From e871e843655617ae75eb5bb688b42b331f1660e2 Mon Sep 17 00:00:00 2001
From: Andrew Goldstein <andrew-goldstein@users.noreply.github.com>
Date: Thu, 8 Apr 2021 12:50:31 -0600
Subject: [PATCH] [Security Solution] Fixes the `Read Less` button rendering
 below the fold (#96524)

## [Security Solution] Fixes the `Read Less` button rendering below the fold

Fixes issue <https://github.com/elastic/kibana/issues/95295> where the `Read Less` button in the Event Details flyout is rendered below the fold when an event's `message` field is too large, per the `Before` and `After` screenshots below:

### Before

![before](https://user-images.githubusercontent.com/4459398/113962310-aa463e80-97e4-11eb-93f9-f4a90bd250f6.png)

_Before: The `Read Less` button is not visible in the `Event details` flyout above_

### After

![after](https://user-images.githubusercontent.com/4459398/113962433-e9748f80-97e4-11eb-8f46-835eb12ea09d.png)

_After: The `Read Less` button is visible in the `Event details` flyout above_

In the _After_ screenshot above, the long `message` is rendered in a vertically scrollable view that occupies ~ one third of the vertical height of the viewport. The `Read Less` button is visible below the message.

### Desk Testing

Desk tested on a 16" MBP, and at larger desktop resolutions in:

- Chrome `89.0.4389.114`
- Firefox `87.0`
- Safari `14.0.3`
---
 .../components/line_clamp/index.test.tsx      | 163 ++++++++++++++++++
 .../common/components/line_clamp/index.tsx    |  19 +-
 2 files changed, 178 insertions(+), 4 deletions(-)
 create mode 100644 x-pack/plugins/security_solution/public/common/components/line_clamp/index.test.tsx

