Add CustomItemModule

common/src/main/kotlin/com/bluedragonmc/server/module/gameplay/CustomItemModule.kt

@@ -0,0 +1,115 @@
+package com.bluedragonmc.server.module.gameplay
+
+import com.bluedragonmc.server.Game
+import com.bluedragonmc.server.module.GameModule
+import net.minestom.server.entity.Player
+import net.minestom.server.event.Event
+import net.minestom.server.event.EventFilter
+import net.minestom.server.event.EventNode
+import net.minestom.server.event.item.ItemDropEvent
+import net.minestom.server.event.item.PickupItemEvent
+import net.minestom.server.event.player.PlayerUseItemEvent
+import net.minestom.server.item.ItemStack
+import net.minestom.server.tag.Tag
+import java.util.*
+
+class CustomItemModule(vararg val items: CustomItem) : GameModule() {
+
+    companion object {
+        private val CUSTOM_UUID_TAG = Tag.String("custom_item_uid")
+    }
+    override fun initialize(parent: Game, eventNode: EventNode<Event>) {
+        items.forEach { registerItem(it) }
+    }
+
+    fun registerItem(item: CustomItem) {
+        eventNode.addChild(item.eventNode)
+    }
+
+    fun giveItem(player: Player, item: CustomItem) {
+        item.onObtain(player)
+        player.inventory.addItemStack(item.getItemStack())
+    }
+
+    fun giveItem(player: Player, item: CustomItem, amount: Int) {
+        item.onObtain(player)
+        player.inventory.addItemStack(item.getItemStack().withAmount(amount))
+    }
+
+    fun giveItem(player: Player, uid: String) = giveItem(player, getCustomItem(uid))
+
+    fun giveItem(player: Player, uid: String, amount: Int) = giveItem(player, getCustomItem(uid), amount)
+
+    fun getCustomItemOrNull(uid: String): CustomItem? {
+        for (i in items) {
+            if (i.uid == uid) return i
+        }
+        return null
+    }
+
+    fun getCustomItem(uid: String): CustomItem = getCustomItemOrNull(uid) ?: error("No custom item matches the given uid!")
+
+    /**
+     * Returns the [CustomItem] that the given `itemStack` is an instance of, or `null` if this item does not represent a CustomItem.
+     */
+    fun getCustomItemOrNull(itemStack: ItemStack): CustomItem? {
+        val uid = itemStack.getTag(CUSTOM_UUID_TAG) ?: return null // itemStack is not a custom item
+        for (i in items) {
+            if (uid == i.uid) return i
+        }
+        return null
+    }
+
+    /**
+     * Returns the [CustomItem] that the given `itemStack` is an instance of, or throws an error if this item does not represent a CustomItem.
+     */
+    fun getCustomItem(itemStack: ItemStack) = getCustomItemOrNull(itemStack) ?: error("No custom item matches the given itemStack!")
+    override fun toString(): String {
+        return "CustomItemModule(startingItems=${items.contentToString()})"
+    }
+
+    abstract class CustomItem {
+        /**
+         * A unique value that identifies all items of this type.
+         */
+        abstract val uid: String
+
+        protected abstract fun createItemStack(): ItemStack
+
+        fun getItemStack(): ItemStack {
+            return createItemStack().withTag(CUSTOM_UUID_TAG, uid)
+        }
+
+        val eventNode by lazy {
+            // Create an event node that only receives events related to this item
+            val eventNode = EventNode.event("custom-item-${UUID.randomUUID()}-$uid", EventFilter.ITEM) { event ->
+                event.itemStack.getTag(CUSTOM_UUID_TAG) == uid
+            }
+
+            eventNode.addListener(net.minestom.server.event.player.PlayerUseItemEvent::class.java) { event ->
+                onUse(event)
+            }
+            eventNode.addListener(ItemDropEvent::class.java) { event ->
+                onDrop(event)
+            }
+            eventNode.addListener(PickupItemEvent::class.java) { event ->
+                onPickup(event)
+            }
+
+            return@lazy eventNode
+        }
+
+        protected open fun onUse(event: PlayerUseItemEvent) {}
+        protected open fun onDrop(event: ItemDropEvent) {}
+        protected open fun onPickup(event: PickupItemEvent) {}
+
+        /**
+         * Called when a player obtains this item from a [giveItem] call.
+         */
+        open fun onObtain(player: Player) {}
+
+        override fun toString(): String {
+            return "CustomItem(uid='$uid')"
+        }
+    }
+}