.DISCONNECTED -> "<yellow>■"
-                                              State.DISABLED -> "<red>○"
-                                            }}<white> simply-minecraft-database"
-                          )
-                          sender.sendMM(
-                                  "status: ${when (App.instance.enabled) {
-                                                          State.ACTIVE -> "<green>active" 
-                                                          State.DISCONNECTED -> "<yellow>disconnected"
-                                                          State.DISABLED -> "<red>disabled"}}"
-                          )
-                          sender.sendMM(
-                                  "<gray>- <white>database test: ${if (Database.ping()) "success" else "failed"}"
-                          )
-                          sender.sendMM(
-                                  "<gray>- <white>config test: ${if (Config.config.getBoolean("enabled")) "enabled" else "disabled"}"
-                          )
-                        },
-                        Route("register") { sender, _ ->
-                          if (sender !is Player) {
-                            sender.sendMM("This command is only available for players.")
-                            return@Route
-                          } else
-                                  when (App.instance.enabled) {
-                                    State.DISABLED ->
-                                            sender.sendMM(
-                                                    "<red>[SMCDB] simplymcdb is disabled.<br>Run /smcdb check to check the status."
-                                            )
-                                    State.DISCONNECTED ->
-                                            sender.sendMM(
-                                                    "<red>[SMCDB] simplymcdb is enabled but disconnected.<br>Run /smcdb check to check the status."
-                                            )
-                                    else -> {
-                                      if (!isRegistered(sender.uniqueId)) {
-                                        sender.sendMM(
-                                                "<gray>[SMCDB] <red>The inventory of the other servers will be overwritten.<newline>" +
-                                                        "Are you sure you want to register?<newline>" +
-                                                        "<green>/smcdb confirm<gray> to confirm."
-                                        )
-                                      } else {
-                                        sender.sendMM("<gray>[SMCDB] You are already registered.")
-                                      }
-                                    }
-                                  }
-                        },
-                        Route("confirm") { sender, _ ->
-                          if (sender !is Player) return@Route
-                          when (command_buffer[sender.uniqueId]) {
-                            "register" -> {
-                              if (App.instance.enabled == State.ACTIVE) {
-                                register(sender)
-                                sender.sendMM("<gray>[SMCDB] Successfully registered.")
-                              } else {
-                                sender.sendMM("<red>[SMCDB] simplymcdb is disabled.")
-                              }
-                            }
-                            else -> {
-                              sender.sendMM("<red>[SMCDB] Invalid command.")
-                            }
-                          }
-                          command_buffer.remove(sender.uniqueId)
-                        }
-                        // Route("update") { sender, _ ->
-                        //   if (sender !is Player) {
-                        //     sender.sendMM("This command is only available for players.")
-                        //     return@Route
-                        //   } else
-                        //           when (App.instance.enabled) {
-                        //             State.DISABLED ->
-                        //                     sender.sendMM(
-                        //                             "<red>[SMCDB] simplymcdb is disabled.<br>Run
-                        // /smcdb check to check the status."
