Generate clipboard data via diff rather than DOM reconstruction

This change uses a new method of generating the clipboard data that
circumvents several strange issues caused by shadow/shady DOM. This
new method is much more legible and abstracts more logic away from the
DOM.

Bug: Issue 4494
Change-Id: I8c186d6cbbe9536548d934f734856b1f9ced1a26

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

@@ -26,11 +26,13 @@ limitations under the License.
         user-select: none;
       }
 
-      :host.selected-right .contentWrapper ::content .side-by-side .right + .content,
-      :host.selected-left .contentWrapper ::content .side-by-side .left + .content,
-      :host.selected-right .contentWrapper ::content .unified .right.lineNum ~ .content,
-      :host.selected-left .contentWrapper ::content .unified .left.lineNum ~ .content:not(.both),
-      :host .contentWrapper ::content .unified .gr-diff-comment .message {
+      :host-context(.selected-left:not(.selected-comment)) .contentWrapper ::content .side-by-side .left + .content .contentText,
+      :host-context(.selected-right:not(.selected-comment)) .contentWrapper ::content .side-by-side .right + .content .contentText,
+      :host-context(.selected-left:not(.selected-comment)) .contentWrapper ::content .unified .left.lineNum ~ .content:not(.both) .contentText,
+      :host-context(.selected-right:not(.selected-comment)) .contentWrapper ::content .unified .right.lineNum ~ .content .contentText,
+      :host-context(.selected-left.selected-comment) .contentWrapper ::content .side-by-side .left + .content .message,
+      :host-context(.selected-right.selected-comment) .contentWrapper ::content .side-by-side .right + .content .message,
+      :host-context(.selected-comment) .contentWrapper ::content .unified .message {
         -webkit-user-select: text;
         -moz-user-select: text;
         -ms-user-select: text;

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

@@ -18,7 +18,12 @@
     is: 'gr-diff-selection',
 
     properties: {
+      diff: Object,
       _cachedDiffBuilder: Object,
+      _linesCache: {
+        type: Object,
+        value: function() { return {left: null, right: null}; },
+      },
     },
 
     listeners: {
@@ -56,9 +61,12 @@
     },
 
     _handleCopy: function(e) {
-      if (!e.target.classList.contains('contentText') &&
-          !e.target.classList.contains('gr-syntax')) {
-        return;
+      var el = e.target;
+      while (!el.classList.contains('content')) {
+        if (!el.parentElement) {
+          return;
+        }
+        el = el.parentElement;
       }
       var lineEl = this.diffBuilder.getLineElByChild(e.target);
       if (!lineEl) {
@@ -76,21 +84,47 @@
         return; // No multi-select support yet.
       }
       var range = sel.getRangeAt(0);
-      var fragment = range.cloneContents();
-      var selector = '.contentText';
-      selector += '[data-side="' + side + '"]';
-      selector += ':not(:empty)';
+      var startLineEl = this.diffBuilder.getLineElByChild(range.startContainer);
+      var endLineEl = this.diffBuilder.getLineElByChild(range.endContainer);
+      var startLineNum = parseInt(startLineEl.getAttribute('data-value'), 10);
+      var endLineNum = parseInt(endLineEl.getAttribute('data-value'), 10);
 
-      var contentEls = Polymer.dom(fragment).querySelectorAll(selector);
-      if (contentEls.length === 0) {
-        return fragment.textContent;
+      return this._getRangeFromDiff(startLineNum, range.startOffset, endLineNum,
+          range.endOffset, side);
+    },
+
+    _getRangeFromDiff: function(startLineNum, startOffset, endLineNum,
+        endOffset, side) {
+      var lines = this._getDiffLines(side).slice(startLineNum - 1, endLineNum);
+      if (lines.length) {
+        lines[0] = lines[0].substring(startOffset);
+        lines[lines.length - 1] = lines[lines.length - 1]
+            .substring(0, endOffset);
+      }
+      return lines.join('\n');
+    },
+
+    _getDiffLines: function(side) {
+      if (this._linesCache[side]) {
+        return this._linesCache[side];
       }
 
