Enable aliases for change query has operands

Site administrators can alias 'has' operands from a plugin using the
'has-operand-alias' section and 'change' subsection in gerrit.config

[has-operand-alias change]
    oldtopic = topic

Aliases are already supported for SSH commands [1], URLs [2] and
Operators [3]

This feature is particularly useful to alias 'has' operands (which may
be long and clunky as they include a plugin name in them) to shorter
operands without the plugin name. Admins should take care to choose
shorter operands that are unique and unlikely to conflict in the future.

Aliases are resolved dynamically at invocation time to the currently
loaded version of plugins. If a referenced plugin is not loaded, or does
not define the command, "unsupported operand" is returned to the user.

Aliases will override existing 'has' operands. In case of multiple
aliases with same name, the last one defined will be used.

When the target of an alias does not exist, the 'has' operand with the
name of the alias will be used (if present). This enables an admin to
configure the system to override a core 'has' operand with an operand
provided by a plugin when present and otherwise fall back to the 'has'
operand provided by core.

The above three features can make aliases useful for cases of moving
functionality from Gerrit core to plugins and vice versa.

[1]
https://gerrit-review.googlesource.com/Documentation/config-gerrit.html#ssh-alias
[2]
https://gerrit-review.googlesource.com/Documentation/config-gerrit.html#urlAlias
[3]
https://gerrit-review.googlesource.com/Documentation/config-gerrit.html#operator-alias

Change-Id: Ifbd4f05079d8bf5eadd497d8e16e0bff203e6021

Documentation/config-gerrit.txt

@@ -2375,6 +2375,40 @@ groups either. This means there is no danger of ambiguous group names
 when this parameter is removed and the system group uses the default
 name again.
 
+[[has-operand-alias]]
+=== Section has operand alias
+
+'has' operand aliasing allows global aliases to be defined for query
+'has' operands. Currently only change queries are supported. The alias
+name is the git config key name, and the 'has' operand being aliased
+is the git config value.
+
+For example:
+
+----
+[has-operand-alias "change"]
+  oldtopic = topic
+----
+
+This section is particularly useful to alias 'has' operands (which may
+be long and clunky as they include a plugin name in them) to shorter
+operands without the plugin name. Admins should take care to choose
+shorter operands that are unique and unlikely to conflict in the future.
+
+Aliases are resolved dynamically at invocation time to the currently
+loaded version of plugins. If a referenced plugin is not loaded, or
+does not define the command, "unsupported operand" is returned to the
+user.
+
+Aliases will override existing 'has' operands. In case of multiple
+aliases with same name, the last one defined will be used.
+
+When the target of an alias does not exist, the 'has' operand with the
+name of the alias will be used (if present). This enables an admin to
+configure the system to override a core 'has' operand with an operand
+provided by a plugin when present and otherwise fall back to the 'has'
+operand provided by core.
+
 [[http]]
 === Section http
 

java/com/google/gerrit/server/config/HasOperandAliasConfig.java

@@ -0,0 +1,46 @@
+// Copyright (C) 2020 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.server.config;
+
+import com.google.inject.Inject;
+import com.google.inject.Singleton;
+import java.util.HashMap;
+import java.util.Map;
+import org.eclipse.jgit.lib.Config;
+
+@Singleton
+public class HasOperandAliasConfig {
+  private static final String SECTION = "has-operand-alias";
+  private static final String SUBSECTION_CHANGE = "change";
+  private final Config cfg;
+  private final Map<String, String> changeQueryHasOperandAliases;
+
+  @Inject
+  HasOperandAliasConfig(@GerritServerConfig Config cfg) {
+    this.cfg = cfg;
+    changeQueryHasOperandAliases = new HashMap<>();
+    loadChangeHasOperandAliases();
+  }
+
+  public Map<String, String> getChangeQueryHasOperandAliases() {
+    return changeQueryHasOperandAliases;
+  }
+
+  private void loadChangeHasOperandAliases() {
+    for (String name : cfg.getNames(SECTION, SUBSECTION_CHANGE)) {
+      changeQueryHasOperandAliases.put(name, cfg.getString(SECTION, SUBSECTION_CHANGE, name));
+    }
+  }
+}

