the-algorithm/tweetypie/server/src/main/scala/com/twitter/tweetypie/handler/UnretweetHandler.scala

package com.twitter.tweetypie
package handler

import com.twitter.stitch.Stitch
import com.twitter.tweetypie.Future
import com.twitter.tweetypie.core.FilteredState
import com.twitter.tweetypie.repository.TweetQuery
import com.twitter.tweetypie.repository.TweetRepository
import com.twitter.tweetypie.thriftscala._
import com.twitter.timelineservice.{thriftscala => tls}
import com.twitter.tweetypie.backends.TimelineService.GetPerspectives

object UnretweetHandler {

  type Type = UnretweetRequest => Future[UnretweetResult]

  def apply(
    deleteTweets: TweetDeletePathHandler.DeleteTweets,
    getPerspectives: GetPerspectives,
    unretweetEdits: TweetDeletePathHandler.UnretweetEdits,
    tweetRepo: TweetRepository.Type,
  ): Type = { request: UnretweetRequest =>
    val handleEdits = getSourceTweet(request.sourceTweetId, tweetRepo).liftToTry.flatMap {
      case Return(sourceTweet) =>
        // If we're able to fetch the source Tweet, unretweet all its other versions
        unretweetEdits(sourceTweet.editControl, request.sourceTweetId, request.userId)
      case Throw(_) => Future.Done
    }

    handleEdits.flatMap(_ => unretweetSourceTweet(request, deleteTweets, getPerspectives))
  }

  def unretweetSourceTweet(
    request: UnretweetRequest,
    deleteTweets: TweetDeletePathHandler.DeleteTweets,
    getPerspectives: GetPerspectives,
  ): Future[UnretweetResult] =
    getPerspectives(
      Seq(tls.PerspectiveQuery(request.userId, Seq(request.sourceTweetId)))
    ).map { results => results.head.perspectives.headOption.flatMap(_.retweetId) }
      .flatMap {
        case Some(id) =>
          deleteTweets(
            DeleteTweetsRequest(tweetIds = Seq(id), byUserId = Some(request.userId)),
            false
          ).map(_.head).map { deleteTweetResult =>
            UnretweetResult(Some(deleteTweetResult.tweetId), deleteTweetResult.state)
          }
        case None => Future.value(UnretweetResult(None, TweetDeleteState.Ok))
      }

  def getSourceTweet(
    sourceTweetId: TweetId,
    tweetRepo: TweetRepository.Type
  ): Future[Tweet] = {
    val options: TweetQuery.Options = TweetQuery
      .Options(include = TweetQuery.Include(tweetFields = Set(Tweet.EditControlField.id)))

    Stitch.run {
      tweetRepo(sourceTweetId, options).rescue {
        case _: FilteredState => Stitch.NotFound
      }
    }
  }
}