-      var text = '';
-      for (var i = 0; i < contentEls.length; i++) {
-        text += contentEls[i].textContent + '\n';
+      var lines = [];
+      var chunk;
+      var key = side === 'left' ? 'a' : 'b';
+      for (var chunkIndex = 0;
+          chunkIndex < this.diff.content.length;
+          chunkIndex++) {
+        chunk = this.diff.content[chunkIndex];
+        if (chunk.ab) {
+          lines = lines.concat(chunk.ab);
+        } else if (chunk[key]) {
+          lines = lines.concat(chunk[key]);
+        }
       }
-      return text;
+
+      this._linesCache[side] = lines;
+      return lines;
     },
   });
 })();

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

@@ -29,31 +29,31 @@ limitations under the License.
     <gr-diff-selection>
       <table class="side-by-side">
         <tr>
-          <td class="lineNum left">1</td>
+          <td class="lineNum left" data-value="1">1</td>
           <td class="content">
             <div class="contentText" data-side="left">ba ba</div>
           </td>
-          <td class="lineNum right">1</td>
+          <td class="lineNum right" data-value="1">1</td>
           <td class="content">
             <div class="contentText" data-side="right">some other text</div>
           </td>
         </tr>
         <tr>
-          <td class="lineNum left">2</td>
+          <td class="lineNum left" data-value="2">2</td>
           <td class="content">
             <div class="contentText" data-side="left">zin</div>
           </td>
-          <td class="lineNum right">2</td>
+          <td class="lineNum right" data-value="2">2</td>
           <td class="content">
             <div class="contentText" data-side="right">more more more</div>
           </td>
         </tr>
         <tr>
-          <td class="lineNum left">2</td>
+          <td class="lineNum left" data-value="3">3</td>
           <td class="content">
             <div class="contentText" data-side="left">ga ga</div>
           </td>
-          <td class="lineNum right">3</td>
+          <td class="lineNum right" data-value="3">3</td>
           <td class="other">
             <div class="contentText" data-side="right">some other text</div>
           </td>
@@ -85,6 +85,22 @@ limitations under the License.
         getLineElByChild: sinon.stub().returns({}),
         getSideByLineEl: sinon.stub(),
       };
+      element.diff = {
+        content: [
+          {
+            a: ['ba ba'],
+            b: ['some other text'],
+          },
+          {
+            a: ['zin'],
+            b: ['more more more'],
+          },
+          {
+            a: ['ga ga'],
+            b: ['some other text'],
+          },
+        ],
+      };
     });
 
     test('applies selected-left on left side click', function() {
@@ -143,13 +159,17 @@ limitations under the License.
     test('copies content correctly', function() {
       element.classList.add('selected-left');
       element.classList.remove('selected-right');
+      // Fetch the line number.
+      element._cachedDiffBuilder.getLineElByChild = function(child) {
+        return child.parentElement.parentElement.previousElementSibling;
+      };
       var selection = window.getSelection();
       var range = document.createRange();
       range.setStart(element.querySelector('div.contentText').firstChild, 3);
       range.setEnd(
           element.querySelectorAll('div.contentText')[4].firstChild, 2);
       selection.addRange(range);
-      assert.equal('ba\nzin\nga\n', element._getSelectedText('left'));
+      assert.equal(element._getSelectedText('left'), 'ba\nzin\nga');
     });
   });
 </script>

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

@@ -155,7 +155,7 @@ limitations under the License.
     <style include="gr-theme-default"></style>
     <div class$="[[_computeContainerClass(_loggedIn, viewMode)]]"
         on-tap="_handleTap">
-      <gr-diff-selection>
+      <gr-diff-selection diff="[[_diff]]">
         <gr-diff-highlight
             id="highlights"
             logged-in="[[_loggedIn]]"