Support creating comments on merge parents

Bug: Issue 4760
Change-Id: I66ced578819b6f48d7d1535a54f1debf0e35374e

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

@@ -95,6 +95,7 @@ limitations under the License.
           baseImage: Object,
           revisionImage: Object,
           projectName: String,
+          parentIndex: Number,
           _builder: Object,
           _groups: Array,
           _layers: Array,
@@ -251,18 +252,25 @@ limitations under the License.
         },
 
         _getDiffBuilder(diff, comments, prefs) {
+          let builder = null;
           if (this.isImageDiff) {
-            return new GrDiffBuilderImage(diff, comments, prefs,
+            builder = new GrDiffBuilderImage(diff, comments, prefs,
                 this.projectName, this.diffElement, this.baseImage,
                 this.revisionImage);
           } else if (this.viewMode === DiffViewMode.SIDE_BY_SIDE) {
-            return new GrDiffBuilderSideBySide(diff, comments, prefs,
+            builder = new GrDiffBuilderSideBySide(diff, comments, prefs,
                 this.projectName, this.diffElement, this._layers);
           } else if (this.viewMode === DiffViewMode.UNIFIED) {
-            return new GrDiffBuilderUnified(diff, comments, prefs,
+            builder = new GrDiffBuilderUnified(diff, comments, prefs,
                 this.projectName, this.diffElement, this._layers);
           }
-          throw Error('Unsupported diff view mode: ' + this.viewMode);
+          if (!builder) {
+            throw Error('Unsupported diff view mode: ' + this.viewMode);
+          }
+          if (this.parentIndex) {
+            builder.setParentIndex(this.parentIndex);
+          }
+          return builder;
         },
 
         _clearDiffContent() {

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

@@ -47,6 +47,7 @@
     this._outputEl = outputEl;
     this.groups = [];
     this._blameInfo = null;
+    this._parentIndex = undefined;
 
     this.layers = layers || [];
 
@@ -353,6 +354,7 @@
     threadGroupEl.isOnParent = isOnParent;
     threadGroupEl.projectName = this._projectName;
     threadGroupEl.range = range;
+    threadGroupEl.parentIndex = this._parentIndex;
     return threadGroupEl;
   };
 
@@ -368,7 +370,9 @@
     let isOnParent = comments[0].side === 'PARENT' || false;
     if (line.type === GrDiffLine.Type.REMOVE ||
         opt_side === GrDiffBuilder.Side.LEFT) {
-      if (this._comments.meta.patchRange.basePatchNum === 'PARENT') {
+      if (this._comments.meta.patchRange.basePatchNum === 'PARENT' ||
+          Gerrit.PatchSetBehavior.isMergeParent(
+              this._comments.meta.patchRange.basePatchNum)) {
         isOnParent = true;
       } else {
         patchNum = this._comments.meta.patchRange.basePatchNum;
@@ -586,6 +590,10 @@
     }
   };
 
+  GrDiffBuilder.prototype.setParentIndex = function(index) {
+    this._parentIndex = index;
+  };
+
   /**
    * Find the blame cell for a given line number.
    * @param {number} lineNum

polygerrit-ui/app/elements/diff/gr-diff-comment-thread-group/gr-diff-comment-thread-group.html

@@ -34,6 +34,7 @@ limitations under the License.
           comments="[[thread.comments]]"
           comment-side="[[thread.commentSide]]"
           is-on-parent="[[isOnParent]]"
+          parent-index="[[parentIndex]]"
           change-num="[[changeNum]]"
           location-range="[[thread.locationRange]]"
           patch-num="[[thread.patchNum]]"

polygerrit-ui/app/elements/diff/gr-diff-comment-thread-group/gr-diff-comment-thread-group.js

@@ -30,6 +30,10 @@
         type: Boolean,
         value: false,
       },
+      parentIndex: {
+        type: Number,
+        value: null,
+      },
       _threads: {
         type: Array,
         value() { return []; },

polygerrit-ui/app/elements/diff/gr-diff-comment-thread/gr-diff-comment-thread.js

@@ -48,7 +48,10 @@
         type: Boolean,
         value: false,
       },
-
+      parentIndex: {
+        type: Number,
+        value: null,
+      },
       _showActions: Boolean,
       _lastComment: Object,
       _orderedComments: Array,
@@ -301,6 +304,9 @@
           end_character: opt_range.endChar,
         };
       }
+      if (this.parentIndex) {
+        d.parent = this.parentIndex;
+      }
       return d;
     },
 

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

@@ -270,7 +270,8 @@ limitations under the License.
               line-wrapping="[[lineWrapping]]"
               is-image-diff="[[isImageDiff]]"
               base-image="[[_baseImage]]"
-              revision-image="[[_revisionImage]]">
+              revision-image="[[_revisionImage]]"
+              parent-index="[[_parentIndex]]">
             <table
                 id="diffTable"
                 class$="[[_diffTableClass]]"

