Adds group suggestions into ListGroups REST API.

This is a different approach of
Ie86de1f73ccd7bdec041730d95301d6aa3bdbdc4. This allows group
auto completion to be used in a plugin's UI.

Change-Id: Ia1cfa068246127c29f1b74f6aa4562a9167c301e

Documentation/rest-api-groups.txt

@@ -172,6 +172,46 @@ Query 25 groups starting from index 50.
   GET /groups/?n=25&S=50 HTTP/1.0
 ----
 
+[[suggest-group]]
+==== Suggest Group
+The `suggest` option indicates a user-entered string that
+should be auto-completed to group names.
+If this option is set and `n` is not set, then `n` defaults to 10.
+
+When using this option,
+the `project` or `p` option can be used to name the current project,
+to allow context-dependent suggestions.
+
+Not compatible with `visible-to-all`, `owned`, `user`, `match`, `q`,
+or `S`.
+(Attempts to use one of those options combined with `suggest` will
+error out.)
+
+.Request
+----
+  GET /groups/?suggest=ad&p=All-Projects HTTP/1.0
+----
+
+.Response
+----
+  HTTP/1.1 200 OK
+  Content-Disposition: attachment
+  Content-Type: application/json; charset=UTF-8
+
+  )]}'
+  {
+    "Administrators": {
+      "url": "#/admin/groups/uuid-59b92f35489e62c80d1ab1bf0c2d17843038df8b",
+      "options": {},
+      "description": "Gerrit Site Administrators",
+      "group_id": 1,
+      "owner": "Administrators",
+      "owner_id": "59b92f35489e62c80d1ab1bf0c2d17843038df8b",
+      "id": "59b92f35489e62c80d1ab1bf0c2d17843038df8b"
+    }
+  }
+----
+
 [[get-group]]
 === Get Group
 --

gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/api/group/GroupsIT.java

@@ -401,6 +401,13 @@ public class GroupsIT extends AbstractDaemonTest {
     assertThat(gApi.groups().list().getAsMap()).containsKey(newGroupName);
   }
 
+  @Test
+  public void testSuggestGroup() throws Exception {
+    Map<String, GroupInfo> groups = gApi.groups().list().withSuggest("adm").getAsMap();
+    assertThat(groups).containsKey("Administrators");
+    assertThat(groups).hasSize(1);
+  }
+
   @Test
   public void testAllGroupInfoFieldsSetCorrectly() throws Exception {
     AccountGroup adminGroup = getFromCache("Administrators");

gerrit-extension-api/src/main/java/com/google/gerrit/extensions/api/groups/Groups.java

@@ -63,6 +63,7 @@ public interface Groups {
     private int limit;
     private int start;
     private String substring;
+    private String suggest;
 
     public List<GroupInfo> get() throws RestApiException {
       Map<String, GroupInfo> map = getAsMap();
@@ -128,6 +129,11 @@ public interface Groups {
       return this;
     }
 
+    public ListRequest withSuggest(String suggest) {
+      this.suggest = suggest;
+      return this;
+    }
+
     public EnumSet<ListGroupsOption> getOptions() {
       return options;
     }
@@ -163,5 +169,9 @@ public interface Groups {
     public String getSubstring() {
       return substring;
     }
+
+    public String getSuggest() {
+      return suggest;
+    }
   }
 }

gerrit-server/src/main/java/com/google/gerrit/server/api/groups/GroupsImpl.java

@@ -138,6 +138,7 @@ class GroupsImpl implements Groups {
     list.setLimit(req.getLimit());
     list.setStart(req.getStart());
     list.setMatchSubstring(req.getSubstring());
+    list.setSuggest(req.getSuggest());
     try {
       return list.apply(tlr);
     } catch (OrmException e) {

gerrit-server/src/main/java/com/google/gerrit/server/group/ListGroups.java

@@ -16,14 +16,18 @@ package com.google.gerrit.server.group;
 
 import com.google.common.base.MoreObjects;
 import com.google.common.base.Strings;
+import com.google.common.collect.Iterables;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
 import com.google.common.collect.Sets;
+import com.google.gerrit.common.Nullable;
+import com.google.gerrit.common.data.GroupDescription;
 import com.google.gerrit.common.data.GroupDescriptions;
 import com.google.gerrit.common.data.GroupReference;
 import com.google.gerrit.common.errors.NoSuchGroupException;
 import com.google.gerrit.extensions.client.ListGroupsOption;
 import com.google.gerrit.extensions.common.GroupInfo;
+import com.google.gerrit.extensions.restapi.BadRequestException;
 import com.google.gerrit.extensions.restapi.RestReadView;
 import com.google.gerrit.extensions.restapi.TopLevelResource;
 import com.google.gerrit.extensions.restapi.Url;
@@ -32,6 +36,7 @@ import com.google.gerrit.reviewdb.client.AccountGroup;
 import com.google.gerrit.server.IdentifiedUser;
 import com.google.gerrit.server.account.AccountResource;
 import com.google.gerrit.server.account.GetGroups;
+import com.google.gerrit.server.account.GroupBackend;
 import com.google.gerrit.server.account.GroupCache;
 import com.google.gerrit.server.account.GroupComparator;
 import com.google.gerrit.server.account.GroupControl;
@@ -64,6 +69,7 @@ public class ListGroups implements RestReadView<TopLevelResource> {
   private final IdentifiedUser.GenericFactory userFactory;
   private final Provider<GetGroups> accountGetGroups;
   private final GroupJson json;
+  private final GroupBackend groupBackend;
 
