Refactored a few things out of the trading upgrade into InventoryUtils, making things a little more consistent, added manual entry for trade upgrade, tweaked the texture for the trade upgrade a bit.

src/main/resources/assets/opencomputers/doc/en_US/item/index.md

@@ -50,6 +50,7 @@ Keep in mind that some of these may not be available, depending on the recipe se
 * [Tank Controller](tankControllerUpgrade.md)
 * [Tank Upgrade](tankUpgrade.md)
 * [Tractor Beam Upgrade](tractorBeamUpgrade.md)
+* [Trading Upgrade](tradingUpgrade.md)
 * [Upgrade Container](upgradeContainer1.md)
 
 ### Other

src/main/resources/assets/opencomputers/doc/en_US/item/tradingUpgrade.md

@@ -0,0 +1,5 @@
+# Trading Upgrade
+
+![Equivalent Exchange](oredict:oc:tradingUpgrade)
+
+The trading upgrade enables automatic trading with merchants, such as villagers. It can be used in agents such as [robots](../block/robot.md) and [drones](drone.md) and provides capabilities to identify available trades from nearby merchants, retrieve information on individual trade offers, and finally for performing trades.

src/main/resources/assets/opencomputers/recipes/default.recipes

@@ -335,6 +335,11 @@ tractorBeamUpgrade {
           [ingotIron, "oc:capacitor", ingotIron]
           [ingotGold, "oc:circuitChip3", ingotGold]]
 }
+tradingUpgrade {
+  input: [[ingotGold, chest, ingotGold]
+          [emerald, "oc:circuitChip2", emerald]
+          [dropper, "oc:materialCircuitBoardPrinted", craftingPiston]]
+}
 
 cardContainer1 {
   input: [[ingotIron, "oc:circuitChip1", ingotIron]
@@ -367,12 +372,6 @@ upgradeContainer3 {
           [ingotGold, "oc:materialCircuitBoardPrinted", ingotGold]]
 }
 
-upgradeTrading {
-  input: [[ingotGold, chest, ingotGold]
-          [emerald, "oc:circuitChip2", emerald]
-          [dropper, "oc:materialCircuitBoardPrinted", craftingPiston]]
-}
-
 # Note: iron ingot and nugget recipes are *only* registered if no other mod
 # already provides the same functionality.
 nuggetIron {

src/main/resources/assets/opencomputers/recipes/hardmode.recipes

@@ -181,8 +181,7 @@ solarGeneratorUpgrade {
   input: [[blockGlass, blockGlass, blockGlass]
           ["oc:circuitChip3", "oc:generatorUpgrade", "oc:circuitChip3"]]
 }
-
-upgradeTrading {
+tradingUpgrade {
   input: [["oc:circuitChip2", chest, "oc:circuitChip2"]
           [emerald, "oc:circuitChip2", emerald]
           [dropper, "oc:materialCircuitBoardPrinted", craftingPiston]]

src/main/scala/li/cil/oc/Constants.scala

@@ -154,7 +154,7 @@ object Constants {
     final val TerminalServer = "terminalServer"
     final val TexturePicker = "texturePicker"
     final val TractorBeamUpgrade = "tractorBeamUpgrade"
-    final val TradingUpgrade = "upgradeTrading"
+    final val TradingUpgrade = "tradingUpgrade"
     final val Transistor = "transistor"
     final val UpgradeContainerTier1 = "upgradeContainer1"
     final val UpgradeContainerTier2 = "upgradeContainer2"

src/main/scala/li/cil/oc/common/init/Items.scala

@@ -532,8 +532,7 @@ object Items extends ItemAPI {
     // 1.6.0
     Recipes.addSubItem(new item.TerminalServer(multi), Constants.ItemName.TerminalServer, "oc:terminalServer")
     Recipes.addSubItem(new item.DiskDriveMountable(multi), Constants.ItemName.DiskDriveMountable, "oc:diskDriveMountable")
-
-    Recipes.addSubItem(new item.UpgradeTrading(multi), Constants.ItemName.TradingUpgrade, "oc:upgradeTrading")
+    Recipes.addSubItem(new item.UpgradeTrading(multi), Constants.ItemName.TradingUpgrade, "oc:tradingUpgrade")
 
