Fix display of ellipsis in search fragments (#1896)

Display ellipsis as an indicator that there is more content before or behind a search result fragment only if there really is more content.

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

@@ -0,0 +1,44 @@
+/*
+ * 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 lombok.Getter;
+
+@Getter
+public class ContentFragment {
+  private final String fragment;
+  private final boolean matchesContentStart;
+  private final boolean matchesContentEnd;
+
+  ContentFragment(String fragment) {
+    this(fragment, false, false);
+  }
+
+  ContentFragment(String fragment, boolean matchesContentStart, boolean matchesContentEnd) {
+    this.fragment = fragment;
+    this.matchesContentStart = matchesContentStart;
+    this.matchesContentEnd = matchesContentEnd;
+  }
+}

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

@@ -70,25 +70,32 @@ public final class LuceneHighlighter {
     return field.isHighlighted() && queriedFields.contains(field.getName());
   }
 
-  public String[] highlight(String fieldName, Indexed.Analyzer fieldAnalyzer, String value) throws InvalidTokenOffsetsException, IOException {
+  public ContentFragment[] highlight(String fieldName, Indexed.Analyzer fieldAnalyzer, String value) throws InvalidTokenOffsetsException, IOException {
     String[] fragments = highlighter.getBestFragments(analyzer, fieldName, value, MAX_NUM_FRAGMENTS);
     if (fieldAnalyzer == Indexed.Analyzer.CODE) {
-      fragments = keepWholeLine(value, fragments);
+      return keepWholeLine(value, fragments);
     }
-    return Arrays.stream(fragments)
-      .toArray(String[]::new);
+    return Arrays.stream(fragments).map(ContentFragment::new)
+      .toArray(ContentFragment[]::new);
   }
 
-  private String[] keepWholeLine(String content, String[] fragments) {
+  private ContentFragment[] keepWholeLine(String content, String[] fragments) {
     return Arrays.stream(fragments)
       .map(fragment -> keepWholeLine(content, fragment))
-      .toArray(String[]::new);
+      .toArray(ContentFragment[]::new);
   }
 
-  private String keepWholeLine(String content, String fragment) {
+  private ContentFragment keepWholeLine(String content, String fragment) {
+    boolean matchesContentStart = false;
+    boolean matchesContentEnd = false;
+
     String raw = fragment.replace(PRE_TAG, "").replace(POST_TAG, "");
     int index = content.indexOf(raw);
 
+    if (index == 0) {
+      matchesContentStart = true;
+    }
+
     int start = content.lastIndexOf('\n', index);
 
     String snippet;
@@ -109,9 +116,10 @@ public final class LuceneHighlighter {
     int end = content.indexOf('\n', index + raw.length());
     if (end < 0) {
       end = content.length();
+      matchesContentEnd = true;
     }
 
-    return snippet + content.substring(index + raw.length(), end) + "\n";
+    return new ContentFragment(snippet + content.substring(index + raw.length(), end) + (matchesContentEnd ? "" : "\n"), matchesContentStart, matchesContentEnd);
   }
 
 }

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

@@ -34,6 +34,7 @@ import org.apache.lucene.search.highlight.InvalidTokenOffsetsException;
 
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -75,9 +76,11 @@ public class QueryResultFactory {
     Object value = field.value(document);
     if (value != null) {
       if (highlighter.isHighlightable(field)) {
-        String[] fragments = createFragments(field, value.toString());
+        ContentFragment[] fragments = createFragments(field, value.toString());
         if (fragments.length > 0) {
-          return of(new Hit.HighlightedField(fragments));
+          boolean firstFragmentMatchesContentStart = fragments[0].isMatchesContentStart();
+          boolean lastFragmentMatchesContentEnd = fragments[fragments.length - 1].isMatchesContentEnd();
+          return of(new Hit.HighlightedField(Arrays.stream(fragments).map(ContentFragment::getFragment).toArray(String[]::new), firstFragmentMatchesContentStart, lastFragmentMatchesContentEnd));
         }
       }
       return of(new Hit.ValueField(value));
@@ -85,7 +88,7 @@ public class QueryResultFactory {
     return empty();
   }
 
-  private String[] createFragments(LuceneSearchableField field, String value) throws InvalidTokenOffsetsException, IOException {
+  private ContentFragment[] createFragments(LuceneSearchableField field, String value) throws InvalidTokenOffsetsException, IOException {
     return highlighter.highlight(field.getName(), field.getAnalyzer(), value);
   }