package com.twitter.tweetypie.additionalfields

import com.twitter.tweetypie.thriftscala.Tweet
import com.twitter.scrooge.TFieldBlob
import com.twitter.scrooge.ThriftStructField

object AdditionalFields {
  type FieldId = Short

  /** additional fields really start at 100, be we are ignoring conversation id for now */
  val StartAdditionalId = 101

  /** all known [[Tweet]] field IDs */
  val CompiledFieldIds: Seq[FieldId] = Tweet.metaData.fields.map(_.id)

  /** all known [[Tweet]] fields in the "additional-field" range (excludes id) */
  val CompiledAdditionalFieldMetaDatas: Seq[ThriftStructField[Tweet]] =
    Tweet.metaData.fields.filter(f => isAdditionalFieldId(f.id))

  val CompiledAdditionalFieldsMap: Map[Short, ThriftStructField[Tweet]] =
    CompiledAdditionalFieldMetaDatas.map(field => (field.id, field)).toMap

  /** all known [[Tweet]] field IDs in the "additional-field" range */
  val CompiledAdditionalFieldIds: Seq[FieldId] =
    CompiledAdditionalFieldsMap.keys.toSeq

  /** all [[Tweet]] field IDs which should be rejected when set as additional
   * fields on via PostTweetRequest.additionalFields or RetweetRequest.additionalFields */
  val RejectedFieldIds: Seq[FieldId] = Seq(
    // Should be provided via PostTweetRequest.conversationControl field. go/convocontrolsbackend
    Tweet.ConversationControlField.id,
    // This field should only be set based on whether the client sets the right community
    // tweet annotation.
    Tweet.CommunitiesField.id,
    // This field should not be set by clients and should opt for
    // [[PostTweetRequest.ExclusiveTweetControlOptions]].
    // The exclusiveTweetControl field requires the userId to be set
    // and we shouldn't trust the client to provide the right one.
    Tweet.ExclusiveTweetControlField.id,
    // This field should not be set by clients and should opt for
    // [[PostTweetRequest.TrustedFriendsControlOptions]].
    // The trustedFriendsControl field requires the trustedFriendsListId to be
    // set and we shouldn't trust the client to provide the right one.
    Tweet.TrustedFriendsControlField.id,
    // This field should not be set by clients and should opt for
    // [[PostTweetRequest.CollabControlOptions]].
    // The collabControl field requires a list of Collaborators to be
    // set and we shouldn't trust the client to provide the right one.
    Tweet.CollabControlField.id
  )

  def isAdditionalFieldId(fieldId: FieldId): Boolean =
    fieldId >= StartAdditionalId

  /**
   * Provides a list of all additional field IDs on the tweet, which include all
   * the compiled additional fields and all the provided passthrough fields.  This includes
   * compiled additional fields where the value is None.
   */
  def allAdditionalFieldIds(tweet: Tweet): Seq[FieldId] =
    CompiledAdditionalFieldIds ++ tweet._passthroughFields.keys

  /**
   * Provides a list of all field IDs that have a value on the tweet which are not known compiled
   * additional fields (excludes [[Tweet.id]]).
   */
  def unsettableAdditionalFieldIds(tweet: Tweet): Seq[FieldId] =
    CompiledFieldIds
      .filter { id =>
        !isAdditionalFieldId(id) && id != Tweet.IdField.id && tweet.getFieldBlob(id).isDefined
      } ++
      tweet._passthroughFields.keys

  /**
   * Provides a list of all field IDs that have a value on the tweet which are explicitly disallowed
   * from being set via PostTweetRequest.additionalFields and RetweetRequest.additionalFields
   */
  def rejectedAdditionalFieldIds(tweet: Tweet): Seq[FieldId] =
    RejectedFieldIds
      .filter { id => tweet.getFieldBlob(id).isDefined }

  def unsettableAdditionalFieldIdsErrorMessage(unsettableFieldIds: Seq[FieldId]): String =
    s"request may not contain fields: [${unsettableFieldIds.sorted.mkString(", ")}]"

  /**
   * Provides a list of all additional field IDs that have a value on the tweet,
   * compiled and passthrough (excludes Tweet.id).
   */
  def nonEmptyAdditionalFieldIds(tweet: Tweet): Seq[FieldId] =
    CompiledAdditionalFieldMetaDatas.collect {
      case f if f.getValue(tweet) != None => f.id
    } ++ tweet._passthroughFields.keys

  def additionalFields(tweet: Tweet): Seq[TFieldBlob] =
    (tweet.getFieldBlobs(CompiledAdditionalFieldIds) ++ tweet._passthroughFields).values.toSeq

  /**
   * Merge base tweet with additional fields.
   * Non-additional fields in the additional tweet are ignored.
   * @param base: a tweet that contains basic fields
   * @param additional: a tweet object that carries additional fields
   */
  def setAdditionalFields(base: Tweet, additional: Tweet): Tweet =
    setAdditionalFields(base, additionalFields(additional))

  def setAdditionalFields(base: Tweet, additional: Option[Tweet]): Tweet =
    additional.map(setAdditionalFields(base, _)).getOrElse(base)

  def setAdditionalFields(base: Tweet, additional: Traversable[TFieldBlob]): Tweet =
    additional.foldLeft(base) { case (t, f) => t.setField(f) }

  /**
   * Unsets the specified fields on the given tweet.
   */
  def unsetFields(tweet: Tweet, fieldIds: Iterable[FieldId]): Tweet = {
    tweet.unsetFields(fieldIds.toSet)
  }
}