Add CURRENT_ACTIONS to revision information

This exports any plugin actions that apply to the current revision,
telling the UI what can be invoked over the REST API.

Change-Id: Ieb5e182d43628497c20077b3bc746a6b5bf71abb

Documentation/rest-api-changes.txt

@@ -213,6 +213,13 @@ default. Optional fields are:
 * `MESSAGES`: include messages associated with the change.
 --
 
+[[actions]]
+--
+* `CURRENT_ACTIONS`: include information on available actions
+  for the change and its current revision. The caller must be
+  authenticated to obtain the available actions.
+--
+
 .Request
 ----
   GET /changes/?q=97&o=CURRENT_REVISION&o=CURRENT_COMMIT&o=CURRENT_FILES HTTP/1.0
@@ -2285,6 +2292,37 @@ Message to be added as review comment to the change when abandoning the
 change.
 |===========================
 
+[[action-info]]
+ActionInfo
+~~~~~~~~~~
+The `ActionInfo` entity describes a REST API call the client can
+make to manipulate a resource. These are frequently implemented by
+plugins and may be discovered at runtime.
+
+[options="header",width="50%",cols="1,^1,5"]
+|====================================
+|Field Name             ||Description
+|`method`               |optional|
+HTTP method to use with the action. Most actions use `POST`, `PUT`
+or `DELETE` to cause state changes.
+|`label`                |optional|
+Short title to display to a user describing the action. In the
+Gerrit web interface the label is used as the text on the button
+presented in the UI.
+|`title`                |optional|
+Longer text to display describing the action. In a web UI this
+should be the title attribute of the element, displaying when
+the user hovers the mouse.
+|`enabled`              |optional|
+If true the action is permitted at this time and the caller is
+likely allowed to execute it. This may change if state is updated
+at the server or permissions are modified. Not present if false.
+|`confirmation_message` |optional|
+Warning message to display to the user at the client side after
+the user has selected to use this action, but before the action
+request is sent to the server.
+|====================================
+
 [[add-reviewer-result]]
 AddReviewerResult
 ~~~~~~~~~~~~~~~~~
@@ -2853,6 +2891,10 @@ link:#commit-info[CommitInfo] entity.
 |`files`       ||
 The files of the patch set as a map that maps the file names to
 link:#file-info[FileInfo] entities.
+|`actions`     ||
+Actions the caller might be able to perform on this revision. The
+information is a map of view name to link:#action-info[ActionInfo]
+entities.
 |===========================
 
 [[rule-input]]

gerrit-common/src/main/java/com/google/gerrit/common/changes/ListChangesOption.java

@@ -37,7 +37,10 @@ public enum ListChangesOption {
   DETAILED_ACCOUNTS(7),
 
   /** Include messages associated with the change. */
-  MESSAGES(9);
+  MESSAGES(9),
+
+  /** Include allowed actions client could perform. */
+  CURRENT_ACTIONS(10);
 
   private final int value;
 

gerrit-server/src/main/java/com/google/gerrit/server/change/ChangeJson.java

@@ -17,6 +17,7 @@ package com.google.gerrit.server.change;
 import static com.google.gerrit.common.changes.ListChangesOption.ALL_COMMITS;
 import static com.google.gerrit.common.changes.ListChangesOption.ALL_FILES;
 import static com.google.gerrit.common.changes.ListChangesOption.ALL_REVISIONS;
+import static com.google.gerrit.common.changes.ListChangesOption.CURRENT_ACTIONS;
 import static com.google.gerrit.common.changes.ListChangesOption.CURRENT_COMMIT;
 import static com.google.gerrit.common.changes.ListChangesOption.CURRENT_FILES;
 import static com.google.gerrit.common.changes.ListChangesOption.CURRENT_REVISION;
@@ -45,7 +46,9 @@ import com.google.gerrit.common.data.LabelValue;
 import com.google.gerrit.common.data.Permission;
 import com.google.gerrit.common.data.PermissionRange;
 import com.google.gerrit.common.data.SubmitRecord;
+import com.google.gerrit.common.data.UiCommandDetail;
 import com.google.gerrit.extensions.restapi.Url;
+import com.google.gerrit.extensions.webui.UiCommand;
 import com.google.gerrit.reviewdb.client.Account;
 import com.google.gerrit.reviewdb.client.Change;
 import com.google.gerrit.reviewdb.client.Change.Status;
@@ -63,6 +66,7 @@ import com.google.gerrit.server.IdentifiedUser;
 import com.google.gerrit.server.account.AccountInfo;
 import com.google.gerrit.server.config.CanonicalWebUrl;
 import com.google.gerrit.server.config.GerritServerConfig;
+import com.google.gerrit.server.extensions.webui.UiCommands;
 import com.google.gerrit.server.git.LabelNormalizer;
 import com.google.gerrit.server.patch.PatchListNotAvailableException;
 import com.google.gerrit.server.patch.PatchSetInfoFactory;
@@ -125,6 +129,8 @@ public class ChangeJson {
   private final AccountInfo.Loader.Factory accountLoaderFactory;
   private final Provider<String> urlProvider;
   private final Urls urls;
+  private final Revisions revisions;
+
   private ChangeControl.Factory changeControlUserFactory;
   private SshInfo sshInfo;
   private EnumSet<ListChangesOption> options;
@@ -143,7 +149,8 @@ public class ChangeJson {
       FileInfoJson fileInfoJson,
       AccountInfo.Loader.Factory ailf,
       @CanonicalWebUrl Provider<String> curl,
-      Urls urls) {
+      Urls urls,
+      Revisions revisions) {
     this.db = db;
     this.labelNormalizer = ln;
     this.user = u;
@@ -155,6 +162,7 @@ public class ChangeJson {
     this.accountLoaderFactory = ailf;
     this.urlProvider = curl;
     this.urls = urls;
+    this.revisions = revisions;
 
     options = EnumSet.noneOf(ListChangesOption.class);
   }
@@ -769,6 +777,16 @@ public class ChangeJson {
         log.warn("Cannot load PatchList " + in.getId(), e);
       }
     }
+
+    if (out.isCurrent && has(CURRENT_ACTIONS) && user instanceof IdentifiedUser) {
+      out.actions = Maps.newTreeMap();
+      for (UiCommandDetail c : UiCommands.from(
+          revisions,
+          new RevisionResource(new ChangeResource(control(cd)), in),
+          EnumSet.of(UiCommand.Place.PATCHSET_ACTION_PANEL))) {
+        out.actions.put(c.id, new ActionInfo(c));
+      }
+    }
     return out;
   }
 
@@ -876,6 +894,7 @@ public class ChangeJson {
     Map<String, FetchInfo> fetch;
     CommitInfo commit;
     Map<String, FileInfoJson.FileInfo> files;
+    Map<String, ActionInfo> actions;
   }
 
   static class FetchInfo {
@@ -943,4 +962,20 @@ public class ChangeJson {
     String message;
     Integer _revisionNumber;
   }
+
+  static class ActionInfo {
+    String method;
+    String label;
+    String title;
+    Boolean enabled;
+    String confirmationMessage;
+
+    ActionInfo(UiCommandDetail c) {
+      method = c.method;
+      label = c.label;
+      title = c.title;
+      enabled = c.enabled ? true : null;
+      confirmationMessage = c.confirmationMessage;
+    }
+  }
 }