package com.twitter.recos.user_tweet_entity_graph

import com.twitter.finagle.stats.StatsReceiver
import com.twitter.graphjet.algorithms.{
  RecommendationInfo,
  RecommendationType => JavaRecommendationType
}
import com.twitter.graphjet.algorithms.socialproof.{
  NodeMetadataSocialProofResult => EntitySocialProofJavaResult,
  SocialProofResult => SocialProofJavaResult
}
import com.twitter.recos.decider.UserTweetEntityGraphDecider
import com.twitter.recos.util.Stats
import com.twitter.recos.util.Stats._
import com.twitter.recos.recos_common.thriftscala.{SocialProofType => SocialProofThriftType}
import com.twitter.recos.user_tweet_entity_graph.thriftscala.{
  HashtagRecommendation,
  TweetRecommendation,
  UrlRecommendation,
  UserTweetEntityRecommendationUnion,
  RecommendationSocialProofRequest => SocialProofThriftRequest,
  RecommendationSocialProofResponse => SocialProofThriftResponse,
  RecommendationType => ThriftRecommendationType
}
import com.twitter.servo.request.RequestHandler
import com.twitter.util.{Future, Try}
import scala.collection.JavaConverters._

class SocialProofHandler(
  tweetSocialProofRunner: TweetSocialProofRunner,
  entitySocialProofRunner: EntitySocialProofRunner,
  decider: UserTweetEntityGraphDecider,
  statsReceiver: StatsReceiver)
    extends RequestHandler[SocialProofThriftRequest, SocialProofThriftResponse] {
  private val stats = statsReceiver.scope(this.getClass.getSimpleName)

  private def getThriftSocialProof(
    entitySocialProof: EntitySocialProofJavaResult
  ): Map[SocialProofThriftType, Map[Long, Seq[Long]]] = {
    val socialProofAttempt = Try(entitySocialProof.getSocialProof)
      .onFailure { e =>
        stats.counter(e.getClass.getSimpleName).incr()
      }

    socialProofAttempt.toOption match {
      case Some(socialProof) if socialProof.isEmpty =>
        stats.counter(Stats.EmptyResult).incr()
        Map.empty[SocialProofThriftType, Map[Long, Seq[Long]]]
      case Some(socialProof) if !socialProof.isEmpty =>
        socialProof.asScala.map {
          case (socialProofType, socialProofUserToTweetsMap) =>
            val userToTweetsSocialProof = socialProofUserToTweetsMap.asScala.map {
              case (socialProofUser, connectingTweets) =>
                (socialProofUser.toLong, connectingTweets.asScala.map(Long2long).toSeq)
            }.toMap
            (SocialProofThriftType(socialProofType.toInt), userToTweetsSocialProof)
        }.toMap
      case _ =>
        Map.empty[SocialProofThriftType, Map[Long, Seq[Long]]]
    }
  }

  private def getThriftSocialProof(
    tweetSocialProof: SocialProofJavaResult
  ): Map[SocialProofThriftType, Seq[Long]] = {
    val socialProofAttempt = Try(tweetSocialProof.getSocialProof)
      .onFailure { e =>
        stats.counter(e.getClass.getSimpleName).incr()
      }

    socialProofAttempt.toOption match {
      case Some(socialProof) if socialProof.isEmpty =>
        stats.counter(Stats.EmptyResult).incr()
        Map.empty[SocialProofThriftType, Seq[Long]]
      case Some(socialProof) if !socialProof.isEmpty =>
        socialProof.asScala.map {
          case (socialProofType, connectingUsers) =>
            (
              SocialProofThriftType(socialProofType.toInt),
              connectingUsers.asScala.map { Long2long }.toSeq)
        }.toMap
      case _ =>
        Map.empty[SocialProofThriftType, Seq[Long]]
    }
  }

  private def getEntitySocialProof(
    request: SocialProofThriftRequest
  ): Future[Seq[UserTweetEntityRecommendationUnion]] = {
    val socialProofsFuture = entitySocialProofRunner(request)

    socialProofsFuture.map { socialProofs: Seq[RecommendationInfo] =>
      stats.counter(Stats.Served).incr(socialProofs.size)
      socialProofs.flatMap { entitySocialProof: RecommendationInfo =>
        val entitySocialProofJavaResult =
          entitySocialProof.asInstanceOf[EntitySocialProofJavaResult]
        if (entitySocialProofJavaResult.getRecommendationType == JavaRecommendationType.URL) {
          Some(
            UserTweetEntityRecommendationUnion.UrlRec(
              UrlRecommendation(
                entitySocialProofJavaResult.getNodeMetadataId,
                entitySocialProofJavaResult.getWeight,
                getThriftSocialProof(entitySocialProofJavaResult)
              )
            )
          )
        } else if (entitySocialProofJavaResult.getRecommendationType == JavaRecommendationType.HASHTAG) {
          Some(
            UserTweetEntityRecommendationUnion.HashtagRec(
              HashtagRecommendation(
                entitySocialProofJavaResult.getNodeMetadataId,
                entitySocialProofJavaResult.getWeight,
                getThriftSocialProof(entitySocialProofJavaResult)
              )
            )
          )
        } else {
          None
        }
      }
    }
  }

  private def getTweetSocialProof(
    request: SocialProofThriftRequest
  ): Future[Seq[UserTweetEntityRecommendationUnion]] = {
    val socialProofsFuture = tweetSocialProofRunner(request)

    socialProofsFuture.map { socialProofs: Seq[RecommendationInfo] =>
      stats.counter(Stats.Served).incr(socialProofs.size)
      socialProofs.flatMap { tweetSocialProof: RecommendationInfo =>
        val tweetSocialProofJavaResult = tweetSocialProof.asInstanceOf[SocialProofJavaResult]
        Some(
          UserTweetEntityRecommendationUnion.TweetRec(
            TweetRecommendation(
              tweetSocialProofJavaResult.getNode,
              tweetSocialProofJavaResult.getWeight,
              getThriftSocialProof(tweetSocialProofJavaResult)
            )
          )
        )
      }
    }
  }

  def apply(request: SocialProofThriftRequest): Future[SocialProofThriftResponse] = {
    trackFutureBlockStats(stats) {
      val recommendationsWithSocialProofFut = Future
        .collect {
          request.recommendationIdsForSocialProof.keys.map {
            case ThriftRecommendationType.Tweet if decider.tweetSocialProof =>
              getTweetSocialProof(request)
            case (ThriftRecommendationType.Url | ThriftRecommendationType.Hashtag)
                if decider.entitySocialProof =>
              getEntitySocialProof(request)
            case _ =>
              Future.Nil
          }.toSeq
        }.map(_.flatten)
      recommendationsWithSocialProofFut.map { recommendationsWithSocialProof =>
        SocialProofThriftResponse(recommendationsWithSocialProof)
      }
    }
  }
}