Support for parent diff bases in merge changes

With this change, in merge changes, patch ranges can diff against a
specific parent (as indicated by a negative parent index) similarly to
the GWT UI.
- Parent options appear in patch range selectors when available.
- The router no longer redirects parent indexed patch ranges now that
  they are supported.
- The RevisionInfo class is added to house revision related functions in
  a form that's easily passed between components.
- On merge changes the default patch range base is labeled as
  "AutoMerge" rather than "Base".

Feature: Issue 4760
Change-Id: I221ba97e28be52f225f7d90f5f8c5a0f17ddb8c2

polygerrit-ui/app/elements/change/gr-change-view/gr-change-view_test.html

@@ -226,7 +226,7 @@ limitations under the License.
               change_id: 'Iad9dc96274af6946f3632be53b106ef80f7ba6ca',
               _number: 42,
               revisions: {
-                rev1: {_number: 1},
+                rev1: {_number: 1, commit: {parents: []}},
               },
               current_revision: 'rev1',
               status: 'NEW',
@@ -408,10 +408,10 @@ limitations under the License.
       element._change = {
         change_id: 'Iad9dc96274af6946f3632be53b106ef80f7ba6ca',
         revisions: {
-          rev2: {_number: 2},
+          rev2: {_number: 2, commit: {parents: []}},
-          rev1: {_number: 1},
+          rev1: {_number: 1, commit: {parents: []}},
-          rev13: {_number: 13},
+          rev13: {_number: 13, commit: {parents: []}},
-          rev3: {_number: 3},
+          rev3: {_number: 3, commit: {parents: []}},
         },
         current_revision: 'rev3',
         status: 'NEW',
@@ -914,8 +914,8 @@ limitations under the License.
       element._change = {
         change_id: 'Iad9dc96274af6946f3632be53b106ef80f7ba6ca',
         revisions: {
-          rev1: {_number: 1},
+          rev1: {_number: 1, commit: {parents: []}},
-          rev2: {_number: 2},
+          rev2: {_number: 2, commit: {parents: []}},
         },
         current_revision: 'rev1',
         status: element.ChangeStatus.MERGED,

polygerrit-ui/app/elements/change/gr-file-list-header/gr-file-list-header.html

@@ -26,6 +26,7 @@ limitations under the License.
 <link rel="import" href="../../shared/gr-select/gr-select.html">
 <link rel="import" href="../../shared/gr-button/gr-button.html">
 <link rel="import" href="../../shared/gr-icons/gr-icons.html">
+<link rel="import" href="../../shared/revision-info/revision-info.html">
 <link rel="import" href="../gr-file-list-constants.html">
 
 <dom-module id="gr-file-list-header">
@@ -155,6 +156,7 @@ limitations under the License.
               base-patch-num="[[basePatchNum]]"
               available-patches="[[allPatchSets]]"
               revisions="[[change.revisions]]"
+              revision-info="[[_revisionInfo]]"
               on-patch-range-change="_handlePatchChange">
           </gr-patch-range-select>
           <span class="separator"></span>

polygerrit-ui/app/elements/change/gr-file-list-header/gr-file-list-header.js

@@ -65,6 +65,10 @@
           UNIFIED: 'UNIFIED_DIFF',
         },
       },
+      _revisionInfo: {
+        type: Object,
+        computed: '_getRevisionInfo(change)',
+      },
     },
 
     behaviors: [
@@ -212,5 +216,9 @@
       }
       return 'patchInfoOldPatchSet';
     },
+
+    _getRevisionInfo(change) {
+      return new Gerrit.RevisionInfo(change);
+    },
   });
 })();

polygerrit-ui/app/elements/core/gr-router/gr-router.js

@@ -412,14 +412,8 @@
 
       // Diffing a patch against itself is invalid, so if the base and revision
       // patches are equal clear the base.
-      // NOTE: while selecting numbered parents of a merge is not yet
-      // implemented, normalize parent base patches to be un-selected parents in
-      // the same way.
-      // TODO(issue 4760): Remove the isMergeParent check when PG supports
-      // diffing against numbered parents of a merge.
       if (hasBasePatchNum &&
-          (this.patchNumEquals(params.basePatchNum, params.patchNum) ||
+          this.patchNumEquals(params.basePatchNum, params.patchNum)) {
-              this.isMergeParent(params.basePatchNum))) {
         needsRedirect = true;
         params.basePatchNum = null;
       } else if (hasBasePatchNum && !hasPatchNum) {

