add examples to the query suggestions

pdb-ui/src/main/java/org/lucares/pdbui/PdbController.java

@@ -15,6 +15,7 @@ import java.util.SortedSet;
 import java.util.TreeSet;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.locks.ReentrantLock;
+import java.util.regex.Pattern;
 
 import org.apache.commons.lang3.StringUtils;
 import org.lucares.pdb.api.DateTimeRange;
@@ -75,6 +76,9 @@ public class PdbController implements HardcodedValues, PropertyKeys {
 	@Value("${" + PRODUCTION_MODE + ":true}")
 	private boolean modeProduction;
 	
+	@Value("${"+QUERY_EXAMPLES+":}")
+	private String queryExamples;
+
 	public PdbController(final PerformanceDb db, final Plotter plotter) {
 		this.db = db;
 		this.plotter = plotter;
@@ -224,6 +228,9 @@ public class PdbController implements HardcodedValues, PropertyKeys {
 		final AutocompleteResponse result = new AutocompleteResponse();
 
 		final List<Proposal> proposals = db.autocomplete(q);
+		if (query.trim().length() == 0) {
+		  proposals.addAll(exampleProposals());
+		}
 
 		final List<AutocompleteProposal> autocompleteProposals = toAutocompleteProposals(proposals);
 		Collections.sort(autocompleteProposals, new AutocompleteProposalByValue());
@@ -232,7 +239,21 @@ public class PdbController implements HardcodedValues, PropertyKeys {
 		return result;
 	}
 
-	@RequestMapping(path = "/fields", //
+  private List<Proposal> exampleProposals() {
+    List<Proposal> result = new ArrayList<Proposal>();
+    
+    if (queryExamples.length() > 0) {
+      final String[] exampleQueries = queryExamples.split(Pattern.quote(";"));
+      for (String example : exampleQueries) {
+        Proposal p = new Proposal(" Example: "+example, example, true, example+" ", example.length()+1);
+        result.add(p);
+      }
+    }
+    
+    return result;
+  }
+
+  @RequestMapping(path = "/fields", //
 			method = RequestMethod.GET, //
 			//consumes = MediaType.APPLICATION_JSON_UTF8_VALUE, //
 			produces = MediaType.APPLICATION_JSON_VALUE //

pdb-ui/src/main/java/org/lucares/pdbui/PropertyKeys.java

@@ -17,4 +17,6 @@ public interface PropertyKeys {
 	 * property is used to switch Vue.js into production or development mode.
 	 */
 	String PRODUCTION_MODE = "mode.production";
+	
+	String QUERY_EXAMPLES = "query.examples";
 }