/*
 * Copyright (C) 2014-2021 Lightbend Inc. <https://www.lightbend.com>
 */

package akka.stream

import org.scalatest.matchers.should.Matchers
import org.scalatest.wordspec.AnyWordSpec

class DslFactoriesConsistencySpec extends AnyWordSpec with Matchers {

  // configuration //

  val scalaIgnore =
    Set(
      "equals",
      "hashCode",
      "notify",
      "notifyAll",
      "wait",
      "toString",
      "getClass",
      "shape",
      "identityTraversalBuilder",
      // futures in scaladsl vs completion stage in javadsl
      "lazyFutureSource", // lazyCompletionStageSource
      "futureSource", // completionStageSource
      "lazyFuture", // lazyCompletionStage
      "lazyFutureFlow", // lazyCompletionStageFlow
      "futureFlow", // completionStageFlow
      "futureSink", // completionStageSink
      "lazyFutureSink" // lazyCompletionStageSink
    )

  val javaIgnore =
    Set("adapt") // the scaladsl -> javadsl bridge

  val `scala -> java aliases` =
    ("apply" -> "create") ::
    ("apply" -> "of") ::
    ("apply" -> "from") ::
    ("apply" -> "fromGraph") ::
    ("apply" -> "fromIterator") ::
    ("apply" -> "fromFunctions") ::
    Nil

  // format: OFF
  val `scala -> java types` =
    (classOf[scala.collection.immutable.Iterable[_]],      classOf[java.lang.Iterable[_]]) ::
      (classOf[scala.collection.Iterator[_]],              classOf[java.util.Iterator[_]]) ::
      (classOf[scala.collection.Seq[_]],                   classOf[java.util.List[_]]) ::
      (classOf[scala.collection.immutable.Seq[_]],         classOf[java.util.List[_]]) ::
      (classOf[scala.collection.immutable.Set[_]],         classOf[java.util.Set[_]]) ::
      (classOf[Boolean],                                   classOf[akka.stream.javadsl.AsPublisher]) ::
      (classOf[scala.Function0[_]],                        classOf[akka.japi.function.Creator[_]]) ::
      (classOf[scala.Function0[_]],                        classOf[java.util.concurrent.Callable[_]]) ::
      (classOf[scala.Function1[_, Unit]],                  classOf[akka.japi.function.Procedure[_]]) ::
      (classOf[scala.Function1[_, _]],                     classOf[akka.japi.function.Function[_, _]]) ::
      (classOf[scala.Function2[_, _, _]],                  classOf[java.util.function.BiFunction[_, _, _]]) :: // setup
      (classOf[scala.Function1[scala.Function1[_, _], _]], classOf[akka.japi.function.Function2[_, _, _]]) ::
      (classOf[akka.stream.scaladsl.Source[_, _]],         classOf[akka.stream.javadsl.Source[_, _]]) ::
      (classOf[akka.stream.scaladsl.Sink[_, _]],           classOf[akka.stream.javadsl.Sink[_, _]]) ::
      (classOf[akka.stream.scaladsl.Flow[_, _, _]],        classOf[akka.stream.javadsl.Flow[_, _, _]]) ::
      (classOf[akka.stream.scaladsl.RunnableGraph[_]],     classOf[akka.stream.javadsl.RunnableGraph[_]]) ::
      (2 to 22) .map { i => (Class.forName(s"scala.Function$i"), Class.forName(s"akka.japi.function.Function$i")) }.toList
  // format: ON

  val sSource = classOf[scaladsl.Source[_, _]]
  val jSource = classOf[javadsl.Source[_, _]]

  val sSink = classOf[scaladsl.Sink[_, _]]
  val jSink = classOf[javadsl.Sink[_, _]]

  val sFlow = classOf[scaladsl.Flow[_, _, _]]
  val jFlow = classOf[javadsl.Flow[_, _, _]]

  val sRunnableGraph = classOf[scaladsl.RunnableGraph[_]]
  val jRunnableGraph = classOf[javadsl.RunnableGraph[_]]

  val graph = classOf[Graph[_, _]]

  case class TestCase(name: String, sClass: Option[Class[_]], jClass: Option[Class[_]], jFactory: Option[Class[_]])
  object TestCase {
    def apply(name: String, sClass: Class[_], jClass: Class[_], jFactory: Class[_]): TestCase =
      TestCase(name, Some(sClass), Some(jClass), Some(jFactory))

    def apply(name: String, sClass: Class[_], jClass: Class[_]): TestCase =
      TestCase(name, Some(sClass), Some(jClass), None)
  }

