Nullable withdrawal or deposit tasks

Author: Avanatiker

common/src/main/kotlin/com/lambda/interaction/construction/result/BuildResult.kt

@@ -206,7 +206,7 @@ abstract class BuildResult : ComparableResult<Rank>, Nameable {
         override val pausesParent get() = true
 
         override fun resolve() = neededItem.select()
-            .transfer(MainHandContainer, inventory) ?: MaterialContainer.Nothing()
+            .transfer(MainHandContainer, inventory) ?: MaterialContainer.Nothing("Couldn't find ${neededItem.name.string} anywhere.")
 
         override fun SafeContext.buildRenderer() {
             if (blockPos.blockState(world).isAir) {
@@ -242,7 +242,7 @@ abstract class BuildResult : ComparableResult<Rank>, Nameable {
         override val pausesParent get() = true
 
         override fun resolve() =
-            neededStack.select().transfer(MainHandContainer, inventory) ?: MaterialContainer.Nothing()
+            neededStack.select().transfer(MainHandContainer, inventory) ?: MaterialContainer.Nothing("Couldn't find ${neededStack.item.name.string} anywhere.")
 
         override fun SafeContext.buildRenderer() {
             if (blockPos.blockState(world).isAir) {

common/src/main/kotlin/com/lambda/interaction/material/container/MaterialContainer.kt

@@ -82,21 +82,21 @@ abstract class MaterialContainer(
 
     class Nothing(override val name: String = "Nothing") : Task<Unit>() {
         override fun SafeContext.onStart() {
-            success()
+            failure(name)
         }
     }
 
     /**
      * Withdraws items from the container to the player's inventory.
      */
     @Task.Ta5kBuilder
-    open fun withdraw(selection: StackSelection): Task<*> = Nothing(name)
+    open fun withdraw(selection: StackSelection): Task<*>? = null
 
     /**
      * Deposits items from the player's inventory into the container.
      */
     @Task.Ta5kBuilder
-    open fun deposit(selection: StackSelection): Task<*> = Nothing(name)
+    open fun deposit(selection: StackSelection): Task<*>? = null
 
     open fun matchingStacks(selection: StackSelection) =
         selection.filterStacks(stacks)

common/src/main/kotlin/com/lambda/interaction/material/transfer/TransferResult.kt

@@ -31,11 +31,25 @@ abstract class TransferResult : Task<Unit>() {
         override val name = "Container Transfer of [$selection] from [${from.name}] to [${to.name}]"
 
         override fun SafeContext.onStart() {
-            from.withdraw(selection).then {
-                to.deposit(selection).finally {
-                    success()
+            val withdrawal = from.withdraw(selection)
+            val deposit = to.deposit(selection)
+
+            val task = when {
+                withdrawal != null && deposit != null -> {
+                    withdrawal.then {
+                        deposit.finally { success() }
+                    }
+                }
+                withdrawal != null -> {
+                    withdrawal.finally { success() }
                 }
-            }.execute(this@ContainerTransfer)
+                deposit != null -> {
+                    deposit.finally { success() }
+                }
+                else -> null
+            }
+
+            task?.execute(this@ContainerTransfer)
         }
     }