polygerrit-ui/app/elements/core/gr-router/gr-router_test.html

@@ -493,16 +493,6 @@ limitations under the License.
           assert.isNotOk(params.basePatchNum);
           assert.equal(params.patchNum, 'edit');
         });
-
-        // TODO(issue 4760): Remove when PG supports diffing against numbered
-        // parents of a merge.
-        test('range -n..m normalizes to m', () => {
-          const params = {basePatchNum: -2, patchNum: 4};
-          const needsRedirect = element._normalizePatchRangeParams(params);
-          assert.isTrue(needsRedirect);
-          assert.isNotOk(params.basePatchNum);
-          assert.equal(params.patchNum, 4);
-        });
       });
     });
 

polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view.html

@@ -26,6 +26,7 @@ limitations under the License.
 <link rel="import" href="../../shared/gr-fixed-panel/gr-fixed-panel.html">
 <link rel="import" href="../../shared/gr-rest-api-interface/gr-rest-api-interface.html">
 <link rel="import" href="../../shared/gr-select/gr-select.html">
+<link rel="import" href="../../shared/revision-info/revision-info.html">
 <link rel="import" href="../gr-comment-api/gr-comment-api.html">
 <link rel="import" href="../gr-diff-cursor/gr-diff-cursor.html">
 <link rel="import" href="../gr-diff-preferences/gr-diff-preferences.html">
@@ -227,6 +228,7 @@ limitations under the License.
               files-weblinks="[[_filesWeblinks]]"
               available-patches="[[_allPatchSets]]"
               revisions="[[_change.revisions]]"
+              revision-info="[[_revisionInfo]]"
               on-patch-range-change="_handlePatchChange">
           </gr-patch-range-select>
           <span class="download desktop">

polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view.js

@@ -147,6 +147,10 @@
         type: Array,
         computed: 'computeAllPatchSets(_change, _change.revisions.*)',
       },
+      _revisionInfo: {
+        type: Object,
+        computed: '_getRevisionInfo(_change)',
+      },
     },
 
     behaviors: [
@@ -869,5 +873,9 @@
     _computeBlameLoaderClass(isImageDiff, supported) {
       return !isImageDiff && supported ? 'show' : '';
     },
+
+    _getRevisionInfo(change) {
+      return new Gerrit.RevisionInfo(change);
+    },
   });
 })();

polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view_test.html

@@ -85,7 +85,7 @@ limitations under the License.
       element._change = {
         _number: 42,
         revisions: {
-          a: {_number: 10},
+          a: {_number: 10, commit: {parents: []}},
         },
       };
       element._fileList = ['chell.go', 'glados.txt', 'wheatley.md'];
@@ -170,8 +170,8 @@ limitations under the License.
       element._change = {
         _number: 42,
         revisions: {
-          a: {_number: 10},
+          a: {_number: 10, commit: {parents: []}},
-          b: {_number: 5},
+          b: {_number: 5, commit: {parents: []}},
         },
       };
       element._fileList = ['chell.go', 'glados.txt', 'wheatley.md'];
@@ -234,8 +234,8 @@ limitations under the License.
       element._change = {
         _number: 42,
         revisions: {
-          a: {_number: 1},
+          a: {_number: 1, commit: {parents: []}},
-          b: {_number: 2},
+          b: {_number: 2, commit: {parents: []}},
         },
       };
       element._fileList = ['chell.go', 'glados.txt', 'wheatley.md'];
@@ -407,7 +407,7 @@ limitations under the License.
         element._change = {
           _number: 42,
           revisions: {
-            a: {_number: 10},
+            a: {_number: 10, commit: {parents: []}},
           },
         };
         element._fileList = ['chell.go', 'glados.txt', 'wheatley.md'];
@@ -448,8 +448,8 @@ limitations under the License.
         element._change = {
           _number: 42,
           revisions: {
-            a: {_number: 5},
+            a: {_number: 5, commit: {parents: []}},
-            b: {_number: 10},
+            b: {_number: 10, commit: {parents: []}},
           },
         };
         element._fileList = ['chell.go', 'glados.txt', 'wheatley.md'];

polygerrit-ui/app/elements/diff/gr-patch-range-select/gr-patch-range-select.js

@@ -34,7 +34,7 @@
       _baseDropdownContent: {
         type: Object,
         computed: '_computeBaseDropdownContent(availablePatches, patchNum,' +
-            '_sortedRevisions, changeComments)',
+            '_sortedRevisions, changeComments, revisionInfo)',
       },
       _patchDropdownContent: {
         type: Object,
@@ -48,6 +48,7 @@
       patchNum: String,
       basePatchNum: String,
       revisions: Object,
+      revisionInfo: Object,
       _sortedRevisions: Array,
     },
 
