/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * license agreements; and to You under the Apache License, version 2.0:
 *
 *   https://www.apache.org/licenses/LICENSE-2.0
 *
 * This file is part of the Apache Pekko project, which was derived from Akka.
 */

/*
 * Copyright (C) 2009-2022 Lightbend Inc. <https://www.lightbend.com>
 */

package org.apache.pekko.testkit

import java.lang.{ Iterable => JIterable }

import scala.collection.immutable
import scala.concurrent.duration.Duration
import scala.reflect.ClassTag
import scala.util.matching.Regex

import org.apache.pekko
import pekko.actor.{ ActorSystem, DeadLetter, UnhandledMessage }
import pekko.actor.Dropped
import pekko.actor.NoSerializationVerificationNeeded
import pekko.dispatch.sysmsg.{ SystemMessage, Terminate }
import pekko.event.Logging
import pekko.event.Logging.{ Debug, Error, Info, InitializeLogger, LogEvent, LoggerInitialized, Warning }
import pekko.japi.Util.immutableSeq
import pekko.util.BoxedType

/**
 * Implementation helpers of the EventFilter facilities: send `Mute`
 * to the TestEventListener to install a filter, and `UnMute` to
 * uninstall it.
 *
 * You should always prefer the filter methods in the package object
 * (see `org.apache.pekko.testkit` `filterEvents` and `filterException`) or on the
 * EventFilter implementations.
 */
sealed trait TestEvent

/**
 * Implementation helpers of the EventFilter facilities: send <code>Mute</code>
 * to the TestEventFilter to install a filter, and <code>UnMute</code> to
 * uninstall it.
 *
 * You should always prefer the filter methods in the package object
 * (see `org.apache.pekko.testkit` `filterEvents` and `filterException`) or on the
 * EventFilter implementations.
 */
object TestEvent {
  object Mute {
    def apply(filter: EventFilter, filters: EventFilter*): Mute = new Mute(filter +: filters.to(immutable.Seq))
  }
  final case class Mute(filters: immutable.Seq[EventFilter]) extends TestEvent with NoSerializationVerificationNeeded {

    /**
     * Java API: create a Mute command from a list of filters
     */
    def this(filters: JIterable[EventFilter]) = this(immutableSeq(filters))
  }
  object UnMute {
    def apply(filter: EventFilter, filters: EventFilter*): UnMute = new UnMute(filter +: filters.to(immutable.Seq))
  }
  final case class UnMute(filters: immutable.Seq[EventFilter])
      extends TestEvent
      with NoSerializationVerificationNeeded {

    /**
     * Java API: create an UnMute command from a list of filters
     */
    def this(filters: JIterable[EventFilter]) = this(immutableSeq(filters))
  }
}

/**
 * Facilities for selectively filtering out expected events from logging so
 * that you can keep your test run’s console output clean and do not miss real
 * error messages.
 *
 * See the companion object for convenient factory methods.
 *
 * If the `occurrences` is set to Int.MaxValue, no tracking is done.
 */
abstract class EventFilter(occurrences: Int) {

  @volatile // JMM does not guarantee visibility for non-final fields
  private var todo = occurrences

  /**
   * This method decides whether to filter the event (<code>true</code>) or not
   * (<code>false</code>).
   */
  protected def matches(event: LogEvent): Boolean

  final def apply(event: LogEvent): Boolean = {
    if (matches(event)) {
      if (todo != Int.MaxValue) todo -= 1
      true
    } else false
  }

  def awaitDone(max: Duration): Boolean = {
    if (todo != Int.MaxValue && todo > 0) TestKit.awaitCond(todo <= 0, max, noThrow = true)
    todo == Int.MaxValue || todo == 0
  }

  /**
   * Assert that this filter has matched as often as requested by its
   * `occurrences` parameter specifies.
   */
  def assertDone(max: Duration): Unit =
    assert(
      awaitDone(max),
      if (todo > 0) s"$todo messages outstanding on $this"
      else s"received ${-todo} excess messages on $this")

