[Lens] Fix context formula functions (#172710)

## Summary
Fix #170762



https://github.com/elastic/kibana/assets/315764/f5b50ffa-4a03-45ee-bc7a-2f2aca7fa3bd



### Checklist
- [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

---------

Co-authored-by: Kibana Machine <[email protected]>

packages/kbn-es-query/src/expressions/types.ts

@@ -9,6 +9,7 @@
 import { Filter, Query, TimeRange } from '../filters';
 
 export interface ExecutionContextSearch {
+  now?: number;
   filters?: Filter[];
   query?: Query | Query[];
   timeRange?: TimeRange;

packages/kbn-optimizer/limits.yml

@@ -86,7 +86,7 @@ pageLoadAssetSize:
   kibanaUsageCollection: 16463
   kibanaUtils: 79713
   kubernetesSecurity: 77234
-  lens: 39000
+  lens: 41000
   licenseManagement: 41817
   licensing: 29004
   links: 44490

src/plugins/data/common/search/expressions/kibana.test.ts

@@ -20,6 +20,7 @@ describe('interpreter/functions#kibana', () => {
   beforeEach(() => {
     input = { timeRange: { from: '0', to: '1' } };
     search = {
+      now: 0,
       type: 'kibana_context',
       query: { language: 'lucene', query: 'geo.src:US' },
       filters: [

src/plugins/data/common/search/expressions/kibana.ts

@@ -41,6 +41,7 @@ export const kibana: ExpressionFunctionKibana = {
       // TODO: But it shouldn't be need.
       ...input,
       type: 'kibana_context',
+      now: getSearchContext().now ?? Date.now(),
       query: [...toArray(getSearchContext().query), ...toArray((input || {}).query)],
       filters: [...(getSearchContext().filters || []), ...((input || {}).filters || [])],
       timeRange: getSearchContext().timeRange || (input ? input.timeRange : undefined),

src/plugins/expressions/common/expression_functions/specs/index.ts

@@ -17,6 +17,7 @@ export * from './overall_metric';
 export * from './derivative';
 export * from './moving_average';
 export * from './ui_setting';
+export * from './math_column';
 export type { MapColumnArguments } from './map_column';
 export { mapColumn } from './map_column';
 export type { MathArguments, MathInput } from './math';

src/plugins/expressions/common/expression_functions/specs/math_column.ts

@@ -18,12 +18,14 @@ export type MathColumnArguments = MathArguments & {
   copyMetaFrom?: string | null;
 };
 
-export const mathColumn: ExpressionFunctionDefinition<
+export type ExpressionFunctionMathColumn = ExpressionFunctionDefinition<
   'mathColumn',
   Datatable,
   MathColumnArguments,
   Promise<Datatable>
-> = {
+>;
+
+export const mathColumn: ExpressionFunctionMathColumn = {
   name: 'mathColumn',
   type: 'datatable',
   inputTypes: ['datatable'],

src/plugins/expressions/common/expression_functions/types.ts

@@ -20,6 +20,7 @@ import {
   ExpressionFunctionDerivative,
   ExpressionFunctionMovingAverage,
   ExpressionFunctionOverallMetric,
+  ExpressionFunctionMathColumn,
 } from './specs';
 import { ExpressionAstFunction } from '../ast';
 
@@ -132,4 +133,5 @@ export interface ExpressionFunctionDefinitions {
   overall_metric: ExpressionFunctionOverallMetric;
   derivative: ExpressionFunctionDerivative;
   moving_average: ExpressionFunctionMovingAverage;
+  math_column: ExpressionFunctionMathColumn;
 }

x-pack/plugins/lens/common/expressions/formula_context/context_fns.test.ts

@@ -0,0 +1,91 @@
+/*
+ * 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 { ExecutionContext } from '@kbn/expressions-plugin/common';
+import { Adapters } from '@kbn/inspector-plugin/common';
+import { formulaIntervalFn, formulaNowFn, formulaTimeRangeFn } from './context_fns';
+
+describe('interval', () => {
+  it('should return 0 if no time range available', () => {
+    // (not sure if this case is actually possible)
+    const result = formulaIntervalFn.fn(undefined, { targetBars: 100 }, {
+      getSearchContext: () => ({
+        /* no time range */
+      }),
+    } as ExecutionContext<Adapters>);
+    expect(result).toEqual(0);
+  });
+
+  it('should return 0 if no targetBars is passed', () => {
+    const result = formulaIntervalFn.fn(
+      undefined,
+      {
+        /* no targetBars */
+      },
+      {
+        getSearchContext: () => ({
+          timeRange: {
+            from: 'now-15m',
+            to: 'now',
+          },
+        }),
+      } as ExecutionContext<Adapters>
+    );
+    expect(result).toEqual(0);
+  });
+
+  it('should return a valid value > 0 if both timeRange and targetBars is passed', () => {
+    const result = formulaIntervalFn.fn(undefined, { targetBars: 100 }, {
+      getSearchContext: () => ({
+        timeRange: {
+          from: 'now-15m',
+          to: 'now',
+        },
+      }),
+    } as ExecutionContext<Adapters>);
+    expect(result).toEqual(10000);
+  });
+});
+
+describe('time range', () => {
+  it('should return 0 if no time range is available', () => {
+    // (not sure if this case is actually possible)
+    const result = formulaTimeRangeFn.fn(undefined, {}, {
+      getSearchContext: () => ({
+        /* no time range */
+      }),
+    } as ExecutionContext<Adapters>);
+    expect(result).toEqual(0);
+  });
+
+  it('should return a valid value > 0 if time range is available', () => {
+    const result = formulaTimeRangeFn.fn(undefined, {}, {
+      getSearchContext: () => ({
+        timeRange: {
+          from: 'now-15m',
+          to: 'now',
+        },
+        now: 1000000, // important to provide this to make the result consistent
+      }),
+    } as ExecutionContext<Adapters>);
+
+    expect(result).toBe(900000);
+  });
+});
+
+describe('now', () => {
+  it('should return the now value when passed', () => {
+    const now = 123456789;
+    expect(
+      formulaNowFn.fn(undefined, {}, {
+        getSearchContext: () => ({
+          now,
+        }),
+      } as ExecutionContext<Adapters>)
+    ).toEqual(now);
+  });
+});