-                        //                     )
-                        //             State.DISCONNECTED ->
-                        //                     sender.sendMM(
-                        //                             "<red>[SMCDB] simplymcdb is enabled but
-                        // disconnected.<br>Run /smcdb check to check the status."
-                        //                     )
-                        //             else -> {
-                        //               if (isRegistered(sender.uniqueId)) {
-                        //                 update(sender)
-                        //                 sender.sendMM("<gray>[SMCDB] Successfully updated.")
-                        //               } else {
-                        //                 sender.sendMM("<red>[SMCDB] You are not registered.")
-                        //               }
-                        //             }
-                        //           }
-                        // },
-                        // Route("fetch") { sender, _ ->
-                        //   if (sender !is Player) {
-                        //     sender.sendMM("This command is only available for players.")
-                        //     return@Route
-                        //   } else
-                        //           when (App.instance.enabled) {
-                        //             State.DISABLED ->
-                        //                     sender.sendMM(
-                        //                             "<red>[SMCDB] simplymcdb is disabled.<br>Run
-                        // /smcdb check to check the status."
-                        //                     )
-                        //             State.DISCONNECTED ->
-                        //                     sender.sendMM(
-                        //                             "<red>[SMCDB] simplymcdb is enabled but
-                        // disconnected.<br>Run /smcdb check to check the status."
-                        //                     )
-                        //             else -> {
-                        //               if (isRegistered(sender.uniqueId)) {
-                        //                 sender.sendMM(
-                        //                         "<gray>[SMCDB] Welcome back,
-                        // ${sender.name}.<newline>Fetching your data..."
-                        //                 )
-                        //                 fetch(sender)
-                        //               } else {
-                        //                 sender.sendMM(
-                        //                         "<gray>[SMCDB] Welcome, ${sender.name}.<newline>"
-                        // +
-                        //                                 "SMCDB is active but you have already
-                        // played before.<newline>" +
-                        //                                 "Run <green>/smcdb register<gray> to
-                        // register yourself."
-                        //                 )
-                        //               }
-                        //             }
-                        //           }
-                        // },
-                        )
+private fun Audience.sendConfigHelp() {
+  sendMM(
+      "<red>simplymcdb config help<newline><gray>reload: <green>reload the config from config.yml<newline><gray>fetch: <green>fetch the config from the database<newline><gray>upload: <green>upload the current config to the database")
+}
+
+public fun registerCommands(plugin: JavaPlugin): KommandLib =
+    kommand(plugin) {
+      command("smcdb") {
+        description = "Control Simply-Minecraft-DB"
+        permission = "simplydb.command"
+
+        executes {
+          sender.sendMessage("simplymcdb command")
+        }
+
+        literal("config") {
+          requires("simplydb.command.config")
+          executes { sender.sendConfigHelp() }
+
+          literal("reload") {
+            requires("simplydb.command.config.reload")
+            executes {
+              sender.sendMessage("reloading config...")
+              Config.reload()
+              sender.sendMessage("reloaded.")
+            }
+          }
+
+          literal("fetch") {
+            requires("simplydb.command.config.fetch")
+            executes { sender.sendMessage("fetching config...") }
+          }
+
