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/*
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package wvlet.airframe.surface.reflect

import wvlet.airframe.surface.CanonicalNameFormatter._
import wvlet.airframe.surface._
import wvlet.airframe.surface.reflect.ReflectTypeUtil._
import wvlet.log.LogSupport

import scala.collection.mutable
import scala.collection.mutable.ArrayBuffer
import scala.jdk.CollectionConverters._
import scala.language.existentials

//--------------------------------------
//
// ObjectBuilder.scala
// Since: 2012/01/25 12:41
//
//--------------------------------------

/**
  */
object ObjectBuilder extends LogSupport {
  def apply(s: Surface): ObjectBuilder = {
    new SimpleObjectBuilder(s)
  }

  def fromObject[A](surface: Surface, obj: A): ObjectBuilder = {
    val b = new SimpleObjectBuilder(surface)
    for (p <- surface.params) {
      b.set(p.name, p.get(obj))
    }
    b
  }

  sealed trait BuilderElement
  case class Holder(holder: ObjectBuilder)                 extends BuilderElement
  case class Value(value: Any)                             extends BuilderElement
  case class ArrayHolder(holder: mutable.ArrayBuffer[Any]) extends BuilderElement
}

trait GenericBuilder {
  def set(path: String, value: Any): Unit = set(Path(path), value)
  def set(path: Path, value: Any): Unit

  def get(name: String): Option[Any]
}

/**
  * Generic object builder
  *
  * @author leo
  */
trait ObjectBuilder extends GenericBuilder {
  def build: Any
}

/**
  * ObjectBuilder support overriding nested parameters by specifying a parameter path (Path)
  */
trait StandardBuilder extends GenericBuilder with LogSupport {
  import ObjectBuilder._

  protected val holder = collection.mutable.Map.empty[String, BuilderElement]

  protected def findParameter(name: String): Option[Parameter]
  protected def getParameterTypeOf(name: String) = findParameter(name).get

  protected def defaultValues: collection.immutable.Map[String, Any]

  // set the default values of the object
  for ((name, value) <- defaultValues) {
    val v: BuilderElement = findParameter(name).map {
      case p if canBuildFromBuffer(p.surface)      => Value(value)
      case p if canBuildFromStringValue(p.surface) => Value(value)

      case p if p.surface.objectFactory.isEmpty =>
        Value(value) // When no constructor to build p is found
      case p => {
        // nested object
        val b = new SimpleObjectBuilder(p.surface)
        for (x <- p.surface.params) {
          b.set(x.name.canonicalName, x.get(value))
        }
        Holder(b)
      }
    } getOrElse Value(value)

    holder += name -> v
  }

  private def canBuildFromStringValue(t: Surface): Boolean = {
    t match {
      case t if canBuildFromString(t) => true
      case o: OptionSurface           => canBuildFromStringValue(o.elementSurface)
      case _                          => false
    }
  }

  private def getArrayHolder(name: String): ArrayHolder = {
    // Clear the default value holder if exists
    holder.get(name) match {
      case Some(Value(v)) =>
        // remove the default value
        holder.remove(name)
      case _ => // do nothing
    }
    holder
      .getOrElseUpdate(name, ArrayHolder(new ArrayBuffer[Any]))
      .asInstanceOf[ArrayHolder]
  }

  def set(path: Path, value: Any): Unit = {
    if (path.isEmpty) {
      // do nothing
    } else {
      val name = path.head.canonicalName
      val p    = findParameter(name)
      if (p.isEmpty) {
        error(s"no parameter is found for path $path")
      } else {
        trace(s"set path $path : $value")
        if (path.isLeaf) {
          val targetType = p.get.surface
          trace(
            s"update value holder name:$name, valueType:$targetType (isArray:${isArray(targetType)}) with value:$value (${value.getClass})"
          )
          if (canBuildFromBuffer(targetType)) {
            val arr = getArrayHolder(name)
            targetType.typeArgs.length match {
              case 1 =>
                // Append array elements to the buffer
                val elementType = targetType.typeArgs(0)
                val lst = value match {
                  case a if isArrayCls(value.getClass) =>
                    a.asInstanceOf[Array[_]].toIndexedSeq
                  case a if isJavaColleciton(value.getClass) =>
                    a.asInstanceOf[java.util.Collection[_]].asScala.toIndexedSeq
                  case s if isSeq(value.getClass) => s.asInstanceOf[Seq[_]]
                  case other =>
                    Seq(other)
                }
                lst
                  .flatMap { x =>
                    TypeConverter.convert(x, elementType)
                  }
                  .foreach { arr.holder += _ }
              case 2 =>
                // Append map elements to the buffer
                val lst = value match {
                  case m if isJavaMap(value.getClass) =>
                    m.asInstanceOf[java.util.Map[_, _]].asScala.toMap
                  case m if isMap(m.getClass) => m.asInstanceOf[Map[_, _]]
                  case other                  => Seq(other)
                }
                val keyType   = targetType.typeArgs(0)
                val valueType = targetType.typeArgs(1)
                val tupleSurface =
                  TupleSurface(classOf[Tuple2[_, _]], Seq(keyType, valueType))
                lst
                  .flatMap { x =>
                    TypeConverter.convert(x, tupleSurface)
                  }
                  .foreach { arr.holder += _ }
              case other =>
                error(s"Cannot convert ${value} to ${targetType}")
            }
          } else if (canBuildFromStringValue(targetType)) {
            TypeConverter.convert(value, targetType).map { v =>
              holder += name -> Value(v)
            }
          } else {
            holder += name -> Value(value)
          }
        } else {
          // nested object
          val paramName = path.head.canonicalName
          val h         = holder.getOrElseUpdate(paramName, Holder(ObjectBuilder(p.get.surface)))
          h match {
            case Holder(b) => b.set(path.tailPath, value)
            case other     =>
              // overwrite the existing holder
              throw new IllegalStateException(
                "invalid path:%s, value:%s, holder:%s"
                  .format(path, value, other)
              )
          }
        }
      }
    }
  }

  def get(name: String): Option[Any] = {
    val paramName = name.canonicalName
    holder.get(paramName) flatMap {
      case Holder(h) => Some(h.build)
      case Value(v)  => Some(v)
      case ArrayHolder(h) => {
        val p = getParameterTypeOf(paramName)
        debug(s"convert array holder:$h into $p")
        TypeConverter.convert(h, p.surface)
      }
    }
  }
}

class SimpleObjectBuilder(surface: Surface) extends ObjectBuilder with StandardBuilder with LogSupport {
  require(surface.objectFactory.isDefined, s"No object factory is found for ${surface}")

  protected def findParameter(name: String) = {
    assert(surface != null)
    val cname = name.canonicalName
    surface.params.find(_.name.canonicalName == cname)
  }

  protected def defaultValues = {
    // collect default values of the object
    val prop = Map.newBuilder[String, Any]

    // get the default values of the constructor
    for (p <- surface.params; v <- p.getDefaultValue) {
      trace(s"set default parameter $p to $v")
      prop += p.name.canonicalName -> v
    }
    val r = prop.result()
    trace(s"surface ${surface}. values to set: $r")
    r
  }

  def build: Any = {
    trace(s"holder contents: $holder")
    val factory = surface.objectFactory.get
    val args = for (p <- surface.params) yield {
      get(p.name.canonicalName).getOrElse(Zero.zeroOf(p.surface))
    }
    trace(s"build: ${surface} from args:${args.mkString(", ")}")
    factory.newInstance(args)
  }
}




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