x-pack/plugins/lens/common/expressions/formula_context/context_fns.ts

@@ -0,0 +1,97 @@
+/*
+ * 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 { getAbsoluteTimeRange, calcAutoIntervalNear } from '@kbn/data-plugin/common';
+import type { TimeRange } from '@kbn/es-query';
+import type { ExpressionFunctionDefinition } from '@kbn/expressions-plugin/common';
+import moment from 'moment';
+import { i18n } from '@kbn/i18n';
+
+export type ExpressionFunctionFormulaTimeRange = ExpressionFunctionDefinition<
+  'formula_time_range',
+  undefined,
+  object,
+  number
+>;
+
+const getTimeRangeAsNumber = (timeRange: TimeRange | undefined, now: number | undefined) => {
+  if (!timeRange) return 0;
+  const absoluteTimeRange = getAbsoluteTimeRange(
+    timeRange,
+    now != null ? { forceNow: new Date(now) } : {}
+  );
+  return timeRange ? moment(absoluteTimeRange.to).diff(moment(absoluteTimeRange.from)) : 0;
+};
+
+export const formulaTimeRangeFn: ExpressionFunctionFormulaTimeRange = {
+  name: 'formula_time_range',
+
+  help: i18n.translate('xpack.lens.formula.timeRange.help', {
+    defaultMessage: 'The specified time range, in milliseconds (ms).',
+  }),
+
+  args: {},
+
+  fn(_input, _args, { getSearchContext }) {
+    const { timeRange, now } = getSearchContext();
+    return getTimeRangeAsNumber(timeRange, now);
+  },
+};
+
+export type ExpressionFunctionFormulaInterval = ExpressionFunctionDefinition<
+  'formula_interval',
+  undefined,
+  {
+    targetBars?: number;
+  },
+  number
+>;
+
+export const formulaIntervalFn: ExpressionFunctionFormulaInterval = {
+  name: 'formula_interval',
+
+  help: i18n.translate('xpack.lens.formula.interval.help', {
+    defaultMessage: 'The specified minimum interval for the date histogram, in milliseconds (ms).',
+  }),
+
+  args: {
+    targetBars: {
+      types: ['number'],
+      help: i18n.translate('xpack.lens.formula.interval.targetBars.help', {
+        defaultMessage: 'The target number of bars for the date histogram.',
+      }),
+    },
+  },
+
+  fn(_input, args, { getSearchContext }) {
+    const { timeRange, now } = getSearchContext();
+    return timeRange && args.targetBars
+      ? calcAutoIntervalNear(args.targetBars, getTimeRangeAsNumber(timeRange, now)).asMilliseconds()
+      : 0;
+  },
+};
+
+export type ExpressionFunctionFormulaNow = ExpressionFunctionDefinition<
+  'formula_now',
+  undefined,
+  object,
+  number
+>;
+
+export const formulaNowFn: ExpressionFunctionFormulaNow = {
+  name: 'formula_now',
+
+  help: i18n.translate('xpack.lens.formula.now.help', {
+    defaultMessage: 'The current now moment used in Kibana expressed in milliseconds (ms).',
+  }),
+
+  args: {},
+
+  fn(_input, _args, { getSearchContext }) {
+    return getSearchContext().now ?? Date.now();
+  },
+};

x-pack/plugins/lens/common/expressions/formula_context/index.ts

@@ -0,0 +1,8 @@
+/*
+ * 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.
+ */
+
+export * from './context_fns';

x-pack/plugins/lens/common/expressions/index.ts

@@ -11,3 +11,4 @@ export * from './format_column';
 export * from './map_to_columns';
 export * from './time_scale';
 export * from './datatable';
+export * from './formula_context';