     // Register aliases.
     for ((k, v) <- aliases) {

src/main/scala/li/cil/oc/integration/opencomputers/DriverUpgradeTrading.scala

@@ -1,16 +1,15 @@
 package li.cil.oc.integration.opencomputers
 
-import li.cil.oc.api
 import li.cil.oc.Constants
+import li.cil.oc.api
 import li.cil.oc.api.driver.EnvironmentProvider
-import li.cil.oc.api.network.EnvironmentHost
 import li.cil.oc.api.driver.item.HostAware
-import li.cil.oc.common.{Tier, Slot}
+import li.cil.oc.api.network.EnvironmentHost
+import li.cil.oc.common.Slot
+import li.cil.oc.common.Tier
+import li.cil.oc.server.component
 import li.cil.oc.server.component.UpgradeTrading
 import net.minecraft.item.ItemStack
-import li.cil.oc.common.entity.Drone
-import li.cil.oc.common.tileentity.Robot
-import li.cil.oc.server.component
 
 object DriverUpgradeTrading extends Item with HostAware {
   override def worksWith(stack: ItemStack) = isOneOf(stack,
@@ -18,11 +17,7 @@ object DriverUpgradeTrading extends Item with HostAware {
 
   override def createEnvironment(stack: ItemStack, host: EnvironmentHost) =
     if (host.world.isRemote) null
-    else host match {
-      case host: EnvironmentHost with Robot => new UpgradeTrading(host)
-      case host: EnvironmentHost with Drone => new UpgradeTrading(host)
-      case _ => null
-    }
+    else new UpgradeTrading(host)
 
   override def slot(stack: ItemStack) = Slot.Upgrade
 
@@ -34,4 +29,5 @@ object DriverUpgradeTrading extends Item with HostAware {
         classOf[component.UpgradeTrading]
       else null
   }
+
 }

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

@@ -4,253 +4,192 @@ import java.util.UUID
 
 import li.cil.oc.Settings
 import li.cil.oc.api.machine._
+import li.cil.oc.api.network.EnvironmentHost
 import li.cil.oc.api.prefab.AbstractValue
 import li.cil.oc.common.EventHandler
 import li.cil.oc.util.InventoryUtils
-import net.minecraft.entity.passive.EntityVillager
+import net.minecraft.entity.Entity
+import net.minecraft.entity.IMerchant
 import net.minecraft.item.ItemStack
 import net.minecraft.nbt.NBTTagCompound
+import net.minecraft.tileentity.TileEntity
 import net.minecraft.village.MerchantRecipe
 import net.minecraftforge.common.DimensionManager
 import net.minecraftforge.common.util.ForgeDirection
-import ref.WeakReference
-import li.cil.oc.api.network.EnvironmentHost
-import scala.collection.JavaConverters._
 
-class Trade(info: TradeInfo) extends AbstractValue {
+import scala.collection.convert.WrapAsScala._
+import scala.ref.WeakReference
 
+class Trade(val info: TradeInfo) extends AbstractValue {
   def this() = this(new TradeInfo())
-  def this(upgr: UpgradeTrading, villager: EntityVillager, recipeID: Int) = {
-    this(new TradeInfo(upgr.host, villager, recipeID))
-  }
 
+  def this(upgrade: UpgradeTrading, merchant: IMerchant, recipeID: Int) =
+    this(new TradeInfo(upgrade.host, merchant, recipeID))
 
-  override def load(nbt: NBTTagCompound) = {
-    EventHandler.scheduleServer(() => {
-      //Tell the info to load from NBT, behind EventHandler because when load is called we can't access the world yet
-      //and we need to access it to get the Robot/Drone TileEntity/Entity
-      info.load(nbt)
-    })
-  }
+  def maxRange = Settings.get.tradingRange
 
