such a kotlin moment

setup shop command
setup shop listener
setup item registration

src/main/java/dev/plex/ShopModule.kt

@@ -1,11 +1,48 @@
 package dev.plex
 
+import dev.plex.commands.ShopCommand
+import dev.plex.config.ModuleConfig
+import dev.plex.listener.ShopListener
 import dev.plex.module.PlexModule
+import dev.plex.shop.ShopMenu
+import dev.plex.shop.item.impl.FireballItem
+import dev.plex.util.PlexLog
+import dev.plex.util.item.ItemBuilder
+import dev.plex.util.minimessage.SafeMiniMessage
+import org.bukkit.Material
 
-public class ShopModule : PlexModule() {
+class ShopModule : PlexModule() {
+    companion object {
+        private var module: ShopModule? = null;
+        fun get(): ShopModule
+        {
+            return module!!
+        }
+    }
+
+    private var config: ModuleConfig? = null
+
+    override fun load()
+    {
+        module = this;
+        config = ModuleConfig(this, "data/config.yml", "config.yml")
+        getConfig().load()
+    }
 
     override fun enable() {
+        ShopMenu.registerItem(18, FireballItem(
+                ItemBuilder(Material.FIRE_CHARGE).displayName(SafeMiniMessage.mmDeserialize("<!italic><red>Fireball")).build(),
+                getConfig().getDouble("shop.prices.fireball", 0.0)
+        ))
 
+        registerListener(ShopListener())
+        registerCommand(ShopCommand())
+        PlexLog.debug("Shop loaded!")
+    }
+
+    fun getConfig(): ModuleConfig
+    {
+        return config!!
     }
 
 }

src/main/java/dev/plex/commands/ShopCommand.kt

@@ -0,0 +1,23 @@
+package dev.plex.commands
+
+import dev.plex.cache.DataUtils
+import dev.plex.command.PlexCommand
+import dev.plex.command.annotation.CommandParameters
+import dev.plex.command.annotation.CommandPermissions
+import dev.plex.command.source.RequiredCommandSource
+import dev.plex.rank.enums.Rank
+import dev.plex.shop.ShopMenu
+import net.kyori.adventure.text.Component
+import org.bukkit.command.CommandSender
+import org.bukkit.entity.Player
+
+@CommandParameters(name = "shop", description = "Opens the shop menu")
+@CommandPermissions(level = Rank.OP, source = RequiredCommandSource.IN_GAME, permission = "plex.shop.open")
+class ShopCommand: PlexCommand()
+{
+    override fun execute(sender: CommandSender, player: Player?, args: Array<out String>?): Component?
+    {
+        ShopMenu.open(DataUtils.getPlayer(player!!.uniqueId))
+        return null
+    }
+}

src/main/java/dev/plex/listener/ShopListener.kt

@@ -0,0 +1,23 @@
+package dev.plex.listener
+
+import dev.plex.util.minimessage.SafeMiniMessage
+import net.kyori.adventure.text.Component
+import org.bukkit.event.EventHandler
+import org.bukkit.event.inventory.InventoryClickEvent
+
+class ShopListener : PlexListener()
+{
+    private val shopMenuTitle: Component = SafeMiniMessage.mmDeserialize("<gold>Shop")
+
+    @EventHandler
+    fun onClick(event: InventoryClickEvent)
+    {
+        if (!event.view.title().equals(shopMenuTitle))
+        {
+            return
+        }
+        event.isCancelled = true
+
+    }
+
+}

src/main/java/dev/plex/shop/ShopMenu.kt

@@ -1,9 +1,12 @@
 package dev.plex.shop
 
+import com.google.common.collect.Maps
 import dev.plex.player.PlexPlayer
 import dev.plex.shop.item.AbstractItem
+import dev.plex.util.item.ItemBuilder
 import dev.plex.util.minimessage.SafeMiniMessage
 import org.bukkit.Bukkit
+import org.bukkit.Material
 import org.bukkit.entity.Player
 import org.bukkit.inventory.Inventory
 
@@ -13,22 +16,35 @@ import org.bukkit.inventory.Inventory
  * @since 11:21 PM [10-06-2022]
  *
  */
-class ShopMenu {
-    companion object {
-        val ITEMS = mapOf<Int, AbstractItem>()
-    }
-
-    fun open(plexPlayer: PlexPlayer)
+class ShopMenu
+{
+    companion object
     {
-        val player: Player? = plexPlayer.player
-        val inventory: Inventory = constructInventory()
-        player?.openInventory(inventory)
-    }
+        val ITEMS: HashMap<Int, AbstractItem> = Maps.newHashMap()
+        fun registerItem(index: Int, item: AbstractItem)
+        {
+            ITEMS.put(index, item);
+        }
 
-    private fun constructInventory(): Inventory
-    {
-        val inventory: Inventory = Bukkit.createInventory(null, 54, SafeMiniMessage.mmDeserialize("<gold>Shop"))
-        ITEMS.forEach { (t, u) ->  inventory.setItem(t, u.item) }
-        return inventory
+        fun open(plexPlayer: PlexPlayer)
+        {
+            val player: Player? = plexPlayer.player
+            val inventory: Inventory = constructInventory()
+            player?.openInventory(inventory)
+        }
+
+        private fun constructInventory(): Inventory
+        {
+            val inventory: Inventory = Bukkit.createInventory(null, 54, SafeMiniMessage.mmDeserialize("<gold>Shop"))
+            ITEMS.forEach { (t, u) -> inventory.setItem(t, u.item) }
+            for (i in 0 until inventory.size)
+            {
+                if (inventory.getItem(i) == null || inventory.getItem(i)?.type == Material.AIR)
+                {
+                    inventory.setItem(i, ItemBuilder(Material.GRAY_STAINED_GLASS_PANE).displayName(SafeMiniMessage.mmDeserialize("<!italic> ")).build())
+                }
+            }
+            return inventory
+        }
     }
 }

src/main/java/dev/plex/shop/item/impl/FireballItem.kt

@@ -0,0 +1,8 @@
+package dev.plex.shop.item.impl
+
+import dev.plex.shop.item.AbstractItem
+import org.bukkit.inventory.ItemStack
+
+class FireballItem(item: ItemStack, cost: Double) : AbstractItem(item, cost)
+{
+}

src/main/resources/module.yml

@@ -1,4 +1,4 @@
-name: Module-Example
+name: Plex-Shop
 main: dev.plex.ShopModule
 description: An example module for Plex
 version: 1.0