[ES|QL] Supports TS agg functions (elastic#226539)

## Summary

Closes elastic#220730

Supports of TS inner agg functions.

1. Retrieves the functions and the docs from
elastic/elasticsearch#130290
2. Suggest them only when an agg is already selected and only if the
source command is TS


![meow](https://github.com/user-attachments/assets/9143ff0d-c5ab-4e93-a802-3e535dbc5121)


Atm you won't see any changes in the editor. You can test it though if
you change the
`src/platform/packages/shared/kbn-esql-validation-autocomplete/src/definitions/generated/time_series_agg_functions.ts`
`ignoreAsSuggestion` flags to false.

### Checklist

- [ ] 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/src/platform/packages/shared/kbn-i18n/README.md)
- [ ]
[Documentation](https://www.elastic.co/guide/en/kibana/master/development-documentation.html)
was added for features that require explanation or tutorials
- [ ] [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: Vadim Kibana <[email protected]>

Author: 2 people

src/platform/packages/private/kbn-language-documentation/scripts/generate_esql_docs.ts

@@ -20,7 +20,6 @@ interface DocsSectionContent {
 
 (function () {
   const pathToElasticsearch = process.argv[2];
-
   if (!pathToElasticsearch) {
     throw new Error('Path to Elasticsearch must be provided as the first argument.');
   }
@@ -29,6 +28,10 @@ interface DocsSectionContent {
   const functionTypes = [
     { fnType: 'scalar', outputFile: '../src/sections/generated/scalar_functions.tsx' },
     { fnType: 'agg', outputFile: '../src/sections/generated/aggregation_functions.tsx' },
+    {
+      fnType: 'time_series_agg',
+      outputFile: '../src/sections/generated/timeseries_aggregation_functions.tsx',
+    },
     { fnType: 'grouping', outputFile: '../src/sections/generated/grouping_functions.tsx' },
     { fnType: 'operator', outputFile: '../src/sections/generated/operators.tsx' },
   ];

src/platform/packages/private/kbn-language-documentation/src/sections/esql_documentation_sections.tsx

@@ -795,5 +795,6 @@ Refer to **Operators** for an overview of the supported operators.
 
 export { functions as scalarFunctions } from './generated/scalar_functions';
 export { functions as aggregationFunctions } from './generated/aggregation_functions';
+export { functions as timeseriesAggregationFunctions } from './generated/timeseries_aggregation_functions';
 export { functions as groupingFunctions } from './generated/grouping_functions';
 export { functions as operators } from './generated/operators';

src/platform/packages/private/kbn-language-documentation/src/sections/generated/timeseries_aggregation_functions.tsx

@@ -0,0 +1,25 @@
+/*
+ * 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", the "GNU Affero General Public License v3.0 only", and the "Server Side
+ * Public License v 1"; you may not use this file except in compliance with, at
+ * your election, the "Elastic License 2.0", the "GNU Affero General Public
+ * License v3.0 only", or the "Server Side Public License, v 1".
+ */
+
+import { i18n } from '@kbn/i18n';
+
+// DO NOT RENAME!
+export const functions = {
+  label: i18n.translate('languageDocumentation.documentationESQL.timeseriesAggregationFunctions', {
+    defaultMessage: 'Timeseries aggregation functions',
+  }),
+  description: i18n.translate(
+    'languageDocumentation.documentationESQL.timeseriesAggregationFunctionsDocumentationESQLDescription',
+    {
+      defaultMessage: `These functions can by used with STATS ...BY when a TS command is used:`,
+    }
+  ),
+  // items are managed by scripts/generate_esql_docs.ts
+  items: [],
+};

src/platform/packages/shared/kbn-esql-ast/index.ts

@@ -11,7 +11,6 @@ export type {
   ESQLAst,
   ESQLAstItem,
   ESQLAstCommand,
-  ESQLAstTimeseriesCommand,
   ESQLAstJoinCommand,
   ESQLCommand,
   ESQLCommandOption,

src/platform/packages/shared/kbn-esql-ast/scripts/generate_function_definitions.ts

@@ -49,6 +49,10 @@ function getFunctionDefinition(ESFunctionDefinition: Record<string, any>): Funct
   if (FULL_TEXT_SEARCH_FUNCTIONS.includes(ESFunctionDefinition.name)) {
     locationsAvailable = [Location.WHERE, Location.STATS_WHERE];
   }
+
+  if (ESFunctionDefinition.type === FunctionDefinitionTypes.TIME_SERIES_AGG) {
+    locationsAvailable = [Location.STATS_TIMESERIES];
+  }
   const ret = {
     type: ESFunctionDefinition.type,
     name: ESFunctionDefinition.name,
@@ -356,7 +360,7 @@ ${
     .join('\n\n');
 
   const fileContents = `${fileHeader}${functionDefinitionsString}
-  export const ${functionsType}FunctionDefinitions = [${functionDefinitions
+  export const ${_.camelCase(functionsType)}FunctionDefinitions = [${functionDefinitions
     .map(({ name }) => getDefinitionName(name))
     .join(',\n')}];`;
 
@@ -418,6 +422,7 @@ export const esqlFunctionNames = ${JSON.stringify(functionNames, null, 2)};
 
   const scalarFunctionDefinitions: FunctionDefinition[] = [];
   const aggFunctionDefinitions: FunctionDefinition[] = [];
+  const timeSeriesFunctionDefinitions: FunctionDefinition[] = [];
   const operatorDefinitions: FunctionDefinition[] = [];
   const groupingFunctionDefinitions: FunctionDefinition[] = [];
 
@@ -449,6 +454,8 @@ export const esqlFunctionNames = ${JSON.stringify(functionNames, null, 2)};
       aggFunctionDefinitions.push(functionDefinition);
     } else if (functionDefinition.type === FunctionDefinitionTypes.GROUPING) {
       groupingFunctionDefinitions.push(functionDefinition);
+    } else if (functionDefinition.type === FunctionDefinitionTypes.TIME_SERIES_AGG) {
+      timeSeriesFunctionDefinitions.push(functionDefinition);
     }
   }
 
@@ -462,6 +469,13 @@ export const esqlFunctionNames = ${JSON.stringify(functionNames, null, 2)};
     join(__dirname, '../src/definitions/generated/aggregation_functions.ts'),
     printGeneratedFunctionsFile(aggFunctionDefinitions, FunctionDefinitionTypes.AGG)
   );
+  await writeFile(
+    join(__dirname, '../src/definitions/generated/time_series_agg_functions.ts'),
+    printGeneratedFunctionsFile(
+      timeSeriesFunctionDefinitions,
+      FunctionDefinitionTypes.TIME_SERIES_AGG
+    )
+  );
   await writeFile(
     join(__dirname, '../src/definitions/generated/operators.ts'),
     printGeneratedFunctionsFile(

src/platform/packages/shared/kbn-esql-ast/src/commands_registry/types.ts

@@ -182,6 +182,11 @@ export enum Location {
    */
   STATS_WHERE = 'stats_where',
 
+  /**
+   * WHEN TS is used as a source command, inner STATS functions
+   */
+  STATS_TIMESERIES = 'stats_timeseries',
+
   /**
    * Top-level ENRICH command
    */