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

@@ -137,6 +137,11 @@
         notify: true,
         computed: '_computeIsBlameLoaded(_blame)',
       },
+
+      _parentIndex: {
+        type: Number,
+        computed: '_computeParentIndex(patchRange.*)',
+      },
     },
 
     behaviors: [
@@ -415,12 +420,27 @@
       return threadEl;
     },
 
-    /** @return {number} */
+    /**
+     * The value to be used for the patch number of new comments created at the
+     * given line and content elements.
+     *
+     * In two cases of creating a comment on the left side, the patch number to
+     * be used should actually be right side of the patch range:
+     * - When the patch range is against the parent comment of a normal change.
+     *   Such comments declare themmselves to be on the left using side=PARENT.
+     * - If the patch range is against the indexed parent of a merge change.
+     *   Such comments declare themselves to be on the given parent by
+     *   specifying the parent index via parent=i.
+     *
+     * @return {number}
+     */
     _getPatchNumByLineAndContent(lineEl, contentEl) {
       let patchNum = this.patchRange.patchNum;
+
       if ((lineEl.classList.contains(DiffSide.LEFT) ||
           contentEl.classList.contains('remove')) &&
-          this.patchRange.basePatchNum !== 'PARENT') {
+          this.patchRange.basePatchNum !== 'PARENT' &&
+          !this.isMergeParent(this.patchRange.basePatchNum)) {
         patchNum = this.patchRange.basePatchNum;
       }
       return patchNum;
@@ -428,13 +448,13 @@
 
     /** @return {boolean} */
     _getIsParentCommentByLineAndContent(lineEl, contentEl) {
-      let isOnParent = false;
       if ((lineEl.classList.contains(DiffSide.LEFT) ||
           contentEl.classList.contains('remove')) &&
-          this.patchRange.basePatchNum === 'PARENT') {
+          (this.patchRange.basePatchNum === 'PARENT' ||
-        isOnParent = true;
+          this.isMergeParent(this.patchRange.basePatchNum))) {
+        return true;
       }
-      return isOnParent;
+      return false;
     },
 
     /** @return {string} */
@@ -717,5 +737,15 @@
     _computeWarningClass(showWarning) {
       return showWarning ? 'warn' : '';
     },
+
+    /**
+     * @return {number|null}
+     */
+    _computeParentIndex(patchRangeRecord) {
+      if (!this.isMergeParent(patchRangeRecord.base.basePatchNum)) {
+        return null;
+      }
+      return this.getParentIndex(patchRangeRecord.base.basePatchNum);
+    },
   });
 })();

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

@@ -64,6 +64,92 @@ limitations under the License.
       assert.equal(element._diffLength(mock.diffResponse), 52);
     });
 
+
+    suite('_get{PatchNum|IsParentComment}ByLineAndContent', () => {
+      let lineEl;
+      let contentEl;
+
+      setup(() => {
+        element = fixture('basic');
+        lineEl = document.createElement('td');
+        contentEl = document.createElement('span');
+      });
+
+      suite('_getPatchNumByLineAndContent', () => {
+        test('right side', () => {
+          element.patchRange = {patchNum: 4, basePatchNum: 'PARENT'};
+          lineEl.classList.add('right');
+          assert.equal(element._getPatchNumByLineAndContent(lineEl, contentEl),
+              4);
+        });
+
+        test('left side parent by linenum', () => {
+          element.patchRange = {patchNum: 4, basePatchNum: 'PARENT'};
+          lineEl.classList.add('left');
+          assert.equal(element._getPatchNumByLineAndContent(lineEl, contentEl),
+              4);
+        });
+
+        test('left side parent by content', () => {
+          element.patchRange = {patchNum: 4, basePatchNum: 'PARENT'};
+          contentEl.classList.add('remove');
+          assert.equal(element._getPatchNumByLineAndContent(lineEl, contentEl),
+              4);
+        });
+
+        test('left side merge parent', () => {
+          element.patchRange = {patchNum: 4, basePatchNum: -2};
+          contentEl.classList.add('remove');
+          assert.equal(element._getPatchNumByLineAndContent(lineEl, contentEl),
+              4);
+        });
+
+        test('left side non parent', () => {
+          element.patchRange = {patchNum: 4, basePatchNum: 3};
+          contentEl.classList.add('remove');
+          assert.equal(element._getPatchNumByLineAndContent(lineEl, contentEl),
+              3);
+        });
+      });
+
+      suite('_getIsParentCommentByLineAndContent', () => {
+        test('right side', () => {
+          element.patchRange = {patchNum: 4, basePatchNum: 'PARENT'};
+          lineEl.classList.add('right');
+          assert.isFalse(
+              element._getIsParentCommentByLineAndContent(lineEl, contentEl));
+        });
+
+        test('left side parent by linenum', () => {
+          element.patchRange = {patchNum: 4, basePatchNum: 'PARENT'};
+          lineEl.classList.add('left');
+          assert.isTrue(
+              element._getIsParentCommentByLineAndContent(lineEl, contentEl));
+        });
+
+        test('left side parent by content', () => {
+          element.patchRange = {patchNum: 4, basePatchNum: 'PARENT'};
+          contentEl.classList.add('remove');
+          assert.isTrue(
+              element._getIsParentCommentByLineAndContent(lineEl, contentEl));
+        });
+
+        test('left side merge parent', () => {
+          element.patchRange = {patchNum: 4, basePatchNum: -2};
+          contentEl.classList.add('remove');
+          assert.isTrue(
+              element._getIsParentCommentByLineAndContent(lineEl, contentEl));
+        });
+
+        test('left side non parent', () => {
+          element.patchRange = {patchNum: 4, basePatchNum: 3};
+          contentEl.classList.add('remove');
+          assert.isFalse(
+              element._getIsParentCommentByLineAndContent(lineEl, contentEl));
+        });
+      });
+    });
+
     suite('not logged in', () => {
       setup(() => {
         stub('gr-rest-api-interface', {