   private EnumSet<ListGroupsOption> options =
       EnumSet.noneOf(ListGroupsOption.class);
@@ -73,6 +79,7 @@ public class ListGroups implements RestReadView<TopLevelResource> {
   private int limit;
   private int start;
   private String matchSubstring;
+  private String suggest;
 
   @Option(name = "--project", aliases = {"-p"},
       usage = "projects for which the groups should be listed")
@@ -121,6 +128,11 @@ public class ListGroups implements RestReadView<TopLevelResource> {
     this.matchSubstring = matchSubstring;
   }
 
+  @Option(name = "--suggest", usage = "to get a suggestion of groups")
+  public void setSuggest(String suggest) {
+    this.suggest = suggest;
+  }
+
   @Option(name = "-o", usage = "Output options per group")
   void addOption(ListGroupsOption o) {
     options.add(o);
@@ -137,7 +149,8 @@ public class ListGroups implements RestReadView<TopLevelResource> {
       final GroupControl.GenericFactory genericGroupControlFactory,
       final Provider<IdentifiedUser> identifiedUser,
       final IdentifiedUser.GenericFactory userFactory,
-      final Provider<GetGroups> accountGetGroups, GroupJson json) {
+      final Provider<GetGroups> accountGetGroups, GroupJson json,
+      GroupBackend groupBackend) {
     this.groupCache = groupCache;
     this.groupControlFactory = groupControlFactory;
     this.genericGroupControlFactory = genericGroupControlFactory;
@@ -145,6 +158,7 @@ public class ListGroups implements RestReadView<TopLevelResource> {
     this.userFactory = userFactory;
     this.accountGetGroups = accountGetGroups;
     this.json = json;
+    this.groupBackend = groupBackend;
   }
 
   public void setOptions(EnumSet<ListGroupsOption> options) {
@@ -161,7 +175,7 @@ public class ListGroups implements RestReadView<TopLevelResource> {
 
   @Override
   public SortedMap<String, GroupInfo> apply(TopLevelResource resource)
-      throws OrmException {
+      throws OrmException, BadRequestException {
     SortedMap<String, GroupInfo> output = Maps.newTreeMap();
     for (GroupInfo info : get()) {
       output.put(MoreObjects.firstNonNull(
@@ -172,53 +186,107 @@ public class ListGroups implements RestReadView<TopLevelResource> {
     return output;
   }
 