+          literal("upload") {
+            requires("simplydb.command.config.upload")
+            executes { sender.sendMessage("uploading config...") }
+          }
+
+          literal("help") { executes { sender.sendConfigHelp() } }
+        }
+
+        literal("help") {
+          executes {
+            sender.sendMM(
+                "<red>simplymcdb help<newline><gray>config: <green>configre the plugin<newline><gray>activate: <green>when the plugin is disabled, activate it<newline><gray>deactivate: <green>when the plugin is enabled, deactivate it")
+          }
+        }
+
+        literal("activate") {
+          requires("simplydb.command.on")
+          executes {
+            if (App.instance.enabled == State.ACTIVE) {
+              sender.sendMessage("simplymcdb is already enabled.")
+              return@executes
+            }
+            App.instance.enable()
+            sender.sendMessage("simplymcdb enabled.")
+          }
+        }
+
+        literal("deactivate") {
+          requires("simplydb.command.off")
+          executes {
+            if (App.instance.enabled == State.DISABLED) {
+              sender.sendMessage("simplymcdb is already disabled.")
+              return@executes
+            }
+            App.instance.disable()
+            sender.sendMessage("simplymcdb disabled.")
+          }
+        }
+
+        literal("database") {
+          literal("init") {
+            executes {
+              Database.initialize()
+              sender.sendMessage("database initialized.")
+            }
+          }
+          literal("reset") {
+            executes {
+              Database.reset()
+              sender.sendMessage("database reset.")
+            }
+          }
+        }
+
+        literal("migrate") {
+          executes {
+            val player = sender as? Player
+            if (player == null) {
+              sender.sendMM("<red>[SMCDB] This command can only be run by players.")
+              return@executes
+            }
+            when (App.instance.enabled) {
+              State.DISABLED -> {
+                sender.sendMM("<red>[SMCDB] simplymcdb is disabled.")
+                return@executes
+              }
+              State.DISCONNECTED -> {
+                sender.sendMM("<yellow>[SMCDB] Database disconnected. Try again later.")
+                return@executes
+              }
+              else -> {}
+            }
+            if (!isRegistered(player.uniqueId)) {
+              sender.sendMM("<red>[SMCDB] You are not registered in the database.")
+              return@executes
+            }
+            try {
+              sender.sendMM("<gray>[SMCDB] Applying legacy data...")
+              fetch(player)
+              update(player)
+              sender.sendMM("<green>[SMCDB] Migration complete. Data updated to the latest format.")
+            } catch (e: Exception) {
+              App.instance.logger.warning("Failed to migrate data for ${player.uniqueId}: ${e.message}")
+              sender.sendMM("<red>[SMCDB] Migration failed. Check server logs.")
+            }
+          }
+
+          literal("all") {
+            executes {
+              val executor = sender as? Player
+              if (executor == null) {
+                sender.sendMM("<red>[SMCDB] This command can only be run by players.")
+                return@executes
+              }
+              when (App.instance.enabled) {
+                State.DISABLED -> {
+                  sender.sendMM("<red>[SMCDB] simplymcdb is disabled.")
+                  return@executes
+                }
+                State.DISCONNECTED -> {
+                  sender.sendMM("<yellow>[SMCDB] Database disconnected. Try again later.")
+                  return@executes
+                }
+                else -> {}
+              }
+              val targets = findPlayersNeedingMigration()
+              if (targets.isEmpty()) {
+                sender.sendMM("<gray>[SMCDB] No legacy data found.")
+                return@executes
+              }
+              sender.sendMM("<gray>[SMCDB] Migrating ${targets.size} legacy profiles... Please wait.")
+              val backup = PlayerSerializer.serialize(executor)
+              var migrated = 0
+              try {
+                targets.forEach { entry ->
+                  try {
+                    PlayerSerializer.deserialize(executor, entry.serialized)
