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/*
 * Copyright 2017-2022 John Snow Labs
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.johnsnowlabs.nlp.embeddings

import com.johnsnowlabs.ml.ai.Elmo
import com.johnsnowlabs.ml.tensorflow._
import com.johnsnowlabs.ml.util.LoadExternalModel.{modelSanityCheck, notSupportedEngineError}
import com.johnsnowlabs.ml.util.TensorFlow
import com.johnsnowlabs.nlp._
import com.johnsnowlabs.nlp.annotators.common._
import com.johnsnowlabs.storage.HasStorageRef
import org.apache.spark.broadcast.Broadcast
import org.apache.spark.ml.param.{IntArrayParam, IntParam, Param}
import org.apache.spark.ml.util.Identifiable
import org.apache.spark.sql.{DataFrame, SparkSession}

/** Word embeddings from ELMo (Embeddings from Language Models), a language model trained on the 1
  * Billion Word Benchmark.
  *
  * Note that this is a very computationally expensive module compared to word embedding modules
  * that only perform embedding lookups. The use of an accelerator is recommended.
  *
  * Pretrained models can be loaded with `pretrained` of the companion object:
  * {{{
  * val embeddings = ElmoEmbeddings.pretrained()
  *   .setInputCols("sentence", "token")
  *   .setOutputCol("elmo_embeddings")
  * }}}
  * The default model is `"elmo"`, if no name is provided.
  *
  * For available pretrained models please see the
  * [[https://sparknlp.org/models?task=Embeddings Models Hub]].
  *
  * The pooling layer can be set with `setPoolingLayer` to the following values:
  *   - `"word_emb"`: the character-based word representations with shape `[batch_size,
  *     max_length, 512]`.
  *   - `"lstm_outputs1"`: the first LSTM hidden state with shape `[batch_size, max_length,
  *     1024]`.
  *   - `"lstm_outputs2"`: the second LSTM hidden state with shape `[batch_size, max_length,
  *     1024]`.
  *   - `"elmo"`: the weighted sum of the 3 layers, where the weights are trainable. This tensor
  *     has shape `[batch_size, max_length, 1024]`.
  *
  * For extended examples of usage, see the
  * [[https://github.com/JohnSnowLabs/spark-nlp/blob/master/examples/python/training/english/dl-ner/ner_elmo.ipynb Examples]]
  * and the
  * [[https://github.com/JohnSnowLabs/spark-nlp/blob/master/src/test/scala/com/johnsnowlabs/nlp/embeddings/ElmoEmbeddingsTestSpec.scala ElmoEmbeddingsTestSpec]].
  *
  * '''References:'''
  *
  * [[https://tfhub.dev/google/elmo/3]]
  *
  * [[https://arxiv.org/abs/1802.05365 Deep contextualized word representations]]
  *
  * ''' Paper abstract:'''
  *
  * ''We introduce a new type of deep contextualized word representation that models both (1)
  * complex characteristics of word use (e.g., syntax and semantics), and (2) how these uses vary
  * across linguistic contexts (i.e., to model polysemy). Our word vectors are learned functions
  * of the internal states of a deep bidirectional language model (biLM), which is pre-trained on
  * a large text corpus. We show that these representations can be easily added to existing models
  * and significantly improve the state of the art across six challenging NLP problems, including
  * question answering, textual entailment and sentiment analysis. We also present an analysis
  * showing that exposing the deep internals of the pre-trained network is crucial, allowing
  * downstream models to mix different types of semi-supervision signals.''
  *
  * ==Example==
  * {{{
  * import spark.implicits._
  * import com.johnsnowlabs.nlp.base.DocumentAssembler
  * import com.johnsnowlabs.nlp.annotators.Tokenizer
  * import com.johnsnowlabs.nlp.embeddings.ElmoEmbeddings
  * import com.johnsnowlabs.nlp.EmbeddingsFinisher
  * import org.apache.spark.ml.Pipeline
  *
  * val documentAssembler = new DocumentAssembler()
  *   .setInputCol("text")
  *   .setOutputCol("document")
  *
  * val tokenizer = new Tokenizer()
  *   .setInputCols("document")
  *   .setOutputCol("token")
  *
  * val embeddings = ElmoEmbeddings.pretrained()
  *   .setPoolingLayer("word_emb")
  *   .setInputCols("token", "document")
  *   .setOutputCol("embeddings")
  *
  * val embeddingsFinisher = new EmbeddingsFinisher()
  *   .setInputCols("embeddings")
  *   .setOutputCols("finished_embeddings")
  *   .setOutputAsVector(true)
  *   .setCleanAnnotations(false)
  *
  * val pipeline = new Pipeline().setStages(Array(
  *   documentAssembler,
  *   tokenizer,
  *   embeddings,
  *   embeddingsFinisher
  * ))
  *
  * val data = Seq("This is a sentence.").toDF("text")
  * val result = pipeline.fit(data).transform(data)
  *
  * result.selectExpr("explode(finished_embeddings) as result").show(5, 80)
  * +--------------------------------------------------------------------------------+
  * |                                                                          result|
  * +--------------------------------------------------------------------------------+
  * |[6.662458181381226E-4,-0.2541114091873169,-0.6275503039360046,0.5787073969841...|
  * |[0.19154725968837738,0.22998669743537903,-0.2894386649131775,0.21524395048618...|
  * |[0.10400570929050446,0.12288510054349899,-0.07056470215320587,-0.246389418840...|
  * |[0.49932169914245605,-0.12706467509269714,0.30969417095184326,0.2643227577209...|
  * |[-0.8871506452560425,-0.20039963722229004,-1.0601330995559692,0.0348707810044...|
  * +--------------------------------------------------------------------------------+
  * }}}
  *
  * @see
  *   [[https://sparknlp.org/docs/en/annotators Annotators Main Page]] for a list of other
  *   transformer based embeddings
  * @param uid
  *   required uid for storing annotator to disk
  * @groupname anno Annotator types
  * @groupdesc anno
  *   Required input and expected output annotator types
  * @groupname Ungrouped Members
  * @groupname param Parameters
  * @groupname setParam Parameter setters
  * @groupname getParam Parameter getters
  * @groupname Ungrouped Members
  * @groupprio param  1
  * @groupprio anno  2
  * @groupprio Ungrouped 3
  * @groupprio setParam  4
  * @groupprio getParam  5
  * @groupdesc param
  *   A list of (hyper-)parameter keys this annotator can take. Users can set and get the
  *   parameter values through setters and getters, respectively.
  */
class ElmoEmbeddings(override val uid: String)
    extends AnnotatorModel[ElmoEmbeddings]
    with HasSimpleAnnotate[ElmoEmbeddings]
    with WriteTensorflowModel
    with HasEmbeddingsProperties
    with HasStorageRef
    with HasCaseSensitiveProperties
    with HasEngine {