  /**
   * Apply this filter while executing the given code block. Care is taken to
   * remove the filter when the block is finished or aborted.
   */
  def intercept[T](code: => T)(implicit system: ActorSystem): T = {
    system.eventStream.publish(TestEvent.Mute(this))
    val leeway = TestKitExtension(system).TestEventFilterLeeway.dilated
    try {
      val result = code
      if (!awaitDone(leeway))
        if (todo > 0)
          throw new AssertionError(s"timeout ($leeway) waiting for $todo messages on $this")
        else
          throw new AssertionError(s"received ${-todo} excess messages on $this")
      result
    } finally system.eventStream.publish(TestEvent.UnMute(this))
  }

  /*
   * these default values are just there for easier subclassing
   */
  protected val source: Option[String] = None
  protected val message: Either[String, Regex] = Left("")
  protected val complete: Boolean = false

  /**
   * internal implementation helper, no guaranteed API
   */
  protected def doMatch(src: String, msg: Any) = {
    val msgstr = if (msg != null) msg.toString else "null"
    (source.isDefined && source.get == src || source.isEmpty) &&
    (message match {
      case Left(s)  => if (complete) msgstr == s else msgstr.startsWith(s)
      case Right(p) => p.findFirstIn(msgstr).isDefined
    })
  }
}

/**
 * Facilities for selectively filtering out expected events from logging so
 * that you can keep your test run’s console output clean and do not miss real
 * error messages.
 *
 * '''Also have a look at the `org.apache.pekko.testkit` package object’s `filterEvents` and
 * `filterException` methods.'''
 *
 * The source filters do accept `Class[_]` arguments, matching any
 * object which is an instance of the given class, e.g.
 *
 * {{{
 * EventFilter.info(source = classOf[MyActor]) // will match Info events from any MyActor instance
 * }}}
 *
 * The message object will be converted to a string before matching (`"null"` if it is `null`).
 */
object EventFilter {

  /**
   * Create a filter for Error events. Give up to one of <code>start</code> and <code>pattern</code>:
   *
   * {{{
   * EventFilter[MyException]()                                         // filter only on exception type
   * EventFilter[MyException]("message")                                // filter on exactly matching message
   * EventFilter[MyException](source = obj)                             // filter on event source
   * EventFilter[MyException](start = "Expected")                       // filter on start of message
   * EventFilter[MyException](source = obj, pattern = "weird.*message") // filter on pattern and message
   * }}}
   *
   * ''Please note that filtering on the `source` being
   * `null` does NOT work (passing `null` disables the
   * source filter).''
   */
  def apply[A <: Throwable: ClassTag](
      message: String = null,
      source: String = null,
      start: String = "",
      pattern: String = null,
      occurrences: Int = Int.MaxValue): EventFilter =
    ErrorFilter(
      implicitly[ClassTag[A]].runtimeClass,
      Option(source),
      if (message ne null) Left(message) else Option(pattern).map(new Regex(_)).toRight(start),
      message ne null)(occurrences)

  /**
   * Create a filter for Error events. See apply() for more details.
   */
  def error(
      message: String = null,
      source: String = null,
      start: String = "",
      pattern: String = null,
      occurrences: Int = Int.MaxValue): EventFilter =
    ErrorFilter(
      Logging.Error.NoCause.getClass,
      Option(source),
      if (message ne null) Left(message) else Option(pattern).map(new Regex(_)).toRight(start),
      message ne null)(occurrences)

  /**
   * Create a filter for Warning events. Give up to one of <code>start</code> and <code>pattern</code>:
   *
   * {{{
   * EventFilter.warning()                                         // filter only on warning event
   * EventFilter.warning(source = obj)                             // filter on event source
   * EventFilter.warning(start = "Expected")                       // filter on start of message
   * EventFilter.warning(source = obj, pattern = "weird.*message") // filter on pattern and message
   * }}}
   *
   * ''Please note that filtering on the `source` being
   * `null` does NOT work (passing `null` disables the
   * source filter).''
   */
  def warning(
      message: String = null,
      source: String = null,
      start: String = "",
      pattern: String = null,
      occurrences: Int = Int.MaxValue): EventFilter =
    WarningFilter(
      Option(source),
      if (message ne null) Left(message) else Option(pattern).map(new Regex(_)).toRight(start),
      message ne null)(occurrences)

