[8.x] [data usage] add line series for totals (#201038) (#201057)

# Backport

This will backport the following commits from `main` to `8.x`:
- [[data usage] add line series for totals
(#201038)](#201038)

<!--- Backport version: 9.4.3 -->

### Questions ?
Please refer to the [Backport tool
documentation](https://github.com/sqren/backport)

<!--BACKPORT [{"author":{"name":"Sandra
G","email":"[email protected]"},"sourceCommit":{"committedDate":"2024-11-21T00:03:59Z","message":"[data
usage] add line series for totals (#201038)\n\n## Summary\r\n\r\nadd
line series for totals\r\n\r\n<img width=\"2294\" alt=\"Screenshot
2024-11-20 at 3 04
11 PM\"\r\nsrc=\"https://github.com/user-attachments/assets/275214b9-a1c5-45a9-ae1e-d42c4ef31cb9\">\r\n\r\n\r\n###
Checklist\r\n\r\nCheck the PR satisfies following conditions.
\r\n\r\nReviewers should verify this PR satisfies this list as
well.\r\n\r\n- [ ] Any text added follows [EUI's
writing\r\nguidelines](https://elastic.github.io/eui/#/guidelines/writing),
uses\r\nsentence case text and includes
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functional\r\ntests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)\r\nwere
updated or added to match the most common scenarios\r\n- [ ] If a plugin
configuration key changed, check if it needs to be\r\nallowlisted in the
cloud and added to the
[docker\r\nlist](https://github.com/elastic/kibana/blob/main/src/dev/build/tasks/os_packages/docker_generator/resources/base/bin/kibana-docker)\r\n-
[ ] This was checked for breaking HTTP API changes, and any
breaking\r\nchanges have been approved by the breaking-change committee.
The\r\n`release_note:breaking` label should be applied in these
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Test\r\nRunner](https://ci-stats.kibana.dev/trigger_flaky_test_runner/1)
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the appropriate Release Notes section,\r\nand the correct
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the\r\n[guidelines](https://www.elastic.co/guide/en/kibana/master/contributing.html#kibana-release-notes-process)\r\n\r\n###
Identify risks\r\n\r\nDoes this PR introduce any risks? For example,
consider risks like hard\r\nto test bugs, performance regression,
potential of data loss.\r\n\r\nDescribe the risk, its severity, and
mitigation for each identified\r\nrisk. Invite stakeholders and evaluate
how to proceed before merging.\r\n\r\n- [ ] [See some
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\r\n\r\nReviewers should verify this PR satisfies this list as
well.\r\n\r\n- [ ] Any text added follows [EUI's
writing\r\nguidelines](https://elastic.github.io/eui/#/guidelines/writing),
uses\r\nsentence case text and includes
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]\r\n[Documentation](https://www.elastic.co/guide/en/kibana/master/development-documentation.html)\r\nwas
added for features that require explanation or tutorials\r\n- [ ] [Unit
or
functional\r\ntests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)\r\nwere
updated or added to match the most common scenarios\r\n- [ ] If a plugin
configuration key changed, check if it needs to be\r\nallowlisted in the
cloud and added to the
[docker\r\nlist](https://github.com/elastic/kibana/blob/main/src/dev/build/tasks/os_packages/docker_generator/resources/base/bin/kibana-docker)\r\n-
[ ] This was checked for breaking HTTP API changes, and any
breaking\r\nchanges have been approved by the breaking-change committee.
The\r\n`release_note:breaking` label should be applied in these
situations.\r\n- [ ] [Flaky
Test\r\nRunner](https://ci-stats.kibana.dev/trigger_flaky_test_runner/1)
was\r\nused on any tests changed\r\n- [ ] The PR description includes
the appropriate Release Notes section,\r\nand the correct
`release_note:*` label is applied per
the\r\n[guidelines](https://www.elastic.co/guide/en/kibana/master/contributing.html#kibana-release-notes-process)\r\n\r\n###
Identify risks\r\n\r\nDoes this PR introduce any risks? For example,
consider risks like hard\r\nto test bugs, performance regression,
potential of data loss.\r\n\r\nDescribe the risk, its severity, and
mitigation for each identified\r\nrisk. Invite stakeholders and evaluate
how to proceed before merging.\r\n\r\n- [ ] [See some
risk\r\nexamples](https://github.com/elastic/kibana/blob/main/RISK_MATRIX.mdx)\r\n-
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usage] add line series for totals (#201038)\n\n## Summary\r\n\r\nadd
line series for totals\r\n\r\n<img width=\"2294\" alt=\"Screenshot
2024-11-20 at 3 04
11 PM\"\r\nsrc=\"https://github.com/user-attachments/assets/275214b9-a1c5-45a9-ae1e-d42c4ef31cb9\">\r\n\r\n\r\n###
Checklist\r\n\r\nCheck the PR satisfies following conditions.
\r\n\r\nReviewers should verify this PR satisfies this list as
well.\r\n\r\n- [ ] Any text added follows [EUI's
writing\r\nguidelines](https://elastic.github.io/eui/#/guidelines/writing),
uses\r\nsentence case text and includes
[i18n\r\nsupport](https://github.com/elastic/kibana/blob/main/packages/kbn-i18n/README.md)\r\n-
[
]\r\n[Documentation](https://www.elastic.co/guide/en/kibana/master/development-documentation.html)\r\nwas
added for features that require explanation or tutorials\r\n- [ ] [Unit
or
functional\r\ntests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)\r\nwere
updated or added to match the most common scenarios\r\n- [ ] If a plugin
configuration key changed, check if it needs to be\r\nallowlisted in the
cloud and added to the
[docker\r\nlist](https://github.com/elastic/kibana/blob/main/src/dev/build/tasks/os_packages/docker_generator/resources/base/bin/kibana-docker)\r\n-
[ ] This was checked for breaking HTTP API changes, and any
breaking\r\nchanges have been approved by the breaking-change committee.
The\r\n`release_note:breaking` label should be applied in these
situations.\r\n- [ ] [Flaky
Test\r\nRunner](https://ci-stats.kibana.dev/trigger_flaky_test_runner/1)
was\r\nused on any tests changed\r\n- [ ] The PR description includes
the appropriate Release Notes section,\r\nand the correct
`release_note:*` label is applied per
the\r\n[guidelines](https://www.elastic.co/guide/en/kibana/master/contributing.html#kibana-release-notes-process)\r\n\r\n###
Identify risks\r\n\r\nDoes this PR introduce any risks? For example,
consider risks like hard\r\nto test bugs, performance regression,
potential of data loss.\r\n\r\nDescribe the risk, its severity, and
mitigation for each identified\r\nrisk. Invite stakeholders and evaluate
how to proceed before merging.\r\n\r\n- [ ] [See some
risk\r\nexamples](https://github.com/elastic/kibana/blob/main/RISK_MATRIX.mdx)\r\n-
[ ] ...","sha":"d39d0d67a516abd5f4be63577f58c833962f27e6"}}]}]
BACKPORT-->

