package com.twitter.recos.user_tweet_entity_graph

import com.twitter.finagle.stats.StatsReceiver
import com.twitter.frigate.common.util.StatsUtil
import com.twitter.graphjet.algorithms.RecommendationType
import com.twitter.graphjet.algorithms.counting.tweet.TweetMetadataRecommendationInfo
import com.twitter.graphjet.algorithms.counting.tweet.TweetRecommendationInfo
import com.twitter.recos.user_tweet_entity_graph.thriftscala._
import com.twitter.recos.util.Stats
import com.twitter.servo.request._
import com.twitter.util.Future

/**
 * Implementation of the Thrift-defined service interface.
 *
* A wrapper of magicRecsRunner.
 */
class RecommendationHandler(
  tweetRecsRunner: TweetRecommendationsRunner,
  statsReceiver: StatsReceiver)
    extends RequestHandler[RecommendTweetEntityRequest, RecommendTweetEntityResponse] {
  private val stats = statsReceiver.scope(this.getClass.getSimpleName)
  private val socialProofHydrator = new SocialProofHydrator(stats)

  override def apply(request: RecommendTweetEntityRequest): Future[RecommendTweetEntityResponse] = {
    val scopedStats: StatsReceiver = stats.scope(request.displayLocation.toString)

    StatsUtil.trackBlockStats(scopedStats) {
      val candidatesFuture = tweetRecsRunner.apply(request)

      candidatesFuture.map { candidates =>
        if (candidates.isEmpty) scopedStats.counter(Stats.EmptyResult).incr()
        else scopedStats.counter(Stats.Served).incr(candidates.size)

        RecommendTweetEntityResponse(candidates.flatMap {
          _ match {
            case tweetRec: TweetRecommendationInfo =>
              Some(
                UserTweetEntityRecommendationUnion.TweetRec(
                  TweetRecommendation(
                    tweetRec.getRecommendation,
                    tweetRec.getWeight,
                    socialProofHydrator.addTweetSocialProofByType(tweetRec),
                    socialProofHydrator.addTweetSocialProofs(tweetRec)
                  )
                )
              )
            case tweetMetadataRec: TweetMetadataRecommendationInfo =>
              if (tweetMetadataRec.getRecommendationType == RecommendationType.HASHTAG) {
                Some(
                  UserTweetEntityRecommendationUnion.HashtagRec(
                    HashtagRecommendation(
                      tweetMetadataRec.getRecommendation,
                      tweetMetadataRec.getWeight,
                      socialProofHydrator.addMetadataSocialProofByType(tweetMetadataRec)
                    )
                  )
                )
              } else if (tweetMetadataRec.getRecommendationType == RecommendationType.URL) {
                Some(
                  UserTweetEntityRecommendationUnion.UrlRec(
                    UrlRecommendation(
                      tweetMetadataRec.getRecommendation,
                      tweetMetadataRec.getWeight,
                      socialProofHydrator.addMetadataSocialProofByType(tweetMetadataRec)
                    )
                  )
                )
              } else {
                None: Option[UserTweetEntityRecommendationUnion]
              }
            case _ => None
          }
        })
      }
    }
  }
}