java/com/google/gerrit/server/query/change/ChangeQueryBuilder.java

@@ -67,6 +67,7 @@ import com.google.gerrit.server.change.MergeabilityComputationBehavior;
 import com.google.gerrit.server.config.AllProjectsName;
 import com.google.gerrit.server.config.AllUsersName;
 import com.google.gerrit.server.config.GerritServerConfig;
+import com.google.gerrit.server.config.HasOperandAliasConfig;
 import com.google.gerrit.server.config.OperatorAliasConfig;
 import com.google.gerrit.server.git.GitRepositoryManager;
 import com.google.gerrit.server.index.change.ChangeField;
@@ -232,6 +233,7 @@ public class ChangeQueryBuilder extends QueryBuilder<ChangeData, ChangeQueryBuil
     final Provider<AnonymousUser> anonymousUserProvider;
     final OperatorAliasConfig operatorAliasConfig;
     final boolean indexMergeable;
+    final HasOperandAliasConfig hasOperandAliasConfig;
 
     private final Provider<CurrentUser> self;
 
@@ -265,7 +267,8 @@ public class ChangeQueryBuilder extends QueryBuilder<ChangeData, ChangeQueryBuil
         GroupMembers groupMembers,
         Provider<AnonymousUser> anonymousUserProvider,
         OperatorAliasConfig operatorAliasConfig,
-        @GerritServerConfig Config gerritConfig) {
+        @GerritServerConfig Config gerritConfig,
+        HasOperandAliasConfig hasOperandAliasConfig) {
       this(
           queryProvider,
           rewriter,
@@ -294,7 +297,8 @@ public class ChangeQueryBuilder extends QueryBuilder<ChangeData, ChangeQueryBuil
           groupMembers,
           anonymousUserProvider,
           operatorAliasConfig,
-          MergeabilityComputationBehavior.fromConfig(gerritConfig).includeInIndex());
+          MergeabilityComputationBehavior.fromConfig(gerritConfig).includeInIndex(),
+          hasOperandAliasConfig);
     }
 
     private Arguments(
@@ -325,7 +329,8 @@ public class ChangeQueryBuilder extends QueryBuilder<ChangeData, ChangeQueryBuil
         GroupMembers groupMembers,
         Provider<AnonymousUser> anonymousUserProvider,
         OperatorAliasConfig operatorAliasConfig,
-        boolean indexMergeable) {
+        boolean indexMergeable,
+        HasOperandAliasConfig hasOperandAliasConfig) {
       this.queryProvider = queryProvider;
       this.rewriter = rewriter;
       this.opFactories = opFactories;
@@ -354,6 +359,7 @@ public class ChangeQueryBuilder extends QueryBuilder<ChangeData, ChangeQueryBuil
       this.anonymousUserProvider = anonymousUserProvider;
       this.operatorAliasConfig = operatorAliasConfig;
       this.indexMergeable = indexMergeable;
+      this.hasOperandAliasConfig = hasOperandAliasConfig;
     }
 
     Arguments asUser(CurrentUser otherUser) {
@@ -385,7 +391,8 @@ public class ChangeQueryBuilder extends QueryBuilder<ChangeData, ChangeQueryBuil
           groupMembers,
           anonymousUserProvider,
           operatorAliasConfig,
-          indexMergeable);
+          indexMergeable,
+          hasOperandAliasConfig);
     }
 
     Arguments asUser(Account.Id otherId) {
@@ -426,6 +433,7 @@ public class ChangeQueryBuilder extends QueryBuilder<ChangeData, ChangeQueryBuil
   }
 
   private final Arguments args;
+  protected Map<String, String> hasOperandAliases = Collections.emptyMap();
 