Co-authored-by: Sandra G <[email protected]>

x-pack/plugins/data_usage/public/app/components/chart_panel.tsx

@@ -16,6 +16,7 @@ import {
   niceTimeFormatter,
   DARK_THEME,
   LIGHT_THEME,
+  LineSeries,
 } from '@elastic/charts';
 import { i18n } from '@kbn/i18n';
 import { LegendAction } from './legend_action';
@@ -59,6 +60,18 @@ export const ChartPanel: React.FC<ChartPanelProps> = ({
     [minTimestamp, maxTimestamp]
   );
 
+  // Calculate the total for each time bucket
+  const totalSeries = useMemo(() => {
+    const totalsMap = new Map<number, number>();
+
+    series.forEach((stream) => {
+      stream.data.forEach((point) => {
+        totalsMap.set(point.x, (totalsMap.get(point.x) || 0) + point.y);
+      });
+    });
+
+    return Array.from(totalsMap.entries()).map(([x, y]) => ({ x, y }));
+  }, [series]);
   const renderLegendAction = useCallback(
     ({ label }: { label: string }) => {
       return (
@@ -87,6 +100,19 @@ export const ChartPanel: React.FC<ChartPanelProps> = ({
             xDomain={{ min: minTimestamp, max: maxTimestamp }}
             legendAction={renderLegendAction}
           />
+          <LineSeries
+            id="Total"
+            name="Total"
+            data={totalSeries}
+            xScaleType={ScaleType.Time}
+            yScaleType={ScaleType.Linear}
+            xAccessor="x"
+            yAccessors={['y']}
+            lineSeriesStyle={{
+              line: { strokeWidth: 2 },
+              point: { visible: 'always', radius: 5 },
+            }}
+          />
           {series.map((stream, streamIdx) => (
             <BarSeries
               key={streamIdx}