Resolve "Relevance Ranking in Metadata"

Required MRs to be merged before

• codeabilitysharingpluginapi!2 (merged)
• !217 (merged)
• codeabilitysharingpluginapi!3 (merged)

Related to #439 (closed)

src/main/java/at/ac/uibk/gitsearch/repository/search/MetaDataRepository.java

@@ -7,6 +7,10 @@ import at.ac.uibk.gitsearch.repository.jpa.StatisticsRepository;
 import at.ac.uibk.gitsearch.service.dto.AutoCompleteEntry;
 import at.ac.uibk.gitsearch.service.dto.StatisticsDTO;
 import co.elastic.clients.elasticsearch.ElasticsearchClient;
+import co.elastic.clients.elasticsearch._types.ScriptSortType;
+import co.elastic.clients.elasticsearch._types.SortOptions;
+import co.elastic.clients.elasticsearch._types.SortOptionsBuilders;
+import co.elastic.clients.elasticsearch._types.SortOrder;
 import co.elastic.clients.elasticsearch._types.query_dsl.BoolQuery;
 import co.elastic.clients.elasticsearch._types.query_dsl.ExistsQuery;
 import co.elastic.clients.elasticsearch._types.query_dsl.MatchPhrasePrefixQuery;
@@ -56,10 +60,12 @@ import java.util.stream.Stream;
 import java.util.stream.StreamSupport;
 import javax.annotation.PostConstruct;
 import javax.ws.rs.NotFoundException;
+import liquibase.repackaged.org.apache.commons.text.StringSubstitutor;
 import org.apache.commons.lang3.StringUtils;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.codeability.sharing.plugins.api.search.SearchInputDTO;
+import org.codeability.sharing.plugins.api.search.SearchOrdering;
 import org.codeability.sharing.plugins.api.search.SearchResultDTO;
 import org.codeability.sharing.plugins.api.search.SearchResultsDTO;
 import org.codeability.sharing.plugins.api.search.UserProvidedMetadataDTO.Person;
@@ -532,8 +538,6 @@ public class MetaDataRepository {
      * parameters.
      *
      * @param searchInputDTO the query parameters.
-     * @param pageSize       the size of the page (i.e. the maximum of returned
-     *                       hits).
      * @param user           the user that queries.
      * @return the search hits.
      * @throws IOException when search index is not available.
@@ -565,7 +569,13 @@ public class MetaDataRepository {
             final BoolQuery query = queryBuilder.build();
             // LOGGER.info("ElasticSearch Query using Java Client API:\n{}", query)
             co.elastic.clients.elasticsearch.core.SearchResponse<SearchResultDTO> searchResponse = elasticsearchAPIClient.search(
-                search -> search.index(SearchRepositoryConstants.INDEX_METADATA).query(q -> q.bool(query)).from(from).size(pageSize),
+                search ->
+                    search
+                        .index(SearchRepositoryConstants.INDEX_METADATA)
+                        .query(q -> q.bool(query))
+                        .sort(getSortStrategy(searchInputDTO.getOrdering()))
+                        .from(from)
+                        .size(pageSize),
                 SearchResultDTO.class
             );
 
@@ -583,6 +593,48 @@ public class MetaDataRepository {
         }
     }
 
+    private List<SortOptions> getSortStrategy(SearchOrdering searchOrdering) {
+        String sortingScriptTemplate =
+            "double boost = 0;" +
+            "if (doc.containsKey('${badgeRewarded}') && doc['${badgeRewarded}'].size() > 0) {" +
+            "    boost = boost + (doc['${badgeRewarded}'].value ? 1.0 : 0.0) * params.factorBadge;" +
+            "}" +
+            "if (doc.containsKey('${downloads}') && doc['${downloads}'].size() > 0) {" +
+            "    boost = boost + doc['${downloads}'].value * params.factorDownloads;" +
+            "}" +
+            "if (doc.containsKey('${views}') && doc['${views}'].size() > 0) {" +
+            "    boost = boost + doc['${views}'].value * params.factorViews;" +
+            "}" +
+            "return boost;";
+
+        Map<String, String> templateValueMapping = Map.of(
+            "badgeRewarded",
+            SearchRepositoryConstants.SEARCHSTATISTICS_BADGEREWARDED,
+            "downloads",
+            SearchRepositoryConstants.SEARCHSTATISTICS_DOWNLOADS,
+            "views",
+            SearchRepositoryConstants.SEARCHSTATISTICS_VIEWS
+        );
+
+        var scriptSort = SortOptionsBuilders.script(b ->
+            b
+                .type(ScriptSortType.Number)
+                .order(SortOrder.Desc)
+                .script(sb ->
+                    sb.inline(isb ->
+                        isb
+                            .lang("painless")
+                            .source(StringSubstitutor.replace(sortingScriptTemplate, templateValueMapping))
+                            .params("factorBadge", JsonData.of(searchOrdering.getFactorBadge()))
+                            .params("factorDownloads", JsonData.of(searchOrdering.getFactorDownloads()))
+                            .params("factorViews", JsonData.of(searchOrdering.getFactorViews()))
+                    )
+                )
+        );
+
+        return List.of(SortOptionsBuilders.score(s -> s.order(SortOrder.Desc)), scriptSort);
+    }
+
     /**
      * creates the query (builder) for the searchInput and the user authorization
      *
@@ -774,12 +826,14 @@ public class MetaDataRepository {
      */
     private void addAuthorizationQueryWithJavaApi(Optional<User> user, BoolQuery.Builder queryBuilder) {
         // Authorization restrictions
+        // the boost value of 0 tells elastic to exclude these restrictions from the scoring process
         final TermQuery.Builder simplePublicQuery = new TermQuery.Builder()
             .value("public")
             .field(SearchRepositoryConstants.PROJECT_VISIBILITY)
             .boost(0.0f);
         final ExistsQuery.Builder publicVisibilityQuery = new ExistsQuery.Builder()
-            .field(SearchRepositoryConstants.METADATA_PUBLICVISIBILITY);
+            .field(SearchRepositoryConstants.METADATA_PUBLICVISIBILITY)
+            .boost(0.0f);
         final BoolQuery.Builder publicQuery = new BoolQuery.Builder()
             .should(q -> q.term(simplePublicQuery.build()))
             .should(q -> q.exists(publicVisibilityQuery.build()));