-  public List<GroupInfo> get() throws OrmException {
-    List<GroupInfo> groupInfos;
+  public List<GroupInfo> get() throws OrmException, BadRequestException {
+    if (!Strings.isNullOrEmpty(suggest)) {
+      return suggestGroups();
+    }
+
+    if (owned) {
+      return getGroupsOwnedBy(
+          user != null ? userFactory.create(user) : identifiedUser.get());
+    }
+
     if (user != null) {
-      if (owned) {
-        groupInfos = getGroupsOwnedBy(userFactory.create(user));
-      } else {
-        groupInfos = accountGetGroups.get().apply(
-            new AccountResource(userFactory.create(user)));
+      return accountGetGroups.get().apply(
+          new AccountResource(userFactory.create(user)));
+    }
+
+    return getAllGroups();
+  }
+
+  private List<GroupInfo> getAllGroups() throws OrmException {
+    List<GroupInfo> groupInfos;
+    List<AccountGroup> groupList;
+    if (!projects.isEmpty()) {
+      Map<AccountGroup.UUID, AccountGroup> groups = Maps.newHashMap();
+      for (final ProjectControl projectControl : projects) {
+        final Set<GroupReference> groupsRefs = projectControl.getAllGroups();
+        for (final GroupReference groupRef : groupsRefs) {
+          final AccountGroup group = groupCache.get(groupRef.getUUID());
+          if (group != null) {
+            groups.put(group.getGroupUUID(), group);
+          }
+        }
       }
+      groupList = filterGroups(groups.values());
     } else {
-      if (owned) {
-        groupInfos = getGroupsOwnedBy(identifiedUser.get());
-      } else {
-        List<AccountGroup> groupList;
-        if (!projects.isEmpty()) {
-          Map<AccountGroup.UUID, AccountGroup> groups = Maps.newHashMap();
-          for (final ProjectControl projectControl : projects) {
-            final Set<GroupReference> groupsRefs = projectControl.getAllGroups();
-            for (final GroupReference groupRef : groupsRefs) {
-              final AccountGroup group = groupCache.get(groupRef.getUUID());
-              if (group != null) {
-                groups.put(group.getGroupUUID(), group);
-              }
-            }
-          }
-          groupList = filterGroups(groups.values());
-        } else {
-          groupList = filterGroups(groupCache.all());
-        }
-        groupInfos = Lists.newArrayListWithCapacity(groupList.size());
-        int found = 0;
-        int foundIndex = 0;
-        for (AccountGroup group : groupList) {
-          if (foundIndex++ < start) {
-            continue;
-          }
-          if (limit > 0 && ++found > limit) {
-            break;
-          }
-          groupInfos.add(json.addOptions(options).format(
-              GroupDescriptions.forAccountGroup(group)));
-        }
+      groupList = filterGroups(groupCache.all());
+    }
+    groupInfos = Lists.newArrayListWithCapacity(groupList.size());
+    int found = 0;
+    int foundIndex = 0;
+    for (AccountGroup group : groupList) {
+      if (foundIndex++ < start) {
+        continue;
+      }
+      if (limit > 0 && ++found > limit) {
+        break;
+      }
+      groupInfos.add(json.addOptions(options).format(
+          GroupDescriptions.forAccountGroup(group)));
+    }
+    return groupInfos;
+  }
+
+  private List<GroupInfo> suggestGroups() throws OrmException, BadRequestException {
+    if (conflictingSuggestParameters()) {
+      throw new BadRequestException(
+          "You should only have no more than one --project and -n with --suggest");
+    }
+
+    List<GroupReference> groupRefs = Lists.newArrayList(Iterables.limit(
+        groupBackend.suggest(
+            suggest, Iterables.getFirst(projects, null)),
+        limit <= 0 ? 10 : Math.min(limit, 10)));
+
+    List<GroupInfo> groupInfos = Lists.newArrayListWithCapacity(groupRefs.size());
+    for (final GroupReference ref : groupRefs) {
+      GroupDescription.Basic desc = groupBackend.get(ref.getUUID());
+      if (desc != null) {
+        groupInfos.add(json.addOptions(options).format(desc));
       }
     }
     return groupInfos;
   }
 
+  private boolean conflictingSuggestParameters() {
+    if (Strings.isNullOrEmpty(suggest)) {
+      return false;
+    }
+    if (projects.size() > 1) {
+      return true;
+    }
+    if (visibleToAll) {
+      return true;
+    }
+    if (user != null) {
+      return true;
+    }
+    if (owned) {
+      return true;
+    }
+    if (start != 0) {
+      return true;
+    }
+    if (!groupsToInspect.isEmpty()) {
+      return true;
+    }
+    if (!Strings.isNullOrEmpty(matchSubstring)) {
+      return true;
+    }
+    return false;
+  }
+
   private List<GroupInfo> getGroupsOwnedBy(IdentifiedUser user)
       throws OrmException {
     List<GroupInfo> groups = Lists.newArrayList();

gerrit-sshd/src/main/java/com/google/gerrit/sshd/commands/ListGroupsCommand.java

@@ -19,10 +19,12 @@ import static com.google.gerrit.sshd.CommandMetaData.Mode.MASTER_OR_SLAVE;
 import com.google.common.base.MoreObjects;
 import com.google.common.base.Strings;
 import com.google.gerrit.extensions.common.GroupInfo;
+import com.google.gerrit.extensions.restapi.BadRequestException;
 import com.google.gerrit.extensions.restapi.Url;
 import com.google.gerrit.reviewdb.client.AccountGroup;
 import com.google.gerrit.server.IdentifiedUser;
 import com.google.gerrit.server.account.GetGroups;
+import com.google.gerrit.server.account.GroupBackend;
 import com.google.gerrit.server.account.GroupCache;
 import com.google.gerrit.server.account.GroupControl;
 import com.google.gerrit.server.group.GroupJson;
@@ -71,12 +73,13 @@ public class ListGroupsCommand extends SshCommand {
         final Provider<IdentifiedUser> identifiedUser,
         final IdentifiedUser.GenericFactory userFactory,
         final Provider<GetGroups> accountGetGroups,
-        final GroupJson json) {
+        final GroupJson json,
+        GroupBackend groupBackend) {
       super(groupCache, groupControlFactory, genericGroupControlFactory,
-          identifiedUser, userFactory, accountGetGroups, json);
+          identifiedUser, userFactory, accountGetGroups, json, groupBackend);
     }
 
-    void display(final PrintWriter out) throws OrmException {
+    void display(final PrintWriter out) throws OrmException, BadRequestException {
       final ColumnFormatter formatter = new ColumnFormatter(out, '\t');
       for (final GroupInfo info : get()) {
         formatter.addColumn(MoreObjects.firstNonNull(info.name, "n/a"));