src/main/scala/li/cil/oc/server/driver/Registry.scala

package li.cil.oc.server.driver

import java.util

import li.cil.oc.OpenComputers
import li.cil.oc.api
import li.cil.oc.api.driver.Converter
import li.cil.oc.api.driver.EnvironmentHost
import li.cil.oc.api.driver.item.HostAware
import li.cil.oc.api.machine.Value
import net.minecraft.item.ItemStack
import net.minecraft.world.World

import scala.collection.convert.WrapAsScala._
import scala.collection.mutable
import scala.math.ScalaNumber

/**
 * This class keeps track of registered drivers and provides installation logic
 * for each registered driver.
 *
 * Each component type must register its driver with this class to be used with
 * computers, since this class is used to determine whether an object is a
 * valid component or not.
 *
 * All drivers must be installed once the game starts - in the init phase - and
 * are then injected into all computers started up past that point. A driver is
 * a set of functions made available to the computer. These functions will
 * usually require a component of the type the driver wraps to be installed in
 * the computer, but may also provide context-free functions.
 */
private[oc] object Registry extends api.detail.DriverAPI {
  val blocks = mutable.ArrayBuffer.empty[api.driver.Block]

  val items = mutable.ArrayBuffer.empty[api.driver.Item]

  val converters = mutable.ArrayBuffer.empty[api.driver.Converter]

  /** Used to keep track of whether we're past the init phase. */
  var locked = false

  override def add(driver: api.driver.Block) {
    if (locked) throw new IllegalStateException("Please register all drivers in the init phase.")
    if (!blocks.contains(driver)) blocks += driver
  }

  override def add(driver: api.driver.Item) {
    if (locked) throw new IllegalStateException("Please register all drivers in the init phase.")
    if (!blocks.contains(driver)) items += driver
  }

  override def add(converter: Converter) {
    if (locked) throw new IllegalStateException("Please register all converters in the init phase.")
    if (!converters.contains(converter)) converters += converter
  }

  def driverFor(world: World, x: Int, y: Int, z: Int) =
    blocks.filter(_.worksWith(world, x, y, z)) match {
      case drivers if drivers.nonEmpty => new CompoundBlockDriver(drivers: _*)
      case _ => null
    }

  def driverFor(stack: ItemStack, host: Class[_ <: EnvironmentHost]) =
    if (stack != null) {
      val hostAware = items.collect {
        case driver: HostAware => driver
      }
      if (hostAware.size > 0) {
        hostAware.find(_.worksWith(stack, host)).orNull
      }
      else driverFor(stack)
    }
    else null

  def driverFor(stack: ItemStack) =
    if (stack != null) items.find(_.worksWith(stack)).orNull
    else null

  def convert(value: Array[AnyRef]) = if (value != null) value.map(arg => convertRecursively(arg, new util.IdentityHashMap())) else null

  def convertRecursively(value: Any, memo: util.IdentityHashMap[AnyRef, AnyRef], force: Boolean = false): AnyRef = {
    val valueRef = value match {
      case number: ScalaNumber => number.underlying
      case reference: AnyRef => reference
      case null => null
      case primitive => primitive.asInstanceOf[AnyRef]
    }
    if (!force && memo.containsKey(valueRef)) {
      memo.get(valueRef)
    }
    else valueRef match {
      case null | Unit | None => null

      case arg: java.lang.Boolean => arg
      case arg: java.lang.Byte => arg
      case arg: java.lang.Character => arg
      case arg: java.lang.Short => arg
      case arg: java.lang.Integer => arg
      case arg: java.lang.Long => arg
      case arg: java.lang.Float => arg
      case arg: java.lang.Double => arg
      case arg: java.lang.String => arg

      case arg: Array[Boolean] => arg
      case arg: Array[Byte] => arg
      case arg: Array[Character] => arg
      case arg: Array[Short] => arg
      case arg: Array[Integer] => arg
      case arg: Array[Long] => arg
      case arg: Array[Float] => arg
      case arg: Array[Double] => arg
      case arg: Array[String] => arg

      case arg: Value => arg

      case arg: Array[_] => convertList(arg, arg.zipWithIndex.iterator, memo)
      case arg: Product => convertList(arg, arg.productIterator.zipWithIndex, memo)
      case arg: Seq[_] => convertList(arg, arg.zipWithIndex.iterator, memo)
      case arg: java.lang.Iterable[_] => convertList(arg, arg.zipWithIndex.iterator, memo)

      case arg: Map[_, _] => convertMap(arg, arg, memo)
      case arg: mutable.Map[_, _] => convertMap(arg, arg.toMap, memo)
      case arg: java.util.Map[_, _] => convertMap(arg, arg.toMap, memo)

      case arg =>
        val converted = new util.HashMap[AnyRef, AnyRef]()
        memo += arg -> converted
        converters.foreach(converter => try converter.convert(arg, converted) catch {
          case t: Throwable => OpenComputers.log.warn("Type converter threw an exception.", t)
        })
        if (converted.isEmpty) {
          memo += arg -> null
          null
        }
        else if (converted.size == 1 && converted.containsKey("oc:flatten")) {
          val value = converted.get("oc:flatten")
          memo += arg -> value // Update memoization map.
          value
        }
        else {
          // This is a little nasty but necessary because we need to keep the
          // 'converted' value up-to-date for any reference created to it in
          // the following convertRecursively call. For example:
          // - Converter C is called for A with map M.
          // - C puts A into M again.
          // - convertRecursively(M) encounters A in the memoization map, uses M.
          //   That M is then 'wrong', as in not fully converted. Hence the clear
          //   plus copy action afterwards.
          memo += converted -> converted // Makes convertMap re-use the map.
          convertRecursively(converted, memo, force = true)
          memo -= converted
          converted
        }
    }
  }

  def convertList(obj: AnyRef, list: Iterator[(Any, Int)], memo: util.IdentityHashMap[AnyRef, AnyRef]) = {
    val converted = mutable.ArrayBuffer.empty[AnyRef]
    memo += obj -> converted
    for ((value, index) <- list) {
      converted += convertRecursively(value, memo)
    }
    converted.toArray
  }

  def convertMap(obj: AnyRef, map: Map[_, _], memo: util.IdentityHashMap[AnyRef, AnyRef]) = {
    val converted = memo.getOrElseUpdate(obj, mutable.Map.empty[AnyRef, AnyRef]) match {
      case map: mutable.Map[AnyRef, AnyRef]@unchecked => map
      case map: java.util.Map[AnyRef, AnyRef]@unchecked => mapAsScalaMap(map)
    }
    map.collect {
      case (key: AnyRef, value: AnyRef) => converted += convertRecursively(key, memo) -> convertRecursively(value, memo)
    }
    memo.get(obj)
  }
}