Group Pattern Management

/**
 * GroupPattern represents a composite pattern created by chaining Pattern objects
 * @param jGroupPattern Underlying Java GroupPattern
 * @tparam T Base type of events
 * @tparam F Subtype constraint
 */
class GroupPattern[T, F <: T] extends Pattern[T, F] {
  // Inherits all Pattern methods except where(), or(), and subtype()
  // These methods throw UnsupportedOperationException
}

object GroupPattern {
  /**
   * Wrap Java GroupPattern for Scala API usage
   * @param jGroupPattern Java GroupPattern to wrap
   * @return Scala GroupPattern wrapper
   */
  def apply[T, F <: T](jGroupPattern: JGroupPattern[T, F]): GroupPattern[T, F]
}

class Pattern[T, F <: T] {
  /**
   * Chain with another pattern using followedBy semantics
   * @param pattern The pattern to follow this one
   * @return GroupPattern for further composition
   */
  def followedBy(pattern: Pattern[T, F]): GroupPattern[T, F]
  
  /**
   * Chain with another pattern using followedByAny semantics  
   * @param pattern The pattern to follow this one
   * @return GroupPattern for further composition
   */
  def followedByAny(pattern: Pattern[T, F]): GroupPattern[T, F]
  
  /**
   * Chain with another pattern using strict next semantics
   * @param pattern The pattern to follow this one immediately
   * @return GroupPattern for further composition
   */
  def next(pattern: Pattern[T, F]): GroupPattern[T, F]
}

object Pattern {
  /**
   * Start a new pattern sequence with an existing pattern
   * @param pattern Initial pattern for the sequence
   * @return GroupPattern for building complex sequences
   */
  def begin[T, F <: T](pattern: Pattern[T, F]): GroupPattern[T, F]
  
  /**
   * Start a new pattern sequence with existing pattern and skip strategy
   * @param pattern Initial pattern for the sequence
   * @param afterMatchSkipStrategy Strategy for handling overlapping matches
   * @return GroupPattern for building complex sequences
   */
  def begin[T, F <: T](
    pattern: Pattern[T, F],
    afterMatchSkipStrategy: AfterMatchSkipStrategy
  ): GroupPattern[T, F]
}

case class Event(eventType: String, userId: String, value: Int, timestamp: Long)

// Create individual patterns
val loginPattern = Pattern.begin[Event]("login")
  .where(_.eventType == "login")

val activityPattern = Pattern.begin[Event]("activity")  
  .where(_.eventType == "click")
  .oneOrMore

val logoutPattern = Pattern.begin[Event]("logout")
  .where(_.eventType == "logout")

// Combine patterns into GroupPattern using chaining
val sessionPattern = loginPattern
  .followedBy(activityPattern)
  .followedBy(logoutPattern)

// Start with an existing pattern to create GroupPattern
val complexSessionPattern = Pattern.begin(loginPattern)
  .followedBy("purchase") 
  .where(_.eventType == "purchase")
  .followedBy(logoutPattern)

class GroupPattern[T, F <: T] extends Pattern[T, F] {
  // These methods throw UnsupportedOperationException:
  override def where(condition: IterativeCondition[F]): Pattern[T, F] // NOT SUPPORTED
  override def or(condition: IterativeCondition[F]): Pattern[T, F] // NOT SUPPORTED
  override def subtype[S <: F](clazz: Class[S]): Pattern[T, S] // NOT SUPPORTED
  
  // All other Pattern methods are inherited and functional:
  // - Quantifiers: optional, oneOrMore, times(), etc.
  // - Temporal: within(), until()
  // - Chaining: next(), followedBy(), etc.
  // - Properties: getName, getQuantifier, etc.
}

val individualPattern = Pattern.begin[Event]("first")
  .where(_.eventType == "start")

val groupPattern = individualPattern.followedBy(
  Pattern.begin[Event]("second").where(_.eventType == "end")
)

// Valid GroupPattern operations
val timedGroupPattern = groupPattern
  .within(Duration.ofMinutes(10))
  .optional

// Invalid operations - these throw UnsupportedOperationException:
// groupPattern.where(_.value > 10) // ERROR!
// groupPattern.or(_.eventType == "other") // ERROR!
// groupPattern.subtype(classOf[SpecialEvent]) // ERROR!

// Workaround: Apply conditions to individual patterns before grouping
val conditionedPattern = Pattern.begin[Event]("filtered")
  .where(_.value > 10)
  .where(_.eventType == "special")

val validGroupPattern = individualPattern.followedBy(conditionedPattern)

case class UserEvent(userId: String, action: String, sessionId: String, timestamp: Long)

// Multi-level pattern composition
val userLoginSequence = Pattern.begin[UserEvent]("login")
  .where(_.action == "login")
  .followedBy("initial_activity")
  .where(_.action == "page_view")

val userEngagementSequence = Pattern.begin[UserEvent]("engagement")
  .where(_.action == "click")
  .oneOrMore
  .followedBy("conversion")
  .where(_.action == "purchase")

// Combine sequences into comprehensive user journey pattern
val userJourneyPattern = Pattern.begin(userLoginSequence)
  .followedBy(userEngagementSequence)
  .within(Duration.ofHours(2))

// Use with CEP
import org.apache.flink.cep.scala.CEP

val userJourneyStream = CEP.pattern(userEventStream, userJourneyPattern)
  .select { pattern =>
    val login = pattern("login").head
    val engagementEvents = pattern("engagement")
    val conversion = pattern("conversion").head
    
    s"User ${login.userId} converted after ${engagementEvents.size} engagement events"
  }

import org.apache.flink.cep.nfa.aftermatch.AfterMatchSkipStrategy

case class MarketEvent(symbol: String, price: Double, volume: Long, timestamp: Long)

val priceDropPattern = Pattern.begin[MarketEvent]("drop")
  .where(_.price < 100)

val recoveryPattern = Pattern.begin[MarketEvent]("recovery")
  .where(_.price > 100)

// Different skip strategies for overlapping matches
val skipPastLastEvent = AfterMatchSkipStrategy.skipPastLastEvent()
val skipToNext = AfterMatchSkipStrategy.skipToNext()

// GroupPattern with skip past last event strategy
val marketCyclePattern = Pattern.begin(priceDropPattern, skipPastLastEvent)
  .followedBy(recoveryPattern)
  .within(Duration.ofDays(7))

// Alternative: skip to next match for more overlapping detection
val overlappingCyclesPattern = Pattern.begin(priceDropPattern, skipToNext)
  .followedBy(recoveryPattern)
  .within(Duration.ofDays(7))

// GroupPattern class and companion
import org.apache.flink.cep.pattern.{GroupPattern => JGroupPattern}

class GroupPattern[T, F <: T] extends Pattern[T, F]

object GroupPattern {
  def apply[T, F <: T](jGroupPattern: JGroupPattern[T, F]): GroupPattern[T, F]
}

// Skip strategies for pattern matching
import org.apache.flink.cep.nfa.aftermatch.AfterMatchSkipStrategy

// Duration for time windows
import java.time.Duration