-  override def save(nbt: NBTTagCompound) = {
-    //Tell info to save to nbt
-    info.save(nbt)
-  }
-
-  def inventory = info.inventory
-
-  @Callback(doc="function():table, table -- returns the items the villager wants for this trade")
-  def getInput(context: Context, arguments: Arguments): Array[AnyRef] = {
-    Array(info.recipe.getItemToBuy.copy(),
-      info.recipe.hasSecondItemToBuy match {
-        case true => info.recipe.getSecondItemToBuy.copy()
-        case false => null
-      })
-  }
-
-  @Callback(doc = "function():table -- returns the item the villager offers for this trade")
-  def getOutput(context: Context, arguments: Arguments): Array[AnyRef] = {
-    Array(info.recipe.getItemToSell.copy())
-  }
-
-  @Callback(doc="function():boolean -- returns whether the villager currently wants to trade this")
-  def isEnabled(context: Context, arguments: Arguments): Array[AnyRef] = {
-    Array(info.villager.exists((villager: EntityVillager) => // Make sure villager is neither dead/gone nor the recipe
-      !info.recipe.isRecipeDisabled                          // has been disabled
-    ).asInstanceOf[AnyRef])
-  }
-
-  val maxRange = Settings.get.tradingRange
-  def inRange = info.villager.isDefined && distance.exists((distance: Double) => distance < maxRange)
-  def distance = info.villager match {
-    case Some(villager: EntityVillager) =>
-      info.host match {
-        case Some(h: EnvironmentHost) => Some(Math.sqrt(Math.pow(villager.posX - h.xPosition, 2) + Math.pow(villager.posY - h.yPosition, 2) + Math.pow(villager.posZ - h.zPosition, 2)))
-        case _ => None
-      }
-    case None => None
-  }
-
-  @Callback(doc="function():boolean, string -- returns true when trade succeeds and nil, error when not")
-  def trade(context: Context, arguments: Arguments): Array[AnyRef] = {
-    //Make sure we can access an inventory
-    val inventory = info.inventory match {
-      case Some(i) => i
-      case None => return result(false, "trading requires an inventory upgrade to be installed")
-    }
-
-    //Make sure villager hasn't died, it somehow gone or moved out of range
-    if (info.villager.isEmpty)
-      return result(false, "trade has become invalid")
-    else if (!info.villager.get.isEntityAlive)
-      return result(false, "trader died")
-    if (!inRange) {
-      return result(false, "out of range")
-    }
-
-    //Make sure villager wants to trade this
-    if (info.recipe.isRecipeDisabled)
-      return result(false, "recipe is disabled")
-
-    //Now we'll check if we have enough items to perform the trade, caching first
-    val firstItem = info.recipe.getItemToBuy
-    val secondItem = info.recipe.hasSecondItemToBuy match {
-      case true => Some(info.recipe.getSecondItemToBuy)
-      case false => None
-    }
-
-    //Check if we have enough of the first item
-    var extracting: Int = firstItem.stackSize
-    for (slot <- 0 until inventory.getSizeInventory) {
-      val stack = inventory.getStackInSlot(slot)
-      if (stack != null && stack.isItemEqual(firstItem) && extracting > 0)
-        //Takes the stack in the slot, extracts up to limit and calls the function in the first argument
-        //We don't actually consume anything, we just count that we have extracted as much as we need
-        InventoryUtils.extractFromInventorySlot((stack: ItemStack) => extracting -= stack.stackSize, inventory, ForgeDirection.UNKNOWN, slot, extracting)
-    }
-    //If we had enough, the left-over amount will be 0
-    if (extracting != 0)
-      return result(false, "not enough items to trade")
-
-    //Do the same with the second item if there is one
-    if (secondItem.isDefined) {
-      extracting = secondItem.orNull.stackSize
-      for (slot <- 0 until inventory.getSizeInventory) {
-        val stack = inventory.getStackInSlot(slot)
-        if (stack != null && stack.isItemEqual(secondItem.orNull) && extracting > 0)
-          InventoryUtils.extractFromInventorySlot((stack: ItemStack) => extracting -= stack.stackSize, inventory, ForgeDirection.UNKNOWN, slot, extracting)
-      }
-      if (extracting != 0)
-        return result(false, "not enough items to trade")
-    }
-
-    //Now we need to check if we have enough inventory space to accept the item we get for the trade
-    val outputItemSim = info.recipe.getItemToSell.copy()
-    InventoryUtils.insertIntoInventory(outputItemSim, inventory, None, 64, simulate = true)
-    if (outputItemSim.stackSize != 0)
-      return result(false, "not enough inventory space to trade")
-
-    //We established that out inventory allows to perform the trade, now actaully do the trade
-    extracting = firstItem.stackSize
-    for (slot <- 0 until inventory.getSizeInventory) {
-      if (extracting != 0) {
-        val stack = inventory.getStackInSlot(slot)
-        if (stack != null && stack.isItemEqual(firstItem))
-          //Pretty much the same as earlier (but counting down, and not up now)
-          //but this time we actually consume the stack we get
-          InventoryUtils.extractFromInventorySlot((stack: ItemStack) => {
-            extracting -= stack.stackSize
-            stack.stackSize = 0
-          }, inventory, ForgeDirection.UNKNOWN, slot, extracting)
-      }
-    }
-
-    //Do the same for the second item
-    if (secondItem.isDefined) {
-      extracting = secondItem.orNull.stackSize
-      for (slot <- 0 until inventory.getSizeInventory) {
-        if (extracting != 0) {
-          val stack = inventory.getStackInSlot(slot)
-          if (stack != null && stack.isItemEqual(secondItem.orNull))
-            InventoryUtils.extractFromInventorySlot((stack: ItemStack) => {
-              extracting -= stack.stackSize
-              stack.stackSize = 0
-            }, inventory, ForgeDirection.UNKNOWN, slot, extracting)
-        }
-      }
-    }
-
-    //Now put our output item into the inventory
-    val outputItem = info.recipe.getItemToSell.copy()
-    while (outputItem.stackSize != 0)
-      InventoryUtils.insertIntoInventory(outputItem, inventory, None, outputItem.stackSize)
-
-    //Tell the villager we used the recipe, so MC can disable it and/or enable more recipes
-    info.villager.orNull.useRecipe(info.recipe)
-    result(true)
-  }
-}
-
-class TradeInfo() {
-  def this(host: EnvironmentHost, villager: EntityVillager, recipeID: Int) = {
-    this()
-    _vilRef = new WeakReference[EntityVillager](villager)
-    _recipeID = recipeID
-    this.host = host
-  }
-
-  def getEntityByUUID(dimID: Int, uuid: UUID) = DimensionManager.getProvider(dimID).worldObj.getLoadedEntityList.asScala.find {
-    case entAny: net.minecraft.entity.Entity if entAny.getPersistentID == uuid => true
+  def isInRange = (info.merchant.get, info.host) match {
+    case (Some(merchant: Entity), Some(host)) => merchant.getDistanceSq(host.xPosition, host.yPosition, host.zPosition) < maxRange * maxRange
     case _ => false
   }
 
