prevent 0 size batteries; recharge is minimally lossy

src/main/java/at/petrak/hexcasting/common/casting/ManaHelper.kt

@@ -20,35 +20,12 @@ object ManaHelper {
     }
 
     /**
-     * Try to extract the given amount of mana from this item.
+     * Extract [cost] mana from [stack]. If [cost] is less than zero, extract all mana instead.
-     * This may mutate the itemstack.
+     * This may mutate [stack] (and may consume it) unless [simulate] is set.
      *
-     * Return the actual amount of mana extracted, or null if this cannot have mana extracted.
+     * Return the amount of mana extracted. This may be over [cost] if mana is wasted.
      */
-    fun extractMana(stack: ItemStack, cost: Int): Int? {
+    fun extractMana(stack: ItemStack, cost: Int = -1, simulate: Boolean = false): Int {
-        val base = when (stack.item) {
-            HexItems.AMETHYST_DUST.get() -> HexConfig.dustManaAmount.get()
-            Items.AMETHYST_SHARD -> HexConfig.shardManaAmount.get()
-            HexItems.CHARGED_AMETHYST.get() -> HexConfig.chargedCrystalManaAmount.get()
-            HexItems.BATTERY.get() -> {
-                val battery = stack.item as ItemManaBattery
-                return battery.withdrawMana(stack.orCreateTag, cost)
-            }
-            else -> return null
-        }
-        val itemsReqd = ceil(cost.toFloat() / base.toFloat()).toInt()
-        val actualItemsConsumed = min(stack.count, itemsReqd)
-        stack.shrink(actualItemsConsumed)
-        return base * actualItemsConsumed
-    }
-
-    /**
-     * Extract the entirety of the mana out of this.
-     * This may mutate the itemstack (and will probably consume it).
-     *
-     * Return the amount of mana extracted.
-     */
-    fun extractAllMana(stack: ItemStack): Int {
         val base = when (stack.item) {
             HexItems.AMETHYST_DUST.get() -> HexConfig.dustManaAmount.get()
             Items.AMETHYST_SHARD -> HexConfig.shardManaAmount.get()
@@ -58,13 +35,18 @@ object ManaHelper {
                 val battery = stack.item as ItemManaBattery
                 val tag = stack.orCreateTag
                 val manaThere = battery.getManaAmt(tag)
-                return battery.withdrawMana(tag, manaThere)
+                val manaToExtract = if (cost < 0) manaThere else min(cost, manaThere)
+                if (simulate)
+                    return manaToExtract
+                return battery.withdrawMana(tag, manaToExtract)
             }
             else -> return 0
         }
         val count = stack.count
-        stack.shrink(count)
+        val countToExtract = if (cost < 0) count else min(count, ceil(cost.toDouble() / base).toInt())
-        return base * count
+        if (!simulate)
+            stack.shrink(countToExtract)
+        return base * countToExtract
     }
 
     /**

src/main/java/at/petrak/hexcasting/common/casting/operators/spells/OpMakeBattery.kt

@@ -43,7 +43,7 @@ object OpMakeBattery : SpellOperator {
 
         ctx.assertEntityInRange(entity)
 
-        if (!ManaHelper.isManaItem(entity.item)) {
+        if (!ManaHelper.isManaItem(entity.item) || ManaHelper.extractMana(entity.item, simulate = true) <= 0) {
             throw MishapBadItem.of(
                 entity.item,
                 "mana"
@@ -58,7 +58,7 @@ object OpMakeBattery : SpellOperator {
             val (handStack, hand) = ctx.getHeldItemToOperateOn { it.item == Items.GLASS_BOTTLE }
             if (handStack.item == Items.GLASS_BOTTLE && itemEntity.isAlive) {
                 val entityStack = itemEntity.item.copy()
-                val manaAmt = ManaHelper.extractAllMana(entityStack)
+                val manaAmt = ManaHelper.extractMana(entityStack)
                 if (manaAmt > 0) {
                     val replaceItem = ItemStack(HexItems.BATTERY.get())
                     val tag = replaceItem.orCreateTag

src/main/java/at/petrak/hexcasting/common/casting/operators/spells/OpMakePackagedSpell.kt

@@ -36,7 +36,7 @@ class OpMakePackagedSpell<T : ItemPackagedSpell>(val itemType: T, val cost: Int)
         }
 
         ctx.assertEntityInRange(entity)
-        if (!ManaHelper.isManaItem(entity.item)) {
+        if (!ManaHelper.isManaItem(entity.item) || ManaHelper.extractMana(entity.item, simulate = true) <= 0) {
             throw MishapBadItem.of(
                 entity.item,
                 "mana"
@@ -57,7 +57,7 @@ class OpMakePackagedSpell<T : ItemPackagedSpell>(val itemType: T, val cost: Int)
                 && itemEntity.isAlive
             ) {
                 val entityStack = itemEntity.item.copy()
-                val manaAmt = ManaHelper.extractAllMana(entityStack)
+                val manaAmt = ManaHelper.extractMana(entityStack)
                 if (manaAmt > 0) {
                     tag.putInt(ItemPackagedSpell.TAG_MANA, manaAmt)
                     tag.putInt(ItemPackagedSpell.TAG_MAX_MANA, manaAmt)

src/main/java/at/petrak/hexcasting/common/casting/operators/spells/OpRecharge.kt

@@ -47,19 +47,20 @@ object OpRecharge : SpellOperator {
 
             if (handStack.item is ItemManaHolder && itemEntity.isAlive) {
                 val entityStack = itemEntity.item.copy()
-                val manaAmt = ManaHelper.extractAllMana(entityStack)
+
-                if (manaAmt > 0) {
+                val tag = handStack.orCreateTag
-                    val tag = handStack.orCreateTag
+                val maxMana = if (tag.contains(ItemManaHolder.TAG_MAX_MANA))
-                    val maxMana = if (tag.contains(ItemManaHolder.TAG_MAX_MANA))
+                    tag.getInt(ItemManaHolder.TAG_MAX_MANA)
-                        tag.getInt(ItemManaHolder.TAG_MAX_MANA)
+                else
-                    else
+                    Int.MAX_VALUE
-                        Int.MAX_VALUE
+                val existingMana = if (tag.contains(ItemManaHolder.TAG_MANA))
-                    val existingMana = if (tag.contains(ItemManaHolder.TAG_MANA))
+                    tag.getInt(ItemManaHolder.TAG_MANA)
-                        tag.getInt(ItemManaHolder.TAG_MANA)
+                else
-                    else
+                    0
-                        0
+
-                    tag.putInt(ItemManaHolder.TAG_MANA, Mth.clamp(existingMana + manaAmt, 0, maxMana))
+                val manaAmt = ManaHelper.extractMana(entityStack, maxMana - existingMana)
-                }
+
+                tag.putInt(ItemManaHolder.TAG_MANA, Mth.clamp(existingMana + manaAmt, 0, maxMana))
 
                 itemEntity.item = entityStack
                 if (entityStack.isEmpty)