@@ -58,7 +59,13 @@
     behaviors: [Gerrit.PatchSetBehavior],
 
     _computeBaseDropdownContent(availablePatches, patchNum, _sortedRevisions,
-        changeComments) {
+        changeComments, revisionInfo) {
+      const parentCounts = revisionInfo.getParentCountMap();
+      const currentParentCount = parentCounts.hasOwnProperty(patchNum) ?
+          parentCounts[patchNum] : 1;
+      const maxParents = revisionInfo.getMaxParents();
+      const isMerge = currentParentCount > 1;
+
       const dropdownContent = [];
       for (const basePatch of availablePatches) {
         const basePatchNum = basePatch.num;
@@ -75,10 +82,22 @@
           value: basePatch.num,
         });
       }
+
       dropdownContent.push({
-        text: 'Base',
+        text: isMerge ? 'Auto Merge' : 'Base',
         value: 'PARENT',
       });
+
+      for (let idx = 0; isMerge && idx < maxParents; idx++) {
+        dropdownContent.push({
+          disabled: idx >= currentParentCount,
+          triggerText: `Parent ${idx + 1}`,
+          text: `Parent ${idx + 1}`,
+          mobileText: `Parent ${idx + 1}`,
+          value: -(idx + 1),
+        });
+      }
+
       return dropdownContent;
     },
 
@@ -133,14 +152,27 @@
      * The basePatchNum should always be <= patchNum -- because sortedRevisions
      * is sorted in reverse order (higher patchset nums first), invalid patch
      * nums have an index greater than the index of basePatchNum.
+     *
      * In addition, if the current basePatchNum is 'PARENT', all patchNums are
      * valid.
+     *
+     * If the curent basePatchNum is a parent index, then only patches that have
+     * at least that many parents are valid.
+     *
      * @param {number|string} basePatchNum The current selected base patch num.
      * @param {number|string} patchNum The possible patch num.
      * @param {!Array} sortedRevisions
+     * @return {boolean}
      */
     _computeRightDisabled(basePatchNum, patchNum, sortedRevisions) {
-      if (basePatchNum === 'PARENT') { return false; }
+      if (this.patchNumEquals(basePatchNum, 'PARENT')) { return false; }
+
+      if (this.isMergeParent(basePatchNum)) {
+        // Note: parent indices use 1-offset.
+        return this.revisionInfo.getParentCount(patchNum) <
+            this.getParentIndex(basePatchNum);
+      }
+
       return this.findSortedIndex(basePatchNum, sortedRevisions) <=
           this.findSortedIndex(patchNum, sortedRevisions);
     },

polygerrit-ui/app/elements/diff/gr-patch-range-select/gr-patch-range-select_test.html

@@ -25,6 +25,8 @@ limitations under the License.
 
 <link rel="import" href="../../diff/gr-comment-api/gr-comment-api.html">
 <link rel="import" href="../../shared/gr-rest-api-interface/mock-diff-response_test.html">
+<link rel="import" href="../../shared/revision-info/revision-info.html">
+
 <link rel="import" href="gr-patch-range-select.html">
 
 <script>void(0);</script>
@@ -50,6 +52,14 @@ limitations under the License.
     let sandbox;
     let commentApiWrapper;
 
+    function getInfo(revisions) {
+      const revisionObj = {};
+      for (let i = 0; i < revisions.length; i++) {
+        revisionObj[i] = revisions[i];
+      }
+      return new Gerrit.RevisionInfo({revisions: revisionObj});
+    }
+
     setup(() => {
       sandbox = sinon.sandbox.create();
 