  val testCases = Seq(
    TestCase("Source", scaladsl.Source.getClass, javadsl.Source.getClass),
    TestCase("Flow", scaladsl.Flow.getClass, javadsl.Flow.getClass),
    TestCase("Sink", scaladsl.Sink.getClass, javadsl.Sink.getClass),
    TestCase("BidiFlow", scaladsl.BidiFlow.getClass, javadsl.BidiFlow.getClass),
    TestCase("GraphDSL", scaladsl.GraphDSL.getClass, javadsl.GraphDSL.getClass, classOf[javadsl.GraphCreate]),
    TestCase("ZipWith", Some(scaladsl.ZipWith.getClass), None, Some(javadsl.ZipWith.getClass)),
    TestCase("Merge", scaladsl.Merge.getClass, javadsl.Merge.getClass),
    TestCase("MergePreferred", scaladsl.MergePreferred.getClass, javadsl.MergePreferred.getClass),
    TestCase("Broadcast", scaladsl.Broadcast.getClass, javadsl.Broadcast.getClass),
    TestCase("Balance", scaladsl.Balance.getClass, javadsl.Balance.getClass),
    TestCase("Zip", scaladsl.Zip.getClass, javadsl.Zip.getClass),
    TestCase("UnZip", scaladsl.Unzip.getClass, javadsl.Unzip.getClass),
    TestCase("Concat", scaladsl.Concat.getClass, javadsl.Concat.getClass),
    TestCase("FileIO", scaladsl.FileIO.getClass, javadsl.FileIO.getClass),
    TestCase("StreamConverters", scaladsl.StreamConverters.getClass, javadsl.StreamConverters.getClass))

  "Java DSL" must provide {
    testCases.foreach {
      case TestCase(name, Some(sClass), jClass, jFactoryOption) =>
        name.which {
          s"allows creating the same ${name}s as Scala DSL" in {
            runSpec(
              getSMethods(sClass),
              jClass.toList.flatMap(getJMethods) ++
              jFactoryOption.toList.flatMap(f => getJMethods(f).map(unspecializeName.andThen(curryLikeJava))))
          }
        }
      case invalid => throw new RuntimeException("Invalid testcase: " + invalid)
    }
  }

  // here be dragons...

  private def getJMethods(jClass: Class[_]): List[Method] =
    jClass.getDeclaredMethods.filterNot(javaIgnore contains _.getName).map(toMethod).filterNot(ignore).toList
  private def getSMethods(sClass: Class[_]): List[Method] =
    sClass.getMethods.filterNot(scalaIgnore contains _.getName).map(toMethod).filterNot(ignore).toList

  private def toMethod(m: java.lang.reflect.Method): Method =
    Method(m.getName, List(m.getParameterTypes.toIndexedSeq: _*), m.getReturnType, m.getDeclaringClass)

  private case class Ignore(
      cls: Class[_] => Boolean,
      name: String => Boolean,
      parameters: Int => Boolean,
      paramTypes: List[Class[_]] => Boolean)

  private def ignore(m: Method): Boolean = {
    val ignores = Seq(
      // private scaladsl method
      Ignore(
        _ == akka.stream.scaladsl.Source.getClass,
        _ == "apply",
        _ == 1,
        _ == List(classOf[akka.stream.impl.SourceModule[_, _]])),
      // corresponding matches on java side would need to have Function23
      Ignore(_ == akka.stream.scaladsl.Source.getClass, _ == "apply", _ == 24, _ => true),
      Ignore(_ == akka.stream.scaladsl.Flow.getClass, _ == "apply", _ == 24, _ => true),
      Ignore(_ == akka.stream.scaladsl.Sink.getClass, _ == "apply", _ == 24, _ => true),
      Ignore(_ == akka.stream.scaladsl.Sink.getClass, _ == "collection", _ => true, _ => true),
      Ignore(_ == akka.stream.scaladsl.Sink.getClass, _ == "actorRef", _ => true, _ => true), // Internal in scaladsl
      Ignore(_ == akka.stream.scaladsl.Sink.getClass, _ == "actorRefWithAck", _ => true, _ => true), // Internal in scaladsl
      Ignore(_ == akka.stream.scaladsl.Sink.getClass, _ == "actorRefWithBackpressure", _ => true, _ => true), // Internal in scaladsl
      Ignore(_ == akka.stream.scaladsl.Source.getClass, _ == "actorRef", _ => true, _ => true), // Internal in scaladsl
      Ignore(_ == akka.stream.scaladsl.Source.getClass, _ == "actorRefWithAck", _ => true, _ => true), // Internal in scaladsl
      Ignore(_ == akka.stream.scaladsl.Source.getClass, _ == "actorRefWithBackpressure", _ => true, _ => true), // Internal in scaladsl
      Ignore(_ == akka.stream.scaladsl.BidiFlow.getClass, _ == "apply", _ == 24, _ => true),
      Ignore(_ == akka.stream.scaladsl.GraphDSL.getClass, _ == "runnable", _ == 24, _ => true),
      Ignore(_ == akka.stream.scaladsl.GraphDSL.getClass, _ == "create", _ == 24, _ => true),
      // all generated methods like scaladsl.Sink$.akka$stream$scaladsl$Sink$$newOnCompleteStage$1
      Ignore(_ => true, _.contains("$"), _ => true, _ => true))

    ignores.foldLeft(false) {
      case (acc, i) =>
        acc || (i.cls(m.declaringClass) && i.name(m.name) && i.parameters(m.parameterTypes.length) && i.paramTypes(
          m.parameterTypes))
    }
  }

