add filter to citation page and a on/off button

to display only sentences with citations,
while maintaining the sentence number.
Make the filtered list the default in search result citation link

htroot/api/citation.html

@@ -13,9 +13,18 @@
     <li><a href="#[url]#">#[url]#</a></li>
   #{/links}#</ul>
   #(/similar)#
-  <form action="#" name="" method="post" enctype="multipart/form-data" accept-charset="UTF-8">
+  <form action="citation.html?url=#[url]#" name="" method="post" enctype="multipart/form-data" accept-charset="UTF-8">
     <fieldset>
-    <legend><label>List of Sentences in #[url]#</label></legend>
+    <table width="100%">
+      <tr>
+        <td>
+          <legend><label>List of #(filter)#::Cited#(/filter)# Sentences in #[url]#</label></legend>
+        </td>
+        <td align="right">
+          <button type="submit" name="filter" class="btn btn-default btn-sm" value="#(filter)#true::false#(/filter)#">#(filter)#filter cited sentences::filter off#(/filter)#</button>
+        </td>
+      </tr>
+    </table>
     <dl>#{sentences}#
     <dt>#[dt]#</dt><dd>#[dd]#</dd>
     #{/sentences}#</dl>

htroot/api/citation.java

@@ -61,6 +61,7 @@ public class citation {
         String url = "";
         String hash = "";
         int ch = 10;
+        boolean filter = false; // show cited sentences only
         if (post != null) {
             if (post.containsKey("url")) {
                 url = post.get("url");
@@ -78,8 +79,9 @@ public class citation {
             if (post.containsKey("ch")) {
                 ch = post.getInt("ch", ch);
             }
+            filter = post.getBoolean("filter");
         }
-        
+        prop.put("filter", filter);
         if (url.length() > 0) {
             try {
                 uri = new DigestURL(url, null);
@@ -152,13 +154,28 @@ public class citation {
         
         // iterate the sentences
         int i = 0;
+        int sentenceNr = 0;
         for (Map.Entry<String, Set<DigestURL>> se: sentenceOcc.entrySet()) {
-            prop.put("sentences_" + i + "_dt", i);
-            StringBuilder dd = new StringBuilder(se.getKey());
             Set<DigestURL> app = se.getValue();
+            if (filter) { // prepare list, only include sentence with citation
+                if (app != null && app.size() > 0) {
+                    StringBuilder dd = new StringBuilder(se.getKey());
+                    prop.put("sentences_" + i + "_dt", sentenceNr);
+                    dd.append("<br/>appears in:");
+                    for (DigestURL u : app) {
+                        if (u != null) {
+                            dd.append(" <a href=\"").append(u.toNormalform(false)).append("\">").append(u.getHost()).append("</a>");
+                        }
+                    }
+                    prop.put("sentences_" + i + "_dd", dd.toString());
+                    i++;
+                }
+            } else { // prepare list, include all sentences
+                StringBuilder dd = new StringBuilder(se.getKey());
+                prop.put("sentences_" + i + "_dt", sentenceNr);
                 if (app != null && app.size() > 0) {
                     dd.append("<br/>appears in:");
-                for (DigestURL u: app) {
+                    for (DigestURL u : app) {
                         if (u != null) {
                             dd.append(" <a href=\"").append(u.toNormalform(false)).append("\">").append(u.getHost()).append("</a>");
                         }
@@ -167,6 +184,8 @@ public class citation {
                 prop.put("sentences_" + i + "_dd", dd.toString());
                 i++;
             }
+            sentenceNr++;
+        }
         prop.put("sentences", i);
         
         // iterate the citations in order of number of citations

htroot/yacysearchitem.html

@@ -28,7 +28,7 @@
   #(showSize)#:: | #[sizename]##(/showSize)#
   #(showMetadata)#::&nbsp;|&nbsp;<a href="solr/select?q=id:%22#[urlhash]#%22&defType=edismax&start=0&rows=1&core=collection1&wt=html" target="_blank" onclick="return hs.htmlExpand(this, { objectType: 'ajax'} )">Metadata</a>#(/showMetadata)#
   #(showParser)#::&nbsp;|&nbsp;<a href="ViewFile.html?urlHash=#[urlhash]#&amp;words=#[words]#" target="_blank">Parser</a>#(/showParser)#
-  #(showCitation)#::&nbsp;|&nbsp;<a href="api/citation.html?hash=#[urlhash]#" target="_blank">Citations</a>#(/showCitation)#
+  #(showCitation)#::&nbsp;|&nbsp;<a href="api/citation.html?hash=#[urlhash]#&filter=true" target="_blank">Citations</a>#(/showCitation)#
   #(showPictures)#::&nbsp;|&nbsp;<a href="yacysearch.html?contentdom=image&amp;url=#[link]#&amp;query=#[former]# inurl:#[link]#" target="_blank">Pictures</a>#(/showPictures)#
   #(showCache)#::&nbsp;|&nbsp;<a href="CacheResource_p.html?url=#[link]#" target="_blank">Cache</a>#(/showCache)#
   #(showProxy)#::&nbsp;|&nbsp;<a href="proxy.html?url=#[link]#" target="_blank">Augmented Browsing</a>#(/showProxy)#