-  def getTileEntity(dimID: Int, posX: Int, posY: Int, posZ: Int) = Option(DimensionManager.getProvider(dimID).worldObj.getTileEntity(posX, posY, posZ) match {
-    case robot : li.cil.oc.common.tileentity.Robot => robot
-    case robotProxy : li.cil.oc.common.tileentity.RobotProxy => robotProxy.robot
-    case null => None
-  })
+  // Queue the load because when load is called we can't access the world yet
+  // and we need to access it to get the Robot's TileEntity / Drone's Entity.
+  override def load(nbt: NBTTagCompound) = EventHandler.scheduleServer(() => info.load(nbt))
+
+  override def save(nbt: NBTTagCompound) = info.save(nbt)
+
+  @Callback(doc = "function():table, table -- Returns the items the merchant wants for this trade.")
+  def getInput(context: Context, arguments: Arguments): Array[AnyRef] =
+    result(info.recipe.map(_.getItemToBuy.copy()).orNull,
+      if (info.recipe.exists(_.hasSecondItemToBuy)) info.recipe.map(_.getSecondItemToBuy.copy()).orNull else null)
+
+  @Callback(doc = "function():table -- Returns the item the merchant offers for this trade.")
+  def getOutput(context: Context, arguments: Arguments): Array[AnyRef] =
+    result(info.recipe.map(_.getItemToSell.copy()).orNull)
+
+  @Callback(doc = "function():boolean -- Returns whether the merchant currently wants to trade this.")
+  def isEnabled(context: Context, arguments: Arguments): Array[AnyRef] =
+    result(info.merchant.get.exists(merchant => !info.recipe.exists(_.isRecipeDisabled))) // Make sure merchant is neither dead/gone nor the recipe has been disabled.
+
+  @Callback(doc = "function():boolean, string -- Returns true when trade succeeds and nil, error when not.")
+  def trade(context: Context, arguments: Arguments): Array[AnyRef] = {
+    // Make sure we can access an inventory.
+    info.inventory match {
+      case Some(inventory) =>
+        // Make sure merchant hasn't died, it somehow gone or moved out of range and still wants to trade this.
+        info.merchant.get match {
+          case Some(merchant: Entity) if merchant.isEntityAlive && isInRange =>
+            if (!merchant.isEntityAlive) {
+              result(false, "trader died")
+            } else if (!isInRange) {
+              result(false, "out of range")
+            } else {
+              info.recipe match {
+                case Some(recipe) =>
+                  if (recipe.isRecipeDisabled) {
+                    result(false, "trade is disabled")
+                  } else {
+                    // Now we'll check if we have enough items to perform the trade, caching first
+                    val firstInputStack = recipe.getItemToBuy
+                    val secondInputStack = if (recipe.hasSecondItemToBuy) Option(recipe.getSecondItemToBuy) else None
+
+                    def containsAccumulativeItemStack(stack: ItemStack) =
+                      InventoryUtils.extractFromInventory(stack, inventory, ForgeDirection.UNKNOWN, simulate = true).stackSize == 0
+                    def hasRoomForItemStack(stack: ItemStack) = {
+                      val remainder = stack.copy()
+                      InventoryUtils.insertIntoInventory(remainder, inventory, None, remainder.stackSize, simulate = true)
+                      remainder.stackSize == 0
+                    }
+
+                    // Check if we have enough to perform the trade.
+                    if (containsAccumulativeItemStack(firstInputStack) && secondInputStack.forall(containsAccumulativeItemStack)) {
+                      // Now we need to check if we have enough inventory space to accept the item we get for the trade.
+                      val outputStack = recipe.getItemToSell.copy()
+                      if (hasRoomForItemStack(outputStack)) {
+                        // We established that out inventory allows to perform the trade, now actually do the trade.
+                        InventoryUtils.extractFromInventory(firstInputStack, inventory, ForgeDirection.UNKNOWN)
+                        secondInputStack.map(InventoryUtils.extractFromInventory(_, inventory, ForgeDirection.UNKNOWN))
+                        InventoryUtils.insertIntoInventory(outputStack, inventory, None, outputStack.stackSize)
+
+                        // Tell the merchant we used the recipe, so MC can disable it and/or enable more recipes.
+                        info.merchant.get.orNull.useRecipe(recipe)
+
+                        result(true)
+                      } else {
+                        result(false, "not enough inventory space to trade")
+                      }
+                    } else {
+                      result(false, "not enough items to trade")
+                    }
+                  }
+                case _ => result(false, "trade has become invalid")
+              }
+            }
+          case _ => result(false, "trade has become invalid")
+        }
+      case _ => result(false, "trading requires an inventory upgrade to be installed")
+    }
+  }
+}
+
+class TradeInfo(var host: Option[EnvironmentHost], var merchant: WeakReference[IMerchant], var recipeID: Int) {
+  def this() = this(None, new WeakReference[IMerchant](null), -1)
+
+  def this(host: EnvironmentHost, merchant: IMerchant, recipeID: Int) =
+    this(Option(host), new WeakReference[IMerchant](merchant), recipeID)
+
+  def recipe = merchant.get.map(_.getRecipes(null).get(recipeID).asInstanceOf[MerchantRecipe])
+
+  def inventory = host match {
+    case Some(agent: li.cil.oc.api.internal.Agent) => Option(agent.mainInventory())
+    case _ => None
+  }
 
