Allow passing side to piston upgrade's push() function.

Down won't work in tablets held by players because they're holding it too high, but I honestly don't care.
Refactored and extended ExtendedArguments a bit to be more in line with normal Arguments' methods.

src/main/scala/li/cil/oc/server/component/UpgradePiston.scala

@@ -11,6 +11,7 @@ import li.cil.oc.api.network.Visibility
 import li.cil.oc.api.prefab
 import li.cil.oc.util.BlockPosition
 import li.cil.oc.util.ExtendedWorld._
+import li.cil.oc.util.ExtendedArguments._
 import net.minecraft.init.Blocks
 
 class UpgradePiston(val host: Rotatable with EnvironmentHost) extends prefab.ManagedEnvironment {
@@ -19,11 +20,12 @@ class UpgradePiston(val host: Rotatable with EnvironmentHost) extends prefab.Man
     withConnector().
     create()
 
-  @Callback(doc = """function():boolean -- Tries to push the block in front of the container of the upgrade.""")
+  @Callback(doc = """function([side:number]):boolean -- Tries to push the block on the specified side of the container of the upgrade. Defaults to front.""")
   def push(context: Context, args: Arguments): Array[AnyRef] = {
     val hostPos = BlockPosition(host)
-    val blockPos = hostPos.offset(host.facing)
+    val facing = args.optSideForAction(0, host.facing)
-    if (!host.world.isAirBlock(blockPos) && node.tryChangeBuffer(-Settings.get.pistonCost) && Blocks.piston.tryExtend(host.world, hostPos.x, hostPos.y, hostPos.z, host.facing.ordinal)) {
+    val blockPos = hostPos.offset(facing)
+    if (!host.world.isAirBlock(blockPos) && node.tryChangeBuffer(-Settings.get.pistonCost) && Blocks.piston.tryExtend(host.world, hostPos.x, hostPos.y, hostPos.z, facing.ordinal)) {
       host.world.setBlockToAir(blockPos)
       host.world.playSoundEffect(host.xPosition, host.yPosition, host.zPosition, "tile.piston.out", 0.5f, host.world.rand.nextFloat() * 0.25f + 0.6f)
       context.pause(0.5)

src/main/scala/li/cil/oc/server/component/traits/InventoryControl.scala

@@ -50,7 +50,7 @@ trait InventoryControl extends InventoryAware {
   @Callback(doc = "function(toSlot:number[, amount:number]):boolean -- Move up to the specified amount of items from the selected slot into the specified slot.")
   def transferTo(context: Context, args: Arguments): Array[AnyRef] = {
     val slot = args.checkSlot(inventory, 0)
-    val count = args.optionalItemCount(1)
+    val count = args.optItemCount(1)
     if (slot == selectedSlot || count == 0) {
       result(true)
     }

src/main/scala/li/cil/oc/server/component/traits/InventoryWorldControl.scala

@@ -33,7 +33,7 @@ trait InventoryWorldControl extends InventoryAware with WorldAware with SideRest
   @Callback(doc = "function(side:number[, count:number=64]):boolean -- Drops items from the selected slot towards the specified side.")
   def drop(context: Context, args: Arguments): Array[AnyRef] = {
     val facing = checkSideForAction(args, 0)
-    val count = args.optionalItemCount(1)
+    val count = args.optItemCount(1)
     val stack = inventory.getStackInSlot(selectedSlot)
     if (stack != null && stack.stackSize > 0) {
       val blockPos = position.offset(facing)
@@ -69,7 +69,7 @@ trait InventoryWorldControl extends InventoryAware with WorldAware with SideRest
   @Callback(doc = "function(side:number[, count:number=64]):boolean -- Suck up items from the specified side.")
   def suck(context: Context, args: Arguments): Array[AnyRef] = {
     val facing = checkSideForAction(args, 0)
-    val count = args.optionalItemCount(1)
+    val count = args.optItemCount(1)
 
     val blockPos = position.offset(facing)
     if (InventoryUtils.inventoryAt(blockPos).exists(inventory => {

