openmct/platform/features/search/src/providers/ElasticsearchSearchProvider.js

/*****************************************************************************
 * Open MCT Web, Copyright (c) 2014-2015, United States Government
 * as represented by the Administrator of the National Aeronautics and Space
 * Administration. All rights reserved.
 *
 * Open MCT Web is 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.
 *
 * Open MCT Web includes source code licensed under additional open source
 * licenses. See the Open Source Licenses file (LICENSES.md) included with
 * this source code distribution or the Licensing information page available
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 *****************************************************************************/
/*global define*/

/**
 * Module defining ElasticsearchSearchProvider. Created by shale on 07/16/2015.
 */
define(
    [],
    function () {
        "use strict";

        // JSLint doesn't like underscore-prefixed properties,
        // so hide them here.
        var ID = "_id",
            SCORE = "_score",
            DEFAULT_MAX_RESULTS = 999999;
        
        /**
         * A search service which searches through domain objects in 
         * the filetree using ElasticSearch.
         *
         * @constructor
         * @param $http Angular's $http service, for working with urls.
         * @param {ObjectService} objectService the service from which
         *        domain objects can be gotten.
         * @param ROOT the constant ELASTIC_ROOT which allows us to 
         *        interact with ElasticSearch.
         */
        function ElasticsearchSearchProvider($http, objectService, ROOT) {
            
            // Add the fuzziness operator to the search term 
            function addFuzziness(searchTerm, editDistance) {
                if (!editDistance) {
                    editDistance = '';
                }
                
                return searchTerm.split(' ').map(function (s) {
                    if (s.includes('"')) {
                        return s;
                    } else {
                        return s + '~' + editDistance;
                    }
                }).join(' ');
            }
            
            // Currently specific to elasticsearch
            function processSearchTerm(searchTerm) {
                var spaceIndex;
                
                // Cut out any extra spaces
                while (searchTerm.substr(0, 1) === ' ') {
                    searchTerm = searchTerm.substring(1, searchTerm.length);
                }
                while (searchTerm.substr(searchTerm.length - 1, 1) === ' ') {
                    searchTerm = searchTerm.substring(0, searchTerm.length - 1);
                }
                spaceIndex = searchTerm.indexOf('  ');
                while (spaceIndex !== -1) {
                    searchTerm = searchTerm.substring(0, spaceIndex) +
                                    searchTerm.substring(spaceIndex + 1, searchTerm.length);
                    spaceIndex = searchTerm.indexOf('  ');
                }
                
                // Add fuzziness for completeness
                searchTerm = addFuzziness(searchTerm);
                
                //console.log('search term ', searchTerm);
                return searchTerm;
            }
            
            // Processes results from the format that elasticsearch returns to 
            // a list of search result objects (that contain domain objects), then
            // returns an object in the format {hits: searchResult[], total: number}
            function processResults(rawResults, timestamp) {
                var results = rawResults.data.hits.hits,
                    resultsLength = results.length,
                    ids = [],
                    scores = {},
                    searchResults = [],
                    i;
                
                // Get the result objects' IDs
                for (i = 0; i < resultsLength; i += 1) {
                    ids.push(results[i][ID]);
                }
                
                // Get the result objects' scores
                for (i = 0; i < resultsLength; i += 1) {
                    scores[ids[i]] = results[i][SCORE];
                }
                
                // Get the domain objects from their IDs
                return objectService.getObjects(ids).then(function (objects) {
                    var j,
                        id;
                    
                    for (j = 0; j < resultsLength; j += 1) {
                        id = ids[j];
                        
                        // Include items we can get models for
                        if (objects[id].getModel) {
                            // Format the results as searchResult objects
                            searchResults.push({
                                id: id,
                                object: objects[id],
                                score: scores[id]
                            });
                        }
                    }
                    
                    return {
                        hits: searchResults,
                        total: rawResults.data.hits.total
                    };
                });
            }
            
            // For documentation, see query below.
            function query(searchTerm, timestamp, maxResults, timeout) {
                var esQuery;
                
                // Check to see if the user provided a maximum 
                // number of results to display
                if (!maxResults) {
                    // Else, we provide a default value. 
                    maxResults = DEFAULT_MAX_RESULTS;
                }
                
                // If the user input is empty, we want to have no search results.
                if (searchTerm !== '') {
                    // Process the search term
                    searchTerm = processSearchTerm(searchTerm);

                    // Create the query to elasticsearch
                    esQuery = ROOT + "/_search/?q=" + searchTerm +
                                     "&size=" + maxResults;
                    if (timeout) {
                        esQuery += "&timeout=" + timeout;
                    }

                    // Get the data...
                    return $http({
                        method: "GET",
                        url: esQuery
                    }).then(function (rawResults) {
                        // ...then process the data 
                        return processResults(rawResults, timestamp);
                    });
                } else {
                    return {hits: [], total: 0};
                }
            }
            
            return {
                /**
                 * Searches through the filetree for domain objects using a search 
                 *   term. This is done through querying elasticsearch. Returns a
                 *   promise for a result object that has the format
                 *   {hits: searchResult[], total: number}
                 *   where a searchResult has the format
                 *   {id: domainObject ID, object: domainObject, score: number}
                 *
                 * Notes:
                 *   * The order of the results is from highest to lowest score, 
                 *     as elsaticsearch determines them to be. 
                 *   * Uses the fuzziness operator to get more results. 
                 *   * More about this search's behavior at 
                 *     https://www.elastic.co/guide/en/elasticsearch/reference/current/search-uri-request.html
                 * 
                 * @param searchTerm The text input that is the query. 
                 * @param timestamp The time at which this function was called.
                 *   This timestamp is used as a unique identifier for this 
                 *   query and the corresponding results. 
                 * @param maxResults (optional) The maximum number of results 
                 *   that this function should return.
                 * @param timeout (optional) The time after which the search should 
                 *   stop calculations and return partial results. Elasticsearch 
                 *   does not guarentee that this timeout will be strictly followed. 
                 */
                query: query
            };
        }


        return ElasticsearchSearchProvider;
    }
);