   def load(nbt: NBTTagCompound): Unit = {
-    val dimID = nbt.getInteger("dimensionID")
-    val _hostIsDrone = nbt.getBoolean("hostIsDrone")
-    //If drone we find it again by its UUID, if Robot we know the X/Y/Z of the TileEntity
-    host = Option(_hostIsDrone match {
-      case true => getEntityByUUID(dimID, UUID.fromString(nbt.getString("hostUUID"))).orNull.asInstanceOf[EnvironmentHost]
-      case false => getTileEntity(
-        dimID,
-        nbt.getInteger("hostX"),
-        nbt.getInteger("hostY"),
-        nbt.getInteger("hostZ")
-      ).orNull.asInstanceOf[EnvironmentHost]
+    val isEntity = nbt.getBoolean("hostIsEntity")
+    // If drone we find it again by its UUID, if Robot we know the X/Y/Z of the TileEntity.
+    host = if (isEntity) loadHostEntity(nbt) else loadHostTileEntity(nbt)
+    merchant = new WeakReference[IMerchant](loadEntity(nbt, new UUID(nbt.getLong("merchantUUIDMost"), nbt.getLong("merchantUUIDLeast"))) match {
+      case Some(merchant: IMerchant) => merchant
+      case _ => null
     })
-    _recipeID = nbt.getInteger("recipeID")
-    _vilRef = new WeakReference[EntityVillager](getEntityByUUID(dimID, UUID.fromString(nbt.getString("villagerUUID"))).orNull.asInstanceOf[EntityVillager])
+    recipeID = nbt.getInteger("recipeID")
   }
 
