[ES|QL] Adds the ability to breakdown the histogram in Discover (elas…

…tic#193820)

## Summary

Part of elastic#186369

It enables the users to breakdown the histogram visualization in
Discover.


![meow](https://github.com/user-attachments/assets/d5fdaa41-0a69-4caf-9da2-1221dcfd5ce2)


### Checklist

- [x] Any text added follows [EUI's writing
guidelines](https://elastic.github.io/eui/#/guidelines/writing), uses
sentence case text and includes [i18n
support](https://github.com/elastic/kibana/blob/main/packages/kbn-i18n/README.md)
- [x] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios
- [x] [Flaky Test
Runner](https://ci-stats.kibana.dev/trigger_flaky_test_runner/1) was
used on any tests changed
- [x] Any UI touched in this PR is usable by keyboard only (learn more
about [keyboard accessibility](https://webaim.org/techniques/keyboard/))
- [x] Any UI touched in this PR does not create any new axe failures
(run axe in browser:
[FF](https://addons.mozilla.org/en-US/firefox/addon/axe-devtools/),
[Chrome](https://chrome.google.com/webstore/detail/axe-web-accessibility-tes/lhdoppojpmngadmnindnejefpokejbdd?hl=en-US))
- [x] This renders correctly on smaller devices using a responsive
layout. (You can test this [in your
browser](https://www.browserstack.com/guide/responsive-testing-on-local-server))
- [x] This was checked for [cross-browser
compatibility](https://www.elastic.co/support/matrix#matrix_browsers)

---------

Co-authored-by: kibanamachine <42973632+kibanamachine@users.noreply.github.com>

src/plugins/unified_histogram/public/chart/breakdown_field_selector.test.tsx

@@ -9,12 +9,15 @@
 
 import { render, act, screen } from '@testing-library/react';
 import React from 'react';
+import type { DatatableColumn } from '@kbn/expressions-plugin/common';
+import { convertDatatableColumnToDataViewFieldSpec } from '@kbn/data-view-utils';
+import { DataViewField } from '@kbn/data-views-plugin/common';
 import { UnifiedHistogramBreakdownContext } from '../types';
 import { dataViewWithTimefieldMock } from '../__mocks__/data_view_with_timefield';
 import { BreakdownFieldSelector } from './breakdown_field_selector';
 
 describe('BreakdownFieldSelector', () => {
-  it('should render correctly', () => {
+  it('should render correctly for dataview fields', () => {
     const onBreakdownFieldChange = jest.fn();
     const breakdown: UnifiedHistogramBreakdownContext = {
       field: undefined,
@@ -63,6 +66,67 @@ describe('BreakdownFieldSelector', () => {
     `);
   });
 
+  it('should render correctly for ES|QL columns', () => {
+    const onBreakdownFieldChange = jest.fn();
+    const breakdown: UnifiedHistogramBreakdownContext = {
+      field: undefined,
+    };
+
+    render(
+      <BreakdownFieldSelector
+        dataView={dataViewWithTimefieldMock}
+        breakdown={breakdown}
+        onBreakdownFieldChange={onBreakdownFieldChange}
+        esqlColumns={[
+          {
+            name: 'bytes',
+            meta: { type: 'number' },
+            id: 'bytes',
+          },
+          {
+            name: 'extension',
+            meta: { type: 'string' },
+            id: 'extension',
+          },
+        ]}
+      />
+    );
+
+    const button = screen.getByTestId('unifiedHistogramBreakdownSelectorButton');
+    expect(button.getAttribute('data-selected-value')).toBe(null);
+
+    act(() => {
+      button.click();
+    });
+
+    const options = screen.getAllByRole('option');
+    expect(
+      options.map((option) => ({
+        label: option.getAttribute('title'),
+        value: option.getAttribute('value'),
+        checked: option.getAttribute('aria-checked'),
+      }))
+    ).toMatchInlineSnapshot(`
+      Array [
+        Object {
+          "checked": "true",
+          "label": "No breakdown",
+          "value": "__EMPTY_SELECTOR_OPTION__",
+        },
+        Object {
+          "checked": "false",
+          "label": "bytes",
+          "value": "bytes",
+        },
+        Object {
+          "checked": "false",
+          "label": "extension",
+          "value": "extension",
+        },
+      ]
+    `);
+  });
+
   it('should mark the option as checked if breakdown.field is defined', () => {
     const onBreakdownFieldChange = jest.fn();
     const field = dataViewWithTimefieldMock.fields.find((f) => f.name === 'extension')!;
@@ -111,7 +175,7 @@ describe('BreakdownFieldSelector', () => {
     `);
   });
 
-  it('should call onBreakdownFieldChange with the selected field when the user selects a field', () => {
+  it('should call onBreakdownFieldChange with the selected field when the user selects a dataview field', () => {
     const onBreakdownFieldChange = jest.fn();
     const selectedField = dataViewWithTimefieldMock.fields.find((f) => f.name === 'bytes')!;
     const breakdown: UnifiedHistogramBreakdownContext = {
@@ -135,4 +199,45 @@ describe('BreakdownFieldSelector', () => {
 