  /**
   * Rename
   *   createN => create
   *   runnableN => runnable
   *   createN => create
   */
  private val unspecializeName: PartialFunction[Method, Method] = {
    case m => m.copy(name = m.name.filter(Character.isLetter))
  }

  /**
   * Adapt java side non curried functions to scala side like
   */
  private val curryLikeJava: PartialFunction[Method, Method] = {
    case m if m.parameterTypes.size > 1 =>
      m.copy(
        name = m.name.filter(Character.isLetter),
        parameterTypes = m.parameterTypes.dropRight(1) :+ classOf[akka.japi.function.Function[_, _]])
    case m => m
  }

  def runSpec(sMethods: List[Method], jMethods: List[Method]): Unit = {
    var warnings = 0

    val results = for {
      s <- sMethods
      j <- jMethods
    } yield delegationCheck(s, j)

    for {
      row <- results.groupBy(_.s)
      matches = row._2.filter(_.matches)
    } {
      if (matches.length == 0) {
        warnings += 1
        alert("No match for " + row._1)
        row._2.foreach { m =>
          alert(s" > ${m.j.toString}: ${m.reason}")
        }
      } else if (matches.length == 1) {
        info(
          "Matched: Scala:" + row._1.name + "(" + row._1.parameterTypes
            .map(_.getName)
            .mkString(",") + "): " + returnTypeString(row._1) +
          " == " +
          "Java:" + matches.head.j.name + "(" + matches.head.j.parameterTypes
            .map(_.getName)
            .mkString(",") + "): " + returnTypeString(matches.head.j))
      } else {
        warnings += 1
        alert("Multiple matches for " + row._1 + "!")
        matches.foreach { m =>
          alert(s" > ${m.j.toString}")
        }
      }
    }

    if (warnings > 0) {
      jMethods.foreach { m =>
        info("  java: " + m + ": " + returnTypeString(m))
      }
      sMethods.foreach { m =>
        info(" scala: " + m + ": " + returnTypeString(m))
      }
      fail("Warnings were issued! Fix name / type mappings or delegation code!")
    }
  }

  def returnTypeString(m: Method): String =
    m.returnType.getName.drop("akka.stream.".length)

  case class Method(name: String, parameterTypes: List[Class[_]], returnType: Class[_], declaringClass: Class[_])

  sealed trait MatchResult {
    def j: Method
    def s: Method
    def reason: String
    def matches: Boolean
  }
  case class MatchFailure(s: Method, j: Method, reason: String = "") extends MatchResult { val matches = false }
  case class Match(s: Method, j: Method, reason: String = "") extends MatchResult { val matches = true }

  def delegationCheck(s: Method, j: Method): MatchResult = {
    if (nameMatch(s.name, j.name)) {
      if (s.parameterTypes.length == j.parameterTypes.length)
        if (typeMatch(s.parameterTypes, j.parameterTypes))
          if (returnTypeMatch(s.returnType, j.returnType))
            Match(s, j)
          else
            MatchFailure(s, j, "Return types don't match! " + s.returnType + ", " + j.returnType)
        else
          MatchFailure(s, j, "Types of parameters don't match!")
      else
        MatchFailure(s, j, "Same name, but different number of parameters!")
    } else {
      MatchFailure(s, j, "Names don't match!")
    }
  }

  def nameMatch(scalaName: String, javaName: String): Boolean =
    (scalaName, javaName) match {
      case (s, j) if s == j                        => true
      case t if `scala -> java aliases` contains t => true
      case _                                       => false
    }

  /**
   * Keyed elements in scaladsl must also be keyed elements in javadsl.
   * If scaladsl is not a keyed type, javadsl shouldn't be as well.
   */
  def returnTypeMatch(s: Class[_], j: Class[_]): Boolean =
    (sSource.isAssignableFrom(s) && jSource.isAssignableFrom(j)) ||
    (sSink.isAssignableFrom(s) && jSink.isAssignableFrom(j)) ||
    (sFlow.isAssignableFrom(s) && jFlow.isAssignableFrom(j)) ||
    (sRunnableGraph.isAssignableFrom(s) && jRunnableGraph.isAssignableFrom(j)) ||
    (graph.isAssignableFrom(s) && graph.isAssignableFrom(j))

  def typeMatch(scalaParams: List[Class[_]], javaParams: List[Class[_]]): Boolean =
    (scalaParams.toList, javaParams.toList) match {
      case (s, j) if s == j                     => true
      case (s, j) if s.zip(j).forall(typeMatch) => true
      case _                                    => false
    }

  def typeMatch(p: (Class[_], Class[_])): Boolean =
    if (p._1 == p._2) true
    else if (`scala -> java types` contains p) true
    else false

  private def provide = afterWord("provide")

}