  /**
   * Create a filter for Info events. Give up to one of <code>start</code> and <code>pattern</code>:
   *
   * {{{
   * EventFilter.info()                                         // filter only on info event
   * EventFilter.info(source = obj)                             // filter on event source
   * EventFilter.info(start = "Expected")                       // filter on start of message
   * EventFilter.info(source = obj, pattern = "weird.*message") // filter on pattern and message
   * }}}
   *
   * ''Please note that filtering on the `source` being
   * `null` does NOT work (passing `null` disables the
   * source filter).''
   */
  def info(
      message: String = null,
      source: String = null,
      start: String = "",
      pattern: String = null,
      occurrences: Int = Int.MaxValue): EventFilter =
    InfoFilter(
      Option(source),
      if (message ne null) Left(message) else Option(pattern).map(new Regex(_)).toRight(start),
      message ne null)(occurrences)

  /**
   * Create a filter for Debug events. Give up to one of <code>start</code> and <code>pattern</code>:
   *
   * {{{
   * EventFilter.debug()                                         // filter only on debug type
   * EventFilter.debug(source = obj)                             // filter on event source
   * EventFilter.debug(start = "Expected")                       // filter on start of message
   * EventFilter.debug(source = obj, pattern = "weird.*message") // filter on pattern and message
   * }}}
   *
   * ''Please note that filtering on the `source` being
   * `null` does NOT work (passing `null` disables the
   * source filter).''
   */
  def debug(
      message: String = null,
      source: String = null,
      start: String = "",
      pattern: String = null,
      occurrences: Int = Int.MaxValue): EventFilter =
    DebugFilter(
      Option(source),
      if (message ne null) Left(message) else Option(pattern).map(new Regex(_)).toRight(start),
      message ne null)(occurrences)

  /**
   * Create a custom event filter. The filter will affect those events for
   * which the supplied partial function is defined and returns
   * `true`.
   *
   * {{{
   * EventFilter.custom {
   *   case Warning(ref, "my warning") if ref == actor || ref == null => true
   * }
   * }}}
   */
  def custom(test: PartialFunction[LogEvent, Boolean], occurrences: Int = Int.MaxValue): EventFilter =
    CustomEventFilter(test)(occurrences)
}

/**
 * Filter which matches Error events, if they satisfy the given criteria:
 * <ul>
 * <li><code>throwable</code> applies an upper bound on the type of exception contained in the Error event</li>
 * <li><code>source</code>, if given, applies a filter on the event’s origin</li>
 * <li><code>message</code> applies a filter on the event’s message (either
 *   with String.startsWith or Regex.findFirstIn().isDefined); if the message
 *   itself does not match, the match is retried with the contained Exception’s
 *   message; if both are <code>null</code>, the filter always matches if at
 *   the same time the Exception’s stack trace is empty (this catches
 *   JVM-omitted “fast-throw” exceptions)</li>
 * </ul>
 * If you want to match all Error events, the most efficient is to use <code>Left("")</code>.
 */
final case class ErrorFilter(
    throwable: Class[_],
    override val source: Option[String],
    override val message: Either[String, Regex],
    override val complete: Boolean)(occurrences: Int)
    extends EventFilter(occurrences) {

  def matches(event: LogEvent) = {
    event match {
      case Error(cause, src, _, msg) if (throwable eq Error.NoCause.getClass) || (throwable.isInstance(cause)) =>
        (msg == null && cause.getMessage == null && cause.getStackTrace.length == 0) ||
        doMatch(src, msg) || doMatch(src, cause.getMessage)
      case _ => false
    }
  }

  /**
   * Java API: create an ErrorFilter
   *
   * @param source
   *   apply this filter only to events from the given source; do not filter on source if this is given as <code>null</code>
   * @param message
   *   apply this filter only to events whose message matches; do not filter on message if this is given as <code>null</code>
   * @param pattern
   *   if <code>false</code>, the message string must start with the given
   *   string, otherwise the <code>message</code> argument is treated as
   *   regular expression which is matched against the message (may match only
   *   a substring to filter)
   * @param complete
   *   whether the event’s message must match the given message string or pattern completely
   */
  def this(
      throwable: Class[_],
      source: String,
      message: String,
      pattern: Boolean,
      complete: Boolean,
      occurrences: Int) =
    this(
      throwable,
      Option(source),
      if (message eq null) Left("")
      else if (pattern) Right(new Regex(message))
      else Left(message),
      complete)(occurrences)