     expect(onBreakdownFieldChange).toHaveBeenCalledWith(selectedField);
   });
+
+  it('should call onBreakdownFieldChange with the selected field when the user selects an ES|QL field', () => {
+    const onBreakdownFieldChange = jest.fn();
+    const esqlColumns = [
+      {
+        name: 'bytes',
+        meta: { type: 'number' },
+        id: 'bytes',
+      },
+      {
+        name: 'extension',
+        meta: { type: 'string' },
+        id: 'extension',
+      },
+    ] as DatatableColumn[];
+    const breakdownColumn = esqlColumns.find((c) => c.name === 'bytes')!;
+    const selectedField = new DataViewField(
+      convertDatatableColumnToDataViewFieldSpec(breakdownColumn)
+    );
+    const breakdown: UnifiedHistogramBreakdownContext = {
+      field: undefined,
+    };
+    render(
+      <BreakdownFieldSelector
+        dataView={dataViewWithTimefieldMock}
+        breakdown={breakdown}
+        onBreakdownFieldChange={onBreakdownFieldChange}
+        esqlColumns={esqlColumns}
+      />
+    );
+
+    act(() => {
+      screen.getByTestId('unifiedHistogramBreakdownSelectorButton').click();
+    });
+
+    act(() => {
+      screen.getByTitle('bytes').click();
+    });
+
+    expect(onBreakdownFieldChange).toHaveBeenCalledWith(selectedField);
+  });
 });

src/plugins/unified_histogram/public/chart/breakdown_field_selector.tsx

@@ -11,7 +11,9 @@ import React, { useCallback, useMemo } from 'react';
 import { EuiSelectableOption } from '@elastic/eui';
 import { FieldIcon, getFieldIconProps, comboBoxFieldOptionMatcher } from '@kbn/field-utils';
 import { css } from '@emotion/react';
-import type { DataView, DataViewField } from '@kbn/data-views-plugin/common';
+import { type DataView, DataViewField } from '@kbn/data-views-plugin/common';
+import type { DatatableColumn } from '@kbn/expressions-plugin/common';
+import { convertDatatableColumnToDataViewFieldSpec } from '@kbn/data-view-utils';
 import { i18n } from '@kbn/i18n';
 import { UnifiedHistogramBreakdownContext } from '../types';
 import { fieldSupportsBreakdown } from '../utils/field_supports_breakdown';
@@ -25,17 +27,32 @@ import {
 export interface BreakdownFieldSelectorProps {
   dataView: DataView;
   breakdown: UnifiedHistogramBreakdownContext;
+  esqlColumns?: DatatableColumn[];
   onBreakdownFieldChange?: (breakdownField: DataViewField | undefined) => void;
 }
 
+const mapToDropdownFields = (dataView: DataView, esqlColumns?: DatatableColumn[]) => {
+  if (esqlColumns) {
+    return (
+      esqlColumns
+        .map((column) => new DataViewField(convertDatatableColumnToDataViewFieldSpec(column)))
+        // filter out unsupported field types
+        .filter((field) => field.type !== 'unknown')
+    );
+  }
+
+  return dataView.fields.filter(fieldSupportsBreakdown);
+};
+
 export const BreakdownFieldSelector = ({
   dataView,
   breakdown,
+  esqlColumns,
   onBreakdownFieldChange,
 }: BreakdownFieldSelectorProps) => {
+  const fields = useMemo(() => mapToDropdownFields(dataView, esqlColumns), [dataView, esqlColumns]);
   const fieldOptions: SelectableEntry[] = useMemo(() => {
-    const options: SelectableEntry[] = dataView.fields
-      .filter(fieldSupportsBreakdown)
+    const options: SelectableEntry[] = fields
       .map((field) => ({
         key: field.name,
         name: field.name,
@@ -69,16 +86,16 @@ export const BreakdownFieldSelector = ({
     });
 
     return options;
-  }, [dataView, breakdown.field]);
+  }, [fields, breakdown?.field]);
 
   const onChange = useCallback<NonNullable<ToolbarSelectorProps['onChange']>>(
     (chosenOption) => {
-      const field = chosenOption?.value
-        ? dataView.fields.find((currentField) => currentField.name === chosenOption.value)
+      const breakdownField = chosenOption?.value
+        ? fields.find((currentField) => currentField.name === chosenOption.value)
         : undefined;
-      onBreakdownFieldChange?.(field);
+      onBreakdownFieldChange?.(breakdownField);
     },
-    [dataView.fields, onBreakdownFieldChange]
+    [fields, onBreakdownFieldChange]
   );
 
   return (

src/plugins/unified_histogram/public/chart/chart.tsx

@@ -19,6 +19,7 @@ import type {
   LensEmbeddableInput,
   LensEmbeddableOutput,
 } from '@kbn/lens-plugin/public';
+import type { DatatableColumn } from '@kbn/expressions-plugin/common';
 import type { DataView, DataViewField } from '@kbn/data-views-plugin/public';
 import type { TimeRange } from '@kbn/es-query';
 import { Histogram } from './histogram';
@@ -79,6 +80,7 @@ export interface ChartProps {
   onFilter?: LensEmbeddableInput['onFilter'];
   onBrushEnd?: LensEmbeddableInput['onBrushEnd'];
   withDefaultActions: EmbeddableComponentProps['withDefaultActions'];
+  columns?: DatatableColumn[];
 }
 
 const HistogramMemoized = memo(Histogram);
@@ -114,6 +116,7 @@ export function Chart({
   onBrushEnd,
   withDefaultActions,
   abortController,
+  columns,
 }: ChartProps) {
   const lensVisServiceCurrentSuggestionContext = useObservable(
     lensVisService.currentSuggestionContext$
@@ -312,6 +315,7 @@ export function Chart({
                       dataView={dataView}
                       breakdown={breakdown}
                       onBreakdownFieldChange={onBreakdownFieldChange}
+                      esqlColumns={isPlainRecord ? columns : undefined}
                     />
                   )}
                 </div>

src/plugins/unified_histogram/public/container/container.tsx

@@ -147,6 +147,7 @@ export const UnifiedHistogramContainer = forwardRef<
     query,
     searchSessionId,
     requestAdapter,
+    columns: containerProps.columns,
   });
 
   const handleVisContextChange: UnifiedHistogramLayoutProps['onVisContextChanged'] | undefined =