  /** Input annotator types : DOCUMENT, TOKEN
    *
    * @group anno
    */
  override val inputAnnotatorTypes: Array[String] =
    Array(AnnotatorType.DOCUMENT, AnnotatorType.TOKEN)

  /** Output annotator type : WORD_EMBEDDINGS
    *
    * @group anno
    */
  override val outputAnnotatorType: AnnotatorType = AnnotatorType.WORD_EMBEDDINGS

  /** Batch size (Default: `32`). Large values allows faster processing but requires more memory.
    *
    * @group param
    */
  val batchSize = new IntParam(
    this,
    "batchSize",
    "Batch size. Large values allows faster processing but requires more memory.")

  /** ConfigProto from tensorflow, serialized into byte array. Get with
    * config_proto.SerializeToString()
    *
    * @group param
    */
  val configProtoBytes = new IntArrayParam(
    this,
    "configProtoBytes",
    "ConfigProto from tensorflow, serialized into byte array. Get with config_proto.SerializeToString()")

  /** Set ELMo pooling layer to: `"word_emb"`, `"lstm_outputs1"`, `"lstm_outputs2"`, or `"elmo"`
    * (Default: `"word_emb"`).
    *
    * Possible values are:
    *   - `"word_emb"`: the character-based word representations with shape [batch_size,
    *     max_length, 512].
    *   - `"lstm_outputs1"`: the first LSTM hidden state with shape [batch_size, max_length,
    *     1024].
    *   - `"lstm_outputs2"`: the second LSTM hidden state with shape [batch_size, max_length,
    *     1024].
    *   - `"elmo"`: the weighted sum of the 3 layers, where the weights are trainable. This tensor
    *     has shape [batch_size, max_length, 1024]
    *
    * @group param
    */
  val poolingLayer = new Param[String](
    this,
    "poolingLayer",
    "Set ELMO pooling layer to: word_emb, lstm_outputs1, lstm_outputs2, or elmo")

  private var _model: Option[Broadcast[Elmo]] = None

  /** Annotator reference id. Used to identify elements in metadata or to refer to this annotator
    * type
    */
  def this() = this(Identifiable.randomUID("ELMO_EMBEDDINGS"))

  /** Large values allows faster processing but requires more memory.
    *
    * @group setParam
    */
  def setBatchSize(size: Int): this.type = {
    set(batchSize, size)
  }

  /** Set Dimension of pooling layer. This is meta for the annotation and will not affect the
    * actual embedding calculation.
    *
    * @group setParam
    */
  override def setDimension(value: Int): this.type = {
    set(this.dimension, value)

  }

  /** ConfigProto from tensorflow, serialized into byte array. Get with
    * config_proto.SerializeToString()
    *
    * @group setParam
    */
  def setConfigProtoBytes(bytes: Array[Int]): ElmoEmbeddings.this.type =
    set(this.configProtoBytes, bytes)