  /**
   * Java API: filter only on the given type of exception
   */
  def this(throwable: Class[_]) = this(throwable, null, null, false, false, Int.MaxValue)

}

/**
 * Filter which matches Warning events, if they satisfy the given criteria:
 * <ul>
 * <li><code>source</code>, if given, applies a filter on the event’s origin</li>
 * <li><code>message</code> applies a filter on the event’s message (either with String.startsWith or Regex.findFirstIn().isDefined)</li>
 * </ul>
 * If you want to match all Warning events, the most efficient is to use <code>Left("")</code>.
 */
final case class WarningFilter(
    override val source: Option[String],
    override val message: Either[String, Regex],
    override val complete: Boolean)(occurrences: Int)
    extends EventFilter(occurrences) {

  def matches(event: LogEvent) = {
    event match {
      case Warning(src, _, msg) => doMatch(src, msg)
      case _                    => false
    }
  }

  /**
   * Java API: create a WarningFilter
   *
   * @param source
   *   apply this filter only to events from the given source; do not filter on source if this is given as <code>null</code>
   * @param message
   *   apply this filter only to events whose message matches; do not filter on message if this is given as <code>null</code>
   * @param pattern
   *   if <code>false</code>, the message string must start with the given
   *   string, otherwise the <code>message</code> argument is treated as
   *   regular expression which is matched against the message (may match only
   *   a substring to filter)
   * @param complete
   *   whether the event’s message must match the given message string or pattern completely
   */
  def this(source: String, message: String, pattern: Boolean, complete: Boolean, occurrences: Int) =
    this(
      Option(source),
      if (message eq null) Left("")
      else if (pattern) Right(new Regex(message))
      else Left(message),
      complete)(occurrences)
}

/**
 * Filter which matches Info events, if they satisfy the given criteria:
 * <ul>
 * <li><code>source</code>, if given, applies a filter on the event’s origin</li>
 * <li><code>message</code> applies a filter on the event’s message (either with String.startsWith or Regex.findFirstIn().isDefined)</li>
 * </ul>
 * If you want to match all Info events, the most efficient is to use <code>Left("")</code>.
 */
final case class InfoFilter(
    override val source: Option[String],
    override val message: Either[String, Regex],
    override val complete: Boolean)(occurrences: Int)
    extends EventFilter(occurrences) {

  def matches(event: LogEvent) = {
    event match {
      case Info(src, _, msg) => doMatch(src, msg)
      case _                 => false
    }
  }

  /**
   * Java API: create an InfoFilter
   *
   * @param source
   *   apply this filter only to events from the given source; do not filter on source if this is given as <code>null</code>
   * @param message
   *   apply this filter only to events whose message matches; do not filter on message if this is given as <code>null</code>
   * @param pattern
   *   if <code>false</code>, the message string must start with the given
   *   string, otherwise the <code>message</code> argument is treated as
   *   regular expression which is matched against the message (may match only
   *   a substring to filter)
   * @param complete
   *   whether the event’s message must match the given message string or pattern completely
   */
  def this(source: String, message: String, pattern: Boolean, complete: Boolean, occurrences: Int) =
    this(
      Option(source),
      if (message eq null) Left("")
      else if (pattern) Right(new Regex(message))
      else Left(message),
      complete)(occurrences)
}

/**
 * Filter which matches Debug events, if they satisfy the given criteria:
 * <ul>
 * <li><code>source</code>, if given, applies a filter on the event’s origin</li>
 * <li><code>message</code> applies a filter on the event’s message (either with String.startsWith or Regex.findFirstIn().isDefined)</li>
 * </ul>
 * If you want to match all Debug events, the most efficient is to use <code>Left("")</code>.
 */
final case class DebugFilter(
    override val source: Option[String],
    override val message: Either[String, Regex],
    override val complete: Boolean)(occurrences: Int)
    extends EventFilter(occurrences) {

  def matches(event: LogEvent) = {
    event match {
      case Debug(src, _, msg) => doMatch(src, msg)
      case _                  => false
    }
  }