+                    val updatedSnapshot = PlayerSerializer.serialize(executor)
+                    overwritePlayerData(entry.uuid, updatedSnapshot)
+                    migrated++
+                  } catch (ex: Exception) {
+                    App.instance.logger.warning("Failed to migrate data for ${entry.uuid}: ${ex.message}")
+                  }
+                }
+              } finally {
+                try {
+                  PlayerSerializer.deserialize(executor, backup)
+                } catch (restoreEx: Exception) {
+                  App.instance.logger.warning("Failed to restore migration executor state: ${restoreEx.message}")
+                }
+              }
+              sender.sendMM("<green>[SMCDB] Migration finished ($migrated/${targets.size}). Check logs for failures.")
+            }
+          }
+        }
+
+        literal("check") {
+          executes {
+            val commandSender = sender
+            commandSender.sendMM(
+                "${when (App.instance.enabled) {
+                  State.ACTIVE -> "<green>●"
+                  State.DISCONNECTED -> "<yellow>■"
+                  State.DISABLED -> "<red>○"
+                }}<white> simply-minecraft-database")
+            commandSender.sendMM(
+                "status: ${when (App.instance.enabled) {
+                  State.ACTIVE -> "<green>active"
+                  State.DISCONNECTED -> "<yellow>disconnected"
+                  State.DISABLED -> "<red>disabled"
+                }}")
+            commandSender.sendMM(
+                "<gray>- <white>config test: ${if (Config.config.getBoolean("enabled")) "enabled" else "disabled"}")
+            commandSender.sendMM("<gray>- <white>database test: <yellow>checking...")
+
+            // Run the potentially slow ping off the main thread to avoid freezing the server thread.
+            App.instance.server.scheduler.runTaskAsynchronously(App.instance, Runnable {
+              val pingSuccess = try {
+                Database.ping()
+              } catch (ex: Exception) {
+                App.instance.logger.warning("Database ping failed: ${ex.message}")
+                false
+              }
+              App.instance.server.scheduler.runTask(App.instance, Runnable {
+                commandSender.sendMM(
+                    "<gray>- <white>database test result: ${if (pingSuccess) "success" else "failed"}")
+              })
+            })
+          }
+        }
+
+        literal("register") {
+          executes {
+            val player = sender as? Player
+            if (player == null) {
+              sender.sendMM("This command is only available for players.")
+              return@executes
+            }
+            when (App.instance.enabled) {
+              State.DISABLED -> {
+                sender.sendMM("<red>[SMCDB] simplymcdb is disabled.<br>Run /smcdb check to check the status.")
+                return@executes
+              }
+              State.DISCONNECTED -> {
+                sender.sendMM("<red>[SMCDB] simplymcdb is enabled but disconnected.<br>Run /smcdb check to check the status.")
+                return@executes
+              }
+              else -> {}
+            }
+            if (!isRegistered(player.uniqueId)) {
+              sender.sendMM(
+                  "<gray>[SMCDB] <red>The inventory of the other servers will be overwritten.<newline>" +
+                      "Are you sure you want to register?<newline>" +
+                      "<green>/smcdb confirm<gray> to confirm.")
+              commandBuffer[player.uniqueId] = "register"
+            } else {
+              sender.sendMM("<gray>[SMCDB] You are already registered.")
+            }
+          }
+        }
+
+        literal("confirm") {
+          executes {
+            val player = sender as? Player ?: return@executes
+            when (commandBuffer[player.uniqueId]) {
+              "register" -> {
+                if (App.instance.enabled == State.ACTIVE) {
+                  register(player)
+                  sender.sendMM("<gray>[SMCDB] Successfully registered.")
+                } else {
+                  sender.sendMM("<red>[SMCDB] simplymcdb is disabled.")
+                }
+              }
+              else -> sender.sendMM("<red>[SMCDB] Invalid command.")
+            }
+            commandBuffer.remove(player.uniqueId)
+          }
+        }
+      }
+    }

