/*******************************************************************************
 * Copyright (c) 2015-2018 Skymind, Inc.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Apache License, Version 2.0 which is available at
 * https://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.
 *
 * SPDX-License-Identifier: Apache-2.0
 ******************************************************************************/

package org.datavec.nlp.metadata;


import org.datavec.api.conf.Configuration;
import org.nd4j.util.Index;

/**
 * Track metadata about vocabs
 *
 * @author Adam Gibson
 */
public interface VocabCache {


    /**
     * Increment the number of documents
     * @param by
     */
    void incrementNumDocs(double by);

    /**
     * Number of documents
     * @return the number of documents
     */
    double numDocs();

    /**
     * Returns a word in the vocab at a particular index
     * @param i the index to get
     * @return the word at that index in the vocab
     */
    String wordAt(int i);

    int wordIndex(String word);

    /**
     * Configuration for initializing
     * @param conf the configuration to initialize with
     */
    void initialize(Configuration conf);

    /**
     * Get the word frequency for a word
     * @param word the word to get frequency for
     * @return the frequency for a given word
     */
    double wordFrequency(String word);

    /**
     * The min word frequency
     * needed to be included in the vocab
     * (default 5)
     * @return the min word frequency to
     * be included in the vocab
     */
    int minWordFrequency();

    /**
     * All of the vocab words (ordered)
     * note that these are not all the possible tokens
     * @return the list of vocab words
     */
    Index vocabWords();


    /**
     * Increment the doc count for a word by 1
     * @param word the word to increment the count for
     */
    void incrementDocCount(String word);

    /**
     * Increment the document count for a particular word
     * @param word the word to increment the count for
     * @param by the amount to increment by
     */
    void incrementDocCount(String word, double by);

    /**
     * Increment a word count by 1
     * @param word the word to increment the count for
     */
    void incrementCount(String word);

    /**
     * Increment count for a word
     * @param word the word to increment the count for
     * @param by the amount to increment by
     */
    void incrementCount(String word, double by);

    /**
     * Number of documents word has occurred in
     * @param word the word to get the idf for
     */
    double idf(String word);

    /**
     * Calculate the tfidf of the word given the document frequency
     * @param word the word to get frequency for
     * @param frequency the frequency
     * @return the tfidf for a word
     */
    double tfidf(String word, double frequency, boolean smoothIdf);

}