   def save(nbt: NBTTagCompound): Unit = {
     host match {
-      case Some(h) =>
-        nbt.setInteger("dimensionID", h.world.provider.dimensionId)
-        hostIsDrone match {
-          case true => nbt.setString("hostUUID", h.asInstanceOf[li.cil.oc.common.entity.Drone].getPersistentID.toString)
-          case false =>
-            nbt.setInteger("hostX", h.xPosition.floor.toInt)
-            nbt.setInteger("hostY", h.yPosition.floor.toInt)
-            nbt.setInteger("hostZ", h.zPosition.floor.toInt)
-        }
-      case None =>
+      case Some(entity: Entity) =>
+        nbt.setBoolean("hostIsEntity", true)
+        nbt.setInteger("dimensionID", entity.world.provider.dimensionId)
+        nbt.setLong("hostUUIDLeast", entity.getPersistentID.getLeastSignificantBits)
+        nbt.setLong("hostUUIDMost", entity.getPersistentID.getMostSignificantBits)
+      case Some(tileEntity: TileEntity) =>
+        nbt.setBoolean("hostIsEntity", false)
+        nbt.setInteger("dimensionID", tileEntity.getWorldObj.provider.dimensionId)
+        nbt.setInteger("hostX", tileEntity.xCoord)
+        nbt.setInteger("hostY", tileEntity.yCoord)
+        nbt.setInteger("hostZ", tileEntity.zCoord)
+      case _ => // Welp!
     }
-    villager match {
-      case Some(v) => nbt.setString("villagerUUID", v.getPersistentID.toString)
-      case None =>
+    merchant.get match {
+      case Some(entity: Entity) =>
+        nbt.setLong("merchantUUIDLeast", entity.getPersistentID.getLeastSignificantBits)
+        nbt.setLong("merchantUUIDMost", entity.getPersistentID.getMostSignificantBits)
+      case _ =>
     }
-    nbt.setBoolean("hostIsDrone", hostIsDrone)
-    nbt.setInteger("recipeID", _recipeID)
+    nbt.setInteger("recipeID", recipeID)
   }
 
-  def hostIsDrone = host.orNull match {
-    case h : li.cil.oc.common.tileentity.Robot => false
-    case h : li.cil.oc.common.entity.Drone => true
-    case _ => false
+  private def loadEntity(nbt: NBTTagCompound, uuid: UUID): Option[Entity] = {
+    val dimension = nbt.getInteger("dimensionID")
+    val world = DimensionManager.getProvider(dimension).worldObj
+
+    world.loadedEntityList.find {
+      case entity: Entity if entity.getPersistentID == uuid => true
+      case _ => false
+    }.map(_.asInstanceOf[Entity])
   }
-  private var _host: Option[EnvironmentHost] = None
-  private var _recipeID: Int = _
-  private var _vilRef: WeakReference[EntityVillager] = new WeakReference[EntityVillager](null)
 
-  def host = _host
-  private def host_= (value: EnvironmentHost): Unit = _host = Option(value)
-  private def host_= (value: Option[EnvironmentHost]): Unit = _host = value
-
-  def villager = _vilRef.get
-  def recipeID = _recipeID
-  def recipe : MerchantRecipe = villager.orNull.getRecipes(null).get(recipeID).asInstanceOf[MerchantRecipe]
-
-  def inventory = host match {
-    case Some(h) => hostIsDrone match {
-      case true => Some(h.asInstanceOf[li.cil.oc.common.entity.Drone].mainInventory)
-      case false => Some(h.asInstanceOf[li.cil.oc.common.tileentity.Robot].mainInventory)
+  private def loadHostEntity(nbt: NBTTagCompound): Option[EnvironmentHost] = {
+    loadEntity(nbt, new UUID(nbt.getLong("hostUUIDMost"), nbt.getLong("hostUUIDLeast"))) match {
+      case Some(entity: Entity with li.cil.oc.api.internal.Agent) => Option(entity: EnvironmentHost)
+      case _ => None
     }
-    case None => None
   }
-}
+
+  private def loadHostTileEntity(nbt: NBTTagCompound): Option[EnvironmentHost] = {
+    val dimension = nbt.getInteger("dimensionID")
+    val world = DimensionManager.getProvider(dimension).worldObj
+
+    val x = nbt.getInteger("hostX")
+    val y = nbt.getInteger("hostY")
+    val z = nbt.getInteger("hostZ")
+
+    world.getTileEntity(x, y, z) match {
+      case robotProxy: li.cil.oc.common.tileentity.RobotProxy => Option(robotProxy.robot)
+      case agent: li.cil.oc.api.internal.Agent => Option(agent)
+      case null => None
+    }
+  }
+}