  /**
   * Java API: create a DebugFilter
   *
   * @param source
   *   apply this filter only to events from the given source; do not filter on source if this is given as <code>null</code>
   * @param message
   *   apply this filter only to events whose message matches; do not filter on message if this is given as <code>null</code>
   * @param pattern
   *   if <code>false</code>, the message string must start with the given
   *   string, otherwise the <code>message</code> argument is treated as
   *   regular expression which is matched against the message (may match only
   *   a substring to filter)
   * @param complete
   *   whether the event’s message must match the given message string or pattern completely
   */
  def this(source: String, message: String, pattern: Boolean, complete: Boolean, occurrences: Int) =
    this(
      Option(source),
      if (message eq null) Left("")
      else if (pattern) Right(new Regex(message))
      else Left(message),
      complete)(occurrences)
}

/**
 * Custom event filter when the others do not fit the bill.
 *
 * If the partial function is defined and returns true, filter the event.
 */
final case class CustomEventFilter(test: PartialFunction[LogEvent, Boolean])(occurrences: Int)
    extends EventFilter(occurrences) {
  def matches(event: LogEvent) = {
    test.isDefinedAt(event) && test(event)
  }
}

object DeadLettersFilter {
  def apply[T](implicit t: ClassTag[T]): DeadLettersFilter =
    new DeadLettersFilter(t.runtimeClass.asInstanceOf[Class[T]])(Int.MaxValue)
}

/**
 * Filter which matches DeadLetter events, if the wrapped message conforms to the
 * given type.
 */
final case class DeadLettersFilter(val messageClass: Class[_])(occurrences: Int) extends EventFilter(occurrences) {

  def matches(event: LogEvent) = {
    event match {
      case Warning(_, _, msg) => BoxedType(messageClass).isInstance(msg)
      case _                  => false
    }
  }

}

/**
 * EventListener for running tests, which allows selectively filtering out
 * expected messages. To use it, include something like this into
 * <code>pekko.test.conf</code> and run your tests with system property
 * <code>"pekko.mode"</code> set to <code>"test"</code>:
 *
 * <pre><code>
 * pekko {
 *   loggers = ["org.apache.pekko.testkit.TestEventListener"]
 * }
 * </code></pre>
 */
class TestEventListener extends Logging.DefaultLogger {
  import TestEvent._

  var filters: List[EventFilter] = Nil

  override def receive = {
    case InitializeLogger(bus) =>
      Seq(classOf[Mute], classOf[UnMute], classOf[DeadLetter], classOf[UnhandledMessage], classOf[Dropped])
        .foreach(bus.subscribe(context.self, _))
      sender() ! LoggerInitialized
    case Mute(filters)             => filters.foreach(addFilter)
    case UnMute(filters)           => filters.foreach(removeFilter)
    case event: LogEvent           => if (!filter(event)) print(event)
    case DeadLetter(msg, snd, rcp) =>
      if (!msg.isInstanceOf[Terminate]) {
        val event = Warning(rcp.path.toString, rcp.getClass, msg)
        if (!filter(event)) {
          val msgPrefix =
            if (msg.isInstanceOf[SystemMessage]) "received dead system message"
            else if (snd eq context.system.deadLetters) "received dead letter"
            else "received dead letter from " + snd
          val event2 = Warning(rcp.path.toString, rcp.getClass, msgPrefix + ": " + msg)
          if (!filter(event2)) print(event2)
        }
      }
    case UnhandledMessage(msg, sender, rcp) =>
      val event = Warning(rcp.path.toString, rcp.getClass, s"unhandled message from $sender: $msg")
      if (!filter(event)) print(event)
    case Dropped(msg, reason, sender, rcp) =>
      val event =
        Warning(rcp.path.toString, rcp.getClass, s"dropped message from $sender. $reason: $msg")
      if (!filter(event)) print(event)

    case m => print(Debug(context.system.name, this.getClass, m))
  }

  def filter(event: LogEvent): Boolean =
    filters.exists(f =>
      try {
        f(event)
      } catch { case _: Exception => false })

  def addFilter(filter: EventFilter): Unit = filters ::= filter

  def removeFilter(filter: EventFilter): Unit = {
    @scala.annotation.tailrec
    def removeFirst(list: List[EventFilter], zipped: List[EventFilter] = Nil): List[EventFilter] = list match {
      case head :: tail if head == filter => tail.reverse_:::(zipped)
      case head :: tail                   => removeFirst(tail, head :: zipped)
      case Nil                            => filters // filter not found, just return original list
    }
    filters = removeFirst(filters)
  }

}