src/main/kotlin/net/hareworks/simplymcdb/Event.kt

@@ -46,18 +46,15 @@ public object EventListener : Listener {
     |    not     | confirm  register |
     +------------+------------------*/
     if (isRegistered(event.player.uniqueId)) fetch(event.player)
-    else if (event.player.hasPlayedBefore()) {
-      register(event.player)
-    } else {
-      event.player.sendMessage(
-              MiniMessage.miniMessage()
-                      .deserialize(
-                              "<gray>[SMCDB] Welcome, ${event.player.name}.<newline>" +
-                                      "SMCDB is active but you have already played before.<newline>" +
-                                      "Run <green>/smcdb register<gray> to register yourself."
-                      )
+    else if (event.player.hasPlayedBefore()) register(event.player)
+    else event.player.sendMessage(
+      MiniMessage.miniMessage()
+        .deserialize(
+          "<gray>[SMCDB] Welcome, ${event.player.name}.<newline>" +
+          "SMCDB is active but you have already played before.<newline>" +
+          "Run <green>/smcdb register<gray> to register yourself."
       )
-    }
+    )
   }
 
   @EventHandler

src/main/kotlin/net/hareworks/simplymcdb/PlayerSerializer.kt

@@ -1,68 +1,179 @@
 package net.hareworks.simplymcdb
 
-import de.tr7zw.nbtapi.NBT
+import de.tr7zw.changeme.nbtapi.NBT
+import java.util.Base64
 import java.util.function.Function
+import io.papermc.paper.registry.RegistryAccess
+import io.papermc.paper.registry.RegistryKey
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.SerializationException
+import kotlinx.serialization.json.Json
+import org.bukkit.NamespacedKey
+import org.bukkit.Registry
+import org.bukkit.attribute.Attribute
 import org.bukkit.entity.Player as BukkitPlayer
+import org.bukkit.inventory.ItemStack
+import org.bukkit.potion.PotionEffect
+import org.bukkit.potion.PotionEffectType
 
-data class PlayerData(
-        val health: Float,
-        val hunger: Int,
-        val exp: Float,
-        val effects: String,
-        val inv: String,
-        val enderchest: String
+const val PLAYER_DATA_CURRENT_VERSION = 1
+
+@Serializable
+data class PlayerSnapshot(
+        val version: Int = PLAYER_DATA_CURRENT_VERSION,
+        val health: Double,
+        val foodLevel: Int,
+        val xpProgress: Float,
+        val selectedItemSlot: Int,
+        val potionEffects: List<PotionEffectSnapshot>,
+        val inventory: List<ItemStackSnapshot?>,
+        val enderChest: List<ItemStackSnapshot?>
 )
 
+@Serializable
+data class PotionEffectSnapshot(
+        val type: String,
+        val amplifier: Int,
+        val duration: Int,
+        val ambient: Boolean,
+        val particles: Boolean,
+        val icon: Boolean
+)
+
+@Serializable data class ItemStackSnapshot(val payload: String)
+
+private val json =
+        Json {
+          encodeDefaults = true
+          ignoreUnknownKeys = true
+        }
+private val mobEffectRegistry: Registry<PotionEffectType>?
+  get() = RegistryAccess.registryAccess().getRegistry(RegistryKey.MOB_EFFECT)
+
 object PlayerSerializer {
   fun serialize(player: BukkitPlayer): String {
-    val result =
-            NBT.get(
-                    player,
-                    Function { nbt ->
-                      var output = NBT.createNBTObject()
-
-                      output.setFloat("Health", player.health.toFloat())
-                      output.setInteger("foodLevel", player.foodLevel)
-                      output.setFloat("XpP", player.exp)
-                      output.setInteger("SelectedItemSlot", player.inventory.heldItemSlot)
-                      var active_effects = output.getCompoundList("active_effects")
-                      nbt.getCompoundList("active_effects").forEach {
-                        active_effects.addCompound(it)
-                      }
-                      var inventory = output.getCompoundList("Inventory")
-                      nbt.getCompoundList("Inventory").forEach { inventory.addCompound(it) }
-                      var enderchest = output.getCompoundList("EnderItems")
-                      nbt.getCompoundList("EnderItems").forEach { enderchest.addCompound(it) }
-
-                      output.toString()
-                    }
+    val snapshot =
+            PlayerSnapshot(
+                    health = player.health,
+                    foodLevel = player.foodLevel,
+                    xpProgress = player.exp,
+                    selectedItemSlot = player.inventory.heldItemSlot,
+                    potionEffects = player.activePotionEffects.map(::serializePotionEffect),
+                    inventory = player.inventory.contents.map { it?.let(::serializeItemStack) },
+                    enderChest = player.enderChest.contents.map { it?.let(::serializeItemStack) }
             )
-    return result
+    return json.encodeToString(PlayerSnapshot.serializer(), snapshot)
   }
 
