the-algorithm/visibilitylib/src/main/scala/com/twitter/visibility/generators/LocalizedInterstitialGenerator.scala

package com.twitter.visibility.generators

import com.twitter.decider.Decider
import com.twitter.finagle.stats.StatsReceiver
import com.twitter.visibility.builder.VisibilityResult
import com.twitter.visibility.common.actions.LocalizedMessage
import com.twitter.visibility.common.actions.MessageLink
import com.twitter.visibility.configapi.configs.VisibilityDeciderGates
import com.twitter.visibility.results.richtext.PublicInterestReasonToRichText
import com.twitter.visibility.results.translation.LearnMoreLink
import com.twitter.visibility.results.translation.Resource
import com.twitter.visibility.results.translation.SafetyResultReasonToResource
import com.twitter.visibility.results.translation.Translator
import com.twitter.visibility.rules.EmergencyDynamicInterstitial
import com.twitter.visibility.rules.Interstitial
import com.twitter.visibility.rules.InterstitialLimitedEngagements
import com.twitter.visibility.rules.PublicInterest
import com.twitter.visibility.rules.Reason
import com.twitter.visibility.rules.TweetInterstitial

object LocalizedInterstitialGenerator {
  def apply(
    visibilityDecider: Decider,
    baseStatsReceiver: StatsReceiver,
  ): LocalizedInterstitialGenerator = {
    new LocalizedInterstitialGenerator(visibilityDecider, baseStatsReceiver)
  }
}

class LocalizedInterstitialGenerator private (
  val visibilityDecider: Decider,
  val baseStatsReceiver: StatsReceiver) {

  private val visibilityDeciderGates = VisibilityDeciderGates(visibilityDecider)
  private val localizationStatsReceiver = baseStatsReceiver.scope("interstitial_localization")
  private val publicInterestInterstitialStats =
    localizationStatsReceiver.scope("public_interest_copy")
  private val emergencyDynamicInterstitialStats =
    localizationStatsReceiver.scope("emergency_dynamic_copy")
  private val regularInterstitialStats = localizationStatsReceiver.scope("interstitial_copy")

  def apply(visibilityResult: VisibilityResult, languageTag: String): VisibilityResult = {
    if (!visibilityDeciderGates.enableLocalizedInterstitialGenerator()) {
      return visibilityResult
    }

    visibilityResult.verdict match {
      case ipi: InterstitialLimitedEngagements if PublicInterest.Reasons.contains(ipi.reason) =>
        visibilityResult.copy(
          verdict = ipi.copy(
            localizedMessage = Some(localizePublicInterestCopyInResult(ipi, languageTag))
          ))
      case edi: EmergencyDynamicInterstitial =>
        visibilityResult.copy(
          verdict = EmergencyDynamicInterstitial(
            edi.copy,
            edi.linkOpt,
            Some(localizeEmergencyDynamicCopyInResult(edi, languageTag))
          ))
      case interstitial: Interstitial =>
        visibilityResult.copy(
          verdict = interstitial.copy(
            localizedMessage = localizeInterstitialCopyInResult(interstitial, languageTag)
          ))
      case tweetInterstitial: TweetInterstitial if tweetInterstitial.interstitial.isDefined =>
        tweetInterstitial.interstitial.get match {
          case ipi: InterstitialLimitedEngagements if PublicInterest.Reasons.contains(ipi.reason) =>
            visibilityResult.copy(
              verdict = tweetInterstitial.copy(
                interstitial = Some(
                  ipi.copy(
                    localizedMessage = Some(localizePublicInterestCopyInResult(ipi, languageTag))
                  ))
              ))
          case edi: EmergencyDynamicInterstitial =>
            visibilityResult.copy(
              verdict = tweetInterstitial.copy(
                interstitial = Some(
                  EmergencyDynamicInterstitial(
                    edi.copy,
                    edi.linkOpt,
                    Some(localizeEmergencyDynamicCopyInResult(edi, languageTag))
                  ))
              ))
          case interstitial: Interstitial =>
            visibilityResult.copy(
              verdict = tweetInterstitial.copy(
                interstitial = Some(
                  interstitial.copy(
                    localizedMessage = localizeInterstitialCopyInResult(interstitial, languageTag)
                  ))
              ))
          case _ => visibilityResult
        }
      case _ => visibilityResult
    }
  }

  private def localizeEmergencyDynamicCopyInResult(
    edi: EmergencyDynamicInterstitial,
    languageTag: String
  ): LocalizedMessage = {
    val text = edi.linkOpt
      .map(_ => s"${edi.copy} {${Resource.LearnMorePlaceholder}}")
      .getOrElse(edi.copy)

    val messageLinks = edi.linkOpt
      .map { link =>
        val learnMoreText = Translator.translate(LearnMoreLink, languageTag)
        Seq(MessageLink(Resource.LearnMorePlaceholder, learnMoreText, link))
      }.getOrElse(Seq.empty)

    emergencyDynamicInterstitialStats.counter("localized").incr()
    LocalizedMessage(text, languageTag, messageLinks)
  }

  private def localizePublicInterestCopyInResult(
    ipi: InterstitialLimitedEngagements,
    languageTag: String
  ): LocalizedMessage = {
    val safetyResultReason = PublicInterest.ReasonToSafetyResultReason(ipi.reason)
    val text = Translator.translate(
      SafetyResultReasonToResource.resource(safetyResultReason),
      languageTag,
    )

    val learnMoreLink = PublicInterestReasonToRichText.toLearnMoreLink(safetyResultReason)
    val learnMoreText = Translator.translate(LearnMoreLink, languageTag)
    val messageLinks = Seq(MessageLink(Resource.LearnMorePlaceholder, learnMoreText, learnMoreLink))

    publicInterestInterstitialStats.counter("localized").incr()
    LocalizedMessage(text, languageTag, messageLinks)
  }

  private def localizeInterstitialCopyInResult(
    interstitial: Interstitial,
    languageTag: String
  ): Option[LocalizedMessage] = {
    val localizedMessageOpt = Reason
      .toInterstitialReason(interstitial.reason)
      .flatMap(InterstitialReasonToLocalizedMessage(_, languageTag))

    if (localizedMessageOpt.isDefined) {
      regularInterstitialStats.counter("localized").incr()
      localizedMessageOpt
    } else {
      regularInterstitialStats.counter("empty").incr()
      None
    }
  }
}