[ML] DF Analytics: Collapsable sections on results pages (elastic#76641)

- Fixes cell color coding based on influence score for outlier detection results page data grid. (Part of elastic#77046)
- Introduces expandable sections (<ExpandableSection />). In contrast to plain accordions, the main idea of this component is that it should also provide some sort of useful summary when collapsed instead of just being an expandable title. For example, the "Analysis" section is collapsed by default, but still offers information like analysis type, source and destination index. This concept should allow us to keep the analytics results pages usable with more content (additional results, evaluations, visualizations) being added over time.
- The "Analysis" section is a reuse of the expandable row from the analytics jobs list. Some design adjustments have been made to make it usable in both places.

x-pack/plugins/ml/public/application/components/color_range_legend/color_range_legend.tsx

@@ -7,7 +7,7 @@
 import React, { useEffect, useRef, FC } from 'react';
 import d3 from 'd3';
 
-import { EuiFlexGroup, EuiFlexItem, EuiText } from '@elastic/eui';
+import { EuiText } from '@elastic/eui';
 
 const COLOR_RANGE_RESOLUTION = 10;
 
@@ -134,15 +134,11 @@ export const ColorRangeLegend: FC<ColorRangeLegendProps> = ({
   }
 
   return (
-    <EuiFlexGroup gutterSize="s">
-      <EuiFlexItem grow={false}>
-        <EuiText size="xs">
-          <strong>{title}</strong>
-        </EuiText>
-      </EuiFlexItem>
-      <EuiFlexItem grow={false}>
-        <svg ref={d3Container} />
-      </EuiFlexItem>
-    </EuiFlexGroup>
+    <>
+      <EuiText size="xs" color="subdued">
+        <p>{title}</p>
+      </EuiText>
+      <svg ref={d3Container} />
+    </>
   );
 };

x-pack/plugins/ml/public/application/data_frame_analytics/common/fields.ts

@@ -48,6 +48,8 @@ export const EXTENDED_NUMERICAL_TYPES = new Set([
 
 // eslint-disable-next-line @typescript-eslint/naming-convention
 export const ML__ID_COPY = 'ml__id_copy';
+// eslint-disable-next-line @typescript-eslint/naming-convention
+export const ML__INCREMENTAL_ID = 'ml__incremental_id';
 
 export const isKeywordAndTextType = (fieldName: string): boolean => {
   const { fields } = newJobCapsService;

x-pack/plugins/ml/public/application/data_frame_analytics/pages/analytics_exploration/components/expandable_section/expandable_section.scss

@@ -0,0 +1,3 @@
+.mlExpandableSection {
+  padding: 0 $euiSizeS $euiSizeS $euiSizeS;
+}

x-pack/plugins/ml/public/application/data_frame_analytics/pages/analytics_exploration/components/expandable_section/expandable_section.tsx

@@ -0,0 +1,94 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+
+import './expandable_section.scss';
+
+import React, { useState, FC, ReactNode } from 'react';
+
+import {
+  EuiBadge,
+  EuiButtonEmpty,
+  EuiFlexGroup,
+  EuiFlexItem,
+  EuiLoadingContent,
+  EuiPanel,
+  EuiText,
+} from '@elastic/eui';
+
+interface HeaderItem {
+  // id is used as the React key and to construct a data-test-subj
+  id: string;
+  label?: ReactNode;
+  value: ReactNode;
+}
+
+const isHeaderItems = (arg: any): arg is HeaderItem[] => {
+  return Array.isArray(arg);
+};
+
+export interface ExpandableSectionProps {
+  content: ReactNode;
+  headerItems?: HeaderItem[] | 'loading';
+  isExpanded?: boolean;
+  dataTestId: string;
+  title: ReactNode;
+}
+
+export const ExpandableSection: FC<ExpandableSectionProps> = ({
+  headerItems,
+  // For now we don't have a need for complete external control
+  // and just want to pass in a default value. If we wanted
+  // full external control we'd also need to add a onToggleExpanded()
+  // callback.
+  isExpanded: isExpandedDefault = true,
+  content,
+  dataTestId,
+  title,
+}) => {
+  const [isExpanded, setIsExpanded] = useState(isExpandedDefault);
+  const toggleExpanded = () => {
+    setIsExpanded(!isExpanded);
+  };
+
+  return (
+    <EuiPanel paddingSize="none" data-test-subj={`mlDFExpandableSection-${dataTestId}`}>
+      <div className="mlExpandableSection">
+        <EuiButtonEmpty
+          onClick={toggleExpanded}
+          iconType={isExpanded ? 'arrowUp' : 'arrowDown'}
+          size="l"
+          iconSide="right"
+          flush="left"
+        >
+          {title}
+        </EuiButtonEmpty>
+        {headerItems === 'loading' && <EuiLoadingContent lines={1} />}
+        {isHeaderItems(headerItems) && (
+          <EuiFlexGroup>
+            {headerItems.map(({ label, value, id }) => (
+              <EuiFlexItem
+                grow={false}
+                key={id}
+                data-test-subj={`mlDFExpandableSectionItem-${dataTestId}-${id}`}
+              >
+                {label !== undefined && value !== undefined && (
+                  <>
+                    <EuiText size="xs" color="subdued">
+                      <p>{label}</p>
+                    </EuiText>
+                    <EuiBadge>{value}</EuiBadge>
+                  </>
+                )}
+                {label === undefined && value}
+              </EuiFlexItem>
+            ))}
+          </EuiFlexGroup>
+        )}
+      </div>
+      {isExpanded && content}
+    </EuiPanel>
+  );
+};

x-pack/plugins/ml/public/application/data_frame_analytics/pages/analytics_exploration/components/expandable_section/index.ts

@@ -0,0 +1,7 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+
+export { ExpandableSection, ExpandableSectionProps } from './expandable_section';