fix(popover): update positioning logic to render within body

projects/angular/src/utils/popover/providers/popover-position.service.spec.ts

@@ -394,6 +394,28 @@ export default function (): void {
           expect(handleVerticalAxisTwoViolationsSpy).not.toHaveBeenCalled();
           expect(handleHorizontalAxisTwoViolationsSpy.calls.count()).toEqual(1);
         });
+
+        it('content is rendered within the the body (y >= 0) when AXIS is HORIZONTAL and there is a BOTTOM ViewportViolation', function (this: TestContext) {
+          const bottomLeftViolation: ClrPopoverPosition = {
+            axis: ClrAxis.VERTICAL,
+            side: ClrSide.AFTER,
+            anchor: ClrAlignment.END,
+            content: ClrAlignment.START,
+          };
+
+          // Set the popover content to be as big as the window
+          popoverContent.style.width = '25px';
+          popoverContent.style.height = window.innerHeight + 'px';
+          // Set the anchor element to render at the bottom of the body/window
+          this.eventService.anchorButtonRef.nativeElement.style.bottom = '100%';
+          this.eventService.anchorButtonRef.nativeElement.style.position = 'absolute';
+          this.positionService.position = bottomLeftViolation;
+          document.body.appendChild(popoverContent);
+          const result = this.positionService.alignContent(popoverContent);
+
+          // Verify the yOffset is not a negative value (on the view this would translate to a negative top value).
+          expect(result.yOffset).toBeGreaterThanOrEqual(0);
+        });
       });
 
       describe('handles content realignment', function (this: TestContext) {

projects/angular/src/utils/popover/providers/popover-position.service.ts

@@ -65,12 +65,12 @@ export class ClrPopoverPositionService {
      *
      *   Note, more than 3 viewport violations and there isn't anything we can do to help. Also when there are two
      *   violations, we can't help if the violations are TOP+BOTTOM || LEFT+RIGHT => There is no transformation we
-     *   can make to the postion that will help.
+     *   can make to the position that will help.
      *
      *   Some examples:
      *   There is only one error and Primary axis is VERTICAL
      *   - this.handleVerticalAxisOneViolation has a switch that will use the error sum to apply the correct
-     *   transform to the postion based on the reduction of visibilityViolations.
+     *   transform to the position based on the reduction of visibilityViolations.
      *
      *   There are two errors and Primary axis is HORIZONTAL
      *   - handleHorizontalAxisTwoViolations has a switch that uses the error sum to apply both transforms needed to
@@ -103,6 +103,15 @@ export class ClrPopoverPositionService {
       this.contentOffsets.yOffset += Math.abs(this.currentContentCoords.top);
     }
 
+    /**
+     * This detects the condition where the popover is flipped because it would violate the bottom of the viewport, but flipping it results in the
+     * popover rendering above the top of the body (y coordinate outside the body). In that event, it should be rendered within the body
+     * as much as possible, so this logic sets the top of popover to render touching the top of the body.
+     */
+    if (this.contentOffsets.yOffset + this.currentAnchorCoords.y < 0) {
+      this.contentOffsets.yOffset = 0 - this.currentContentCoords.top;
+    }
+
     return this.contentOffsets;
   }