@@ -112,6 +122,17 @@ limitations under the License.
         {num: 2},
         {num: 1},
       ];
+      const revisions = [
+        {
+          commit: {parents: []},
+          _number: 2,
+          description: 'description',
+        },
+        {commit: {parents: []}},
+        {commit: {parents: []}},
+        {commit: {parents: []}},
+      ];
+      element.revisionInfo = getInfo(revisions);
       const patchNum = 1;
       const sortedRevisions = [
         {_number: 3},
@@ -158,17 +179,19 @@ limitations under the License.
         },
       ];
       assert.deepEqual(element._computeBaseDropdownContent(availablePatches,
-          patchNum, sortedRevisions, element.changeComments),
+          patchNum, sortedRevisions, element.changeComments,
+          element.revisionInfo),
           expectedResult);
     });
 
     test('_computeBaseDropdownContent called when patchNum updates', () => {
       element.revisions = [
-        {commit: {}},
+        {commit: {parents: []}},
-        {commit: {}},
+        {commit: {parents: []}},
-        {commit: {}},
+        {commit: {parents: []}},
-        {commit: {}},
+        {commit: {parents: []}},
       ];
+      element.revisionInfo = getInfo(element.revisions);
       element.availablePatches = [
         {num: 1},
         {num: 2},
@@ -189,11 +212,12 @@ limitations under the License.
     test('_computeBaseDropdownContent called when changeComments update',
         done => {
           element.revisions = [
-        {commit: {}},
+            {commit: {parents: []}},
-        {commit: {}},
+            {commit: {parents: []}},
-        {commit: {}},
+            {commit: {parents: []}},
-        {commit: {}},
+            {commit: {parents: []}},
           ];
+          element.revisionInfo = getInfo(element.revisions);
           element.availablePatches = [
             {num: 'edit'},
             {num: 3},
@@ -215,11 +239,12 @@ limitations under the License.
 
     test('_computePatchDropdownContent called when basePatchNum updates', () => {
       element.revisions = [
-        {commit: {}},
+        {commit: {parents: []}},
-        {commit: {}},
+        {commit: {parents: []}},
-        {commit: {}},
+        {commit: {parents: []}},
-        {commit: {}},
+        {commit: {parents: []}},
       ];
+      element.revisionInfo = getInfo(element.revisions);
       element.availablePatches = [
         {num: 1},
         {num: 2},
@@ -238,11 +263,12 @@ limitations under the License.
 
     test('_computePatchDropdownContent called when comments update', done => {
       element.revisions = [
-        {commit: {}},
+        {commit: {parents: []}},
-        {commit: {}},
+        {commit: {parents: []}},
-        {commit: {}},
+        {commit: {parents: []}},
-        {commit: {}},
+        {commit: {parents: []}},
       ];
+      element.revisionInfo = getInfo(element.revisions);
       element.availablePatches = [
         {num: 1},
         {num: 2},

polygerrit-ui/app/elements/shared/gr-rest-api-interface/gr-rest-api-interface.js

@@ -861,6 +861,7 @@
      */
     getDiffChangeDetail(changeNum, opt_errFn, opt_cancelCondition) {
       const params = this.listChangesOptionsToHex(
+          this.ListChangesOption.ALL_COMMITS,
           this.ListChangesOption.ALL_REVISIONS
       );
       return this._getChangeDetail(changeNum, params, opt_errFn,

polygerrit-ui/app/elements/shared/revision-info/revision-info.html

@@ -0,0 +1,79 @@
+<!--
+Copyright (C) 2017 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.
+-->
+<link rel="import" href="../../../behaviors/gr-patch-set-behavior/gr-patch-set-behavior.html">
+<script>
+  (function() {
+    'use strict';
+
+    /**
+     * @param {Object} change A change object resulting from a change detail
+     *     call that includes revision information.
+     */
+    function RevisionInfo(change) {
+      this._change = change;
+    }
+
+    /**
+     * Get the largest number of parents of the commit in any revision. For
+     * example, with normal changes this will always return 1. For merge changes
+     * wherein the revisions are merge commits this will return 2 or potentially
+     * more.
+     * @return {Number}
+     */
+    RevisionInfo.prototype.getMaxParents = function() {
+      return Object.values(this._change.revisions)
+          .reduce((acc, rev) => Math.max(rev.commit.parents.length, acc), 0);
+    };
+
+    /**
+     * Get an object that maps revision numbers to the number of parents of the
+     * commit of that revision.
+     * @return {!Object}
+     */
+    RevisionInfo.prototype.getParentCountMap = function() {
+      const result = {};
+      Object.values(this._change.revisions)
+          .forEach(rev => { result[rev._number] = rev.commit.parents.length; });
+      return result;
+    };
+
+    /**
+     * @param {number|string} patchNum
+     * @return {number}
+     */
+    RevisionInfo.prototype.getParentCount = function(patchNum) {
+      return this.getParentCountMap()[patchNum];
+    };
+
+    /**
+     * Get the commit ID of the (0-offset) indexed parent in the given revision
+     * number.
+     * @param {number|string} patchNum
+     * @param {number} parentIndex (0-offset)
+     * @return {string}
+     */
+    RevisionInfo.prototype.getParentId = function(patchNum, parentIndex) {
+      const rev = Object.values(this._change.revisions).find(rev =>
+          Gerrit.PatchSetBehavior.patchNumEquals(rev._number, patchNum));
+      return rev.commit.parents[parentIndex].commit;
+    };
+
+    if (!window.Gerrit) {
+      window.Gerrit = {};
+    }
+    window.Gerrit.RevisionInfo = RevisionInfo;
+  })();
+</script>

