feat: add Smaller Stacks module to reduce maximum item stack sizes

Author: Sybsuper

README.md

@@ -31,6 +31,7 @@ The following modules are currently available:
 - **Bad Air Caves**: Sometimes, poisonous gas will fill caves, causing damage to players.
 - **Baby Creatures**: Any LivingEntity can spawn as a baby, babies are faster and smaller than their adult counterparts.
 - **Expensive Trades**: Villager trades are more expensive, making it harder to obtain valuable items.
+- **Smaller Stack Sizes**: Item stack sizes are reduced, making inventory management more challenging.
 - **More to come**: This plugin is a work in progress, with more modules planned for future releases.
 
 ## Configuration

src/main/kotlin/com/sybsuper/sybsafetyfirst/modules/ModuleManager.kt

@@ -34,7 +34,8 @@ object ModuleManager {
         SkillBasedInventory(),
         BadAirCaves(),
         BabyCreatures(),
-        ExpensiveTrades()
+        ExpensiveTrades(),
+        SmallerStacks()
     )
     private val currentModuleInstances = modules.associateBy { it.id }.toMutableMap()
     private val nameMap = modules.associateBy { it.name }

src/main/kotlin/com/sybsuper/sybsafetyfirst/modules/SmallerStacks.kt

@@ -0,0 +1,57 @@
+package com.sybsuper.sybsafetyfirst.modules
+
+import kotlinx.serialization.Serializable
+import org.bukkit.event.EventHandler
+import org.bukkit.event.inventory.InventoryClickEvent
+import org.bukkit.event.inventory.InventoryMoveItemEvent
+import org.bukkit.event.player.PlayerAttemptPickupItemEvent
+import org.bukkit.event.player.PlayerSwapHandItemsEvent
+import org.bukkit.inventory.ItemStack
+
+class SmallerStacks : Module {
+    override val description: String = "Reduces the maximum stack size of items."
+    override var options: ModuleOptions = SmallerStacksOptions()
+    val typeSafeOptions
+        get() = (options as? SmallerStacksOptions)
+            ?: error("Options are not of type SmallerStacksOptions")
+
+    @Serializable
+    data class SmallerStacksOptions(
+        override var enabled: Boolean = true,
+        /**
+         * The maximum stack size for all items.
+         */
+        var maxStackSize: Int = 31
+    ) : ModuleOptions
+
+    fun patchItem(item: ItemStack?) {
+        val meta = item?.itemMeta ?: return
+        val maxStackSize = if (meta.hasMaxStackSize()) {
+            meta.maxStackSize
+        } else {
+            item.type.maxStackSize
+        }
+        meta.setMaxStackSize(maxStackSize.coerceAtMost(typeSafeOptions.maxStackSize))
+        item.itemMeta = meta
+    }
+
+    @EventHandler(ignoreCancelled = true)
+    fun on(event: InventoryClickEvent) {
+        patchItem(event.currentItem ?: return)
+    }
+
+    @EventHandler(ignoreCancelled = true)
+    fun on(event: PlayerAttemptPickupItemEvent) {
+        patchItem(event.item.itemStack)
+    }
+
+    @EventHandler(ignoreCancelled = true)
+    fun on(event: PlayerSwapHandItemsEvent) {
+        patchItem(event.mainHandItem ?: return)
+    }
+
+    @EventHandler(ignoreCancelled = true)
+    fun on(event: InventoryMoveItemEvent) {
+        patchItem(event.item ?: return)
+    }
+}