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

@@ -1,16 +1,19 @@
 package li.cil.oc.server.component
 
 import li.cil.oc.Settings
-import li.cil.oc.api.network.EnvironmentHost
-import li.cil.oc.api.prefab
 import li.cil.oc.api.Network
+import li.cil.oc.api.machine.Arguments
+import li.cil.oc.api.machine.Callback
+import li.cil.oc.api.machine.Context
+import li.cil.oc.api.network.EnvironmentHost
 import li.cil.oc.api.network.Visibility
+import li.cil.oc.api.prefab
 import li.cil.oc.util.BlockPosition
-import li.cil.oc.api.machine.{Callback, Arguments, Context}
-import net.minecraft.entity.passive.EntityVillager
+import net.minecraft.entity.Entity
+import net.minecraft.entity.IMerchant
 import net.minecraft.util.Vec3
 
-import scala.collection.mutable.ArrayBuffer
+import scala.collection.convert.WrapAsScala._
 
 class UpgradeTrading(val host: EnvironmentHost) extends prefab.ManagedEnvironment with traits.WorldAware {
   override val node = Network.newNode(this, Visibility.Network).
@@ -19,29 +22,15 @@ class UpgradeTrading(val host: EnvironmentHost) extends prefab.ManagedEnvironmen
 
   override def position = BlockPosition(host)
 
-  var maxRange = Settings.get.tradingRange
+  def maxRange = Settings.get.tradingRange
 
-  def inRange(vil: EntityVillager): Boolean = {
-    Vec3.createVectorHelper(vil.posX, vil.posY, vil.posZ).distanceTo(position.toVec3) <= maxRange
-  }
+  def isInRange(entity: Entity) = Vec3.createVectorHelper(entity.posX, entity.posY, entity.posZ).distanceTo(position.toVec3) <= maxRange
 
-  @Callback(doc = "function():table -- Returns a table of trades in range as userdata objects")
+  @Callback(doc = "function():table -- Returns a table of trades in range as userdata objects.")
   def getTrades(context: Context, args: Arguments): Array[AnyRef] = {
-
-    val boundsLow = position.bounds.offset(-maxRange, -maxRange, -maxRange)
-    val boundsHigh = position.bounds.offset(maxRange, maxRange, maxRange)
-    val bounds = boundsLow.func_111270_a(boundsHigh)
-
-    val trades = ArrayBuffer[Trade]()
-    entitiesInBounds[EntityVillager](bounds).foreach((vil: EntityVillager) => {
-      if (inRange(vil)) {
-        val merchantRecipes = vil.getRecipes(null)
-        for (i <- 0 to merchantRecipes.size() - 1) {
-          val trade = new Trade(this, vil, i)
-          trades += trade
-        }
-      }
-    })
-    trades.toArray[Object]
+    result(entitiesInBounds[Entity](position.bounds.expand(maxRange, maxRange, maxRange)).
+      filter(isInRange).
+      collect { case merchant: IMerchant => merchant }.
+      flatMap(merchant => merchant.getRecipes(null).indices.map(new Trade(this, merchant, _))))
   }
 }

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

@@ -73,7 +73,7 @@ trait InventoryWorldControl extends InventoryAware with WorldAware with SideRest
 
     val blockPos = position.offset(facing)
     if (InventoryUtils.inventoryAt(blockPos).exists(inventory => {
-      inventory.isUseableByPlayer(fakePlayer) && mayInteract(blockPos, facing.getOpposite) && InventoryUtils.extractFromInventory(InventoryUtils.insertIntoInventory(_, this.inventory, slots = Option(insertionSlots)), inventory, facing.getOpposite, count)
+      inventory.isUseableByPlayer(fakePlayer) && mayInteract(blockPos, facing.getOpposite) && InventoryUtils.extractAnyFromInventory(InventoryUtils.insertIntoInventory(_, this.inventory, slots = Option(insertionSlots)), inventory, facing.getOpposite, count)
     })) {
       context.pause(Settings.get.suckDelay)
       result(true)