src/main/scala/li/cil/oc/server/component/traits/InventoryWorldControlMk2.scala

@@ -14,7 +14,7 @@ trait InventoryWorldControlMk2 extends InventoryAware with WorldAware with SideR
   @Callback(doc = """function(facing:number, slot:number[, count:number]):boolean -- Drops the selected item stack into the specified slot of an inventory.""")
   def dropIntoSlot(context: Context, args: Arguments): Array[AnyRef] = {
     val facing = checkSideForAction(args, 0)
-    val count = args.optionalItemCount(2)
+    val count = args.optItemCount(2)
     val stack = inventory.getStackInSlot(selectedSlot)
     if (stack != null && stack.stackSize > 0) {
       withInventory(facing, inventory => {
@@ -43,7 +43,7 @@ trait InventoryWorldControlMk2 extends InventoryAware with WorldAware with SideR
   @Callback(doc = """function(facing:number, slot:number[, count:number]):boolean -- Sucks items from the specified slot of an inventory.""")
   def suckFromSlot(context: Context, args: Arguments): Array[AnyRef] = {
     val facing = checkSideForAction(args, 0)
-    val count = args.optionalItemCount(2)
+    val count = args.optItemCount(2)
     withInventory(facing, inventory => {
       val slot = args.checkSlot(inventory, 1)
       if (InventoryUtils.extractFromInventorySlot(InventoryUtils.insertIntoInventory(_, this.inventory, slots = Option(insertionSlots)), inventory, facing.getOpposite, slot, count)) {

src/main/scala/li/cil/oc/server/component/traits/TankControl.scala

@@ -53,7 +53,7 @@ trait TankControl extends TankAware {
   @Callback(doc = "function(index:number[, count:number=1000]):boolean -- Move the specified amount of fluid from the selected tank into the specified tank.")
   def transferFluidTo(context: Context, args: Arguments): Array[AnyRef] = {
     val index = args.checkTank(tank, 0)
-    val count = args.optionalFluidCount(1)
+    val count = args.optFluidCount(1)
     if (index == selectedTank || count == 0) {
       result(true)
     }

src/main/scala/li/cil/oc/server/component/traits/TankInventoryControl.scala

@@ -35,7 +35,7 @@ trait TankInventoryControl extends WorldAware with InventoryAware with TankAware
 
   @Callback(doc = """function([amount:number]):boolean -- Transfers fluid from a tank in the selected inventory slot to the selected tank.""")
   def drain(context: Context, args: Arguments): Array[AnyRef] = {
-    val amount = args.optionalFluidCount(0)
+    val amount = args.optFluidCount(0)
     Option(tank.getFluidTank(selectedTank)) match {
       case Some(into) => inventory.getStackInSlot(selectedSlot) match {
         case stack: ItemStack =>
@@ -77,7 +77,7 @@ trait TankInventoryControl extends WorldAware with InventoryAware with TankAware
 
   @Callback(doc = """function([amount:number]):boolean -- Transfers fluid from the selected tank to a tank in the selected inventory slot.""")
   def fill(context: Context, args: Arguments): Array[AnyRef] = {
-    val amount = args.optionalFluidCount(0)
+    val amount = args.optFluidCount(0)
     Option(tank.getFluidTank(selectedTank)) match {
       case Some(from) => inventory.getStackInSlot(selectedSlot) match {
         case stack: ItemStack =>

src/main/scala/li/cil/oc/server/component/traits/TankWorldControl.scala

@@ -36,7 +36,7 @@ trait TankWorldControl extends TankAware with WorldAware with SideRestricted {
   @Callback(doc = "function(side:boolean[, amount:number=1000]):boolean, number or string -- Drains the specified amount of fluid from the specified side. Returns the amount drained, or an error message.")
   def drain(context: Context, args: Arguments): Array[AnyRef] = {
     val facing = checkSideForAction(args, 0)
-    val count = args.optionalFluidCount(1)
+    val count = args.optFluidCount(1)
     getTank(selectedTank) match {
       case Some(tank) =>
         val space = tank.getCapacity - tank.getFluidAmount
@@ -97,7 +97,7 @@ trait TankWorldControl extends TankAware with WorldAware with SideRestricted {
   @Callback(doc = "function(side:number[, amount:number=1000]):boolean, number of string -- Eject the specified amount of fluid to the specified side. Returns the amount ejected or an error message.")
   def fill(context: Context, args: Arguments): Array[AnyRef] = {
     val facing = checkSideForAction(args, 0)
-    val count = args.optionalFluidCount(1)
+    val count = args.optFluidCount(1)
     getTank(selectedTank) match {
       case Some(tank) =>
         val amount = math.min(count, tank.getFluidAmount)