   @Inject
   ChangeQueryBuilder(Arguments args) {
@@ -441,6 +449,7 @@ public class ChangeQueryBuilder extends QueryBuilder<ChangeData, ChangeQueryBuil
 
   private void setupAliases() {
     setOperatorAliases(args.operatorAliasConfig.getChangeQueryOperatorAliases());
+    hasOperandAliases = args.hasOperandAliasConfig.getChangeQueryHasOperandAliases();
   }
 
   public Arguments getArgs() {
@@ -518,6 +527,7 @@ public class ChangeQueryBuilder extends QueryBuilder<ChangeData, ChangeQueryBuil
 
   @Operator
   public Predicate<ChangeData> has(String value) throws QueryParseException {
+    value = hasOperandAliases.getOrDefault(value, value);
     if ("star".equalsIgnoreCase(value)) {
       return starredby(self());
     }

javatests/com/google/gerrit/acceptance/api/change/QueryChangeIT.java

@@ -22,6 +22,7 @@ import static java.util.stream.Collectors.toList;
 import static javax.servlet.http.HttpServletResponse.SC_OK;
 
 import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
 import com.google.gerrit.acceptance.AbstractDaemonTest;
 import com.google.gerrit.acceptance.NoHttpd;
 import com.google.gerrit.acceptance.UseClockStep;
@@ -30,7 +31,9 @@ import com.google.gerrit.acceptance.testsuite.account.AccountOperations;
 import com.google.gerrit.acceptance.testsuite.project.ProjectOperations;
 import com.google.gerrit.common.data.Permission;
 import com.google.gerrit.entities.Account;
+import com.google.gerrit.entities.Patch;
 import com.google.gerrit.entities.Project;
+import com.google.gerrit.extensions.api.changes.ReviewInput;
 import com.google.gerrit.extensions.common.ChangeInfo;
 import com.google.gerrit.extensions.restapi.BadRequestException;
 import com.google.gerrit.extensions.restapi.TopLevelResource;
@@ -247,6 +250,39 @@ public class QueryChangeIT extends AbstractDaemonTest {
     assertThat(e).hasMessageThat().isEqualTo("invalid regular expression: [A");
   }
 
+  @Test
+  @SuppressWarnings("unchecked")
+  @GerritConfig(name = "has-operand-alias.change.unaddressedaliastest", value = "unresolved")
+  public void hasOperandAliasQuery() throws Exception {
+    String cId1 = createChange().getChangeId();
+    String cId2 = createChange().getChangeId();
+    int numericId1 = gApi.changes().id(cId1).get()._number;
+    int numericId2 = gApi.changes().id(cId2).get()._number;
+
+    ReviewInput input = new ReviewInput();
+    ReviewInput.CommentInput comment = new ReviewInput.CommentInput();
+    comment.line = 1;
+    comment.message = "comment";
+    comment.unresolved = true;
+    input.comments = ImmutableMap.of(Patch.COMMIT_MSG, ImmutableList.of(comment));
+    gApi.changes().id(cId2).current().review(input);
+
+    QueryChanges queryChanges = queryChangesProvider.get();
+    queryChanges.addQuery("is:open repo:" + project.get());
+    queryChanges.addQuery("has:unaddressedaliastest repo:" + project.get());
+
+    List<List<ChangeInfo>> result =
+        (List<List<ChangeInfo>>) queryChanges.apply(TopLevelResource.INSTANCE).value();
+    assertThat(result).hasSize(2);
+    assertThat(result.get(0)).hasSize(2);
+    assertThat(result.get(1)).hasSize(1);
+
+    List<Integer> firstResultIds =
+        ImmutableList.of(result.get(0).get(0)._number, result.get(0).get(1)._number);
+    assertThat(firstResultIds).containsExactly(numericId1, numericId2);
+    assertThat(result.get(1).get(0)._number).isEqualTo(numericId2);
+  }
+
   private static void assertNoChangeHasMoreChangesSet(List<ChangeInfo> results) {
     for (ChangeInfo info : results) {
       assertThat(info._moreChanges).isNull();

javatests/com/google/gerrit/server/index/change/FakeQueryBuilder.java

@@ -54,7 +54,8 @@ public class FakeQueryBuilder extends ChangeQueryBuilder {
             null,
             null,
             null,
-            new Config()));
+            new Config(),
+            null));
   }
 
   @Operator