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

@@ -21,7 +21,7 @@ trait ItemInventoryControl extends InventoryAware {
   def dropIntoItemInventory(context: Context, args: Arguments): Array[AnyRef] = {
     withItemInventory(args.checkSlot(inventory, 0), itemInventory => {
       val count = args.optItemCount(1)
-      result(InventoryUtils.extractFromInventory(InventoryUtils.insertIntoInventory(_, itemInventory), inventory, ForgeDirection.UNKNOWN, count))
+      result(InventoryUtils.extractAnyFromInventory(InventoryUtils.insertIntoInventory(_, itemInventory), inventory, ForgeDirection.UNKNOWN, count))
     })
   }
 
@@ -29,7 +29,7 @@ trait ItemInventoryControl extends InventoryAware {
   def suckFromItemInventory(context: Context, args: Arguments): Array[AnyRef] = {
     withItemInventory(args.checkSlot(inventory, 0), itemInventory => {
       val count = args.optItemCount(1)
-      result(InventoryUtils.extractFromInventory(InventoryUtils.insertIntoInventory(_, inventory, slots = Option(insertionSlots)), itemInventory, ForgeDirection.UNKNOWN, count))
+      result(InventoryUtils.extractAnyFromInventory(InventoryUtils.insertIntoInventory(_, inventory, slots = Option(insertionSlots)), itemInventory, ForgeDirection.UNKNOWN, count))
     })
   }
 

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

@@ -209,7 +209,7 @@ object InventoryUtils {
 
   /**
    * Extracts a slot from an inventory.
-   * </p>
+   * <p/>
    * This will try to extract a stack from any inventory slot. It will iterate
    * all slots until an item can be extracted from a slot.
    * <p/>
@@ -218,7 +218,7 @@ object InventoryUtils {
    * <p/>
    * This returns <tt>true</tt> if at least one item was extracted.
    */
-  def extractFromInventory(consumer: (ItemStack) => Unit, inventory: IInventory, side: ForgeDirection, limit: Int = 64) = {
+  def extractAnyFromInventory(consumer: (ItemStack) => Unit, inventory: IInventory, side: ForgeDirection, limit: Int = 64) = {
     val range = inventory match {
       case sided: ISidedInventory => sided.getAccessibleSlotsFromSide(side.ordinal).toIterable
       case _ => 0 until inventory.getSizeInventory
@@ -226,6 +226,35 @@ object InventoryUtils {
     range.exists(slot => extractFromInventorySlot(consumer, inventory, side, slot, limit))
   }
 
+  /**
+   * Extracts an item stack from an inventory.
+   * <p/>
+   * This will try to remove items of the same type as the specified item stack
+   * up to the number of the stack's size for all slots in the specified inventory.
+   * <p/>
+   * This uses the <tt>extractFromInventorySlot</tt> method, and therefore
+   * handles special cases such as sided inventories and stack size limits.
+   */
+  def extractFromInventory(stack: ItemStack, inventory: IInventory, side: ForgeDirection, simulate: Boolean = false) = {
+    val range = inventory match {
+      case sided: ISidedInventory => sided.getAccessibleSlotsFromSide(side.ordinal).toIterable
+      case _ => 0 until inventory.getSizeInventory
+    }
+    val remaining = stack.copy()
+    for (slot <- range if remaining.stackSize > 0) {
+      extractFromInventorySlot(stack => {
+        if (haveSameItemType(remaining, stack)) {
+          val transferred = stack.stackSize min remaining.stackSize
+          remaining.stackSize -= transferred
+          if (!simulate) {
+            stack.stackSize -= transferred
+          }
+        }
+      }, inventory, side, slot, remaining.stackSize)
+    }
+    remaining
+  }
+
   /**
    * Utility method for calling <tt>insertIntoInventory</tt> on an inventory
    * in the world.
@@ -238,7 +267,7 @@ object InventoryUtils {
    * in the world.
    */
   def extractFromInventoryAt(consumer: (ItemStack) => Unit, position: BlockPosition, side: ForgeDirection, limit: Int = 64) =
-    inventoryAt(position).exists(extractFromInventory(consumer, _, side, limit))
+    inventoryAt(position).exists(extractAnyFromInventory(consumer, _, side, limit))
 
   /**
    * Transfers some items between two inventories.
@@ -254,7 +283,7 @@ object InventoryUtils {
    * This returns <tt>true</tt> if at least one item was transferred.
    */
   def transferBetweenInventories(source: IInventory, sourceSide: ForgeDirection, sink: IInventory, sinkSide: Option[ForgeDirection], limit: Int = 64) =
-    extractFromInventory(
+    extractAnyFromInventory(
       insertIntoInventory(_, sink, sinkSide, limit), source, sourceSide, limit)
 
   /**