polygerrit-ui/app/elements/shared/revision-info/revision-info_test.html

@@ -0,0 +1,85 @@
+<!DOCTYPE html>
+<!--
+Copyright (C) 2017 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.
+-->
+
+<meta name="viewport" content="width=device-width, minimum-scale=1.0, initial-scale=1.0, user-scalable=yes">
+<title>revision-info</title>
+
+<script src="../../../bower_components/webcomponentsjs/webcomponents-lite.min.js"></script>
+<script src="../../../bower_components/web-component-tester/browser.js"></script>
+<link rel="import" href="../../../test/common-test-setup.html"/>
+<link rel="import" href="revision-info.html">
+
+<script>
+  suite('revision-info tests', () => {
+    let mockChange;
+
+    setup(() => {
+      mockChange = {
+        revisions: {
+          r1: {_number: 1, commit: {parents: [
+            {commit: 'p1'},
+            {commit: 'p2'},
+            {commit: 'p3'},
+          ]}},
+          r2: {_number: 2, commit: {parents: [
+            {commit: 'p1'},
+            {commit: 'p4'},
+          ]}},
+          r3: {_number: 3, commit: {parents: [{commit: 'p5'}]}},
+          r4: {_number: 4, commit: {parents: [
+            {commit: 'p2'},
+            {commit: 'p3'},
+          ]}},
+          r5: {_number: 5, commit: {parents: [
+            {commit: 'p5'},
+            {commit: 'p2'},
+            {commit: 'p3'},
+          ]}},
+        },
+      };
+    });
+
+    test('getMaxParents', () => {
+      const ri = new window.Gerrit.RevisionInfo(mockChange);
+      assert.equal(ri.getMaxParents(), 3);
+    });
+
+    test('getParentCountMap', () => {
+      const ri = new window.Gerrit.RevisionInfo(mockChange);
+      assert.deepEqual(ri.getParentCountMap(), {1: 3, 2: 2, 3: 1, 4: 2, 5: 3});
+    });
+
+    test('getParentCount', () => {
+      const ri = new window.Gerrit.RevisionInfo(mockChange);
+      assert.deepEqual(ri.getParentCount(1), 3);
+      assert.deepEqual(ri.getParentCount(3), 1);
+    });
+
+    test('getParentCount', () => {
+      const ri = new window.Gerrit.RevisionInfo(mockChange);
+      assert.deepEqual(ri.getParentCount(1), 3);
+      assert.deepEqual(ri.getParentCount(3), 1);
+    });
+
+    test('getParentId', () => {
+      const ri = new window.Gerrit.RevisionInfo(mockChange);
+      assert.deepEqual(ri.getParentId(1, 2), 'p3');
+      assert.deepEqual(ri.getParentId(2, 1), 'p4');
+      assert.deepEqual(ri.getParentId(3, 0), 'p5');
+    });
+  });
+</script>

polygerrit-ui/app/test/index.html

@@ -161,6 +161,7 @@ limitations under the License.
     'shared/gr-textarea/gr-textarea_test.html',
     'shared/gr-tooltip-content/gr-tooltip-content_test.html',
     'shared/gr-tooltip/gr-tooltip_test.html',
+    'shared/revision-info/revision-info_test.html',
   ];
   /* eslint-enable max-len */
   for (let file of elements) {