  /** Function used to set the embedding output layer of the ELMO model
    *
    * @param layer
    *   Layer specification
    * @group setParam
    */
  def setPoolingLayer(layer: String): this.type = {
    layer match {
      case "word_emb" => set(poolingLayer, "word_emb")
      case "lstm_outputs1" => set(poolingLayer, "lstm_outputs1")
      case "lstm_outputs2" => set(poolingLayer, "lstm_outputs2")
      case "elmo" => set(poolingLayer, "elmo")

      case _ =>
        throw new MatchError(
          "poolingLayer must be either word_emb, lstm_outputs1, lstm_outputs2, or elmo")
    }
  }

  /** Function used to set the embedding output layer of the ELMO model
    *
    * @group getParam
    */
  def getPoolingLayer: String = $(poolingLayer)

  setDefault(batchSize -> 32, poolingLayer -> "elmo", dimension -> 512)

  def setModelIfNotSet(spark: SparkSession, tensorflow: TensorflowWrapper): this.type = {
    if (_model.isEmpty) {

      _model = Some(
        spark.sparkContext.broadcast(
          new Elmo(tensorflow, batchSize = $(batchSize), configProtoBytes = getConfigProtoBytes)))
    }

    this
  }

  /** takes a document and annotations and produces new annotations of this annotator's annotation
    * type
    *
    * @param annotations
    *   Annotations that correspond to inputAnnotationCols generated by previous annotators if any
    * @return
    *   any number of annotations processed for every input annotation. Not necessary one to one
    *   relationship
    */
  override def annotate(annotations: Seq[Annotation]): Seq[Annotation] = {
    val sentences = TokenizedWithSentence.unpack(annotations)
    if (sentences.nonEmpty) {
      val embeddings = getModelIfNotSet.predict(sentences, $(poolingLayer))

      WordpieceEmbeddingsSentence.pack(embeddings)
    } else {
      Seq.empty[Annotation]
    }
  }

  def getModelIfNotSet: Elmo = _model.get.value

  override def onWrite(path: String, spark: SparkSession): Unit = {
    super.onWrite(path, spark)
    writeTensorflowModel(
      path,
      spark,
      getModelIfNotSet.tensorflow,
      "_elmo",
      ElmoEmbeddings.tfFile,
      configProtoBytes = getConfigProtoBytes)
  }

  def getConfigProtoBytes: Option[Array[Byte]] = get(this.configProtoBytes).map(_.map(_.toByte))

  override protected def afterAnnotate(dataset: DataFrame): DataFrame = {
    dataset.withColumn(
      getOutputCol,
      wrapEmbeddingsMetadata(dataset.col(getOutputCol), $(dimension), Some($(storageRef))))
  }

}

trait ReadablePretrainedElmoModel
    extends ParamsAndFeaturesReadable[ElmoEmbeddings]
    with HasPretrained[ElmoEmbeddings] {
  override val defaultModelName: Some[String] = Some("elmo")

  /** Java compliant-overrides */
  override def pretrained(): ElmoEmbeddings = super.pretrained()

  override def pretrained(name: String): ElmoEmbeddings = super.pretrained(name)

  override def pretrained(name: String, lang: String): ElmoEmbeddings =
    super.pretrained(name, lang)

  override def pretrained(name: String, lang: String, remoteLoc: String): ElmoEmbeddings =
    super.pretrained(name, lang, remoteLoc)
}

trait ReadElmoDLModel extends ReadTensorflowModel {
  this: ParamsAndFeaturesReadable[ElmoEmbeddings] =>

  override val tfFile: String = "elmo_tensorflow"

  def readModel(instance: ElmoEmbeddings, path: String, spark: SparkSession): Unit = {
    val tf = readTensorflowModel(path, spark, "_elmo_tf", initAllTables = true)
    instance.setModelIfNotSet(spark, tf)
  }

  addReader(readModel)

  def loadSavedModel(modelPath: String, spark: SparkSession): ElmoEmbeddings = {

    val (localModelPath, detectedEngine) = modelSanityCheck(modelPath)

    val annotatorModel = new ElmoEmbeddings()

    annotatorModel.set(annotatorModel.engine, detectedEngine)

    detectedEngine match {
      case TensorFlow.name =>
        val (wrapper, _) = TensorflowWrapper.read(
          localModelPath,
          zipped = false,
          useBundle = true,
          tags = Array("serve"),
          initAllTables = true)

        /** the order of setSignatures is important if we use getSignatures inside
          * setModelIfNotSet
          */
        annotatorModel
          .setModelIfNotSet(spark, wrapper)

      case _ =>
        throw new Exception(notSupportedEngineError)
    }

    annotatorModel
  }
}

/** This is the companion object of [[ElmoEmbeddings]]. Please refer to that class for the
  * documentation.
  */
object ElmoEmbeddings extends ReadablePretrainedElmoModel with ReadElmoDLModel




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