package com.twitter.home_mixer.functional_component.feature_hydrator

import com.twitter.home_mixer.model.HomeFeatures.AuthorIdFeature
import com.twitter.home_mixer.model.HomeFeatures.ConversationModuleFocalTweetIdFeature
import com.twitter.home_mixer.model.HomeFeatures.ConversationModuleIdFeature
import com.twitter.home_mixer.model.HomeFeatures.FocalTweetAuthorIdFeature
import com.twitter.home_mixer.model.HomeFeatures.FocalTweetInNetworkFeature
import com.twitter.home_mixer.model.HomeFeatures.FocalTweetRealNamesFeature
import com.twitter.home_mixer.model.HomeFeatures.FocalTweetScreenNamesFeature
import com.twitter.home_mixer.model.HomeFeatures.InNetworkFeature
import com.twitter.home_mixer.model.HomeFeatures.RealNamesFeature
import com.twitter.home_mixer.model.HomeFeatures.ScreenNamesFeature
import com.twitter.product_mixer.component_library.model.candidate.TweetCandidate
import com.twitter.product_mixer.core.feature.Feature
import com.twitter.product_mixer.core.feature.featuremap.FeatureMap
import com.twitter.product_mixer.core.feature.featuremap.FeatureMapBuilder
import com.twitter.product_mixer.core.functional_component.feature_hydrator.BulkCandidateFeatureHydrator
import com.twitter.product_mixer.core.model.common.CandidateWithFeatures
import com.twitter.product_mixer.core.model.common.identifier.FeatureHydratorIdentifier
import com.twitter.product_mixer.core.pipeline.PipelineQuery
import com.twitter.stitch.Stitch
import javax.inject.Inject
import javax.inject.Singleton

/**
 * Social context for convo modules is hydrated on the root Tweet but needs info about the focal
 * Tweet (e.g. author) to render the banner. This hydrator copies focal Tweet data into the root.
 */
@Singleton
class FocalTweetFeatureHydrator @Inject() ()
    extends BulkCandidateFeatureHydrator[PipelineQuery, TweetCandidate] {

  override val identifier: FeatureHydratorIdentifier = FeatureHydratorIdentifier("FocalTweet")

  override val features: Set[Feature[_, _]] = Set(
    FocalTweetAuthorIdFeature,
    FocalTweetInNetworkFeature,
    FocalTweetRealNamesFeature,
    FocalTweetScreenNamesFeature
  )

  private val DefaultFeatureMap = FeatureMapBuilder()
    .add(FocalTweetAuthorIdFeature, None)
    .add(FocalTweetInNetworkFeature, None)
    .add(FocalTweetRealNamesFeature, None)
    .add(FocalTweetScreenNamesFeature, None)
    .build()

  override def apply(
    query: PipelineQuery,
    candidates: Seq[CandidateWithFeatures[TweetCandidate]]
  ): Stitch[Seq[FeatureMap]] = {
    // Build a map of all the focal tweets to their corresponding features
    val focalTweetIdToFeatureMap = candidates.flatMap { candidate =>
      val focalTweetId = candidate.features.getOrElse(ConversationModuleFocalTweetIdFeature, None)
      if (focalTweetId.contains(candidate.candidate.id)) {
        Some(candidate.candidate.id -> candidate.features)
      } else None
    }.toMap

    val updatedFeatureMap = candidates.map { candidate =>
      val focalTweetId = candidate.features.getOrElse(ConversationModuleFocalTweetIdFeature, None)
      val conversationId = candidate.features.getOrElse(ConversationModuleIdFeature, None)

      // Check if the candidate is a root tweet and ensure its focal tweet's features are available
      if (conversationId.contains(candidate.candidate.id)
        && focalTweetId.exists(focalTweetIdToFeatureMap.contains)) {
        val featureMap = focalTweetIdToFeatureMap.get(focalTweetId.get).get
        FeatureMapBuilder()
          .add(FocalTweetAuthorIdFeature, featureMap.getOrElse(AuthorIdFeature, None))
          .add(FocalTweetInNetworkFeature, Some(featureMap.getOrElse(InNetworkFeature, true)))
          .add(
            FocalTweetRealNamesFeature,
            Some(featureMap.getOrElse(RealNamesFeature, Map.empty[Long, String])))
          .add(
            FocalTweetScreenNamesFeature,
            Some(featureMap.getOrElse(ScreenNamesFeature, Map.empty[Long, String])))
          .build()
      } else DefaultFeatureMap
    }

    Stitch.value(updatedFeatureMap)
  }
}