diff --git a/x-pack/plugins/security_solution/public/common/components/line_clamp/index.test.tsx b/x-pack/plugins/security_solution/public/common/components/line_clamp/index.test.tsx
new file mode 100644
index 0000000000000..a1547940765c9
--- /dev/null
+++ b/x-pack/plugins/security_solution/public/common/components/line_clamp/index.test.tsx
@@ -0,0 +1,163 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+import { mount } from 'enzyme';
+import { repeat } from 'lodash/fp';
+import React from 'react';
+
+import { LineClamp } from '.';
+
+describe('LineClamp', () => {
+  const message = repeat(1000, 'abcdefghij '); // 10 characters, with a trailing space
+
+  describe('no overflow', () => {
+    test('it does NOT render the expanded line clamp when isOverflow is falsy', () => {
+      const wrapper = mount(<LineClamp content={message} />);
+
+      expect(wrapper.find('[data-test-subj="expanded-line-clamp"]').exists()).toBe(false);
+    });
+
+    test('it does NOT render the styled line clamp expanded when isOverflow is falsy', () => {
+      const wrapper = mount(<LineClamp content={message} />);
+
+      expect(wrapper.find('[data-test-subj="styled-line-clamp"]').exists()).toBe(false);
+    });
+
+    test('it renders the default line clamp when isOverflow is falsy', () => {
+      const wrapper = mount(<LineClamp content={message} />);
+
+      expect(wrapper.find('[data-test-subj="default-line-clamp"]').first().text()).toBe(message);
+    });
+
+    test('it does NOT render the `Read More` button when isOverflow is falsy', () => {
+      const wrapper = mount(<LineClamp content={message} />);
+
+      expect(wrapper.find('[data-test-subj="summary-view-readmore"]').exists()).toBe(false);
+    });
+  });
+
+  describe('overflow', () => {
+    const clientHeight = 400;
+    const scrollHeight = clientHeight + 100; // scrollHeight is > clientHeight
+
+    beforeAll(() => {
+      Object.defineProperty(HTMLElement.prototype, 'clientHeight', {
+        configurable: true,
+        value: clientHeight,
+      });
+
+      Object.defineProperty(HTMLElement.prototype, 'scrollHeight', {
+        configurable: true,
+        value: scrollHeight,
+      });
+    });
+
+    test('it does NOT render the expanded line clamp by default when isOverflow is true', () => {
+      const wrapper = mount(<LineClamp content={message} />);
+
+      expect(wrapper.find('[data-test-subj="expanded-line-clamp"]').exists()).toBe(false);
+    });
+
+    test('it renders the styled line clamp when isOverflow is true', () => {
+      const wrapper = mount(<LineClamp content={message} />);
+
+      expect(wrapper.find('[data-test-subj="styled-line-clamp"]').first().text()).toBe(message);
+    });
+
+    test('it does NOT render the default line clamp when isOverflow is true', () => {
+      const wrapper = mount(<LineClamp content={message} />);
+
+      expect(wrapper.find('[data-test-subj="default-line-clamp"]').exists()).toBe(false);
+    });
+
+    test('it renders the `Read More` button with the expected (default) text when isOverflow is true', () => {
+      const wrapper = mount(<LineClamp content={message} />);
+
+      expect(wrapper.find('[data-test-subj="summary-view-readmore"]').first().text()).toBe(
+        'Read More'
+      );
+    });
+
+    describe('clicking the Read More button', () => {
+      test('it displays the `Read Less` button text after the user clicks the `Read More` button when isOverflow is true', () => {
+        const wrapper = mount(<LineClamp content={message} />);
+
+        wrapper.find('[data-test-subj="summary-view-readmore"]').first().simulate('click');
+        wrapper.update();
+
+        expect(wrapper.find('[data-test-subj="summary-view-readmore"]').first().text()).toBe(
+          'Read Less'
+        );
+      });
+
+      test('it renders the expanded content after the user clicks the `Read More` button when isOverflow is true', () => {
+        const wrapper = mount(<LineClamp content={message} />);
+
+        wrapper.find('[data-test-subj="summary-view-readmore"]').first().simulate('click');
+        wrapper.update();
+
+        expect(wrapper.find('[data-test-subj="expanded-line-clamp"]').first().text()).toBe(message);
+      });
+    });
+
+    test('it renders the expanded content with a max-height of one third the view height when isOverflow is true', () => {
+      const wrapper = mount(<LineClamp content={message} />);
+
+      wrapper.find('[data-test-subj="summary-view-readmore"]').first().simulate('click');
+      wrapper.update();
+
+      expect(wrapper.find('[data-test-subj="expanded-line-clamp"]').first()).toHaveStyleRule(
+        'max-height',
+        '33vh'
+      );
+    });
+
+    test('it automatically vertically scrolls the content when isOverflow is true', () => {
+      const wrapper = mount(<LineClamp content={message} />);
+
+      wrapper.find('[data-test-subj="summary-view-readmore"]').first().simulate('click');
+      wrapper.update();
+
+      expect(wrapper.find('[data-test-subj="expanded-line-clamp"]').first()).toHaveStyleRule(
+        'overflow-y',
+        'auto'
+      );
+    });
+
+    test('it does NOT render the styled line clamp after the user clicks the `Read More` button when isOverflow is true', () => {
+      const wrapper = mount(<LineClamp content={message} />);
+
+      wrapper.find('[data-test-subj="summary-view-readmore"]').first().simulate('click');
+      wrapper.update();
+
+      expect(wrapper.find('[data-test-subj="styled-line-clamp"]').exists()).toBe(false);
+    });
+
+    test('it does NOT render the default line clamp after the user clicks the `Read More` button when isOverflow is true', () => {
+      const wrapper = mount(<LineClamp content={message} />);
+
+      wrapper.find('[data-test-subj="summary-view-readmore"]').first().simulate('click');
+      wrapper.update();
+
+      expect(wrapper.find('[data-test-subj="default-line-clamp"]').exists()).toBe(false);
+    });
+
+    test('it once again displays the `Read More` button text after the user clicks the `Read Less` when isOverflow is true', () => {
+      const wrapper = mount(<LineClamp content={message} />);
+
+      wrapper.find('[data-test-subj="summary-view-readmore"]').first().simulate('click');
+      wrapper.update(); // 1st toggle
+
+      wrapper.find('[data-test-subj="summary-view-readmore"]').first().simulate('click');
+      wrapper.update(); // 2nd toggle
+
+      expect(wrapper.find('[data-test-subj="summary-view-readmore"]').first().text()).toBe(
+        'Read More' // after the 2nd toggle, the button once-again says `Read More`
+      );
+    });
+  });
+});
diff --git a/x-pack/plugins/security_solution/public/common/components/line_clamp/index.tsx b/x-pack/plugins/security_solution/public/common/components/line_clamp/index.tsx
index d3bc4c2d50f98..896b0ec5fd8df 100644
--- a/x-pack/plugins/security_solution/public/common/components/line_clamp/index.tsx
+++ b/x-pack/plugins/security_solution/public/common/components/line_clamp/index.tsx
@@ -11,7 +11,7 @@ import styled from 'styled-components';
 import * as i18n from './translations';
 
 const LINE_CLAMP = 3;
-const LINE_CLAMP_HEIGHT = 4.5;
+const LINE_CLAMP_HEIGHT = 5.5;
 
 const StyledLineClamp = styled.div`
   display: -webkit-box;
@@ -28,6 +28,13 @@ const ReadMore = styled(EuiButtonEmpty)`
   }
 `;
 
+const ExpandedContent = styled.div`
+  max-height: 33vh;
+  overflow-wrap: break-word;
+  overflow-x: hidden;
+  overflow-y: auto;
+`;
+
 const LineClampComponent: React.FC<{ content?: string | null }> = ({ content }) => {
   const [isOverflow, setIsOverflow] = useState<boolean | null>(null);
   const [isExpanded, setIsExpanded] = useState<boolean | null>(null);
@@ -60,11 +67,15 @@ const LineClampComponent: React.FC<{ content?: string | null }> = ({ content })
   return (
     <>
       {isExpanded ? (
-        <p>{content}</p>
+        <ExpandedContent data-test-subj="expanded-line-clamp">
+          <p>{content}</p>
+        </ExpandedContent>
       ) : isOverflow == null || isOverflow === true ? (
-        <StyledLineClamp ref={descriptionRef}>{content}</StyledLineClamp>
+        <StyledLineClamp data-test-subj="styled-line-clamp" ref={descriptionRef}>
+          {content}
+        </StyledLineClamp>
       ) : (
-        <EuiText>{content}</EuiText>
+        <EuiText data-test-subj="default-line-clamp">{content}</EuiText>
       )}
       {isOverflow && (
         <ReadMore onClick={toggleReadMore} size="s" data-test-subj="summary-view-readmore">