   fun deserialize(player: BukkitPlayer, data: String) {
-    NBT.modify(
-            player,
-            Function { nbt ->
-              val input = NBT.parseNBT(data)
-
-              App.instance.logger.info("Deserializing player data: $data")
-              App.instance.logger.info("deserialized: ${input.toString()}")
-
-              nbt.setFloat("Health", input.getFloat("Health"))
-              nbt.setInteger("foodLevel", input.getInteger("foodLevel"))
-              nbt.setFloat("XpP", input.getFloat("XpP"))
-              nbt.setInteger("SelectedItemSlot", input.getInteger("SelectedItemSlot"))
-              val active_effects = nbt.getCompoundList("active_effects")
-              active_effects.clear()
-              input.getCompoundList("active_effects").forEach { active_effects.addCompound(it) }
-              val inventory = nbt.getCompoundList("Inventory")
-              inventory.clear()
-              input.getCompoundList("Inventory").forEach { inventory.addCompound(it) }
-              val enderchest = nbt.getCompoundList("EnderItems")
-              enderchest.clear()
-              input.getCompoundList("EnderItems").forEach { enderchest.addCompound(it) }
+    val snapshot =
+            try {
+              json.decodeFromString(PlayerSnapshot.serializer(), data)
+            } catch (ex: SerializationException) {
+              if (LegacySerializer.deserialize(player, data)) return else throw ex
+            } catch (ex: IllegalArgumentException) {
+              if (LegacySerializer.deserialize(player, data)) return else throw ex
             }
-    )
+    applySnapshot(player, migrateIfNeeded(snapshot))
+  }
+
+  private fun migrateIfNeeded(snapshot: PlayerSnapshot): PlayerSnapshot {
+    var current = snapshot
+    var version = snapshot.version
+    while (version < PLAYER_DATA_CURRENT_VERSION) {
+      current = migrateOnce(version, current)
+      version++
+    }
+    return current
+  }
+
+  private fun migrateOnce(fromVersion: Int, snapshot: PlayerSnapshot): PlayerSnapshot {
+    return when (fromVersion) {
+      1 -> snapshot
+      else -> snapshot
+    }
+  }
+
+  private fun applySnapshot(player: BukkitPlayer, snapshot: PlayerSnapshot) {
+    val maxHealth = player.getAttribute(Attribute.MAX_HEALTH)?.value ?: player.health
+    player.health = snapshot.health.coerceIn(0.0, maxHealth)
+    player.foodLevel = snapshot.foodLevel.coerceIn(0, 20)
+    player.exp = snapshot.xpProgress.coerceIn(0f, 1f)
+    player.inventory.heldItemSlot =
+            snapshot.selectedItemSlot.coerceIn(0, player.inventory.contents.size - 1)
+
+    player.activePotionEffects.forEach { player.removePotionEffect(it.type) }
+    snapshot.potionEffects.forEach { eff ->
+      val typeKey = NamespacedKey.fromString(eff.type)
+      val type = typeKey?.let { key -> mobEffectRegistry?.get(key) }
+      if (type == null) {
+        App.instance.logger.warning("Unknown potion effect key during restore: ${eff.type}")
+        return@forEach
+      }
+      val potion = PotionEffect(type, eff.duration, eff.amplifier, eff.ambient, eff.particles, eff.icon)
+      player.addPotionEffect(potion)
+    }
+
+    player.inventory.clear()
+    snapshot.inventory.forEachIndexed { index, item ->
+      player.inventory.setItem(index, item?.let(::deserializeItemStack))
+    }
+
+    player.enderChest.clear()
+    snapshot.enderChest.forEachIndexed { index, item ->
+      player.enderChest.setItem(index, item?.let(::deserializeItemStack))
+    }
+  }
+}
+
+private fun serializePotionEffect(effect: PotionEffect): PotionEffectSnapshot {
+  val typeKey = effect.type.key().toString()
+  return PotionEffectSnapshot(
+          type = typeKey,
+          amplifier = effect.amplifier,
+          duration = effect.duration,
+          ambient = effect.isAmbient,
+          particles = effect.hasParticles(),
+          icon = effect.hasIcon()
+  )
+}
+
+private fun serializeItemStack(item: ItemStack): ItemStackSnapshot {
+  val bytes = item.ensureServerConversions().serializeAsBytes()
+  return ItemStackSnapshot(Base64.getEncoder().encodeToString(bytes))
+}
+
+private fun deserializeItemStack(snapshot: ItemStackSnapshot): ItemStack {
+  val data = Base64.getDecoder().decode(snapshot.payload)
+  return ItemStack.deserializeBytes(data)
+}
+
+private object LegacySerializer {
+  fun deserialize(player: BukkitPlayer, data: String): Boolean {
+    return try {
+      NBT.modify(
+              player,
+              Function { nbt ->
+                val input = NBT.parseNBT(data)
+                nbt.setFloat("Health", input.getFloat("Health"))
+                nbt.setInteger("foodLevel", input.getInteger("foodLevel"))
+                nbt.setFloat("XpP", input.getFloat("XpP"))
+                nbt.setInteger("SelectedItemSlot", input.getInteger("SelectedItemSlot"))
+                val activeEffects = nbt.getCompoundList("active_effects")
+                activeEffects.clear()
+                input.getCompoundList("active_effects").forEach { activeEffects.addCompound(it) }
+                val inventory = nbt.getCompoundList("Inventory")
+                inventory.clear()
+                input.getCompoundList("Inventory").forEach { inventory.addCompound(it) }
+                val enderchest = nbt.getCompoundList("EnderItems")
+                enderchest.clear()
+                input.getCompoundList("EnderItems").forEach { enderchest.addCompound(it) }
+              }
+      )
+      App.instance.logger.info("Legacy player data applied; will be migrated on next save.")
+      true
+    } catch (_: Exception) {
+      false
+    }
   }
 }