src/main/scala/li/cil/oc/util/ExtendedArguments.scala

@@ -12,17 +12,13 @@ object ExtendedArguments {
   implicit def extendedArguments(args: Arguments): ExtendedArguments = new ExtendedArguments(args)
 
   class ExtendedArguments(val args: Arguments) {
-    def optionalItemCount(n: Int) =
+    def optItemCount(index: Int, default: Int = 64) =
-      if (args.count > n && args.checkAny(n) != null) {
+      if (!isDefined(index) || !hasValue(index)) default
-        math.max(0, math.min(64, args.checkInteger(n)))
+      else math.max(0, math.min(64, args.checkInteger(index)))
-      }
-      else 64
 
-    def optionalFluidCount(n: Int) =
+    def optFluidCount(index: Int, default: Int = 1000) =
-      if (args.count > n && args.checkAny(n) != null) {
+      if (!isDefined(index) || !hasValue(index)) default
-        math.max(0, args.checkInteger(n))
+      else math.max(0, args.checkInteger(index))
-      }
-      else 1000
 
     def checkSlot(inventory: IInventory, n: Int) = {
       val slot = args.checkInteger(n) - 1
@@ -32,9 +28,9 @@ object ExtendedArguments {
       slot
     }
 
-    def optSlot(inventory: IInventory, n: Int, default: Int) = {
+    def optSlot(inventory: IInventory, index: Int, default: Int) = {
-      if (n >= 0 && n < args.count()) checkSlot(inventory, n)
+      if (!isDefined(index)) default
-      else default
+      else checkSlot(inventory, index)
     }
 
     def checkTank(multi: MultiTank, n: Int) = {
@@ -45,14 +41,26 @@ object ExtendedArguments {
       tank
     }
 
-    def checkSideForAction(n: Int) = checkSide(n, ForgeDirection.SOUTH, ForgeDirection.UP, ForgeDirection.DOWN)
+    def checkSideForAction(index: Int) = checkSide(index, ForgeDirection.SOUTH, ForgeDirection.UP, ForgeDirection.DOWN)
 
-    def checkSideForMovement(n: Int) = checkSide(n, ForgeDirection.SOUTH, ForgeDirection.NORTH, ForgeDirection.UP, ForgeDirection.DOWN)
+    def optSideForAction(index: Int, default: ForgeDirection) =
+      if (!isDefined(index)) default
+      else checkSideForAction(index)
 
-    def checkSideForFace(n: Int, facing: ForgeDirection) = checkSide(n, ForgeDirection.VALID_DIRECTIONS.filter(_ != facing.getOpposite): _*)
+    def checkSideForMovement(index: Int) = checkSide(index, ForgeDirection.SOUTH, ForgeDirection.NORTH, ForgeDirection.UP, ForgeDirection.DOWN)
 
-    def checkSide(n: Int, allowed: ForgeDirection*) = {
+    def optSideForMovement(index: Int, default: ForgeDirection) =
-      val side = args.checkInteger(n)
+      if (!isDefined(index)) default
+      else checkSideForMovement(index)
+
+    def checkSideForFace(index: Int, facing: ForgeDirection) = checkSide(index, ForgeDirection.VALID_DIRECTIONS.filter(_ != facing.getOpposite): _*)
+
+    def optSideForFace(index: Int, default: ForgeDirection) =
+      if (!isDefined(index)) default
+      else checkSideForAction(index)
+
+    def checkSide(index: Int, allowed: ForgeDirection*) = {
+      val side = args.checkInteger(index)
       if (side < 0 || side > 5) {
         throw new IllegalArgumentException("invalid side")
       }
@@ -60,6 +68,15 @@ object ExtendedArguments {
       if (allowed.isEmpty || (allowed contains direction)) direction
       else throw new IllegalArgumentException("unsupported side")
     }
+
+    def optSide(index: Int, default: ForgeDirection, allowed: ForgeDirection*) = {
+      if (!isDefined(index)) default
+      else checkSide(index, allowed: _*)
+    }
+
+    private def isDefined(index: Int) = index >= 0 && index < args.count()
+
+    private def hasValue(index: Int) = args.checkAny(index) != null
   }
 
 }