Add search engine and quick search for repositories (#1727)

Add a powerful search engine based on lucene to the scm-manager api.
The api can be used to index objects, simply by annotating them and add them to an index.
The first indexed object is the repository which could queried by quick search in the header.

scm-webapp/src/main/java/sonia/scm/search/LuceneQueryBuilder.java

@@ -0,0 +1,149 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2020-present Cloudogu GmbH and Contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package sonia.scm.search;
+
+import com.google.common.base.Strings;
+import org.apache.lucene.analysis.Analyzer;
+import org.apache.lucene.index.IndexReader;
+import org.apache.lucene.index.Term;
+import org.apache.lucene.queryparser.flexible.core.QueryNodeException;
+import org.apache.lucene.queryparser.flexible.standard.StandardQueryParser;
+import org.apache.lucene.search.BooleanClause;
+import org.apache.lucene.search.BooleanQuery;
+import org.apache.lucene.search.BoostQuery;
+import org.apache.lucene.search.Collector;
+import org.apache.lucene.search.IndexSearcher;
+import org.apache.lucene.search.Query;
+import org.apache.lucene.search.TopDocs;
+import org.apache.lucene.search.TopScoreDocCollector;
+import org.apache.lucene.search.WildcardQuery;
+import org.apache.lucene.search.highlight.InvalidTokenOffsetsException;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import javax.annotation.Nonnull;
+import java.io.IOException;
+import java.util.Locale;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+public class LuceneQueryBuilder extends QueryBuilder {
+
+  private static final Logger LOG = LoggerFactory.getLogger(LuceneQueryBuilder.class);
+
+  private static final Map<Class<?>, SearchableType> CACHE = new ConcurrentHashMap<>();
+
+  private final IndexOpener opener;
+  private final String indexName;
+  private final Analyzer analyzer;
+
+  LuceneQueryBuilder(IndexOpener opener, String indexName, Analyzer analyzer) {
+    this.opener = opener;
+    this.indexName = indexName;
+    this.analyzer = analyzer;
+  }
+
+  @Override
+  protected QueryResult execute(QueryParams queryParams) {
+    String queryString = Strings.nullToEmpty(queryParams.getQueryString());
+
+    SearchableType searchableType = CACHE.computeIfAbsent(queryParams.getType(), SearchableTypes::create);
+
+    Query query = Queries.filter(createQuery(searchableType, queryParams, queryString), queryParams);
+    if (LOG.isDebugEnabled()) {
+      LOG.debug("execute lucene query: {}", query);
+    }
+    try (IndexReader reader = opener.openForRead(indexName)) {
+      IndexSearcher searcher = new IndexSearcher(reader);
+
+      TopScoreDocCollector topScoreCollector = createTopScoreCollector(queryParams);
+      Collector collector = new PermissionAwareCollector(reader, topScoreCollector);
+      searcher.search(query, collector);
+
+      QueryResultFactory resultFactory = new QueryResultFactory(analyzer, searcher, searchableType, query);
+      return resultFactory.create(getTopDocs(queryParams, topScoreCollector));
+    } catch (IOException e) {
+      throw new SearchEngineException("failed to search index", e);
+    } catch (InvalidTokenOffsetsException e) {
+      throw new SearchEngineException("failed to highlight results", e);
+    }
+  }
+
+  @Nonnull
+  private TopScoreDocCollector createTopScoreCollector(QueryParams queryParams) {
+    return TopScoreDocCollector.create(queryParams.getStart() + queryParams.getLimit(), Integer.MAX_VALUE);
+  }
+
+  private TopDocs getTopDocs(QueryParams queryParams, TopScoreDocCollector topScoreCollector) {
+    return topScoreCollector.topDocs(queryParams.getStart(), queryParams.getLimit());
+  }
+
+  private Query createQuery(SearchableType searchableType, QueryParams queryParams, String queryString) {
+    try {
+      if (queryString.contains(":")) {
+        return createExpertQuery(searchableType, queryParams);
+      }
+      return createBestGuessQuery(searchableType, queryParams);
+    } catch (QueryNodeException ex) {
+      throw new QueryParseException(queryString, "failed to parse query", ex);
+    }
+  }
+
+  private Query createExpertQuery(SearchableType searchableType, QueryParams queryParams) throws QueryNodeException {
+    StandardQueryParser parser = new StandardQueryParser(analyzer);
+
+    parser.setPointsConfigMap(searchableType.getPointsConfig());
+    return parser.parse(queryParams.getQueryString(), "");
+  }
+
+  public Query createBestGuessQuery(SearchableType searchableType, QueryBuilder.QueryParams queryParams) {
+    String[] fieldNames = searchableType.getFieldNames();
+    if (fieldNames == null || fieldNames.length == 0) {
+      throw new NoDefaultQueryFieldsFoundException(searchableType.getType());
+    }
+    BooleanQuery.Builder builder = new BooleanQuery.Builder();
+    for (String fieldName : fieldNames) {
+      Term term = new Term(fieldName, appendWildcardIfNotAlreadyUsed(queryParams));
+      WildcardQuery query = new WildcardQuery(term);
+
+      Float boost = searchableType.getBoosts().get(fieldName);
+      if (boost != null) {
+        builder.add(new BoostQuery(query, boost), BooleanClause.Occur.SHOULD);
+      } else {
+        builder.add(query, BooleanClause.Occur.SHOULD);
+      }
+    }
+    return builder.build();
+  }
+
+  @Nonnull
+  private String appendWildcardIfNotAlreadyUsed(QueryParams queryParams) {
+    String queryString = queryParams.getQueryString().toLowerCase(Locale.ENGLISH);
+    if (!queryString.contains("?") && !queryString.contains("*")) {
+      queryString += "*";
+    }
+    return queryString;
+  }
+}