src/main/kotlin/net/hareworks/simplymcdb/Players.kt

@@ -17,6 +17,7 @@ public object Players : Table() {
   val lastIp = varchar("last_ip", 15)
 
   val data = text("data").default("")
+  val dataVersion = integer("data_version").default(0)
 
   override val primaryKey = PrimaryKey(uuid)
 }
@@ -39,6 +40,7 @@ public fun register(player: BukkitPlayer) {
       it[firstLogin] = System.currentTimeMillis()
       it[lastOnline] = System.currentTimeMillis()
       it[lastIp] = player.address?.address?.hostAddress ?: "unknown"
+      it[dataVersion] = 0
     }
   }
 }
@@ -52,6 +54,7 @@ public fun update(player: BukkitPlayer) {
 
       // player.sendMessage(dat)
       it[data] = dat
+      it[dataVersion] = PLAYER_DATA_CURRENT_VERSION
     }
   }
 }
@@ -68,3 +71,25 @@ public fun fetch(player: BukkitPlayer) {
   // player.sendMessage(dat)
   PlayerSerializer.deserialize(player, dat)
 }
+
+data class PlayerDataEntry(val uuid: UUID, val serialized: String, val version: Int)
+
+public fun findPlayersNeedingMigration(): List<PlayerDataEntry> {
+  return transaction(Database.instance) {
+    Players
+            .selectAll()
+            .where { (Players.dataVersion less PLAYER_DATA_CURRENT_VERSION) and (Players.data neq "") }
+            .map {
+              PlayerDataEntry(UUID.fromString(it[Players.uuid]), it[Players.data], it[Players.dataVersion])
+            }
+  }
+}
+
+public fun overwritePlayerData(uuid: UUID, data: String, version: Int = PLAYER_DATA_CURRENT_VERSION) {
+  transaction(Database.instance) {
+    Players.update({ Players.uuid eq uuid.toString() }) {
+      it[Players.data] = data
+      it[Players.dataVersion] = version
+    }
+  }
+}

src/main/kotlin/net/hareworks/simplymcdb/database/Database.kt

@@ -51,6 +51,7 @@ public object Database {
     }
     if (instance == null) return
     App.instance.logger.info("Database connected: $host:$port/$database")
+    transaction(instance) { SchemaUtils.createMissingTablesAndColumns(Players) }
   }
   public fun disconnect() {
     instance?.let {